US2282615A

US2282615A - Brake for draw works

Info

Publication number: US2282615A
Application number: US286098A
Authority: US
Inventors: John D Spalding
Original assignee: Nat Supply Co
Current assignee: National Supply Co
Priority date: 1939-07-24
Filing date: 1939-07-24
Publication date: 1942-05-12
Anticipated expiration: 1959-05-12

Description

May 12, 1942- `J. D; sPALDlNG 2,282,615

BRAKE FOR DRAwwORKs May 12, 1942- J. D. sFfALDlNG BRAKE FOR DRAWWORKS Filed July 24, 1939 3 Sheecs--Shee'I 2 J. D. SPALDING BRAKE'FOR DRAwwoRKs May 12, 1942.

Filed July 24, 1959 3 Sheets-Sheet 5 Patented May 12,1942

NT oFFlCE j BRAKE FOR DRAW WORKS John VD. Spalding, Los Angeles, Calif., assignor to The National Supply Company, Pittsburgh, Pa., a. corporation of Pennsylvania Application `luly 24, 1939, Serial No. 28.6,098

(CL 18S-451) .17 Claims.

' drawworks.

In the drilling of Wells, the drawworks is usually constructed witha spooling drum for the line and one or more band-type friction brakes -for restraining rotation of the drum. These brakes are ordinarily controlled by a brake lever manually actuated by the driller. In keeping pace with increasing requirements of such'drilling apparatus. the drawworks have been steadily increased in size with the consequent increase in size of the brake bands and brake rims in order to enable the drawworks to handle the greatly increased weight and operating requirements as occasioned in deeper drilling and the constant demand for increase in speed of drilling operations.

The brakes of the drawworks have always offered a major problem in drilling apparatus as these brakes are requiredvto sustain loads of great magnitude in controlling the spooling of the line on the drum. The-manual operation of these brakes has always presented a major problemin the drilling of wells and the effective control of the entire drilling apparatus is to a considerable degree dependent upon the degree of control with which the driller is enabled to exert over the operation of the-brakes.

As the brakes have increased in size, as necessitated by the deeper drilling, the control of the operation of the brakes has become a very diiiicult physical operation so that nicety of control is rendered almost impossible. It is therefore sequent restoration of the iiuid pressure to above' Safe 0p- Other objects and advantages of this invention it is believed will be apparent from the following detailed description in its preferred forms as ill lustrated in the accompanying drawings.

In the drawings: i

Figure 1 is a plan view partially in horizontal section and illustrating certain parts broken away for clarity.

Figure 2 is a fragmental front elevation thereof on a reduced scale.

Figure 3 is a fragmental sectional detail of a control pedal therefor.

Figure 4 is a sectional elevation taken substantially on the line 6 4 of Figure 1.

Figure 5 is a detail partly in vertical section of a manual control lever illustrating the same in operative position.

Figure 6 is a similar detail of the manual control lever illustrating the same in released position.

Figure '7 is a fragmental sectional view taken substantially on the line 'l-l of Figure 5.

Figure 8 is apartial plan view of a modified V form of construction embodying my invention.

an object of this invention to provide a means whereby the brakes of a drawworks may be controlled accurately and positively and without the exertion of great physical effort upon the part of the driller or the consequent danger of physical fatigue to the driller.

Another object of this invention is to provide apparatus for operating the brakes of a drawworks by means of iiuid under pressure wherein there is included means which will act to set the brakes in the event of failure of the fluid pressure or that the magnitude of the fluid pressure falls below a safe limit.

Another object of this invention is to provide a means for controlling the operation of the brakes of a drawworks wherein there is provided means for preventing the release of brakes in the event of failure of adequate iiuid pressure and the sub- 55 Figure 9 is afront elevation of the structure illustrated in Figure 8.

skilled in the art, but'it is to be understoodv thatv my invention is in no wayi'limited in its adaptabilityto any particular form or construction of drawworks as is obviously susceptible of use in connection with any hoisting apparatus as the same are, or may be, particularly adapted forthe control of the pipe as it is run in or-out o'fa well.

