US2224859A

US2224859A - Rock drill

Info

Publication number: US2224859A
Application number: US152609A
Authority: US
Inventors: Curtis John Clark
Original assignee: Sullivan Machinery Co
Current assignee: Sullivan Machinery Co
Priority date: 1937-07-08
Filing date: 1937-07-08
Publication date: 1940-12-17
Anticipated expiration: 1957-12-17

Description

J. C. CURTIS 'ROCK DRILL Dec. 17, 1940.

Filed July 8, 1937 3 Sheets-Sheet l C. CURTIS Dec. 17, 194-0.

ROCK DRILL Filed July 8, 1957 3 Sheets- Sheet I5 Jizvenfir: Z @7212 a 6' -1 4' Wm.

Patented Dec. 17, 1940 l UNITED STATES PATENT QFFICE ROCK DRILL John Clark Curtis, Claremont, N..H.,- assignor to SullivanMachineryCompany, a corporation of Massachusetts Application July 8, 1937, Serial N 0. 152,609

33 Claims. (01. 12119.)

This invention relates to rock drills, and more substantially on line 22 of Fig. 1, the drill particularly, but not exclusively, to a rock drill hammer motor being partially shown in end of the pressure fluid actuated, hammer type elevation.

having improved fluid distribution means for the Fig. 3 is an enlarged cross sectional view taken hammer motor. substantially on line 3-3 of Fig. 1. J 5

An object of this invention is to provide a rock Fig; 4 is an enlarged cross sectional view taken drill of an improved design wherein the efficiency substantially on line 4-4 of Fig. 1. is greatly improved and the component parts Fig. 5 is a rear end elevational view of the front are made relatively rugged and durable in convalve element.

struction. Another object is to provide, in arock Fig. 6 is' a front end elevational view of the 10 drill of the hammer type, improved fluid distrirear valve element. bution means for the drill hammer motor where- Fig. '7 is an enlarged fragmentary sectional by pressure fluid is distributed to the motor view taken in the plane of Fig. 1, showing decylinder in a novel and improved manner; A tails of the improved fluid distribution means.

further object is to provide an. improved fluid Figs. 8 and 9 are views similar to Fig. '7 show- 15 distribution means having improved fluid dising the valve elements and hammer piston in tributing valve mechanism and flow passage ardifferent positions.

rangements whereby the motive fluid is dis- Fig, 10is a cross sectional view taken substantributed to the motor cylinder in an improved tially On li e |n|0 O manner. Another object is to provide an im- Fig. 11 is a cross sectional view taken substan- 20 proved valve mechanism of the multi-valve type tially on line I |-l I of Fig. '7. embodying a pair of cooperating, relatively mov-' Fig. 12 is a developed view in longitudinal secable, valve elements for controllingthe flow tion taken substantially on line l2l2 of Fig. 10, of pressure fluid to the motor cylinder in an showing certain of the fluid distributing passages improved manner. A further object is to proandthe'valve throwing passage. 25 vide, in a valve mechanism of the above char- Fig. 13' is a cross sectional view taken substanacter, an improved flow passage arrangement tially on line l3'-I3 of Fig. '7'. associated with the valve elements together with Fig. 14 is a detail sectional view taken on line a novel throwing means for the valve elements I4I4 of Fig. 2.

whereby the speed of operation and efiiciency Fig. 15 is a detail sectional view taken on line 30 of the drill hammer motor are greatly improved. l5|5 of Fig. 2.

Still another object is to provide, in a valve Fig. 16 is an enlarged fragmentary sectional mechanism of the above character, an improved View taken in the plane of Fig. 8, showing the valve construction and associated flow passage distributing valves both in seated position.

rrangement whereby the hammer piston of the In the illustrative embodiment of the inven- 35 hammer motorv is actuatedv to deliver an extion, there is shown a pressure-fiuid-actuated, fremely powerful blow to the drill steel, the valve hammer rock drill of the mounted drifter type, elements of the improved valve structure being although it will be evident that various features arranged in a novel manner so that fluid is dis- 0f the invention may be embodied in rock drills tributed to the motor cylinder to cause the hamof various. other types; 40 mer piston to strike an unimpeded, uncushioned I In this construction, the reference character I blow on the drill shank, while, at the same time, generally designates the drill hammer motor, the consumption of pressure fluid is reduced to a 2 the guide shall, 3 the feeding means for the minimum. These and other objects and adhammer motor, 4 the chuck mechanism and 5 the 5 vantages of the invention will, however, herein improved throttle valve mechanism. The motor after more fully appear. cylinder 6 has

lateral guides

1, 1 slidably re- In the accompanying drawings there is shown ceived in

longitudinal guideways

8, 8 formed on for purposes of illustration one form which the the guide shell 2, and the latter has a bottom invention, in its various aspects, may assume in trunnion support 9 adapted to be; clamped in practice. the usual saddle mounting of a tripod or column. 50

In these drawings- I The feeding means 3 comprises a feed screw l0 Fig. 1 is'a view in longitudinal vertical section journaled at its opposite ends within bearing through a rock drill incorporating an illustrative yokes II. I l secured to the opposite ends of the embodiment of the invention. guide shell and having at its rear end a manual Fig. 2 is an enlarged cross sectional view taken rotating handle !2. The feed screw threadedly 55 engages a non-rotatable feed nut l3 fixed within the bore of a depending boss l4 formed integral with the motor cylinder 6. As the feed screw is rotated by the handle l2 relative to the nonrotatable feed nut, the drill hammer motor is fed either forwardly or rearwardly along the shell guideways, depending upon the direction of feed screw rotation. As the guide shell 2 and feeding means 3 are of a conventional design, further detailed description thereof is unnecessary.

