Free Amended Complaint - District Court of Colorado - Colorado

Case 1:03-cv-02579-RPM

Document 89-3

IIIII IIIIIIII III IIIII IIIII IIIII IIIII IIII US005474142A
[11] Patent Number: [45] Date of Patent: 5,474,142 Dee. 12, 1995

Filed 05/01/2006

Page 1 of 23

United States Patent
Bowden
[54] AUTOMATIC DRILLING SYSTEM

[19]

[76] Inventor: Bobbie J. Bowden, 621 St. Louis St., Gonzaies, Tex. 78629 [21] [22] Appl. No.: 50,527 Filed: Apr. 19, 1993

Assistant Examiner--Frank S. Tsay Attorney, Agent, or Firm--Donald R. Comuzzi; Christopher L. Makay

[57]

ABSTRACT

[51] Int. Clo6 ...................................................... E21B 19/08 [52] U.S. CI ............................... 175/27; 175/162; 175/57; 73/732; 73/790 [58] Field of Search .................................. 175/24, 27, 52, 175/57, 162; 73/732, 790 [56] References Cited U.S. PATENT DOCUMENTS 4,165,789 8/1979 Rogers ...................................... 175/24 4,491,186 1/1985 Alder ........................................ 175/27 4,606,415 8/1986 Gray, Jr. et al ........................... 175/24 4,639,868 1/1987 Tanaka et al ......................... 175/24 X 4,662,608 5/1987 Ball ........................................... 175/27 4,793,421 12/1988 Jasinski ..................................... 175/27 4,875,530 10/1989 Frink et al ................................ 175127 OTHER PUBLICATIONS Petroleum Engineering, Carl Gatlin, Printice-Hall, 1960, pp. 114-132. Primary Examiner--Ramon S. Britts

An automatic drilling system regulates the drill string of a drilling rig in response to any one of, any combination of, or all of drilling fluid pressure, bit weight, drill string torque, and drill string RPM to achieve an optimal rate of bit penetration. The automatic drilling system includes a drilling fluid pressure sensor, a bit weight sensor, a drill string torque sensor, and a drill string RPM sensor which deliver a drilling fluid pressure signal, a bit weight signal, a drill string torque signal, and a drill string RPM signal to a drilling fluid pressure regulator, a bit weight regulator, a drill string torque regulator, and a drill string RPM regulator. The regulators control a drill string controller in response to the above signals so that it manipulates the drilling rig to release the drill string at a rate which maintains the maximum rate of bit penetration.

15 Claims, 8 Drawing Sheets
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AUTOMATIC DRILLING SYSTEM

2

a drilling fluid pressure regulator, a bit weight regulator, a drill string torque regulator, and a drill string RPM regulator, BACKGROUND OF THE INVENTION respectively. The regulators receive their respective signals to measure The present invention relates to automatic drilling syschanges in those signals and produce an output signal tems and, more particularly, but not by way of limitation, to representative of any changes. Specifically, the drilling fluid an automatic drifling system that controls the release of a pressure regulator measures changes in drilling fluid presdrill string in vertical, directional, and horizonal drilling sure and outputs a signal representing those changes. The bit operations in response to any one of or any combination of weight regulator measures changes in bit weight and outputs bit weight, drilling fluid pressure, dri11 string torque, and 10 a signal representing those changes. The drill string torque drill string RPM. regulator measures changes in drill string torque and output a signal representing those changes. The drill string RPM DESCRIPTION OF THE RELATED ART regulator measures changes in drill string RPM and outputs a signal representing those changes. Typical automatic drillers presently control the drill string using only bit weight. Such drillers throttle the brake handle 15 Each of the regulators attaches to a relay which is responsive to that regulators output signal to supply a drill string of the cable drum brake in response to decreases in bit control signal to a drill string controller. The relays connect weight to release the drill string support cable and, thus, in series so that all the regulators may be utilized concurlower the drill string. The lowering of the drill string places rently to provide a drill string control signal to the drill string additional weight of the drill string on top of the drill bit in order to increase bit weight back to its desired value. A 20 controller via their respective relays. Furthermore, the relays attach to relay selectors which switch the relays on and off driller operator enters a desired bit weight value into the to permit an operator of the automatic driller to select which automatic driller which then compares the desired value to one of or which combination of the regulators are to control the actual bit weight measured by a weight indicator. As long the drilling operation. as the actual bit weight remains within the tolerance of the desired bit weight, the cable drum brake remains engaged, 25 The drill string controller attaches to the relays to receive a drill string control signal from the regulator or regulators and the drill string support cable supports the drill string at its present level. However, once the weight indicator meacontrolling the drilling operation. Illustratively, when the sures a bit weight that falls outside the desired bit weight relay connected to the drilling fluid pressure regulator receives a decrease in drilling fluid pressure signal, it entered into the automatic drifler by the drilling rig operator, the automatic driller manipulates the brake handle to release 30 supplies a drill string control signal that operates the drill string controller to effect an increase in the rate of release of the cable drum brake which lowers the drill string cable, the drill string. Conversely, an increase in drilling fluid thereby placing more weight of the drill string upon the drill pressure results in the relay supplying a drill string control bit. The cable drum brake remains released until the weight signal that operates the drill string controller to effect a indicator provides a signal to the automatic driller which 35 decrease in the rate of release of the drill string. substantially equals the desired bit weight. If, however, the relay connected to the bit weight reguAlthough bit weight automatic drillers function lator receives a decrease in bit weight signal, it supplies a adequately for completely vertical boreholes, they cease to drill string control signal that operates the drill string conoperate properly for any type of directional or horizontal troller to effect an increase in the rate of release of the drill drilling operations. Specifically, once the borehole deviates from vertical, the weight indicator, which typically mounts 4o string. Conversely, an increase in bit weight results in the relay supplying a drill string control signal that operates the to the drill string cable, no longer measures direct drill string drill string controller to effect a decrease in the rate of weight but, instead, measures the drill string weight at an angle. As a result, the weight indicator supplies to the release of the drill string. automatic driller an erroneous reading of the actual drill Alternatively, when the relay connected to the drill string string weight on the drill bit. Consequently, the automatic 45 torque regulator receives a decrease in drill string torque driller will fail to properly control the cable drum brake to signal, it supplies a drill string control signal that operates release the drill string cable. The drilling operation, therethe drill string controller to effect an increase in the rate of fore, does not operate at an optimal efficiency which reduces release of the drill string. However, an increase in drill string the likelihood of successfully completing the borehole as torque results in the relay supplying a drill string control 5o signal that operates the drill string controller to effect a well as increasing the cost of the entire operation. decrease in the rate of release of the drill string. Accordingly, a need exists for an automatic driller that not only operates through bit weight measurements but also Finally, if the relay connected the drill string RPM reguoperates in response to other measurements so that direclator receives an increase in drill string RPM signal, it tional or horizontal boreholes may be drilled. ~ supplies a drill string control signal that operates the drill string controller to effect an increase in the rate of release of SUMMARY OF THE INVENTION the drill string. Conversely, a decrease in drill string RPM results in the relay supplying a drill string control signal that In accordance with the present invention, an automatic operates the drill string controller to effect a decrease in the drilling system controls the drill string of a drilling rig in response to any one of, any combination of, or all of drilting 6o rate of release of the drill string. It is, therefore, an object of the present invention to fluid pressure, bit weight, drill string torque, and drill string provide an automatic driller capable of automatically conRPM to automatically release the drill string of the drilling trolling the release the drill string of a drilling rig in response rig during the drilling of a borehole. The automatic driller to changes in any one of, any combination of, or all of includes a drilling fluid pressure sensor, a bit weight sensor, a &rill string torque sensor, and a drill string RPM sensor. 65 drilling fluid pressure, bit weight, drill string torque, and drill string RPM. The sensors output signals representing drilling fluid pressure, bit weight, drill string torque, and drill string RPM to Still other objects, features, and advantages of the present

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invention will become evident to those skilled in the art in light of the following.