InAthe form of drawworks as illustrated, thel' spooling drum l is mounted upon a drum shaiftf 2 between supports 3. As illustrated, the spool-E ing drum I carries at its opposed ends brake rims 4 on which brake bands 5 are mounted. The form of ldrawworks illustrated includes a drive shaft -6 which is adapted to drive through suitable chain and sprocket arrangements illustrated at 1 and 8 the drum I and shaft 2. As there is usually more than one such chain and sprocket drive, clutches 9 are ordinarily provided for releasably clutching in or out these transmission drives.

The drive shaft 6 is normally driven by a suitable form of prime mover (not illustrated) and operatively connected with the transmission sprocket I0. The brake bands are illustrated as of the form where the fixed, or dead end, of each band 5 is anchored to the frame of the drawworks through the medium of anchoring bars II which, as is customary in such constructions, are provided with adjusting means I2 whereby the bands 5 may be individually adjusted to the rims 4. The opposed, or live, ends of each brake band 5 are pivotally connected to a crank I3 of the brake operating shaft I4. The shaft I4 may be of any suitable or desirable construction and as herein illustrated is formed of two sections coupled together as indicated at I5 so that the two sections operate as an integral solid shaft. Spaced bearings I5 secured to the drawworks frame provide rotatable supports for the operating shaft I4.

In order to operate under fluid pressure and to likewise enable selectively the manual operation of the operating shaft I4, I have provided interlocking, manual and fluid pressure means for operating the shaft I4 which include as to the fluid pressure operating mechanism a pressure reservoir I1 which is operatively connected by means of a -conduit I8 with any suitable or desirable source of fluid under pressure.

-The fluid utilized may be any suitable or desirable fluid, but I prefer to utilize compressed air. The reservoir I1 is connected through a conduit I9 with a,master control valve 20 which master control valve 20 connects with the control conduit 2I in which the operating valve 22 is mounted. Extending from the valve 22 is the fluid pressure conduit 23 which connects to the operating cylinder 24.

The valve 22 is preferably of the self-lapping" type such as that shown in the E. K. Lynn et al., Patent No. 2,042,112, issued May 26, 1936.

The operating cylinder 24 contains -a piston 25 carrying a piston rod 26. The piston rod 28 is in turn connected through a coupling 21 with the brake operating arm 28. The arm 28 is pivotally connected to the crank arm 29.

The crank arm 29 is formed on the sleeve 33 which is rotatably mounted upon the brake operating shaft I4. The sleeve 33 carries clutch jaws 3| complementary to clutch jaws 32 carried by a second clutch sleeve 33 splined upon the shaft I4 whereby the clutch sleeve may move longitudinally of the shaft I4 but is restrained from relative rotational movement. Thus, the piston 25 of the operating cylinder 24 is releasably clutched to the operating shaft I4. Upon release of this clutch, it will be obvious that the operating shaft I4 is released from operative connection with the fluid pressure operating means whereby manual operation of the brakes is permitted.

The fluid pressure operating means is provided with a safety means wherein automatic actuation of the brakes to a full braking position is provided in the event the pressure in the reservoir I1 falls below a previously determined safe miniaaeaeis mum,` and is likewise provided with a means wherein engagement of the clutch as thus described is at all times assured when pressure exceeding that minimum is maintained in the pressure reservoir I1 and wherein when the pressure in the reservoir falls.be1ow that safe minimum the master valve 20 is actuated to a closed posinon. fl im In order to provide for this safety operation. there is provided a clutch control cylinder 34 having therein a piston 31 connected to a piston rod 38 with a crank 39 carried on a clutch operating shaft 40. 'I'he piston rod 38 passes freely through a bore formed in the swivel Asleeve 4I carried by the crank 39 and is provided with a nut 42 adiustably threaded on the rod 38 so that when the piston 31 is moved under the inuence of fluid pressure, the adjustable stop nut 42 engages the end of the sleeve 4| to rotate lthe clutch operating shaft 40. The clutch operating shaft 40 is connected by means of crank arms 43 of a crank sleeve 44 with a clutch ring 45. The sleeve 44 is non-rotatably secured to the shaft 40. The clutch ring 45 is secured to the clutch sleeve 33. Mounted in the cylinder 34 is a spring 46 which normally acts to move the piston 31 to such position as to permit the opening of the clutchv jaws. The spring is balanced against the fluid pressure so that when the fluid pressure exceeds the minimum, the piston 31 is moved in position to hold the clutch in engagement. 'I'he clutch may be released through the medium of a clutch op erating pedal 41 suitably journaled on a supportfI ing shaft 48 carried by the drawworks frame.

