US2075706A

US2075706A - Rock drill

Info

Publication number: US2075706A
Application number: US706997A
Authority: US
Inventors: John C Curtis
Original assignee: Cleveland Rock Drill Co
Current assignee: Cleveland Rock Drill Co
Priority date: 1934-01-17
Filing date: 1934-01-17
Publication date: 1937-03-30
Anticipated expiration: 1954-03-30

Description

March 30, 1937. J. c. CURTIS ROCK DRILL Filed Jan. 17, 1934 3 Sheets-Sheet 1 JOHN C. 60 6775 INVENTOR ATTORNEY March 30, 1937. c cu s 2,075,706

ROCK DRILL 3 Sheets-Sheet 2 Filed Jan. 1'7, 1954 JOHN c. c u: 775

' 6 INVENTOR ATTORNEY March 30, 1937. J. c. CURTIS ROCK DRILL Filed Jan. 17, 1934 I5 Sheets-Sheet 3 A, la

JOHN C. CORT/5 INVENTOR ATTORN EY Patented Mar. 30, 1937 UNITED STATES PATENT OFFICE to The Cleveland Rock Drill land, Ohio, a corporation of Ohio Application Jamar-1 17, 1934, Serial No. roam 21 Claims. (01. 121-9) This invention relates broadly to rock drills, but more particularly to a valvular mechanism for controlling the action of the feeding mechanism thereof.

One object of this invention is to provide an improved valvular mechanism for regulating the speed of a feeding mechanism for rock drills.

Another object of this invention is to produce an improved feeding mechanism for 'rock drills,

wherein the rate of feeding speed in one direction may be regulated at the will of the oper-.

ator.

Other objects and advantages more or less ancillary to the foregoing resides in the specific construction and aggroupment of the elements peculiar to this structure, as will become apparent from a more complete examination of this specification.

In the drawings which illustrate one form which the invention may assume in practice:

Fig. l is a view illustrating the complete drilling apparatus together with a portion of the frame on which the former is movably mounted. Fig. 2 is an enlarged cross sectional view taken a plane indicated by line 2-2 in Fig. 1. Fig. 3 is an enlarged view illustrating the clamping device by which the drilling apparatus is secured to its supporting frame.

Fig. 4 is an enlarged sectional" view illustrating 30 tFliie interior of the feeding mechanism shown in g. Fig. 5 is an enlarged sectional view of the valvular mechanism embodying the invention.

Figs. 6 and 7 are perspective views illustrating 35 the locking device used for securing the throttle valve into any desired position.

Figs. 8, 9; and 10 are cross sectional views taken in a plane indicated by line 8--8 in Fig. 5,

illustrating the throttle valve in different posi- 40 tions.

Figs. 11, 12, and 13 are cross sectional views taken in a plane indicated by line ii-li in Fig. 5, illustrating the throttle valve in the positions shown in Figs. 8, 9, and 10.

Fig. 14 is an enlarged view, partly in section,

illustrating the relation of the throttle valve handle with a portion of the valvular mechanism shown in Fig. 5. I

Fig. 15 is a cross sectional view taken in a plane 50 indicated by line i5-i5 in Fig. 5.

Referring to the drawings in which like characters designate corresponding parts through the several views, i0 represents a truck frame which may be anchored by means of pins ii which are 55 detachably secured to the side members of the frame. Detachably secured to-the frame In by bolts ii. there is a U-shaped cross member l2, having mounted therein a feed tube H. Alflxed to the exterior of the latter, there are two parallel guides l8, upon which a rock drill i8 is free to slide. Secured within the feed tube ii at a place substantially equi-distant from the ends thereof, there is a partition I'I dividing the feed tube l4 into an upper and lower portion i8 and I9. Reciprocably mounted within the portion i8, there is a feeding element or piston 20, and similarly mounted within the portion l9, there is a piston 2i, the latter being united to the former by a piston rod 22, which is reciprocably mounted through the partition ii. The pistons 20 and 2! are constructed to rotatably receive a sprocket 22. Adjacent each end of the feed tube I, there is rotatably mounted a sprocket 24. These sprockets are capable of engagement with a chain 25 having the ends thereof secured to a point adjacent the ends of the tube l4. At a point substantially equi-distant from its ends, the chain 25 is also attached to the rock drill I6. The construction of the feeding mechanism comprising the pistons 20 and 2|, together with the disposition of the

sprockets

23 and 24, and the chain 25, being identical to the construction described in my pending application filed February 2, 1933, Serial No. 654,802, now matured into Patent No. 2,029,223, patented January 28, 1936, no further description of the same is thought necessary.