4

zontal boreholes to be drilled. To drill borehole 86 into formation 87, rotary table 24 may drive drill string 21 to rotate drill bit 23, or mud motor 85 may rotate drill bit 23, or drill string 21 and mud motor 85 may be used in tandem. BRIEF DESCRIPTION OF THE DRAWINGS 5 However, during a typical drilling operation, mud motor 85 FIG. 1 is a front view depicting a typical drilling rig drives drill bit 23 only at the directionalization point of controlled by the automatic drilling system according to the borehole 86 in order to ensure a precise borehole angle, preferred embodiment of the present invention. while drill string 21 drives drill bit 23 during straight line drilling. FIG. 2 is a schematic diagram depicting the automatic drilling system according to the preferred embodiment of the 10 Pump 25 pumps drilling fluid (i.e. mud) into drill string 21 present invention. via drilling fluid line 88, where it travels down drill string 21 to mud motor 85 and drill bit 23. The drilling fluid drives FIG. 3 is an enlarged view of the pump pressure regulator mud motor 85, provides pressure within drill bit 23 to of the automatic drilling system depicted in FIG. 2. prevent blowouts, and carries drilled formation materials FIG. 4 is a front view depicting a pump pressure sensor from borehole 86. 15 according to the preferred embodiment of the present invenDrawworks 22 must adjust drill string 21 vertically along tion. derrick 20 in order to retain drill bit 23 "on bottom" (i.e. on FIG. 5 is a front view in partial perspective depicting a the bottom of borehole 86) and maintain the progression of pump fluid pressure sensor utilized in the automatic drilling borehole 86 through formation 87. As long as drill string 21 system of the present invention. maintains sufficient and constant pressure on drill bit 23, 20 FIG. Ii is a cross-sectional front view depicting the drill bit 23 will gouge borehole 811 from formation 87 at an well-head pressure compensation valve according to the optimal rate of penetration chosen based upon the compopreferred embodiment of the present invention. sition of formation 87. Rates of penetration vary from as little as four feet per hour to as much as one hundred and FIG. 7 is a side view depicting a drill line tension sensor utilized in the automatic drilling system of the present 25 eighty feet per hour. If, however, drawworks 22 did not adjust drill string 21, drill bit 23 would rise "off bottom" (i.e. invention. off the bottom of borehole 811) and the progression of FIG. 8 is a side view depicting an alternative drill line borehole 811 through formation 87 would cease. Accordingly, tension sensor utilized in the automatic drilling system of the brake 32 must be manipulated to permit drum 26 to release present invention. 30 cable 28 and adjust drill string 21, thereby providing the FIG. 9 is a schematic diagram depicting a low fluid constant pressure on drill bit 23 required to maintain the warning apparatus and cut-off switch utilized in the drill line optimal rate of penetration. tension sensor illustrated in FIG. 8. To maintain drill bit 23 "on bottom" and, thus, the optimal FIG. 10 is a schematic diagram depicting a pipe rotation rate of penetration, automatic driller 33 connects to brake torque sensor utilized in the automatic drilling system of the 35 handle 208 via cable 207 to regulate the release of cable 28 present invention. from drum 211. Automatic driller 33 senses when drill bit 23 FIG. 11 is a schematic diagram depicting an alternative is "off bottom" and manipulates brake 32 to release cable 28 pipe rotation torque sensor utilized in the automatic drilling and lower drill string 21 until drill bit 23 is again "on system of the present invention. bottom". Automatic driller 33 determines when drill bit 23 FIG. 12 is a schematic diagram depicting a pipe RPM 40 is "off bottom" by measuring drilling fluid pressure, bit sensor utilized in the automatic drilling system of the present weight, drill string torque, and drill string revolutions per invention. minute (RPM). Drilling fluid pressure sensor 34, bit weight sensor 35, torque sensor 36, and RPM sensor 37 mount onto FIG. 13 is a schematic diagram depicting an alternative oil drilling rig 20 to provide signals representative of drilling pipe RPM sensor utilized in the automatic drilling system of the present invention. 45 fluid pressure, bit weight, drill string torque, and drill string RPM to automatic driller 33. Additionally, drilling fluid FIG. 14 is a schematic diagram depicting an alternative pressure gauge 80, drill string weight gauge 81, drill string embodiment of the automatic drilling system configured to torque gauge 82, and drill string RPM gauge 83 mount on control a coil tubing drilling rig. drilling rig 10 to register the respective signals produced by 50 drilling fluid pressure sensor 34, bit weight sensor 35, torque DETAILED DESCRIPTION OF THE sensor 311, and RPM sensor 37 for the drilling rig operator. PREFERRED EMBODIMENTS Automatic driller 33 may be programmed to utilize any one FIG. 1 illustrates a typical drilling rig controlled by the of the above measurements, any combination of the above automatic drilling system of the present invention. Drilling measurements, or all of the above measurements to regulate rig 10 may be utilized to drill vertical, directional, and55 brake 32 and, thus, the position of drill bit 23 within horizontal boreholes. Derrick 20 supports drill string 21 borehole 811. within borehole 86 utilizing drawworks 22. Drawworks 22 As shown in FIG. 4, drilling fluid pressure sensor 34 may includes drilling cable drum 26 and drilling cable anchor 27 comprise dual rubber boot sensor 100. Dual rubber boot having drilling cable 28 strung therebetween. Rollers 29 and sensor 100 comprises blocks 101-1011 which fit together 30 mount onto derrick 20 to wind cable 28 about travelling 60 using any suitable means such as screws to secure rubber block 31, thus suspending drill string 21 from derrick 20. boots 107 and 108 within Cavity 109. Blocks 101-1011 Brake 32 controls the release of cable 28 from drum 26 to further secure piston 110 within cavity 109. Dual rubber adjust the vertical position of drill string 21 with respect to boot sensor 100 connects to automatic driller 33 utilizing derrick 20. hydraulic line 111 and hydraulic line connector 112 which Rotary table 24 drives drill string 21 to rotate drill bit 23, 65 screws within blocks 101 and 104. Safety valve 113 fits thereby drilling borehole 86. Additionally, drill string 21 between rubber boot 108 and hydraulic line connector 112 to includes mud motor 85 which allows directional and hori~ remove the drilling fluid pressure signal from automatic