The pedal 41 is connected through arm 48 with a clutch operating rod 50, which rod 50 is in turn connected to arm 5I carried by a sleeve 52 secured to the clutch operating shaft 40.

When it is desired to manually' operate the brake system, means are provided for maintaining the clutch disengaged, which means include a latch 53 carried by the clutch pedal 41. The latch 53 is adapted to engage the frame of the drawworks to hold the latch pedal 41 down, thus holdingthe clutch disengaged. A spring 54 serves to hold the latch 53 in engagement.

In order to automatically set the brake bands 5 against the brake rims 4 when the fluid pressure in the system falls below the allowable minimum, the following means are provided:

Mounted in the cylinder 24 is a spring 55 which acts to normally urge the piston 25 to the brake releasing position. Thus the spring 55 acts to retrieve the piston 25 when the air pressure in the pipe 23 is reduced or shut oil?- entirely. Mounted adjacent the cylinder 24 is a brake setting cylinder 58 which carries a piston 51 having a piston rod 58.

The piston 51 is normally urged in a position to move the piston rod 58 against the piston 25 to overcome the effects of the spring 55 and to set the brake bands 5 against the brake rim 4.

For this purpose-a relatively strong spring..or

the piston 25 and at its opposite end it is provided with a latch element 60. The latch element by the closing of the master valve 20.

il is adapted to engage a pivoted latch element Il carried by the valve operating arm 32 5i' the master valve 2a, so that when the piston rod is moved under the influence oi the spring 59 latch yelement B engages the latchlelement 3| to rotate the master valve 20 to a closedposition. As the latch element 5I is pivotallyicarried by the valve arm 62, piston rod 58 is moved in a reverse direction without again opening the master valve, which may then be only opened manually, thus assuring that when pressure of the required magnitude is again established in the reservoir Il the master valve 20 will not be opened to immediately release the brake bands 3.

In order to exhaust the air pressure fromgthe cylinder 58 to permit the springs 59 to set the brake bands 5, an exhaust valve 63 is provided. The exhaust valve 83 includes a cylinder 64 within which a piston 65 is mounted. The cylinder 6B is connected with the pressure conduit 2| by means of a pressure conduit S3. 'I'he conduit is connected to the cylinder 64 in such position as to bring the lfluid under pressure below the piston 65 normally urging the same upward' to a position to close the exhaust vent 61. The piston 65 is moved ln the reverse direction by means of a balancing spring 38 set tov operate when the pressure in the conduit 2l falls below the allowable minimum. t

The cylinder St is connected by means of a conduit S9 with the cylinder 56 so that pressure is normally admitted below the piston 51 through the conduit 65 cylinder 64 and line 59. When the piston 65 is moved in the reverse direction under the influence of the spring 38, the same seats on closure seat 1closing this communication and opening communication from the, conduit 69l through the port 1l and exhaust passage 31, thereby exhausting the fluid under pressure within the cylinder 5t permitting the spring 59 to move the piston rod 53 downward against the piston 25 to move the brake arm 28 in a direction to set the brake bands E.

Means are provided whereby exhaust valve 63 may be actuated to rst set the brakes and close the master valve 203, which means include a lever 12 pivotally mounted on the cylinder and carrying a cam 13. The cam 13 engages a second lever .1t pivotally mounted on the cylinder @e through which lever 1t piston rod 15 extends.