Secured to the lower end of the feed tube I, there is a front head 28 which is formed, on the end face thereof, with a semi-circular groove 21 of a diameter equal to that of the cross member i2, and capable of engagement with the latter. The four comers of the front head are provided with apertured lugs 28 adapted to receive the bolts 29. Corresponding to the shape of the front end portion of the front head 26, there is a cap 30 which is also provided with apertured lugs similar to the lugs 28 of the front head 26, through which the bolts 29 are free to pass to receive the nuts 32 for securing the feed tube assembly to the cross member I2. Secured to the upper end of the feed tube l4, there is a back head 33 which is a replica of the front head 28. These two heads are secured to the feed tube I by a pair of rods 34.

Affixed to one side of the feed tube l4, there is a motive fluid conveying conduit or pipe 35, equipped with a throttle valve 38 for controlling the admission of the pressure fluid into the rock drill 86, which is admitted therein through a hose 8i.

Adjacent the pipe 86, there is another pressure fluid conveying conduit 88 admitting pressure fluid into a throttle valve housing 38. This housing is formed with a cylindrical valve chamber 46, having rotatably mounted therein a throttle valve 4|, formed with a shank 42 extending from the valve housing 89 through a restricted bore 48.

10 The right end oi? the chamber 46 is threaded as at 44 to receive, in screw tight engagement therewith, a plug 45 formed with a counterbore 4'6 adapted to slidably receive a locking member 41. This last member is formed with an enlarged head 48 slidably guided within the chamber 46. To

prevent the rotation of the member 41, the latter is provided with a slot 49 adapted to receive a pin 56 secured within the plug 45. The end surface of the head 48 is provided with radially disposed ratchet teeth 5| which are capable of engagement with corresponding teeth 52 formed on the adjacent end surface of the throttle valve 4|. The member 41 is constantly urged against the throttle valve 4| by the action of a compression spring 58 interposed between the plug 45 and the head 48 of the member 41, thus maintaining the teeth of the latter in constant engagement with the teeth of the throttle valve 4|. The pressure fluid conduit 88 is connected to the throttle valve housing 89 as at 54, thus admitting pressure fluid into the valve chamber 46 directly under the head 48 of the member 41 through a passage 55, from where pressure may be admitted into a centrally disposed bore 56, formed within the member 41, through a plurality of radially disposed passages 51. The bore 56 opens into the slot 49 for admitting pressure fluid on the extreme end of the member 41 for the reasons explained hereinafter.

Adjacent to the valve chamber 46, the housing 89 is provided with another bore or chamber 58 having, reciprocable therein, a valve 59. This valve is formed with an external annular recess 66. Each end of the valve is properly machined to form the counterbores 6| and 62, the latter being in constant communication with the recess 66 through a restricted orifice 68. Secured in screw tight engagement within one end of the bore 58, there is a plug 64, having seated thereon one end of a. compression spring 92, while the other end thereof is seated on the bottom of the counterbore 62. Reciprocably mounted within the other end portion of the bore 58, there is a cap 65 formed with a counterbore 66 adapted to receive one end of a compression spring 61. The other end of this spring is seated on the bottom wall of the valve counterbore 6|.

Intermediate its ends, the bore 58 is formed with two annular recesses 68 and 69 capable of 00 intercommunication through the valve recess 66. The recess 68 may also communicate with the throttle valve chamber 46 through a passage 16, while the recess 69 is capable of constant communication with the upper portion l8 of the feed tube l4, through a conduit 1|, which terminates therein at a point adjacent the partition H.