Now referring to the improved hammer motor I, it will be noted that the motor cylinder has a piston chamber or bore l5 containing a reciprocatory hammer piston l6 having a piston head I! fitting the cylinder bore and a forwardly projecting striking bar l8 adapted to deliver impact blows to the shank of a usual drill steel [9. The piston striking bar is guided in a bore 20 formed in a front buffer ring 2! having an external flange 22 at its rearward end fitting the forward end of the cylinder bore to provide a front cylinder head. This buffer ring has a portion 23 fitting in a bore 24 in the front cylinder extension 25, and has an external flange 26 abutting the front end f the cylinder extension, in the manner clearly lhOWll in Fig. 1. The buffer ring extension has a bore 21 providing an elongated bearing for a chuck sleeve 28 rotatably mounted at its forward nd within a chuck housing 29. This chuck busing abuts the forward face of the flange 26 and has a bore receiving the forward portion of the buffer ring extension 23. Within a bore 30 formed in the chuck sleeve is a chuck bushing 3| itting an inwardly directed shoulder 3 I on the Ihuck sleeve and having a bore for receiving the h n: of the drill steel. The chuck bushing is held in position within the chuck sleeve by means of a combined driver and locking member 32 hreaded at 33 within the forward portion of the ck sleeve. The chuck housing has an inard y directed flange 34 providing a shoulder ainst which the forward end of the chuck sleeve abuts, and this flange provides an axial ening through which the forward portion of he member 32 extends. Upon unscrewing of the member 32 from the chuck sleeve, this member may be withdrawn forwardly from the chuck housing to obtain access to the chuck bushing for replacement purposes. Forward release of the member 32 from the chuck housing is also desirable in the event of the lugs and the rear end of the drill shank becoming headed over or distorted due to the repeated impacts thereon, preventing withdrawal of the steel shank from the chuck bushing and the locking member. The chuck sleeve is formed with an external flange 35 arranged between the forward end of the buifer ring extension 23 and a shoulder 36 formed within the chuck housing. The chuck housing and the buffer ring extension provide elongated bearings for the chuck sleeve so that the latter is maintained in proper alinement with the cylinder. The driver and locking member 32, as shown in Fig. 4, has internal driving lugs 31 engageable with lugs 38 on the drill steel shank, and is formed with a key opening 39 for receiving the steel shank lugs. When the lugs on the steel shank are inserted through the key opening within the driver member and the steel is turned to bring the shank lugs 38 into driving engagement with the lugs 31, the shank lugs are brought out of registry with the key opening so that the steel shank is locked against forward displacement from within the driver member. Pressed in a bore 40 formed within the rearward portion of the chuck sleeve is a chuck nut 4| held against rotation relative to the chuck sleeve by means of a key pin 42 fitted in registering grooves on the chuck sleeve and chuck nut. When the chuck sleeve is removed from within the buffer ring extension bore, the chuck nut may be withdrawn axially through the rear end of the chuck sleeve for replacement purposes.

As is usual in rock drills of the type disclosed, means is provided for-rotating the drill steel as it is percussively actuated by the hammer piston, comprising a rotatable pawl carrier 43 carrying usual spring-pressed pawls engageable with the teeth of a non-rotatable ratchet ring 44. Formed integral with the pawl carrier is a rifle bar 45 having spiral grooves slidably interlocked with spiral keys formed on a rifle nut 46 fixed within the hammer piston. As the hammer piston moves forwardly to effect its working stroke, i. e., to deliver an impact blow to the shank of the drill steel, the pawls of the pawl carrier slip over the ratchet teeth so that the hammer piston delivers an unimpeded blow to the steel shank. During the return stroke of the hammer piston, the pawls on the pawl carrier engage the ratchet teeth to hold the rifle bar against rotation, and, as a result, the hammer piston is rotated. The rotary motion of the hammer piston is transmitted to the drill steel shank through straight grooves 41 on the piston striking bar slidingly interlocked with straight keys on the chuck nut 4|, rotating the latter with the piston, and, as a result, effecting rotation of the chuck sleeve, chuck bushing and driver member, and hence the drill steel is locked within the driver member. It will thus be seen that as the drill steel is percussively actuated by the hammer piston, it is intermittently rotated, in the manner well understood by those skilled in the art.

The improved fluid distribution means will now be described. Formed in a rearward extension of the motor cylinder is a bore 50 arranged in axial alinement with the motor cylinder bore, and arranged in this extension bore is a valve seat plate 5| constituting the rear cylinder head and having a sleeve-like portion 52 projecting axially from its rear face, the latter providing a bearing for the rifle bar 45. Also arranged in the extension bore 50 and abutting the rear face of the plate 5| is a valve box 53 having a bore 54 of a uniform diameter throughout its length. The plate 5| forms a front closure for the bore of the valve box 53 while the rear end of the bore is closed by a valve box cover 55 likewise arranged in the extension bore and abutting the rear face of the valve box 53. Arranged within the rearward portion of the extension bore 50, behind the ring 44, is a ratchet collar 56. The collar, ratchet ring and cover are maintained against rotative movement within the bore 50 by a dowel pin or key 51 fitted in registering grooves in the cooperating parts and in the cylinder member 6. Engaging the ratchet collar is a back head 58 adapted to be clamped to the rear end of the cylinder to hold the parts above described within the extension bore, and the front chuck housing is also clamped to the front end of the cylinder to hold the buffer ring and chuck sleeve in position. The back head and the front chuck housing are secured to the cylinder in any appropriate manner, as by usual side rods 59, 59 (Figs. 3, 10, 11 and 13).