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driller 33 if excessive drilling fluid pressure builds up within to provide a differential signal output representing changes drill string 21. in either the drilling fluid pressure within drill string 21 or at the well head. Illustratively, either an increase in the In operation, the drilling fluid contacts robber boot 107 to drilling fluid pressure within drill string 21 or the decrease force rubber boot 107 towards cylinder 110. Rubber boot 107 contacts cylinder 110 and forces it against rubber boot 5 of drilling fluid pressure at the well head will result in an increase in the pressure of the hydraulic fluid delivered to 108. In turn, cylinder 110 moves rubber boot 108 to displace automatic driller 33. Alternatively, either a decrease in the hydraulic fluid within hydraulic line 111. The pressure drilling fluid pressure within drill string 21 or an increase in rubber boot 108 applies against the hydraulic fluid within drilling fluid pressure at the well head will result in a hydraulic line 111 provides a signal corresponding to the drilling fluid pressure. Although the surface area of both 10 decrease in the hydraulic pressure signal delivered to automatic driller 33. sides of cylinder 110 may be equal to provide a one to one drilling fluid to hydraulic fluid pressure ratio, the surface FIGS. 7 and 8 illustrate two standard weight on bit sensors area of the end of cylinder 110 contacting rubber boot 108 that may be utilized to supply a weight on bit signal to may be enlarged to provide a reduction in the measured automatic driller 33. Specifically, FIG. 7 depicts a Martinpressure to actual fluid pressure ratio. Illustratively, the 15 Decker clipper weight indicator that mounts onto cable 28 to cylinder surface area ratio could be four to one to provide a provide a hydraulic signal representative of the weight drill one/fourth reduction between the drilling fluid pressure and string 21 applies on top of drill bit 23. A hydraulic hose (not the pressure of the hydraulic fluid within hydraulic line 111. shown) connects clipper weight indicator 142 to automatic driller 33 to provide automatic driller 33 with a hydraulic However, if excess drilling fluid pressure builds up in drill string 21, safety valve 113 will prevent rubber boot 108 from 2o representation of the weight drill string 21 applies on bit 23. That is, cable 28 applies pressure against defection plug 140 generating a signal to automatic driller 33. Specifically, which, in turn, applies pressure against diaphragm 141. As rubber boot will rise within cavity 109 such that it forces a result, diaphragm 141 contracts to pressurize the hydraulic safety valve 113 over the opening through hydraulic line fluid within the hydraulic hose to deliver a hydraulic presconnector 112, thereby blocking it. Consequently, rubber boot 108 will not exert any pressure on the hydraulic fluid 25 sure signal to automatic driller 33. within hydraulic line 111, and automatic driller 33 will not In FIG. 8, a Martin-Decker anchor weight indicator receive a signal. As a result, automatic driller 33 will not be implements bit weight sensor 35 to provide the hydraulic damaged from overpressure. signal to automatic driller 33 representing the weight drill string 21 applies to drill bit 23. Alternatively, a standard drilling fluid pressure sensor 30 also substitutes for cable drumAnchor weight indicator 145 anchor 27. That is, anchor may be employed. Illustratively, FIG. 5 depicts a Martinweight indicator anchors cable 28 to drilling rig 10 with Decker mud pump pressure gauge which may be employed drilling cable drum 146. In operation, as the tension on cable to supply automatic driller 33 with a signal indicative of 28 varies, arm 147 applies pressure to diaphragm 148 which, drilling fluid pressure. The Martin-Decker mud pump presin turn, compresses hydraulic fluid within hydraulic line 149 sure gauge includes diaphragm 114 which contacts the 35 to supply a hydraulic fluid signal to automatic driller 33 via drilling fluid to exert a pressure against the hydraulic fluid hydraulic line 149. within hydraulic line 115, thereby providing automatic driller 33 with a drilling fluid pressure signal. FIG. 10 illustrates a Martin-Decker idler wheel tension sensor utilized to provide automatic driller 33 with a hydrauFIG. 6 illustrates a wellhead pressure compensation valve that may be utilized in conjunction with either the drilling 40 lic signal indicating drill string torque. Idler wheel tension sensor 160 is utilized when a power source such as a diesel fluid pressure sensor of FIG. 4 or the standard drilling fluid engine drives rotary table 24 (See FIG. 1). Idler wheel pressure sensor of FIG. 5. Wellhead pressure compensation tension sensor 160 mounts against drive chain 161 such that valve 120 provides a drilling fluid pressure signal to autowheel 162 abuts drive chain 161. Thus, as drive chain 161 matic driller 33 that incorporates changes in well head pressure as well as changes in the pressure of the drilling 45 rotates, wheel 162 rotates to apply downward tension pressure against idler arm 163 which, in turn, applies pressure to fluid within drill string 21. Well head pressure compensation hydraulic cylinder 167, thereby increasing the fluid pressure valve 120 comprises enclosure 121 which encloses piston within hydraulic fluid line 164. Hydraulic fluid line 164 122, which is cross-shaped in the preferred embodiment. connects to automatic driller 33 to provide automatic driller O-rings 123-126 mount piston 122 within enclosure 121 and, further, divide the inner cavity of enclosure 121 into 50 33 with a hydraulic signal representing drill string torque. four individual cavities 127-130. Cavity 127 communicates FIG. 11 illustrates a drill string torque sensor utilized with the hydraulic line 111 or hydraulic line 115, depending when an electric motor drives rotary table 24 (See. FIG. 1). upon which drilling fluid pressure sensor is being used, in Specifically, electrical to pneumatic transducer 165 connects order to apply a drilling fluid pressure signal against piston to electric motor 166. As electric motor 166 operates, it 122. Cavity 130 communicates with the output of a pressure 55 generates an electrical current that feeds into electrical to sensors mounted at the wellhead to apply a hydraulically pneumatic transducer 165. Electrical to pneumatic transconveyed wellhead pressure signal to piston 122. The presducer 165 converts that current signal into a pneumatic sure sensor at the wellhead may be of a type similar to those signal which it delivers to automatic driller 33 via pneumatic depicted in FIGS. 4 and 5. Air fills cavity 128 to allow the hose 168. The pneumatic signal supplied to automatic driller motion of piston 122 within enclosure 121, while hydraulic 60 33 by electrical to pneumatic transducer 165 corresponds to fluid fills cavity 129 to provide a hydraulic pressure signal the torque rotary table 24 applies to drill string 21. to automatic driller 33 via hydraulic line 131. That hydraulic FIG. 12 illustrates a drill string RPM sensor utilized to pressure signal corresponds to the difference between the provide automatic driller 33 with a signal indicative of drill drilling fluid pressure within drill string 21 and the drilling string RPM when a power source such as a diesel engine or fluid pressure at the well head. 65 electric motor drives rotary table 24 via gear 170. V-belt 171 In operation, the hydraulic fluid pressure applied against couples generator 172 to gear shaft 170 to drive generator piston 122 via cavities 127-130 balance against each other 172 in unison with gear 170. As a result, generator 172