The throttle valve 4| is provided with a centrally disposed bore 12 capable of constant communication with the bore 56 of the member 41. 70 Leading from the bore 12 to the circumferential wall of the throttle valve, there are two radially disposed

passages

18 and 14, the former being capable of communication with the passage 16,

while the latter is capable of communication with the lower portion l8 of the feed tube l4, through a conduit 15, which terminates therein at a point adjacent the partition l1. In a. cross sectional plane passing through the passage 18, the throttle valve 4| is formed with a groove 16 opening into the passage 18, and with a partly circumferentially disposed groove 11 capable of establishing communication between the passage 16 and another passage 18 which leads into the upper end of the feed tube l4. Similarly disposed in relation to the passage 14 the throttle valve 4| is formed with another partly circumferentially disposed groove 19 capable of establishing communication between the conduit 15 and another passage'86, which leads into the lower end of the feed tube l4. Intermediate the grooves 11 and 19, the throttle valve 4| is provided with a port 8| and a groove 82 opening therein and capable of admitting pressure fluid from the throttle valve bore 12 into the bore 58 through a port 88.

Secured to the shank 42 of the throttle valve 4| by means of a key 84 and nut 85, there is a handle 86. This handle is formed with an enlarged semicircular flange 81 extending over the cap 65, and capable of engagement therewith. For about the face of the flange 81 engageable with the end of the cap 65 is machined into a helical cam 88, the purpose of which will be explained later.

The operation of the mechanism is as follows: Assuming the throttle valve 4| tobe positioned as illustrated in Figs. 8 and 11, motive fluid admitted into the throttle valve chamber 46 through the conduit 88 and passage 55, will act on the head 48 of the member 41. From the chamber 46, motive fluid will flow into the bore 56 of the member 41, via the ports 51, to be admitted on the extreme end of the member 41 through the slot 49, thus cooperating with the pressure fluid acting on the head 48 together with the action of the compression spring 58 for maintaining the engagement of the teeth 5| with the teeth 52 of the throttle valve. Since the member 41 is held against rotation by the pin 56, it will be understood that the throttle valve 4| may be maintained into any desired position. When manual power is applied to the throttle valve handle 86 for rotating the throttle valve 4|, the teeth 52 of the latter engaging the teeth 5| of the member 41, will eilect a camming action causing the member 41 to move toward the right against the action of the pressure fluid thereon, permitting thereby a step by step rotation of the throttle valve. From the bore 56, motive fluid will flow into the throttle valve bore 12, to be admitted therefrom into the lower portion |9 of the feed tube l4, via the throttle valve passage 14 and conduit 15. Motive fluid admitted into the feed tube |4 through the conduit 15, will act on the piston 2| to drive the latter, together with the piston 26 by means of the piston rod 22, downwardly. The chain 25 passing over the sprocket 28 now driven downwardly, will cause the upward movement of the rock drill l6.

Motive fluid previously admitted into the upper portion l8 of the feed tube M, will now exhaust therefrom through the conduit 1|, valve 'groove'66, passage 16, throttle valve groove 11 and conduit 18 into the upper end of the feed tube l4. The chain 25 leading from the upper sprocket 24 to the rock drill is free to move into or out of the upper portion I 8 of the feed tube |4 through an opening 96. The conduit 18 terminates into the feed tube adjacent the opening 96 as shown in Fig. 4, thus permitting the fluid mom-ice from the conduit I8 to'exhaust to the atmosphere through the opening 90. In this manner, any foreign matter such as dust resulting from the drilling operation. which may have collected on .the portion of the chain located in the exterior of the feed tube, will be blown off from the chain before the engagement of the latter with-the upper sprocket 28.

The exhausting fluid flowing from the passage the communication of the passage 18 with the conduit 18 through the groove 'l'l, pressure fluid from the throttle valve 8| is admitted into the bore 88 through the ports 8| and 83, thus cooperating with the compression spring 81 to ex ert pressure on the spool valve 88 to maintain 2 the latter against the plug 84.