Referring more particularly to the specific valve structure, it will be observed that reciprocably mounted in the bore 54 of the valve box is a pair of cooperating, relatively movable, fluid distributing valve elements 69 and GI, herein preferably of the sleeve type arranged in telescopic relation and respectively controlling the flow of pressure fluid to the opposite ends of the cylinder bore, in the manner to be later more fully explained. The rear valve element controls admission and cut-oil for the front end of the cylinder, the front valve element like functions for the rear end of the motor cylinder. The rear valve element 69 comprises a rearwardly located external flange 62 fitting the valve box bore, and a forwardly projecting sleeve-like body portion 63, telescoping over the rearwardly-extending sleeve-like body portion 64 of the front valve element 9 I. Formed on the rear valve element is an inwardly directed internal flange 65 cooperating with a forwardly projecting annular portion 66 integral with the valve box cover 55, to meter motive fluid for the front end of the cylinder. The front valve element has a similar inwardly directed internal flange 61 cooperating with the sleeve-like projection 52 integral with the valve seat plate 5| to meter the motive fluid for the rear end of the motor cylinder. function will be later more fully described. Fitting the valve box bore and formed at the front end of the front valve 6| is an external flange 68. The opposite end faces of the

valves

69 and 6| are formed with annular seating portions 69 and I9 respectively, the former adapted to seat against the front face of the valve box cover 55 and the latter to seat against the rear face of the plate 5|. The front faceof the cover 55 is formed with an annular recess II communicating with the valve receiving bore at the rear side of the valve flange 62 and this recess is connected through a pair of

ports

12, 12 in the cover 55 with ports 13, I3, and these latter in turn communicate with passages I4, I4 formed in the cylinder (Fig. 12) and communicating through ports 15 with the forward end of the cylinder bore. The rear face of the plate 5| is formed with an annular recess I6 communicating with the valve receiving bore at the forward side of the valve 9|, and this recess is connected by a series of passages T! with the rear end of the cylinder bore. Formed externally on the valve'box 53 is an annular groove 18 communicating through a port 19 with the space between the valves 69 and BI, and this groove is connected, as shown in Fig. 12, by a port 89 with a throwing passage 8|, the latter in turn communicating through

ports

82 and 83 with the cylinder bore at points spaced longitudinally of the latter. 4 v

The means for supplying pressure fluid to the valve box bore comprises a throttle valve 84 forming a part of the throttle valve mechanism 5. This throttle valve is arranged within a transverse bore 85 formed in the back head 58. The throttle valve is provided with an internal pressure chamber 86 connectible through a port 9'! with a port 88 formed in the back head and communicating with a pressure chamber 89 formed between the ratchet collar 56 and the back head. This pressurechamber 89 is connected through a series'of ports 99 with an annular recess 9| formed in the forward face of the ratchet collar 56, and this recess communicates through the spaces between the ratchet teeth and pawl carrier with an annular recess 92 formed in the rear face of the valve box cover 55. The recess 92 is connected through a series of ports 93 with a large axial passage 94 extending through the annular projection 66 on the valve box cover and communicating with the internal space This metering within the

valve elements

69 and 6|. As above indicated, pressure fluid may flow from within the space between the valve elements, past restricted clearance spaces and 96 at the inner edges of the

internallvalve flanges

65 and 61 respectively, to provide metering of the fluid flowing past these internal valve flanges so that the flow of pressure fluid to the supply passages is always maintained constant irrespective of any wear of the valves, the valves being guided solely at the exterior peripheries of the external flanges thereof which slidingly fit the valve box bore 54. Formed within the wall of the cylinder bore substantially midway between the ends of the cylinder is an annular exhaust groove 91 connected directly to atmosphere through a lateral exhaust port 98 (see Fig. 11). between the points of communication of the

ports

92 and 93 with the cylinder bore. The valve chamber at the front side of the front valve element 6| is connected to the rear end of the cylinder bore through a restricted leak passage 99, while the recess II is connected to the recess 92 by a restricted leak passage I99.

Now referring again to the improved throttle valve structure, it will be noted that the throttle valve is of cylindric form, as shown in Fig. 2, and is provided with a valve stem I92 projecting outwardly through a bore I93 formed in the back head. Fitted on this valve stem is a handle hub I 94 having a lateral boss I95 in which is suitably threaded at I96 a valve operating handle I91. This valve handle has a tapered inner end I98 adapted to seat within a tapered socket I99 formed within the valve stem. When the handle E91 is unscrewed from within the handle hub boss I95 so that the tapered portion I98 thereof is released from the socket I99, the handle hub I94 may be readily removed from the valve stem. When the parts are in the assembled relation shown in Fig. 14, the handle serves the dual purpose of providing an operating member for the valve and securing means for the handle hub. Pressure fluid is adapted to be supplied to the hollow interior 86 of the throttle valve through This exhaust groove lies a usual supply connection II 9 and when this supply connection is released from the back head and the handle is removed from the valve stem, the throttle valve may be withdrawn axially from its bore within the back head, in an obvious manner. For holding the throttle valve 'in its different positions ofadjustment, a spring-pressed plunger III (see Fig. 15) guided in a bore in the back head is engageable with notches in the valve. v

As is usual in rock drills of the type disclosed, a cleansing liquid is adapted to be conducted through the drill steel to the bottom of the drill hole to clear the cuttings away from the cutting end of the drill steel, and this cleansing means herein comprises a conventional liquid conducting tube 2 secured by a packed gland plug H3 within the back head 58, and this tube extends axially through bores formed in the rifle bar and hammer piston into the bore of the drill steel in a Well known manner. Liquid under pressure is adapted to be supplied to the liquid conducting tube from .any suitable source. As liquid is conducted to the bore of the drill steel, fluid under pressure is commingled therewith, thepressure fluid flowing from the cylinder bore past the piston or from any other suitable pressure fluid source through the bore within the chuck sleeve to the drill steel bore. The liquid and pressure fluid commlngle as they flow axially through the drill steel to the bottom of the drill hole.