This results, as heretofore set forth, in the setting` of the brakes;` f

The lever 12 is'connected by means of a cable 11 extending over direction Vpulley 18 to. the drillers position Where it is provided with an operating handle 19. Once actuated, the nose of the cam 13 acts tormaintain the exhaust valve operative as, of course, will be immediately done manuall operated brake lever 3S is posit'ilz'arrlid intermxediate the spaced `hubs 80 of the yoke 8l which is in turn fixed to the shaft N. Integrally connecting the spaced hubs 80 is an abutment bar B2 which the brake lever 36 is adapted to contact to turn the brake shaft i3.

` A latch 83 is pivoted on the brake lever 36 and compression spring 84 is provided to hold the latch 83 in engagement with the abutment bar 22. A release handle 3l is provided near the outer end oi' the brake lever 23 to enable the driller to vrelease the latch 32 from the bar 82 when desired;

An extension 88 on the rear ofthe latch 83 is Yprovided with a lug 31 which is adapted to engage .the complementary recess Il formed` on the under the recess 88 and the latch 83 is released at the *I open, thereby rendering the pressure system ini same time.

-' The operating valve 22, as is customary inl 'such structures. is provided with a vent 90 whereby theair under pressure may be exhausted into the atmosphere to permit the spring 55 to return the piston 25, thereby releasing brake bands 5 from the brake drums d.

The operation of this modification ofmy invention is that with the master valve 20 open to admit air under pressure into the conduit 2l, and assumingI that the clutch jaws 3i and 32 are engaged, and that the manual control lever 36 is in the inoperative position illustrated in Figure 6, air under pressure may be supplied to the brake setting cylinder 5t through the exhaust valve t3, compressing the spring 59 to hold the piston rod 53 in its rear or cocked" position. 'I'he driller may then actuate the valve 22 to control movement of the brake shaft it by admitting fluid under pressure into the cylinder 26. During such movement of the brakes by 'fluid pressure, the manual control lever 36 does not follow the movement of the brake shaft la because it is disconnected therefrom as illustrated in Figure 6. Thus danger of injury to the driller or .other members of the drilling crew is avoided. The releasev of the brake bands 5 is accomplished by moving control valve 22 to the oi" position whereby the air line 23 is vented to the atmosphere through the exhaust port 9G and the spring 55 retrieves the piston rod 26. v

If for any reason the pressure in the reservoir l1 should fall below the minimum value at which the operating cylinder 23 can safely hold the drum l under full load, the exhaust valve 63 immediately exhausts to the atmosphere -the pressure in the brakesetting cylinder 53. 'I'he spring at this time forces the piston rod 58 forward into contact with the piston 25 and moves the piston rod 36 and brake arm 28 forward against the eiect of the relatively weak It will be noted.

spring 55 to set the brakes. that this action occurs automatically without assistance from the driller.

It will be observed that the failure of the air pressure does not release the clutch members 3l and 32 and therefore the sleeve 30 remains operatively connected to the brake shaft is so that the emergency spring 59 acts to set the brakes. The clutch members 3l and 32 do not disengage because the exhaust valve 63 causes the emergency spring 59 toset the brakes bevalve 22.

of failure of the air pressure, but also provides an emergency means through which the brakes may be set at any' time by any vmember of the If for any reason it is desiredto operate the Y brakes manually as. for example, if adequate air pressure is not available or it is desired to rotate the drum I to raise the load after the air pressure has failed, the manually operable means for the brakes are connected and the fluid pressure operating means are rendered inoperative. This is accomplished by swinging manual ycontrol lever 36 down and latching the same inoperative position with respect to the brake shaft I4, as illustrated in Figure 5. The brakes are then held in set position by means of the lever 36 and at the same time another individual of the drilling crew inserts a bar (not illustrated) in the socket 9| of the sleeve 30 to relieve the pressure between the clutch jaws 3| andv 32. The clutch pedal 41 is then actuatedV to disengage the clutch jaws. If it is desired to continue the manual operation, the clutch pedal is locked down to the frame by means of the latch 53. A