During the travel of the throttle valve fromthe oi! to the open position, the amount of motive fluid admitted into the lower portion ll of the feed tube It, may be varied by a' more or less complete communication of the throttle valve passage 14 with the conduit I8. The move ment of the throttle valve handle engaging the cap 88, will not vary the tension of the com-' pression spring 61, since the cam 88 provided on the handle flange does not extend to that engaging portion of the throttle valve handle. Therefore, it will be understood that the admission of the motive fluid into the lowerportion ll of the feed tube It, may be regulated by the throttle valve Ii, without affecting the operation of the spool valve 89, other than maintaining thelatter into one extreme position by the action of the" pressure 'fluid admitted thereon through the ports 8i and 88. i

From the oil position shown in Figs. 9 and 12, the throttle valve 8! may be rotated into the open position as shown in Figs. 10 and 13, for admitting pressure fluid into the upper portion ll of the feed tube ll from the throttle bore I2, through the throttle valve passage 18, passage I0, groove 88, valve groove 60, groove 88 and flnally passage II. on the piston 20 will cause the upward movement of the latter as well as the upward movement of the piston 2| through the piston rod connection 22. The upward movement of the piston 2i and the consequential movement of the sprocket 28, will cause the chain passing over the last sprocket to transmit downward feeding motion to the rock drill. Pressure. fluid previously admitted into the lower portion I! of the feed tube ll may now exhaust therefrom through the conduit I5, throttle valve groove 18 and conduit 88, which terminates into the extreme lower end of the feed tube ll adjacent the lower opening 9! through which the chain 28 is free to move into or out of the lower portion' I 9 of the feed tube II. The motive fluid exhausting from the conduit 80, will clean the chain 25 as previously explained in connection with the exhaust of the motive fluid through the conduit 18. Motive fluid admitted into the spool valve groove 60, will also flow into the valve counterbore 62, thus cooperatingwith the tension of the compression spring 92 for 75 shifting the valve 59, upwardly against the ten- The motive fluid admitted sion of the compression spring 81. When the throttle valve is positioned as illustrated in Figs. 10 and 13, the cam 88 formed on the valve handle flange 81, is beginning its engagement with the cap However, since the rise of the cam at that point is negligible, the tension of'the spring 81 will remain practically unchanged, thus permitting the valve 58 to be shifted toward the left by the action of the motive fluid admitted into the counterbore 82 thereof through the port 53. The shifting of the valve 89 will tend to prevent the communication of the valve groove 60 with the groove 88, thus restricting the flow of the motive fluid from the port I0 into the port II,

or into the feed tube ll, reducing thereby the rate of speed of the piston 20, together with the rate of speed of the rock drill feeding motion. In this instance, the restricted flow of the motive fluid into the feed tube i8 is calculated to provide a rather slow feeding motion of the rock drill, which has been found desirable when drilling in hard and abrasive rock. when it is desired to' increase the rate of the feeding speed of the rock drill, the operator may rotate the throttle valve handle downwardly, thus causing through the cam 88, the movement of the cap 68 toward the valve 88, and consequently increasing the compression of the spring 61. In this instance, the throttle valve groove 16 is in communication with the passage 10, thereby admitting motive fluid into the upper portion l8 of the feed tube 14 as previously explained. The motive fluid admitted into the valve counterbore 82 through the into the upperportion ill of the feed tube It, with a consequential increase of the feeding speed of the rock drill l8. It will now be understood that the pressure within the upper portion |8 of the feed tube I4 is adapted to remain constant fora predetermined position of the throttle valve handle 86, and irrespective of the feeding speed of the drilling motor in one direction. The pressure of the fluid admitted in that portion of the feed tube through the conduit ll, does not have the opportunity to vary when the throttle valve handle remains stationary, since any variation of the pressure will immediately cause the movement of the valve 89 for increasing or reducing the flow of the fluid through the groove 68. For instance, when the valve 55 15 positioned as illustrated in Fig. 5, a relatively large amount of fluid is admitted into the upper portion of the feed tube l9, thus causing a relatively fast movement of the rock drill due to a certain pressure acting on the piston'2ll. When the speed' of the rock drill is retarded due to a difference of hardness of the rock being drilled,