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generates a voltage signal that it supplies to electrical to string RPM regulator 203 remain off and do not regulate the pneumatic transducer 173. Electrical to pneumatic transsupply of compressed air delivered to air motor 204. Valve ducer 173 converts that voltage signal to a pneumatic signal selectors 232-235 may be manipulated in any combination which it then supplies to automatic driller 33 to provide so that any one, any combination, or all of regulators automatic driller 33 with the RPM of drill string 21. 5 200-203 regulate the delivery of compressed air to air motor 204. FIG. 13 illustrates an alternate drill string RPM sensor which provides automatic driller with a signal representing FIG. 3 depicts an enlarged view of drilling fluid pressure drill string RPM when either a diesel engine or electric regulator 200 and will be referenced to provide an illustramotor drives rotary table 24 via gear 170. Proximity switch tion of the use of regulators 200-203 in automatic driller 33. 174 develops an electrical signal that corresponds to the 10 Specifically, drilling fluid pressure regulator 200 measures speed with which rotary table 24 rotates drill string 21. changes in drilling fluid pressure to regulate a drilling Electrical to pneumatic transducer 175 receives that electrioperation. As previously described, valve selector 232 cal signal and converts it into a pneumatic signal representremains on, and valve selectors 233-235 are switched off so ing drill string RPM. Electrical to pneumatic transducer 175 that only drilling fluid pressure regulator 200 regulates the connects to automatic driller 33 to provide automatic driller flow of compressed air from the air supply to air motor 204. 15 Drilling fluid pressure regulator 200 ensures drill bit 23 33 with a pneumatic signal representing drill string RPM. progresses through formation 87 at an optimal rate of As shown in FIG. 2, automatic driller 33 comprises penetration by maintaining the drilling fluid within drill drilling fluid pressure regulator 200, bit weight regulator string 21 at an optimal pressure. As long as the drilling fluid 201, drill string torque regulator 202, and drill string RPM remains at that optimal pressure, drill bit 23 will resid.e "on regulator 203 which receive the drilling signals developed 20 bottom" with sufficient bit weight to drill borehole 86 by drilling fluid pressure sensor 34, bit weight sensor 35, through formation 87. Drilling fluid pressure regulator 200 drill string torque sensor 36, and drill string RPM sensor 37, regulates drilling fluid pressure by releasing cable 28 from respectively. Automatic driller 33 further comprises air drum 26 in response to decreases in drilling fluid pressure. motor 204 which drives differential gear unit 205. Differential gear unit 205 manipulates cable reel 206 to raise and25 The release of cable lowers drill string 21 to place drill bit 23 "on bottom". With drill bit 23 "on bottom", backpressure lower brake handle 208 via cable 207, thereby adjusting the created within drill string 21 raises drilling fluid pressure braking force brake 32 applies against drum 26. Regulators back to its optimal value. Once drilling fluid pressure 200-203 connect to valves 236-239, respectively, to output reaches its optimal value, drilling fluid pressure regulator a pneumatic signal to air motor 204 which drives air motor 200 stops 204 to control brake 32 and, thus, the release of cable 28 30 string 21. the release of cable 28 to end the lowering of drill from drum 26. Although regulators 200-203 may be used concurrently to control brake 32, they may also be utilized Drilling fluid pressure regulator 200 includes Bourdon individually or in any combination to control the release of tube 210 which connects to drilling fluid pressure sensor 34 cable 28 from drum 26. to sense changes in drilling fluid pressure within drill string In the preferred embodiment, valves 236-239 are pneu- 35 21 and to control valve 236 accordingly. Drilling fluid pressure regulator 200 further includes flapper 213, adjustmatic valves that operate as relays to supply compressed air ing screw 214, plate 215, nozzle 216, spring 230, and safety to air motor 204. Specifically, valves 236-239 connect in shut-down knob 217. Flapper 213 connects to one end of series to deliver compressed air from an air supply (not Bourdon tube 210 with pivot screw 220, while spring 230 shown) to air motor 204. That is, the air supply delivers the compressed air to valve 236 through flow regulator 212. Air 40 connects to plate 215 and flapper 213 in order to provide a restoring force that maintains flapper 213 near nozzle 216. pressure gauge 231 registers the air pressure supplied to Nozzle 216 mounts on plate 215 to deliver variable amounts valve 236 and displays that value for the automatic driller of compressed air from the air supply to diaphragm 240 of operator. Flow regulator 212 functions to limit the pressure valve 236 in response to changes in drilling fluid pressure. of the compressed air delivered to valve 236 and, thus, the. maximum rate at which air motor 204 will drive cable reel45 Adjusting screw 214 connects to plate 215 in order to adjust plate 215 transverse to flapper 213 about pivot screw 225. 206. Flow regulator 212, therefore, determines the maxiThat is, adjusting screw 214 swings the top of plate 215 in mum rate at which drill bit 23 could penetrate into formation an arc about pivot screw 225 to position nozzle 216 either 87. closer or further from flapper 213. In addition, plate 215 Valve selectors 232-235 control which ones of regulators 200-203 control the drilling operation. That is, if all four 50 includes pivot pin 224 which provides the pivot point for flapper 213. regulators are to control the drilling operation, valve selecIn normal operation, Bourdon tube 210 manipulates flaptors 232-235 remain on so that regulators 200-203 control per 213 in response to changes in drilling fluid pressure to the delivery of compressed air from their respective valves vary the amount of compressed air nozzle 216 delivers to 236-239. However, if, for example, only drilling fluid pressure regulator 200 is to control the drilling operation, 55 valve 236. That variable amount of compressed air alters the opening of valve 236 and, thus, the force with which the valve selector 232 remains switched on while valve selectors compressed air drives air motor 204. However, before 233-235 are switched off. In its on position, valve selector drilling fluid regulator 200 will automatically regulate drill232 continues to prevent the air supply from delivering ing fluid pressure, nozzle 216 and flapper 213 must be compressed air directly onto diaphragm 240 of valve 236 so that drilling fluid regulator 200 controls the opening and 60 calibrated to supply a driller operator selected amount of compressed air to valve 236. closing of valve 236. Conversely, with valve selectors 233-235 switched off, they allow the air supply to deliver To calibrate drilling fluid pressure regulator 200 and compressed air directly onto diaphragms 241-243 of valves automatically regulate drilling fluid pressure, the drilling rig 237-239. As a result, valves 237-239 fully open and funcoperators must first manually manipulate brake 32 to place tion only to pass the flow of compressed air regulated by 65 drill bit 23 "on bottom". Once drill bit 23 resides "on drilling fluid pressure regulator 200. That is, bit weight bottom", the drilling rig operators connect cable 207 to regulator 201, drill string torque regulator 202, and drill brake handle 208. Adjustment screw 214 must then be