On release of the sleeve 30 from the shaft I4, the spring 59 merely moves the piston 51 forwardly to the end of the cylinder 56. If it is l desired to -lock the clutch pedal 41 in raised position to prevent the accidental disengagement of the clutch 32 when the uid pressure actuating system of the brakes is being utilized, there is provided on the arm 49 a latch arm 92 which is moved to a position in alignment with a bracket 93 carried by the frame.

Complementary holes are formed through the

elements

92 and 93 to receive a. lock, pin, bolt,

padlock, or the like, 94, thus holding the clutch jaws 3| and 32 in engagement against accidental release. J

If this precaution has been taken, it would, of course, be necessary to remove the latch element 94 before attempting the manual opera-- tion.- When it is desired to return to fluid pressure operation f rom manual operation, the operator, through the medium of the manual lever 36, holds the brakes in applied position while the master valve 20 is manually opened. As' suming there is then -sufcient pressure in the reservoir I1, the exhaust valve 63 is moved immediately to close the exhaust vent and admit pressure under the piston 51 to re-compress the spring 59. 'I'he clutch control cylinder 34 then moves the piston 31 in the direction to re-engage the clutch jaws 3| and 32, this movement being permitted by Jrelease of the latch member 53..

Re-engagement of the clutch jaws 3| and 32 is accomplished by actuation of the control valve 22 to bring the said jaws into correct relative position, at which time full engagement will occur under the impulsel imparted to the jaw 32 from the clutch cylinder 34. The driller may then hold the brake bands 5 in applied position by means of the service valve 22 while he actuates the release 85 and swings the control lever 36 back to the inoperative position of Figure 6.

The exhaust valve 63 not only provides an automatic means for setting the brakes in event crew in case of any ,emergency arising. This emergency setting of the brakes may be accomplished by any member of the crew at any time of any emergency 'by merely pulling upon the cable 19, which action, as heretofore set forth,

qas it allows for an immediate setting of the brakes at any time as is often required in drillingoperations to prevent dropping of the load as carried by the line spooled on the drum I in case of failure of any other part of-the system.

In the modied form of my invention as illus--y trated in Figures 8, 9 and 10, similar parts have been indicated with a similar numeral. with the addition-of an exponent b" thereto.

The principal difference between this modified form of my invention and that as illustrated and described with respect to Figures 1 to 7, inclusive, is that in this modification Iv have dispensed with the clutch including the clutch jaws 3| and 32 for the fluid pressure control systemtogether.

spring |01 is provided to maintain the latch I member |06 in engaged position. If desired, an

opening |08 may be provided in the bumper bar v |05 through which a pin, latch, or other means may be inserted to prevent untimely withdrawal l of the bumper bar.

The operation of this form o'f my, invention is similar to that heretofore described. In so far as the manual control is concerned, it differs only in the manner of the operative connections provided between the brake arm 20h andthe brake shaft I4". When the manual controllever 36h is in its inoperative position and the brakes are being operated by air pressure, the link 28b controls the movement of the brake shaft I4b through the crank |00, bumper bar |05 and latch |06. In the event that the brake-setting cylinder 55 should come into play and set the brakes either because of yfailure of air pressure or as a result of actuation ofthe emergency cable 19, manual control may be resorted to. Manual control is established by swinging the manual control levers 36b'downward into operative position to hold the brake bands 5b in applied position and the connection between the brake actuating arm 28b and brake shaft I4b is disrupted by relieving `the pressure between the crank arm |00 and the bumper bar |05 by inserting a bar (not shown) in the recess 9| b of the sleeve |0I. The pressure thus relieved, the bumper bar |05 is withdrawn acacia p laterally from the openings in the side bars 102, thus disconnecting the fluid pressure system from the brake shaft Mb.