The mode of operation of the improved fluid distribution means will be clearly apparent from the description given. When the parts are in the position shown in Fig. 7, pressure fluid may flow from the interior of the throttle valve 84 through ports El, 88, chamber 89, ports 90, recess 9|, through the spaces between the teeth of the ratchet ring, groove 92, ports 93 and the axial passage 94 to the internal chamber within the valve elements. Pressure fluid flows through the restricted clearance space 95 between the inner peripheral edge of the internal flange 65 on the rear valve element .and the exterior peripheral surface of the annular projection 66, through the valve box bore past the rear face of the rear valve element and through the annular recess 1 I, ports f2, 73, passages 14 and ports 15 to the forward end of the cylinder bore at the front side of the piston head, the pressure fluid acting on the front pressure area of the hammer piston to drive the latter rearwardly to effect its return stroke. The rear end of the cylinder bore is, at this time, connected to exhaust through the exhaust groove 97 and exhaust passage 98. As the hammer piston moves rearwardly, the leading (rearward) edge of the piston head overruns the exhaust groove 9?, cutting off communication of the rear end of the cylinder bore with the exhaust, and upon continued rearward movement of the hammer piston, the rearward end of the piston head covers the port 82 and the forward end of the piston head uncovers the port 83, and pressure fluid then flows from the front end of the cylinder bore through the port 83, throwing passage 8! and port 88, through the annular groove 18 and port 19, into the annular space between the

valve flanges

52 and 68, and the pressure in said annular space immediately throws the rear valve element 50 rearwardly from its position shown in Fig. '7 to its position shown in Fig. 8, causing the annular seating portion 69 on the valve element 69 to seat against the front face of the valve box cover 55 and shut off flow of pressure fluid to the forward end of the cylinder bore. This pressure in the space between the valve flanges also acts to hold the forward valve in closed position. 'Accordingly, the piston continues to move rearwardly, and as it moves towards the rear cylinder head the pressure fluid trapped within the rear end of the cylinder bore is compressed, and when the front edge of the piston head uncovers the exhaust groove 9! the pressure within the space between the

flanges

62 and 68 will be vented to exhaust through passage 19, groove 18, port 80, passage 8|, port 83, and the cylinder bore, while the valve bore at the rear side of the rear valve element 60 is connected to exhaust through the passages 14, and, as a result, the compression pressure built up by the piston within the rear end of the cylinder bore acting on the front pressure area of the front valve element BI is effective to throw this valve element rearwardly from the position shown in Fig. 8 to the position shown in Fig. 9. When the parts arein the position shown in Fig. 9, pressure fluid may flow from the internal chamber within the

valve elements

60, 6|, through the restricted clearance space 96 between the inner peripheral edge of the internal valve flange 61 and the exterior periphery of the sleeve 52, through the valve bore at the forward side of the front valve element BI and through the annular recess 76 and ports 11 to the rear end of the cylinder bore at the rear side of the hammer piston. At this time the front end of the cylinder bore is connected to exhaust through the exhaust groove 91 and exhaust passage 98, as previously explained.

The pressure fluid acting on the rear pressure area of the hammer piston now moves the latter forwardly to effect its working stroke, i. e., to deliver an impact blow to the shank of the drill steel. As the hammer piston moves forwardly, the forward edge of the piston head first covers the exhaust groove 91, cutting off communication of the forward end of the cylinder bore with exhaust, and upon continued forward movement of the hammer piston, the forward end of the piston head covers the port 83 and the rearward edge of the piston head thereafter uncovers the port 82 of the throwing passage 8|, thereby admitting pressure fluid from the space at the rear of the piston through the groove 18 and port 19 to the space between the flanges 62 and '58 of the valves. Due to the restriction at 95 between the internal pressure chamber within the valve elements and the valve receiving bore at the forward side of the internal valve flange 61, and the relatively rapid flow of pressure fluid from the front end of the valve bore to the rear end of the cylinder bore through the ports 11, the pressure of the fluid at the rear of the internal valve flange B! is substantially greater than that in the valve bore at the front side of the flange. As a result, when the hammer piston reaches the position shown in Fig. 8, and pressure at cylinder pressure admitted through port 82, passage 8!, etc. enters the space between the valve flanges, the pressure of the fluid within the space between the external valve flanges and the pressure of the fluid at the rear side of the valve flange B1 overcomes the pressure of the fluid at the forward side of the front valve element 6|, thereby throwing the front valve element from the position shown in Fig. 9 forwardly to the position shown in Fig. 8. At this time, the annular seating portions 69 and HI on the remote faces of the valves are both momentarily held seated against the end surfaces of the valve bore and the supply of pressure fluid to the opposite ends of the cylinder bore is completely out off (see Figs. 8 and 16) Forward movement of the hammer piston continues under the expansive action of the pressure fluid within the rear end of the cylinder bore. When the forward end of the forwardly moving hammer piston overruns the exhaust groove 91, a compression pressure starts to build up at the forward side of the piston since the fluid within the forward end of the-cylinder can not escape. The compression pressure continues to build up with the forward movement of the hammer piston, but not to a value sufficient to move the valve element 60 from its seat against the pressure between the external valve flanges, until after the port 82 is connected to exhaust as a result of the pistons uncovering the exhaust groove 91. When the rear end of the piston head commences to uncover the exhaust groove -91, however, release for the rear end of the cylinder will occur and concurrently, the pressure which has been acting in the annular space between the external flanges on the valves will be vented to the exhaust through the passage 8! and port 82; and the compression pressure transmitted from the front end of the cylinder to the rearward surface of the external flange 62 on the rear of the valve 60, through the port I5, passage 14, and

ports

13 and 12, will cause the rear valve to move to the position of Fig. 7 and admit fluid for the rearward traverse of the motor piston.