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adjusted to move nozzle 216 relative to flapper 213 so that slowly so that drill string 21 will maintain a bit weight it will deliver compressed air to valve 236. The delivery of sufficient to sustain the pressure of the drilling fluid within compressed air by nozzle 216 opens valve 236, thereby drill string 21 at its optimal pressure. allowing the actuation of air motor 204. At this point, drill bit 23 should progress through formaIf adjustment screw 214 and, thus, nozzle 216 remain 5 tion 87 at the optimal rate of penetration. Unfortunately, even under optimal drilling conditions drill bit 23 will rise unadjusted, drilling fluid pressure regulator 200 will not "off bottom", thus requiring drilling fluid pressure regulator maintain a constant drilling fluid pressure. Specifically, 200 to readjust the release of cable 28 from drum 26. Any flapper 213 diverts no compressed air into orifice 222, and time drill bit 23 rises even slightly "off bottom", drilling all the compressed air flowing into nozzle 216 through to fluid pressure within drill string 21 decreases. Drilling fluid orifice 218 exhausts through nozzle oudet 221. Orifice 222, pressure sensor 34 measures that decrease and supplies therefore, delivers no compressed air over top of diaphragm Bourdon tube 210 with a hydraulic signal representing that 240 which results in valve 236 remaining closed. With valve decrease. Any decrease in drilling fluid pressure registered 236 closed, air motor 204 receives no compressed air by Bourdon tube 210 causes it to contract. As Bourdon tube causing brake 32 to remain engaged. Consequently, drum 26 210 contracts, it drives flapper 213 to the left via its does not release cable 28 which results in drill bit 23 rising 15 connection to flapper 213 at pivot screw 220. As flapper 213 "off bottom". Thus, nozzle 216 must be adjusted to deliver moves left at pivot screw 220, its center point pivots about the drilling rig operator selected amount of air pressure to air pin 224 to drive its opposite end towards nozzle outlet 221. motor 204 so that optimal drilling fluid pressure will be The pivoting of flapper 213 to a position closer to nozzle 216 maintained within drill string 21. restricts additional compressed air flow from nozzle outlet Adjusting screw 214 threadably connects to plate 215 in 2o 221 and redirects that compressed air flow into orifice 222. order to adjust plate 215 and, thus, nozzle 216 transverse to Orifice 222 delivers the compressed air to the top of diaflapper 213. As a drilling fig operator tightens adjusting phragm 240, thereby further opening valve 236. With valve screw 214, plate 215 pivots from right to left about pivot 236 opened further, air motor 204 receives an additional screw 225. That is, adjusting screw 214 swings the top of 25 amount of compressed air which increases the speed with plate 215 in an arc from right to left about pivot screw 225 which it rotates. In response, cable reel 206 raises brake to position nozzle 216 closer to flapper 213. As a result, handle 208 causing brake 32 to further disengage from drum flapper 213 deflects the flow of compressed air from nozzle 26. Consequently, drum 26 releases cable 28 an additional outlet 221 into orifice 222 which delivers the compressed air amount, thus lowering drill string 21. Drum 26 lowers drill to valve 236. The diversion of the compressed air into valve 30 stri.ng 21 until drill bit 23 again resides "on bottom" so that 236 drives diaphragm 240 down to compress springs 226 an increase in the pressure of the drilling fluid within drill and 227 and open valve 236. The loosening of adjusting string 21 may be effected. screw 214 moves nozzle 216 away from flapper 213 to As the drilling fluid pressure returns to its optimal value, reduce or eliminate the diversion of compressed air into drilling fluid pressure sensor 34 registers that increase and valve 236. 35 supplies Bourdon tube 210 with a hydraulic signal repreThe opening of valve 236 allows compressed air from the senting that increase. The increasing hydraulic fluid pressure air supply to flow from cavity 228 into cavity 229 and out within Bourdon tube 210 causes it to expand and pull flapper from valve 236 into valve 237. The compressed air then 213 to the right via its connection to flapper 213 at pivot flows through valves 237-239 to air motor 204 because screw 220. With flapper 213 pivoting to the right at pivot valves 237-239 were previously opened by valve selectors 4o screw 220, its center pivots about pin 224 to drive its 233--235. The compressed air entering air motor 204 actiopposite end to the left, thereby moving it further from vates it and begins it rotating. As air motor 204 rotates, nozzle outlet 221. As a result, orifice 222 delivers less differential gear unit 205 transfers that motion to cable wheel compressed air over top of diaphragm 240, while nozzle 206 which picks up brake handle 32 via cable 207 to lessen outlet 221 exhausts more compressed air. Consequently, the braking force brake 32 exerts on drum 26. Consequently, 45 valve 236 closes slightly to deliver less compressed air to air drum 26 releases cable 28 to place more weight of drill motor 204 causing it to rotate more slowly. In response, string 21 on drill bit 23 causing an increase in drilling fluid differential gear unit 205 releases cable reel 206 so that pressure. brake handle 208 lowers. Differential gear unit 205 includes A drilling rig operator tightens adjusting screw 214 to a first shaft connected to cable reel 206 and a second shaft cause the release of drill string 21 until the drilling fluid 5o connected to wheel drum rotation sensor 90 via flexible shaft within drill string 21 reaches its desired pressure. Drilling cable 91. Wheel drum rotation sensor 90 senses the rotation fluid pressure gauge 80 (see FIG. 1) registers and displays of drum 26 and transfers that rotation to the second shaft of the pressure of the drilling fluid within drill string 21 for the differential gear unit 205 via flexible cable shaft 91. Accorddrilling rig operator. Accordingly, when drilling fluid presingly, with air motor 204 rotating more slowly than drum 26, sure gauge 80 registers the desired drilling fluid pressure, the 55 the second shaft speeds up relative to the first shaft resulting drilling rig operator stops tightening adjusting screw 214. in the first shaft slowing down even further. The slowing Alternatively, pneumatic pressure gauge 244 registers and down of the first shaft removes the driving force from cable displays the pressure of the compressed air nozzle 216 reel 206, thus allowing it to unspool cable 207 to lower brake delivers to valve 236. Thus, when pneumatic pressure gauge handle 208. With brake handle 208 lowered, brake 32 244 registers the desired compressed air pressure and, thus, 60 increases its braking of drum 26, resulting in the release of the desired opening of valve 236, the drilling rig operator cable 28 slowing to its calibrated value. stops tightening adjusting screw 214. Safety shut-down knob 217 functions to prevent drilling With adjusting screw 214 no longer being tightened, the fluid pressure regulator 200 from releasing drill string 21 amount of compressed air valve 236 delivers to air motor during either a drilling rig malfunction or dangerous drilling 204 stabilizes to a constant amount. As a result, air motor 65 conditions. As previously described, drilling fluid pressure 204 maintains brake 32 engaged against drum 26 at a regulator 200 will release drill string 21 when it senses a constant force. Consequently, drum 26 will release cable 28 decrease in drilling fluid pressure. Unfortunately, not every