Having fully described my invention, it is to be understood that I do not wish to be limited to the details herein set forth, but my invention is of the full scope of the appended claims.

Iclaim:

l. In a device for operating a friction brake, the combination of a brake shaft, connecting means whereby the brake shaft may actuate said friction brake, a supply conduit adapted 'to deliver fluld under pressure, a master valve in saidv 'terposed between the master valve andthe pressure responsive means for the emergency control means, said protective valve acting to de-energize the pressure responsive means for the emergency control means upon the uid pressure in the protective valve falling below a predetermined value, and thereby permit the resilient means to actuate the brake shaft to apply the brake, and means associated with said emergency control means adapted toclose the master valve upon movement of the emergency control means to apply the brake.

acting in a direction to vapply the brake and pressure responsive means adapted to oppose such action of the spring, means interposed between the uid pressure supply conduit and the emergency control cylinder adapted to de-energize the pressure responsive means upon the vpressure in the supply conduit falling below a predetermined magnitude, whereby the spring may actuate the crank to apply the, brake.

4. Ina device for operatingv a friction brake,

.. the combination of a' brake shaft, connecting 2. In a device for operating a friction brake, o

the combination of a brake shaft, connecting means whereby the brake shaft may actuate said friction brake, a supply conduit adapted to deliver uid under pressure, service control means for said brake shaft including pressureresponsive means adapted to actuate said brake shaft, a passage connecting the supply conduit and the service control means, a service valve operatively interposed in said passage and adapted to regulate the degree of fluid pressure acting on said pressure responsive means, an emergency control means for said brake shaft including resilient means acting in a direction to set the brake and pressure responsive means normally acting to oppose such action by the resilient means, a protective valve operatively interposed between the supply conduit and the pressure responsive means for the emergency control means, said protective valve acting to de-energize the pressure responsive means for the emergency control means upon the Afluid pressure in theprotective valve falling below a predetermined value, whereby the resilient means may actuate the brake shaft to set the brake.

3. In a device for operating a friction brake, the combination of a brake shaft, connecting means whereby the brake shaft may actuate said friction brake, a supply conduit adapted to deliver uid under pressure, a crank operatively connected to said brake shaft, a service control cylinder responsive to uid pressure and adapted to actuate said crank, a service valve operatively interposed between said supply conduit and said service control cylinder and adapted to regulate uid pressure in the latter, an emergency control cylinder positioned in tandem relation with respect to said service control cylinder and adapted to actuate said crank, means associated with means whereby the brake shaft may actuate said friction brake, a supply conduit adapted to deliver fiuid under pressure, -a crank rotatably mounted' on said brake shaft, releasable means selectivelyy operable to connect the crank with said brake shaft, a` service control cylinder responsive to fluid pressure and adapted to actuate said crank, a service valve operatively interposed between said supply conduit andsaid service control cylinder and adapted to regulate fluid pressure in the latter, an emergency control cylinder positioned inl tandem relation with respect to said service control cylinder and adapted to actuate said crank, means associated with said emergency control cylinder including a spring acting in a direction to apply the brake and pressure responsive means adapted to oppose such action of the spring, means interposed between the fluid pressure supply conduit and the emergency control cylinder adapted to de-energize the pressure responsive means upon the pressure in the supply conduit falling below a predetermined magnitude, whereby the spring may actuate the crank to apply the brake.

5. In a device foroperating a friction brake, the combinationof a brake shaft, connecting means whereby the brake shaft may actuate said friction brake,'a fluid pressure supply conduit, a master valve in said conduit, a service cylinder having a service piston and rod therein, operaf tive connections whereby the service piston rod may actuate the brake shaft, a service valve operatively interposed between the master valve and y the service cylinder and adapted to regulate the degree of iuid pressure acting against the service piston and rod when the master valve is in open gency piston rod may contact the service piston, a spring associated with said emergency cylinder adapted to move said emergency piston rod toward said service piston, fluid pressure supply means connecting said emergency cylinder to said conduit, the pressure in said emergency cylinder normally acting to oppose the force of the spring to maintain the emergency piston and rod in inoperative position, a protective valve associated with said fluid pressure supply means and adapted to exhaust the pressure in the emergency cylinder upon the fluid pressure in the said conduit falling below a predetermined value, the spring automatically forcing the emergency piston rod to movey the service piston and'rod to' apply the brake u pon exhaust of the emergency cylinder,