the pressure acting on the piston 20 immediately tends to increase, thus also increasing" the pressure into the chamber 82 through the port 53. The valve 59 subjected to an increased pressure will shift toward the cap for immediately reducing'the amount of pressurefluid admitted into the upper portion l8 of the feed tube l4, therebv maintaining the pressure acting on the piston 20 substantially constant irrespective of the feed ng speed of the rock drill. It will also be understood that the feeding speed of the rock drill l6 may be varied by simply rotating the throttle pletely set forth the invention, it is to be understood that the specific terminology is not intended to be restrictive or confining and it is to be further understood that various rearrangements of parts and modification of structural detail may be resorted to without departing from the scope or spirit of the invention is herein I claim:

1. In a drilling apparatus the combination with a drilling motor, of a feeding mechanism therefor including a feed tube having a fluid actuated feeding element reciprocable therein for imparting feeding motion to said drilling motor, a throttle valve for controlling the admission of a predetermined amount of pressure fluid into passages leading into said feed tube, a handle secured to said throttle for operating the same,

means movable into one direction by the action of the pressure fluid admitted thereon for restricting the flow of the pressure fluid through one-of said passages, and means including said throttle valve handle for variably limiting the movement of said first mentioned means into said one direction, permitting thereby a more or less restricted flow of the pressure fluid through said one passage.

2. In a drilling apparatus the combination with a drilling motor, of a feeding mechanism therefor including a feed tube having a fluid actuated feeding element reciprocable therein for imparting feeding motion to said drilling motor, a throttle valve for controlling the admission of a predetermined amount of pressure fluid into passages leading into said feed tube, a handle secured to said throttle for operating the same, means movable into one direction by the action of the pressure fluid admitted thereon for restricting the flow of the pressure fluid through one of said passages, and means including a cam on said throttle valve handle for variably limiting the movement of said first mentioned means into said one direction, permitting thereby a more or less restricted flow of the pressure fluid through said one passage.

3. In a drilling apparatus the combination with a drilling motor, of a feeding mechanism therefor including a feed tube having a fluid actuated feeding element reciprocable therein for imparting feeding motion to said drilling motor, a throttle valve for controlling the admission of a predetermined amount of pressure fluid into passages leading into said feed tube,means within said throttle valve permitting a limited oscilla tion of the latter without affecting said admission,

a handle secured to said throttle valve for oscillating the latter, means movable into one direction by the action of the pressure fluid admitted thereon for restricting the flow of the pressure fluid through one of said passages, and means responsive to the movement of said handle during the oscillation of said throttle valve for variably limiting the movement of said first mentioned means into said one direction, permitting thereby a more or less restricted flow of the pressure fluid through said one passage.

4. In a drilling apparatus, the combination with a drilling motor, of a fluid actuated feeding length of travel of said mechanism connected to said drilling motor for imparting feeding motion thereto, a throttle valve for controlling the admission of the pressure fluid into passages leading into said feeding mechanism for actuating the same, a handle secured to said throttle valve for operating the latter, a valve movable into one direction by the action of the pressure fluid thereon for restricting one of said passages resilient means for normally limiting the movement of said valve into said one direction, and means including a cam on said handle for variably increasing the compression of said resilient means, affecting thereby the valve into said one direcion and the consequential restriction of said one 5. In a drilling apparatus, the combination with a drilling motor, of a fluid actuated mechanism connected to said drilling motor for feeding the latter, a rotatable throttle valve for controlling the admission of the pressure fluid into passages leading into said feeding mechanism for actuating the same, a handle secured tosaid throttle valve for rotation therewith, means responsive to the action of the pressure fluid thereon for reducing the feeding speed of said drilling motor in one direction irrespective of the feeding speed of said drilling motor in the other direction, and means responsive to the rotation of said handle for increasing the flrst mentioned feeding speed of said drilling motor.