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decrease in drilling fluid pressure should result in the release the pivot point for flapper 251. of drill string 21. For example, if drilling fluid pump 25 stops In normal operation, Bourdon tube 250 manipulates flappumping, drill string 21 breaks, or drill bit 23 enters a per 251 in response to changes in bit weight to vary the cavern, drilling fluid pressure will decrease, however, drillamount of compressed air nozzle 254 delivers to valve 237. ing fluid pressure regulator 200 should not release drill 5 That variable amount of compressed air alters the opening of string 21. The release of drill string 21 under such conditions valve 237 and, thus, the force with which the compressed air could damage drilling rig 10 or create a situation where drives air motor 204. However, before drilling fluid regulainjury to the drilling rig operators could occur. tor 200 will automatically regulate bit weight, nozzle 254 In the event of a large decrease in drilling fluid pressure, and flapper 251 must be calibrated to supply a driller safety shut-down knob 217 pivots flapper 213 from nozzle 10 operator selected amount of compressed air to valve 237. outlet 221. That is, under normal operation, Bourdon tube To calibrate bit weight regulator 201 and automaticaily 210 pivots flapper 213 towards nozzle 216, thus causing regulate bit weight, the drilling rig operators must first nozzle 216 to open valve 236 further. However, if drilling manually manipulate brake 32 to place drill bit 23 "on fluid pressure drops below an operator set minimum, Bourbottom". Once drill bit 23 resides "on bottom", the drilling don tube 210 will push flapper 213 against safety shut-down knob 217. As Bourdon tube 210 pushes flapper 213 against t5 rig operators connect cable 207 to brake handle 208. Adjustment screw 252 must then be adjusted to move nozzle 254 safety shut-down knob 217, flapper 213 rotates in an arc to relative to flapper 251 so that it will deliver compressed air the right about pivot screw 220. As a result, the opposite end to valve 237. The delivery of compressed air by nozzle 254 of flapper 213 pivots away from nozzle outlet 221 to allow opens nozzle outlet 221 to exhaust all the compressed air delivered 20 204. valve 237, thereby allowing the actuation of air motor from the air supply to nozzle 216. Accordingly, nozzle 216 If adjustment screw 252 and, thus, nozzle 254 remain delivers no compressed air to valve 236, and valve 236 unadjusted, bit weight regulator 201 will not maintain a closes. With valve 236 closed, air motor 204 shuts off to stop constant bit weight. Specifically, flapper 251 diverts no the release of cable 28 from drum 26, thereby ending the compressed air into orifice 260, and all the compressed air drilling operation. 25 flowing into nozzle 254 through orifice 259 exhausts As shown in FIG. 2, bit weight regulator 201 may be through nozzle outlet 261. Orifice 260, therefore, delivers no utilized to control a drilling operation. Specifically, bit compressed air over top of diaphragm 241 which results in weight regulator 201 measures changes in bit weight to valve 237 remaining closed. With valve 237 closed, air regulate the rate at which drill bit 23 penetrates formation motor 87. For bit weight regulator 201 to control the drilling 3o remain204 receives no compressed air causing brake 32 to engaged. Consequently, drum 26 does not release operation, valve selector 233 must be switched on, and valve cable 28 which results in drill bit 23 rising "off bottom". selectors 232, 234, and 235 must be switched off so that only Thus, nozzle 254 must be adjusted to deliver the drilling rig bit weight regulator 201 regulates the flow of compressed air operator selected amount of air pressure to air motor 204 so from the air supply to air motor 204. Bit weight regulator 201 ensures drill bit 23 progresses through formation 87 at 35 that optimal bit weight will be maintained. Adjusting screw 252 threadably connects to plate 253 in an optimal rate of penetration by maintaining the weight order to adjust plate 253 and, thus, nozzle 254 transverse to drill string 21 applies to drill bit 23 at an optimal weight. As flapper 251. As a drilling rig operator loosens adjusting long as drill string 21 applies that optimal weight, drill bit 23 screw 252, plate 253 pivots from left to right about pivot will reside "on bottom" with sufficient bit weight to drill borehole 86 through formation 87. Bit weight regulator 201 40 screw 257. That is, adjusting screw 252 swings the top of plate 253 in an arc from left to right about pivot screw 257 regulates bit weight by releasing cable 28 from drum 26 in to position nozzle 254 closer to flapper 251. As a result, response to hook load weight (i.e. tension) increases expeflapper 251 deflects the flow of compressed air from nozzle rienced by cable 28. The release of cable 28 lowers drill outlet 261 into orifice 260 which delivers the compressed air string 21 to place drill bit 23 "on bottom", thereby reducing the hook load weight of cable 28. Drum 26 continues to 45 to valve 237. The diversion of the compressed air into valve 237 drives diaphragm 241 down to compress springs 262 release cable 28 until the weight drill string 21 applies to and 263 and open valve 237. The tightening of adjusting drill bit returns to its optimal value. Once the weight drill screw 252 moves nozzle 254 away from flapper 251 to string 21 applies to drill bit 23 reaches its optimal value, bit reduce or eliminate the diversion of compressed air into weight regulator 201 stops the release of cable 28 to end the lowering of drill string 21. 50 valve 237. The opening of valve 237 allows compressed air from the Bit weight regulator 201 includes Bourdon tube 250 air supply to flow from cavity 264 into cavity 265 and out which connects to bit weight sensor 35 to sense changes in from valve 237 into valve 238. Compressed air initially bit weight and to control valve 237 accordingly. Bit weight flows to valve 237 because valve selector 232 locks valve regulator 201 further includes flapper 251, adjusting screw 252, plate 253, nozzle 254, and spring 255. Flapper 251 55 236 open. The compressed air flows from valve 237 through valves 238 and 239 to air motor 204 because valves 238 and connects to one end of Bourdon tube 250 with pivot screw 239 were previously opened by valve selectors 234 and 235. 256, while spring 255 connects to plate 253 and flapper 251 The compressed air entering air motor 204 activates it and in order to provide a restoring force that maintains flapper begins it rotating. As air motor 204 rotates, differential gear 251 near nozzle 254. Nozzle 254 mounts on plate 253 to deliver variable amounts of compressed air from the air 60 unit 205 transfers that motion to cable wheel 206 which picks up brake handle 32 via cable 207 to lessen the braking supply to diaphragm 241 of vaive 237 in response to changes force brake 32 exerts on drum 26. Consequently, drum 26 in bit weight. Adjusting screw 252 connects to plate 253 in releases cable 28 to place more weight of drill string 21 on order to adjust plate 253 transverse to flapper 251 about drill bit 23. pivot screw 257. That is, adjusting screw 252 swings the top of plate 253 in an arc about pivot screw 257 to position 65 A drilling rig operator loosens adjusting screw 252 to nozzle 254 either closer or further from flapper 251. In cause the release of drill string 21 until drill string 21 resides addition, plate 253 includes pivot pin 258 which provides on drill bit 23 at the desired weight. Drill string weight gauge