tive to the brake shaft, pressure responsive means;

operativelyy connected to actuate said member, a

said emergency` control cylinder including a spring l 6 l afstaan;`

uid pressure supply conduit communicating with said pressure responsive means, a vvalve associated with said conduit adapted to control the operation of said pressure responsive means, releasable means to connect said member with the brake shaft in non-rotatable relation, and auxiliary pressure responsive means connected to said conduit and acting to maintain said releasable means in engaged position.

7. In a device for operating a friction brake. the combination of a brake shaft, connecting means whereby the brake shaft may actuate said friction brake, a supply conduit adapted t6" deliver fluid under pressure, al master valve in said conduit, a member rotatably mounted on said i brake shaft, releasable clutch means selectively operable 4to engage said member with said brake shaft, an auxiliary cylinder responsive to iluid pressure and operatively interposed between said master valve and said clutch means, said auxiliary cylinder acting to maintainv said clutch means in engaged position while said master valve is in open position, a'service control cylinder re- ,Y

sponsive to iluid ypressure and operatively con-T nected to actuate said member, a, service valve i operatively inteosed between said master valve and said service control cylinder and adapted to control the operation of the latter,vand means acting automatically to close said master vaiveupon the pressurein the 'supply conduit falling below a predetermined magnitude. l

r 8. In 'a fluid pressure device for operating the brakes of a drawworks, the combination of a uid pressure supply conduit, a brake shaft, a lever on said shaft whereby the brakes may be manually operated, a member rotatably mounted on said brake shaft, releasable clutch means adapted to operatively connect lthe member to the brake shaft, pressure responsive means adapted to actuate said member to control the operation of the brakes, valve means operatively interposed between said supply conduit and said pressure responsive means and adapted to control the operation of the latter, auxiliary uid ,.pressure means connected to said supply conduit 5 normally acting to maintain said clutch means in engagement, and shifter means manually -operable to release said clutch means.

9. In a rotary drawworks having a spooling drum and a friction brake for said spooling drum, the combination of a brake shaft, connecting means whereby the brake shaft may actuate said friction brake, a supply conduit adapted to deliver fiuid under pressure, service control means for said brake shaft including pressure responsive means adapted to actuate said brake shaft, a service valve operatively interposed between said supply conduit and said service control means and adapted to regulate operation of the latter,

an emergency cont'rol means for said brake shaft including resilient means acting in a direction to set the brake and pressure responsive means normally acting to oppose such action by the resilient means, a protective valve operatively interposed between the supply conduit and the pressure responsive means for the emergency control means, said protective valve being operable independently of the emergency control means and adapted to automatically de-energize the pressure responsive means for the emergency control means upon the fluid pressure in said conduit falling below a predetermined magnitude, and manually operable means including an emergency cable connected to said protective valve whereby the pressure responsive means for the 5 10. In a drilling rig including a drawworks having a spooling drum and a friction brake'for said spooling drum, the combination of a brake shaft, connecting means whereby the brake shaft may actuate said friction brake, a supply conduit adapted to deliver uid under pressure, service control means for said brake shaft including pressure. responsive means adapted to actuate said brake shaft, a service valve operatively interposed between said supply conduit and said service control means and adapted to regulate operation of the latter, a manually operatedcontrol lever for said service valve', an emergency control means for said brake shaft including a cylinder having a piston therein and a rod for` said piston, spring means acting to move saidrod in a direction to apply the brake, means to' admit fluid pressure 'from said conduit into said ,cylinder whereby the piston normally acts-to oppose such movement of the rod, and

manually operable means adapted to exhaust the pressure in said cylinder to permit the spring to apply the brake, said manually operable means including an emergency cable which may be actuated in emergency from any one of a plurality of locations remote from said service valve control lever.