6. In a drilling apparatus, the combination with a drilling motor, of a feeding mechanism therefor including a feed tube having a fluid motor for transmitting the reciprocation of the former to the latter, anopening through which said flexible member is free to be pulled into said feed tube by said piston, means for admitting and exhausting pressure fluid into and from said feed tube for actuating said piston, and means for directing'the fluid exhausting from said tube on said flexible member during its passage through said opening on its way into said feed tube.

7. In a drilling apparatus, the combination with a drilling motor, of a feeding mechanism therefor including a feed tube having a fluid actuated piston reciprocable therein, a flexible member connecting said piston to said drilling motor for transmitting the movement of the former to. the latter, a wheel upon which the portion of the flexible member extending between said piston and said drilling motor is free to ride, passages for admitting and exhausting pressure fluid into and from said feed tube, and means for directing pressure fluid on the portion of said flexible member extending between said wheel and said drilling motor prior to its engagement with said wheel. I

8. In a drilling apparatus, the combination with a drilling motor, of a feeding mechanism therefor including a feed tube having a fluid actuated piston reciprocable therein, a member connecting said piston to said drilling motor for transmitting the reciprocation of the former to the latter, an orifice through which said member is free to move into or out of said feed tube, means for nmdtiitting pressure fluid into said feed tube for admission of the pressure fluid into passages leading into said feeding mechanism for actuating the same, means for normally reducing the feeding speed of said drilling motor in one direction irrespective of its feeding speed in the other direction, and unitary means for operating said throttle valve and for increasing the first mentioned feeding speed of said drilling motor.

10. In a drilling apparatus, the combination with a drilling motor, of a fluid actuated feeding mechanism connected to said motor for imparting feeding motion thereto, at least one 'fluid conveying port for admitting and exhausting motive fluid to and from said feeding mechanism, a valve automatically movable for varying the motive fluid conveying capacity of said port during the inlet travel of the motive fluid through said port, and means independent of said port for pneumatically shifting and maintaining said valve in one predetermined position during the outlet travel of the motive fluid through said port.

11. In a drilling apparatus, the combination with a drilling motor, of afluid actuated feeding mechanism connected to said motor for imparting feeding motion thereto,a fluid conveying port for admitting and exhausting motive fluid to and from said feeding mechanism, a valve automatically movable for varying the motive fluid conveying capacity of said port during the inlet travel of the motive fluid through said port, a throttle valve for initially controlling the admission and exhaust of the motive fluid through said port, and a passage controlled by said throttle valve for admitting motive fluid on said valve for shifting and maintaining the same in a predetermined position during the outlet travel of the motive fluid through said port.

12. In a drilling apparatus, the combination with a drilling motor, of a fluid actuating feeding mechanism connected to said drilling motor for feeding the latter, a motive fluid inlet controlling valve for normally controlling the admission of the motive fluid into a passage leading into said feeding mechanism for actuating the same, a

pressure controlling valve movable for varying the pressure of the motive fluid actuating said feeding mechanism, and a single element manually operable for causing the rotation of one of said valves and the slidable movement of the other, effecting thereby a variation of the pressure of the motive fluid actuating said feeding mechanism without afiecting the admission of the motive fluid into said passage.

13. In a drilling apparatus, the combination with a drilling motor, of a fluid actuating feeding mechanism connected to said drilling motor for feeding the latter, a motive fluid inlet controlling valve for normally controlling the admission of the motive fluid into a passage leading into said feeding mechanism for operating the same, a pressure controlling valve movable for varying the pressure of the motive fluid actuating said feeding mechanism, unitary means manually operable for simultaneously causing the movement of said valves, efiecting thereby a variation of the pressure of the motive fluid actuating said feeding mechanism due to the movement of one of said valves, and means for maintaining constant the admission of the motive fluid into said passage irrespective of the corresponding movement of the other of said valves.

14. In a drilling apparatus, the combination with a drillingmotor, of a fluid actuated feeding mechanism connected to said drilling motor for imparting fee ng motion thereto, a motive fluid conveying con uit for admitting motive fluid into said spring for causing the movement of. said valve in a more or less complete open position with respect to said conduit, said means including a cam mounted eccentrically of said valve and associated with said cap.