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81 (see FIG. 1) registers and displays the weight drill string of drum 26 and transfers that rotation to the second shaft of 21 applies on top of drill bit 23 for the drilling rig operator. differential gear unit 205 via flexible cable shaft 91. AccordAccordingly, when drill string weight gauge 81 registers the ingly, with air motor 204 rotating more slowly than drum 26, desired bit weight, the drilling rig operator stops loosening the second shaft speeds up relative to the first shaft resulting adjusting screw 252. Alternatively, pneumatic pressure 5 in the first shaft slowing down even further. The slowing gauge 2611 registers and displays the pressure of the comdown of the first shaft removes the driving force from cable pressed air nozzle 254 delivers to valve 237. Thus, when reel 206, thus allowing it to unspool cable 207 to lower brake pneumatic pressure gauge 2611 registers the desired comhandle 208. With brake handle 208 lowered, brake 32 pressed air pressure and, thus, the desired opening of valve increases its braking of drum 26, resulting in the release of 237, the drilling rig operator stops loosening adjusting screw cable 28 slowing to its calibrated value. 10 252. As shown in FIG. 2, drill string torque regulator 202 may With adjusting screw 252 no longer being loosened, the be utilized to control a drilling operation. Specifically, drill amount of compressed air valve 237 delivers to air motor string torque regulator 202 measures changes in drill string torque to regulate the rate at which drill bit 23 penetrates 204 stabilizes to a constant amount. As a result, air motor formation string torque regulator 202 204 maintains brake 32 engaged against drum 26 at a 15 the drilling87. For drill valve selector 234 must be to control operation, switched constant force. Consequently, drum 211 will release cable 28 on, and valve selectors 232, 233, and 235 must be switched slowly so that drill string 21 will maintain it optimal bit off so that only drill string torque regulator 202 regulates the weight. flow of compressed air from the air supply to air motor 204. At this point, drill bit 23 should progress through formation 87 at the optimal rate of penetration. Unfortunately, 20 Drill string torque regulator 202 ensures drill bit 23 progresses through formation 87 at an optimal rate of even under optimal drilling conditions drill bit 23 will rise penetration by maintaining drill string torque at an optimal "off bottom", thus requiring bit weight regulator 201 to level. As long as drill string torque remains at that optimal readjust the release of cable 28 from drum 26. Any time drill level, drill bit 23 will reside "on bottom" with sufficient bit bit 23 rises even slightly "off bottom", the hook load experienced by cable 28 increases. That is, the tension 25 weight to drill borehole 86 through formation 87. Drill string torque regulator 202 regulates drill string torque by releasing within cable 28 increases. Bit weight sensor 35 measures cable 28 from drum 26 in response to changes in drill string that increase and supplies Bourdon tube 250 with a hydrautorque. The release of cable 28 lowers drill string 21 to place lic signal representing that increase. Any increase in hook drill bit 23 "on bottom". With drill bit 23 "on bottom", the load registered by Bourdon tube 250 causes it to expand. As Bourdon tube 250 expands, it pulls flapper 251 to the right 30 torque drill string 21 applies to drill bit 23 increases to its optimal value. Once the torque of drill string 21 reaches its via its connection to flapper 251 at pivot screw 256. As optimal value, drill string torque regulator 202 stops the flapper 251 moves right at pivot screw 256, its center point release of cable 28 to end the lowering of drill string 21. pivots about pin 258 to drive its opposite end towards nozzle Drill string torque regulator 202 includes Bourdon tube outlet 261. The pivoting of flapper 251 to a position closer to nozzle 254 restricts additional compressed air flow from 35 270 which connects to drill string torque sensor 36 to sense changes in drill string 21 torque and to control valve 238 nozzle outlet 2~11 and redirects that compressed air flow into accordingly. Drill string torque regulator 202 further orifice 2~i0. Orifice 260 delivers the compressed air to the includes flapper 271, adjusting screw 272, plate 273, nozzle top of diaphragm 241, thereby further opening valve 237. 274, spring 275, and safety shut-down knob 276. Flapper With valve 237 opened further, air motor 204 receives an additional amount of compressed air which increases the 40 271 connects to one end of Bourdon tube 270 with pivot screw 277, while spring 275 connects to plate 273 and speed with which it rotates. In response, cable reel 206 raises flapper 271 in order to provide a restoring force that mainbrake handle 208 causing brake 32 to further disengage from tains flapper 271 near nozzle 274. Nozzle 274 mounts on drum 26. Consequently, drum 2ti releases cable 28 an plate 273 to deliver variable amounts of compressed air from additional amount, thus lowering drill string 21. Drum 26 lowers drill string 21 until drill bit 23 again resides "on 45 the air supply to diaphragm 242 of valve 238 in response to changes in drill string torque. Adjusting screw 272 connects bottom" so that an increase in the weight drill string 21 to plate 273 in order to adjust plate 273 transverse to flapper applies onto drill bit 23 may be effected. 271 about pivot screw 278. That is, adjusting screw 272 As the weight drill string applies onto drill bit 23 returns swings the top of plate 273 in an arc about pivot screw 278 to its optimal value, bit weight sensor 35 registers the decrease in hook load (i.e. tension) experienced by cable 28 50 to position nozzle 274 either closer or further from flapper 271. In addition, plate 273 includes pivot pin 279 which and supplies Bourdon tube 250 with a hydraulic signal provides the pivot point for flapper 271. representing that decrease. The decreasing hydraulic fluid In normal operation, Bourdon tube 270 manipulates flappressure within Bourdon tube 250 causes it to retract and per 271 in response to changes in drill string torque to vary push flapper 251 to the left via its connection to flapper 251 at pivot screw 25~i. With flapper 251 pivoting to the left at 55 the amount of compressed air nozzle 274 delivers to valve 238. That variable amount of compressed air alters the pivot screw 2511, its center pivots about pin 258 to drive its opening of valve 238 and, thus, the force with which the opposite end to the right, thereby moving it further from compressed air drives air motor 204. However, before drill nozzle outlet 261. As a result, orifice 260 delivers less string torque regulator 202 will automatically regulate drill compressed air over top of diaphragm 241, while nozzle outlet 261 exhausts more compressed air. Consequently, 60 string torque, nozzle 274 and flapper 271 must be calibrated to supply a driller operator selected amount of compressed valve 237 closes slightly to deliver less compressed air to air air to valve 238. motor 204 causing it to rotate more slowly. In response, differential gear unit 205 releases cable reel 206 so that To calibrate drill string torque regulator 202 so that it brake handle 208 lowers. Differential gear unit 205 includes automatically regulates drill string torque, the drilling rig a first shaft connected to cable reel 206 and a second shaft 65 operators must first manually manipulate brake 32 to place connected to wheel drum rotation sensor 90 via flexible shaft drill bit 23 "on bottom". Once drill bit 23 resides "on cable 91. Wheel drum rotation sensor 90 senses the rotation bottom", the drilling rig operators connect cable 207 to

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brake handle 208. Adjustment screw 272 must then be adjusted to move nozzle 274 relative to flapper 271 so that it will deliver compressed air to valve 238. The delivery of compressed air by nozzle 274 opens valve 238, thereby allowing the actuation of air motor 204. 5 If adjustment screw 272 and, thus, nozzle 274 remain unadjusted, drill string torque regulator 202 will not maintain a constant drill string torque. Specifically, flapper 271 diverts no compressed air into orifice 281, and all the compressed air flowing into nozzle 274 through orifice 280 10 exhausts through nozzle outlet 282. Orifice 281, therefore, delivers no compressed air over top of diaphragm 242 which results in valve 238 remaining closed. With valve 238 closed, air motor 204 receives no compressed air, causing brake 32 to remain engaged. Consequently, drum 26 does 15 not release cable 28 which results in drill bit 23 rising "off bottom". Thus, nozzle 274 must be adjusted to deliver the drilling rig operator selected amount of air pressure to air motor 204 so that optimal drill string torque will be main20 tained.