11. In a drawworks having a spooling drum and a friction brake for said spooling drum, the combination of a lbrake shaft, connecting means .whereby the brake shaft may aCctuate the friction brake, a pair of crank members secured on said brake shaft in fixed angular relation, a lever associated with each o'f said crank members and pivotally mounted upon said brake shaft,

40 an abutment element operatively interposed bev tween each crank member and its respective lever whereby movement of either lever in one direction acts to turn the brake shaft in that direction, a releasable latch operatively interposed between one of said crank members and its respective lever whereby movement'of said lever in the other direction acts to turn the brake shaft iny the other direction, the abutment element for the otherlof said crank members being removable to permit operation of the brake shaft independently of the lever associated therewith, the lever having the latch being adapted for manual operation, and fiuid pressure means operatively connected to operate the other lever.

12, In a device for operating a friction brake, the combination of an actuating element, means whereby the actuating element may operate the friction brake, resilient means acting on said ac tuating element to apply the friction brake, pres sure responsive means .associated with said actuating element .and adapted to' oppose such action of the resilient means, means adapted to supply fluid under pressure to said pressure responsive means, and means operable independent ly of the pressure responsive means and adapted to vent the fluid pressure in the pressure responsive means upon said pressure falling below a predetermined value, whereby the resilient means may move the actuating element to apply the friction brake.

f 13. In adevice for operating a friction brake,

the combination of an actuating element. connecting means'whereby the actuating element 'may operate the friction brake, resilient means acting on said actuating element to apply the y 2,282,615 f l 7 friction brake, pressure responsive means associated with said actuating element and adapted to oppose such action of the resilient means, a conduit adapted to supply fluid under pressure to said pressure responsive means, a valve in said conduit means adapted to vent the fluid pressure in the pressure responsive means upon said'pressure falling below a predetermined value, whereby the resilient means may move the actuating element to apply the friction brake, and meanstion brakeresiiient means acting to urge said V posed, and a protective valve automatically and associated with said actuating element adapted to close the valve upon movement of the actuating element to apply the friction brake.

14. In a device for operating a friction brake, the combination oia. cylinder having a piston slidably mounted therein, a piston rod secured to said piston, connecting means whereby the piston rod may actuate the friction brake, resilient means acting to urge said piston rod in a direction to apply the friction brake, means including a conduit to supply fluid under pressure to said piston and cylinder whereby such action of the resilient means maybe pneumatically opposed, and a protective valve operable independently of said piston and adapted to vent the cylinder to atmosphere in the event the fluid pressure therein falls below a predetermined value, whereby the resilient means may move the piston rod to apply the friction brake;

15. In a device for operating a friction brake,

` the combination of a service control cylinder responsive to air pressure `and operatively connected to actuate the friction brake, means adapted to deliver air under pressure to said service control cylinder, a self lapping valve operatively associated with said means and adapted to regulate the degree of pressure in said service control cylinder, an emergency control cylinder having an element adapted to actuate the fricindependently operable in the event that the air pressure available for actuating the service control cylinder falls below a predetermined value and adapted to vent the emergency control cylin der toatmosphere, whereby the resilient means may move said element to apply the friction brake.

vaisle independently of the pressure responsive means adapted upon decrease in availablesupply line pressure to reduce the pressure in the pressure responsive means to a value below that in the supply line.

17. In a device for actuating a friction brake, the combination of pressure responsive means .adapted for service operation of the brake, a pressure supply line for said means, emergency means for applying the brake upon failure or reduction of supply line pressure including a spring acting in a direction to apply the brake and a second pressure responsive means for opposing the spring, and means automatically operable independently of the pressure responsive means adapted to vent said second pressure responsive means upon reduction of supply line pressure whereby the spring may apply the brake.

JOHN D. SPALDING.