15. In a drilling apparatus, the combination with a drilling motor, of a fluid actuated feeding mechanism connected to said drilling motor for imparting feeding motion thereto, a motive fluid conveying conduit for admitting motive fluid into said mechanism for actuating the same, a valve movable for varying the motive fluid conveying capacity of said conduit, means acting on one side of said valve tending to move the valve in a closing position. with respect to said conduit, a spring acting on the other side of said valve tending to move the valve in open position with respect to said conduit, and means for varying the compression of said spring for causing the movement of said valve in a more or less complete open position with respect to said conduits, said means including a rotatable element locked against longitudinal movement having a surface machined in a manner capable of causing a variation in the compression of said spring during the rotation of said element. n

16. In a drilling apparatus, the combination with a drilling motor, of a fluid actuated feeding mechanism connected to said motor for imparting feeding motion thereto, at least one fluid conveying conduit for admitting and exhausting motive fluid to and from said feeding mechanism, a pressure subjected valve movable in more or less complete open position relative to said conduit for controlling the inlet travel of the motive fluid therethrough, and means operable for subjecting said valve to additional pressure for shifting and maintaining the same in complete open position relative to said conduit during the outlet travel of the-motive fluid through the latter conduit.

17. In a drilling apparatus, the combination with a frame having a drilling motor slidable thereon, of a feeding mechanism for said motor including a feed tube formed with two piston chambers having a partition therebetween, a piston within each of said chambers reciprocable therein and associated with said motor for imparting feeding motion thereto in two directions, a rod through said partition uniting said pistons, means including passages for alternatively admitting motive fluid into said chambers adjacent said partition for actuating said pistons, a valve subjected to the action of the motive fluid for normally closing one of said passages and thereby preventing the movement of said pistons and motor in one direction, and pressure adjustable means engageable with said valve for partly overcoming the action of the motive, fluid thereon for causing a partial opening of said last mentioned passage by said valve, permitting thereby a restricted amount of motive fluid to be admitted into said mechanism for actuating said piston in a manner whereby the rate of speed of the feeding motion of said motor in one direction is less than that of itsfeedingmotion in the other direction.

18. In a drilling apparatus, the combination with a drilling motor, of a fluid actuated feeding mechanism for said motor, and inlet controlling valve operable for controlling the admission of the motive fluid into said mechanism, a pressure vcontrolling valve operable for varying the pressure of the motive fluid actuating said mechanism, and a single element manually movable for operating both of said valves.

- 19. In a pressure regulating device for a rock drill fluid actuated feeding means, a normally closed valve mounted between said feeding means and the fluid supply therefor, a spring exerting a relatively light pressure on said valve to maintain the same in closed position, resilient means acting on said valve tending to overcome the pressure exerted by said spring to cause a partial opening of said valve, a throttle valve for controlling the fluid supply to said fluid actuated means, and a single element manually movable for operating said throttleyalve and for increasing the pressure of said resilient means to cause the opening of said valve.

20. In a pressure regulating device for a rock drill fluid actuating feeding means, a conduit for admitting and exhausting motive mud to and from said feeding means, a valve controlling said conduit normally closed with respect thereto, a spring exerting a relatively light pressure on said valve to maintain the same in closed position, resilient means acting on said valve tending to overcome the pressure exerted by said spring to cause a partial opening of said valve, means manually operable for increasing the pressure of said resilient means to cause a more complete opening of said valve during the inlet travel of the motive fluid through said conduit, and means for admitting motive fluid to said valve to cause the complete opening thereof during the outlet travel of the motive fluid through said conduit.

'21. In a pressure regulating device for a rock drill fluid actuated feeding mechanism, a conduit for admitting and exhausting motive fluid to and from said mechanism, a valve controlling said conduit, means for admitting motive fluid on one side of said valve for normally closing said conduit, pressure adjustable means acting on the other side of said valve to cause a more or less complete opening of said conduit for admitting motive fluid to said feeding mechanism, and means for admitting motive fluid to said other side of said valve to cause the opening of said conduit during the outlet travel of the motive fluid from said mechanism.

JOHN C. CURTIS.