16

204 maintains brake 32 engaged against drum 26 at a constant force. Consequently, dram 26 will release cable 28 slowly so that drill string 21 will maintain drill string torque at its optimal level. At this point, drill bit 23 should progress through formation 87 at the optimal rate of penetration. Unfortunately, even under optimal drilling conditions drill bit 23 will rise "off bottom", thus requiring drill string torque regulator 202 to readjust the release of cable 28 from drum 26. Any time drill bit 23 rises even slightly "off bottom", the torque drill string 21 applies to drill bit 23 decreases. Drill string torque sensor 36 measures that decrease and supplies Bourdon tube 270 with a hydraulic signal representing that decrease if the torque sensor depicted in FIG. 10 is utilized. Alternatively, if the torque sensor depicting in FIG. 11 is utilized, Bourdon tube 270 receives a pneumatic signal. In either case, any decrease in drill string torque registered by Bourdon tube 270 causes it to contract. As Bourdon tube 270 contracts, it drives flapper 271 to the left via its connection to flapper 271 at pivot screw 277. As flapper 271 moves left at pivot screw 277, its center point pivots about pin 279 to drive its opposite Adjusting screw 272 threadably connects to plate 273 in end towards nozzle outlet 282. The pivoting of flapper 271 order to adjust plate 273 and, thus, nozzle 274 transverse to to a position closer to nozzle 274 restricts additional comflapper 271. As a drilling rig operator tightens adjusting pressed air flow from nozzle outlet 282 and redirects that screw 272, plate 273 pivots from right to left about pivot 25 compressed air flow into orifice 281. Office 281 delivers the screw 278. That is, adjusting screw 272 swings the top of compressed air to the top of diaphragm 242, thereby further plate 273 in an arc from right to left about pivot screw 278 opening valve 238. With valve 238 opened further, air motor to position nozzle 274 closer to flapper 271. As a result, 204 receives an additional amount of compressed air which flapper 271 deflects the flow of compressed air from nozzle increases the speed with which it rotates. In response, cable outlet 282 into orifice 281 which delivers the compressed air reel 206 raises brake handle 208 causing brake 32 to further to valve 238. The diversion of the compressed air into valve 30 disengage from drum 26. Consequently, drum 26 releases 238 drives diaphragm 242 down to compress springs 283 cable 28 an additional amount, thus lowering drill string 21. and 284 and open valve 238. The loosening of adjusting Drum 26 lowers drill string 21 until drill bit 23 again resides screw 272 moves nozzle 274 away from flapper 271 to "on bottom" so that an increase in the torque drill string 21 reduce or eliminate the diversion of compressed air into 35 applies to drill bit 23 may be effected. valve 238. As drill string torque returns to its optimal value, drill The opening of valve 238 allows compressed air from the string torque sensor 36 registers that increase and supplies air supply to flow from cavity 285 into cavity 28ti and out Bourdon tube 270 with either a hydraulic or pneumatic from valve 238 into valve 239. Compressed air initially signal representing that increase. The increasing hydraulic flows to valve 238 because valve selectors 232 and 233 lock 40 fluid pressure within Bourdon tube 270 causes it to expand valves 2311 and 237 open. The compressed air flows from and pull flapper 271 to the right via its connection to flapper valve 238 through valves 239 to air motor 204 because 271 at pivot screw 277. With flapper 271 pivoting to the right valves 239 was also previously opened by valve selector at pivot screw 277, its center pivots about pin 279 to drive 235. The compressed air entering air motor 204 activates it its opposite end to the left, thereby moving it further from and begins it rotating. As air motor 204 rotates, differential 45 nozzle outlet 282. As a result, orifice 281 delivers less gear unit 205 transfers that motion to cable reel 2011 which compressed air over top of diaphragm 242, while nozzle picks up brake handle 32 via cable 207 to lessen the braking outlet 282 exhausts more compressed air. Consequently, force brake 32 exerts on drum 2~i. Consequently, drum 2ti valve 238 closes slightly to deliver less compressed air to air releases cable 28 to place more weight of drill string 21 on motor 204 causing it to rotate more slowly. In response, drill bit 23 causing an increase in the amount of torque drill 50 differential gear unit 205 releases cable reel 206 so that string 21 applies to drill bit 23. brake handle 208 lowers. Differential gear unit 205 includes A drilling rig operator tightens adjusting screw 272 to a first shaft connected to cable reel 206 and a second shaft cause the release of drill string 21 until the torque drill string connected to wheel drum rotation sensor 90 via flexible shaft 21 applies to drill bit 23 reaches its desired level. Drill string cable 91. Wheel drum rotation sensor 90 senses the rotation torque gauge 82 (see FIG. 1) registers and displays drill 55 of drum 26 and transfers that rotation to the second shaft of string torque for the drilling rig operator. Accordingly, when differential gear unit 205 via flexible cable shaft 91. Accorddrill string torque gauge 82 registers the desired drill string ingly, with air motor 204 rotating more slowly than drum 26, torque, the drilling rig operator stops tightening adjusting the second shaft speeds up relative to the first shaft resulting screw 272. Alternatively, pneumatic pressure gauge 287 in the first shaft slowing down even further. The slowing registers and displays the pressure of the compressed air 60 down of the first shaft removes the driving force from cable nozzle 274 delivers to valve 238. Thus, when pneumatic reel 206, thus allowing it to unspool cable 207 to lower brake pressure gauge 287 registers the desired compressed air handle 208. With brake handle 208 lowered, brake 32 pressure and, thus, the desired opening of valve 238, the increases its braking of drum 26, resulting in the release of drilling rig operator stops tightening adjusting screw 272. cable 28 slowing to its calibrated value. With adjusting screw 272 no longer being tightened, the 65 Safety shut-down knob 276 functions to prevent drill amount of compressed air valve 238 delivers to air motor string torque regulator 202 from releasing drill string 21 204 stabilizes to a constant amount. As a result, air motor during either a drilling rig malfunction or dangerous drilling

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conditions. As previously described, drill string torque reguto position nozzle 294 either closer or further from flapper lator 203 will release drill string 21 when it senses a decrease 291. In addition, plate 293 includes pivot pin 299 which in drill string torque. Unfortunately, not every decrease in provides the pivot point for flapper 291. drill string torque should result in the release of drill string In normal operation, Bourdon tube 290 manipulates flap21. For example, if drill string 21 breaks or drill bit 23 enters 5 per 291 in response to changes in drill string RPM to vary a cavern,