It will be evident, however, that the motor piston will substantially complete its full working stroke before any motive fluid is admitted to the forward side thereof, andv accordingly a largely unimpeded blow will be struck the shank of the drill steel-a much less impeded blow than would be possible with any construction utilizing a single valve, such constructions permitting but little time between cut-off at the rear end of the cylinder .and admission to the forward end of the cylinder.

The further operation of the motor will consist of repetitions of the cycles which have been described.

It will be noted that throwing of the valve which controls the supply of pressure fluid to a given cylinder end is effected in an opening directicn by compression pressure, upon the venting of the pressure from the annular space between the external flangesupon the two valves, and that the opposite movement of such valve is effected by pressure admitted between such valve flanges from the cylinder bore, such opposite movement facilitated by the fact that the relatively free flow to the cylinder from the spaces beyond the restricted annular passages bounded exteriorly by the internal valve flanges results in less strong pressures holding the valves in open position than would exist were the restriction of flow, so to speak, not provided by these flanges.

The functions of the passages 99 and I00 will be readily understood. The passage 99 will admit pressure from the space inside the valves, should both of these valves be closed and the piston be at the rear end of the cylinder, into the restricted space to the rear of the piston, and this pressure will pass back through the port 11 and groove l6 and act on the forward side of the flange 68, and accordingly, the forward valve will be moved to open position and the motor will then begin to operate in a normal manner.

In the case of the passage Hlll, if the piston happens to be at the forwardend of the cylinder and both valves closed when air is turned on, the pressure will pass through the passage Hill and act upon the rearward surface of the flange 62 and movethe rearward valve 60 into open position and cause the motor to start. In the normal operation of the motor, the passages st and Hill play no material part, as they are so small that their effect upon the operating cycle is negligible.

As a result of this invention, it will be noted that by reason of the improved valve mechanism and passage arrangement, a, relatively powerful and eflicient hammer motor is attained. It will further be evident that by providing cooperating, relatively movable, fluid distributing valve elements respectively controlling the flow of pressure fluid to the opposite ends of the cylinder bore and both capable of being closed at the same time for a substantial portion of the working piston stroke, it is possible greatly to increase the efficiency of the motor, while at the same time a more powerful blow is imparted to the drill steel shank, this, in part, being made possible by effecting simultaneous momentary closure of the supply passages to the opposite ends of the cylinder bore, thereby permitting the hammer piston to strike a largely unimpeded or uncushioned blow to the drill steel shank. It will still further be evident that by the particular hammer motor structure and the improved arrangement of the parts, a rock drill is provided which is not only extremely efiicient in operation but which is also relatively rugged and durable in construction, well adapted to meet the severe demands of service in the drilling of rock. Other uses and advantages of the improved rock drill will be clearly apparent to those skilled in the art.

While there is in this application specifically described one form which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in various-other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a pressure fluid motor, in combination, a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore for eifecting reciprocation of said piston comprising means providing a valve chamber, passage means providing fluid supply passages for connecting the opposite ends of said valve chamber with the opposite ends of said cylinder bore, and a pair of cooperating, relatively movable, fluid distributing valves arranged in sliding telescopic relation and movably mounted in said valve chamber for respectively controlling said supply passages.

2. Ina pressure fluid motor, in combination, a cylinder. having a bore, .a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore for effecting reciprocation of said piston comprising means providing a valve chamber, cooperating, relatively movable, fluid distributing valves reciprocably mounted in said valve chamber, said valves always engaging one another and cooperating to provide a space therebetween, means forming passages leading from said valve chamber to the opposite ends of said cylinder 'bore'at the opposite sides of said piston, said passages controlled by said valves respectively'for conducting presure fluid from said valve chamber to the cylinder bore, and throwing passage means communicating with the cylinder bore and controlled by said piston for conducting throwing pressure to said space between said valves.

3. In a pressure fluid motor, in combination, a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore for'efiecting reciprocation of said piston comprising means providing a valve chamber, cooperating, relatively movable, fluid distributing valves movably mounted in said valve chamber and having pressure areas adapted to be subjected to valve throwing pressure, said valves cooperating to provide an internal pressure chamber therein, means for constantly supplying pressure fluid to said internal pressure chamber, means forming passages leading from the opposite ends of said valve chamber to the opposite ends of said cylinder bore for conducting pressure fluid from said valve chamber to said cylinder bore, said passages controlled by said valves respectively, the pressure fluid flowing froms'aid internal pressure chamber past the opposite ends of said valves to said supply passages,

and valve throwing means controlled by said piston for conducting pressure fluid from said cylinder bore to pressure areas on said valves for throwing the latter into their different operating positions.

4. In combination, in a motor, a cylinder, a piston reciprocable in said cylinder, and fluid distribution means for said motor including a valve chest, passages leading from said valve chest to the opposite ends of said cylinder, a pair of valve elements arranged within said valve chest and movable relative to each other and to said valve chest and having means cooperating with said valve chest in one position of said valve elements to provide internally of the valve elements a chamber sealed from communication with said cylinder through said passages, and means for delivering motive fluid to said chamber for distribution therefrom under the control of said valve elements through said passages to the opposite ends of said motor cylinder.

5. In combination, in a motor, a cylinder, a piston reciprocable in said cylinder, and fluid distribution means for said motor including a valve chest, passages leading from said valve chest to the opposite ends of said cylinder, a pair of valve elements arranged in said valve chest and movable relative to each other and to said valve chest, an internal fluid supply chamber arranged within said valve elements, said valve elements controlling the flow of pressure fluid from said internal fluid supply chamber to said passages, and means for effecting throwing of said valve elements including surfaces on each of said elements cooperating in the formation of a chamher to which fluid is delivered to effect valve closure and means under the control of said piston for delivering fluid to and venting fluid from said last mentioned chamber.

6. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to effect reciprocation of said piston comprising means providing a valve chamber, a pair of cooperating, relatively movable, fluid distributing valves arranged in said valve chamber, said valves each having an external flange slidingly fitting a portion of the valve chamber, means for effecting movement of said valves relative to one another into their different normal operating positions in said valve chamber including means for subjecting the inner adjacent sides of said valve flanges directly to a valve throwing pressure, and means providing fluid supply passages communicating with the ends of said valve chamber directly at the remote sides of said valve flanges respectively for conducting pressure fluid to the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure fluid through the opposite ends of said valve chamber past the remote sides of said valve flanges to said supply passages.

7. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to effect reciprocation of said piston comprising means providing a valve chamber, cooperating, relatively movable, fluid distributing valves arranged in said valve chamber, said valves each having a sleeve-like body portion, said body portions arranged in telescopic sliding relation and each valve having an annular flange formed externally on the sleeve-like body portion thereof, said valve flanges slidingly fitting portions of the valve chamber, means for effecting movement of said valves relative to one another into their different normal operating positions in said valve chamber including means for subjecting the inner adjacent sides of said valve flanges directly to a valve throwing pressure, and means providing fluid supply passages communicating with the ends of said valve chamber directly at the remote sides of said valve flanges respectively for conducting pressure fluid to the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure fluid through the opposite ends of said valve chamber past the remote sides of said valve flanges to said supply passages.

8. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to effect reciprocation of said piston comprising means providing a valve chamber, a pair of cooperating, relatively movable, fluid distributing valves reciprocably mounted in said valve chamber, said valves movable into and out of abutting relation, one valve controlling the flow of pressure fluid to one end of said cylinder bore and the other valve controlling the flow of pressure fluid to the other end of the cylinder bore, means for effecting movement of said valves relative to one another into their different normal operating positions in said valve chamber, a pressure fluid supply, means cooperating with said valves respectively for providing a metered flow of pressure fluid from said fluid supply to the opposite ends of said valve chamber and means providing fluid supply passages for conducting pressure fluid from the ends of said valve chamber respectively to the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure fluid from said fluid supply through the opposite ends of said valve chamber to said supply passages.

9. A pressure fluid motor comprising, in combination, a cylinder, a piston therein, and fluid distribution means for the motor including passage means for supplying operating fluid to the opposite ends of the cylinder at the opposite ends of said piston respectively, an operating fluid supply, valve means including a pair of cooperating, relatively movable, valve elements movable into abutting relation and respectively controlling the flow of operating fluid to the opposite ends of said cylinder, for controlling the communication of said passage means with the fluid supply, and means cooperating with said valve elements for providing metered flow of operating fluid to the opposite ends of the cylinder, said valve elements of said valve means in certain positions thereof momentarily concurrently completely cutting 01f communication of both of said passage means with said fluid supply.

10. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to effect reciprocation of said piston comprising means providing a valve chamber, a pair of cooperating, relatively movable, fluid distributing valves movably mounted in said valve chamber, means for effecting movement of said valves rela tive to one another into their diiferent normal operating positions in said valve chamber, means cooperating with said valves providing an inber through the opposite ends of said valve cham-' her to said supply passages.

11. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to effect reciprocation of said piston comprising means providing a valve chamber, cooperating, relatively movable, fluid distributing valves movably mounted in said valve chamber, said valves being guided solely at their exterior peripheries and having inwardly directed flanges, means for effecting movement of said valves relative to one another into their different normal operating positions in said valve chamber, means cooperating with said valves providing an internal fluid supply chamber within-the valves, means cooperating with said inwardly directed valve flanges for providing a metered flow of pressure :fluid from said fluid supply chamberto the Opposite ends of said valve chamber, and means providing fluid supply passages connecting the opposite ends of said valve chamber 'at the remote sides of said valves respectively to the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure fluid from said fluid supply chamber past said m'etering-providing means and through the opposite ends of said valve chamber to said supply passages.

12. In a pressure fluid motor, the combination comprising a cylinder "having a bore, a piston re- 40 ciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to effect reciprocationof said piston comprising means providing a valve chamber having a uniform bore and valveseat surfaces at its opposite ends, a

pair of coaxial, relatively movable, fluid distributing valves reciprocably mounted'in said valve chamber, said valves having sleeve-like'body portions and external flanges surrounding said body portions and slidingly fitting said valve chamber bore, said sleeve-like body portions of said valves at their remote ends "having valve seating surfaces. respectively adapted "to seat against said valve seat surfaces, means for effecting movement of said valves relative to one another'into their different normal operating positions in said valve chamber, and means providing fluid supply passages leading from the opposite ends of said valve chamber respectively to the opposite ends of said cylinder bore,.said valves respectively controlling the flow of pressure fluid through the opposite ends of said valve chambertosaid supply passages.

13. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in .said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from saidcylinder bore to effect reciprocation of said piston comprising means providing a valve chamber having'a uniform bore and valve seat surfaces at its opposite ends, a pair of coaxial, relatively movable, fluid distributing valves movable into and out of abutting engagement and reciprocably mounted in said valve chamber, said valves having sleeve-like body portions and external flanges surrounding said body portions and slidingly fitting said valve chamber bore, said sleeve-like body portions of said valves at their remote ends having valve seating isurfaces respectively adapted to seat ing movement of said valves relative to one another into their different normal operating posiagainst said valve seat surfaces, means for effecttions in said valve-chamber, and'means providing fluid supply passages leading from the opposite ends of said valve chamber respectively to the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure fluid through the opposite ends of said valve chamber to said supply passages.

14. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to effect reciprocation of said piston comprising means providing a valve chamber, cooperating, relatively movable, fluid distributing valves reciprocably mounted in said Valve chamber, means for eflecting movement of said valves relative to one another into their different normal operating positions in said valve chamber, means cooperating With said valves respectively providing metering spaces through which fluid must flow to the opposite ends of said valve chamber, and means providing fluid supply passages for connecting the opposite ends of said valve chamber respectively with the opposite" ends of said cylinder bore, said valves respectively controlling the flow of fluid past said metering spaces and through the opposite ends of said valve'chamber tosaid supply passages.

15. In a pressure fluid motor, the combination comprising acylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fl-uid from said cylinder bore to eiTect reciprocation of said piston comprising means providinga valve chamber, cooperating, relative- 1y movable, fluid distributing valves mounted in said valve chamber and reciprocably guided in said valve chamber solely at their exterior peripheries, said valves having internal bores, means for effectingmovement of said valves relative to one another into their different normal operating positions in said valve chamber, means including portions projecting within said valve bores respectively .for metering "the flow of fluid past saidvalves to the opposite ends of said valve chamber, and means providing fluid supply passages for connecting the opposite ends of said valve chamber respectively to the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure fluid past said flowmetering means and through the opposite ends of said valve chamber to said supply passages.

16. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to efiect reciprocation of said piston comprising means providing a valve chamber, cooperating, relatively movable, fluid distributing valves reciprocably mounted in said valve chamber, means for effecting movement of said valves relative to one another into their diflerent normal operating positions in said valve chamber, means cooperating with said valves respectively providing metering spaces through whichfluid must flowftothe opposite ends of said valve chamber, and means providing fluid supply passages for conducting pressure fluid from the opposite ends of said valve chamber respectively to the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure fluid through said metering spaces and through the opposite ends of said valve chamber to said supply passages, and said valves when in certain positions in said valve chamber momentarily completely cutting off the flow of pressure fluid through both metering spaces to said valve chamber ends.

17. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to effect reciprocation of said piston comprising means providing a valve chamber, cooperating, relatively movable, fluid distributing valves reciprocably mounted in said valve chamber, said valves arranged in coaxial relation and movable into and out of abutting relation, means for effecting movement of said valves relative to one another into their diiferent normal operating positions in said valve chamber, means cooperating with said valves respectively providing metering spaces through which fluid must flow to the opposite ends of said valve chamber, and means providing fluid supply passages for conducting pressure fluid from the opposite ends of said valve chamber respectively to the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure fluid through said metering spaces and through the opposite ends of said valve chamber to said supply passages, and said valves in certain positions thereof in said valve chamber momentarily completely cutting off the flow of pressure fluid through both metering spaces to said valve chamber ends.

18. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to eflect reciprocation of said piston comprising means providing a valve chamber, a pair of cooperating, relatively movable, annular fluid distributing valves, said valves arranged in coaxial relation and reciprocably mounted in said valve chamber, said valves dividing said valve chamber into inner and outer pressure spaces and end pressure spaces at the remote ends of said valves, means for effecting movement of said valves relative to one another into their different normal operating positions in said valve chamber, means for supplying motive pressure fluid to one of said inner and outer {pressure spaces, said jvalvemovement-effecting means including means for supplying pressure fluid to and exhausting fluid from said other of said inner and outer pressure spaces for effecting movement of said valves into certain of their operating positions, means providing fluid supply passages for connecting said end pressure spaces respectively with the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure fluid from the motive pressure fluid supply space through said end pressure spaces to said supply passages.

19. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid dis tribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to efiect reciprocation of said piston comprising means providing a valve chamber, a pair of cooperatingrelatively movable, annular fluid distributing valves, said valves arranged in coaxial relation and reciprocably mounted in said valve chamber, said valves movable into and out of abutting relation, said valves dividing said valve chamber into inner and outer pressure spaces and end pressure spaces at the remote ends of said valves, means for effecting movement of said valves relative to one another into their different normal operating positions in said valve chamber, means for supplying motive pressure fluid to one of said inner and outer pressure spaces, said valve-movement-effecting means including means for supplying pressure fluid to and exhausting fluid from saidother of said inner and outer pressure spaces for effecting movement of said valves into certain of their operating positions, and means providing fluid supply passages for connecting said end pressure spaces respectively with the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure fluid from the motive pressure fluid supply space through said end pressure spaces to said supply passages.

20. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to effect reciprocation of said piston comprising means providing a valve chamber, a pair of cooperating relatively movable, annular, fluid distributing valves, said valves having telescopic sliding engagement and movable into and out of abutting relation, said valves arranged in coaxial relation and reciprocably mounted in said valve chamber, said valves-dividing said valve chamber into inner and outer pressure spaces and end pressure spaces at the remote ends of said valves, means for effecting movement of said valves relative to one another into their different normal operating positions in said valve chamber, means for supplying motive pressure fluid to one of said inner and outer pressure spaces, said valve-movement-effecting means including means for supplying pressure fluid to and exhausting fluid from said other of said inner and outer pressure spaces for effecting movement of said valves into certain of their operating positions, and means providing fluid supply passages for connecting said end pressure spaces respectively with the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure .fluid from the motive pressure fluid supply space through said end pressure spaces to said supply passages.

21. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to effect reciprocation of said piston comprising means providing a valve chamber, a pair of cooperating, relatively movable, fluid distributing valves reciprocably mounted in said valve chamber, said valves being hollow, means for effecting movement of said valves relative to one another into their different normal operating positions in said valve chamber, means including portions projecting in opposite directions from the opposite ends of said valve chamber within said hollow valves respectively, for providing metered flow of fluid past said-valves to the opposite ends of said valve chamber, and means providing fluid supply passages for connecting the opposite en of said valve chamber respectively to the 0pposite ends of said cylinder bore, said valves re spectively controlling the flow of pressure fluid past said metering-providing means and through the opposite ends of said valve chamber to said supply passages.

22. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to effect reciprocation of said piston comprising means providing a valve chamber, a pair of cooperating, relatively movable, fluid distributing valves reciprocably mounted in said valve chamber, said valves each having a sleeve-like body portion and an annular flange surrounding the body portion, said external annular flanges slidinglyfitting portionsof the valve chamber, means for eifecting movement of said valves relative to one another into their different normal operating positions in said valve chamber, means including portions projecting in opposite directions from the opposite ends of said valve chamber within the sleeve-like body portions of said valves respectively, for providing a metered flow o-f pressure fluid past said valves to the ends of said valve chamber, and means providing fluid supply passages for connecting the opposite ends of said valve chamber respectively to the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure fluid past said metering-providing means and through the opposite ends of said valve chamber to said supply passages.

23. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to effect reciprocation of said piston comprising means providing a valve chamber having valve seat surfaces at its opposite ends, a pair of cooperating, relatively movable, fluid distributing valves reciprocably mounted in said valve chamber, said valves each having a sleeve-like body portion and an annular flange surrounding the body portion, said external annular flanges slidingly fitting portions of said valve chamber, the remote ends of said sleeve-like body portions of said valves having annular valve seating surfaces respectively adapted to seat against said valve seat surfaces at, the ends of said valve chamber, means for efiecting movement of said valves relative to one another into their difierentnormal operating positions in said valve chamber, means projecting in opposite directions from the opposite ends of said valve chamber within the sleeve-like body portions of said valves respectively and cooperating with said valves for providing a metered flow of pressure fluid past said valves to the ends of said valve chamber, and means providing fluid supply passages for connecting the opposite ends of said valve chamber respectively to the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure fluid past said metering-providing means and through the opposite. ends of said valve chamber to said supply passages.-

24. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocable in said cylinder bore, and fluid disoperating, relatively movable, fluid distributing valves movably mounted in said valve chamber, said valves arranged in coaxial relation and being hollow, one valve controlling the fluid supply solely to one end of said cylinder bore and the other valve controlling the fluid supply solely to the opposite end of said cylinder bore, and the pressure fluid flowing to one end of said cylinder bore through both of said hollow valves, means .for effecting movement of said valves, relative to one another into their difierent normal operating-positions in said valve chamber, and means providing fluid supply passages leading from the opposite ends of said valve chamber respectively to the opposite ends of said cylinder bore, said valves-respectively controlling the flow of pressure fluid through the ends of said valve chamber to said supply passages.

25. A pressure fluid motor comprising, in combination, a cylinder, a piston therein, and fluid distribution means for the motor including passage means forsupplying operating fluid to the opposite ends of the cylinder at the opposite ends of the piston respectively, an operating fluid supply, valve means including apair of cooperating, relatively movable valve elements each movable into -a position in which it exerts a pressure to hold the other stationary and respectively controlling the flow of operating fluid to the opjecting saidvalve elements to valve throwing pres-sures to move said valve elements into their different operating positions, said valve throwing means including surfaces on said valve elements subjected by fluid flowing past said valve elements when the latter are in open position to pressures tending to close said valve elements, one of said valve elements when open exerting a pressure which holds the other in closed position, and said valve elements in certain positions thereof momentarily concurrently completely cutting off communication of both of said passage means with said fluid supply.

26. A pressure fluid motor comprising, in combination, a cylinder, a piston therein, and fluid distribution means for the motor including pa'ssage means for supplying operating fluid to the opposite ends of the cylinder at the opposite ends of theipiston respectively, an operating fluid supply, valve means including a pair of cooperating, relatively movable valve elements movable into abutting engagement and respectively controlling the flow of operating fluid to the opposite ends of said cylinder, for controlling the communication of said passage means with said fluid supply, andvalve throwing meansfor subjecting said; valve elements to valve throwing pressures towmove said valve elements into their different operating positions, said valve throwing means including portions on at least one of said valve elements subjected by fluid flowing past said valve element to the cylinder, to a force tending to sweep said valve element to its closed position, one of said valve elements being held in closed position by the other valve element abuttingly acting thereon and said valve elements in certain positions when they are out of abutting engagement momentarily concurrently completely'cutting off communication of both of said passage means with said fluid supply.

27. A pressure fluid motor comprising, in combination, a cylinder, a piston therein, and fluid distribution. meansfor the motor including pas+ sage means for supplying operating fluidto the opposite ends of :the cylinder atthe oppositeends of the piston respectively, an operating fluid supply, valve means including a pair of cooperating,-:relatively 1 movable valve elements re spectively controlling the flow of operating fluid to the opposite ends of said cylinder, for'c'ontrollingthe communication oflsaid passage means with said fluid supply, and valve throwing'means for subjecting said valve elements to valve throw ing pressures to move said valve elements'into their different operating positions including means for subjecting each valve element to closing forces respectively-exerted by motive'fluid passing it on the way to the cylinder and by fluid pressure controlled by the motor piston in its movement, said valve elements being movable toward and from one another and whenin their remote positions momentarilyconcurrently completely cutting off communication of both of said passage meanswith'said fluid supply andeach exerting in its full open position a force forholding the other closed.

28. A pressure fluid motor comprising-,- incombination, a cylinder, a piston therein, and fluid distribution meansforthe motorvincluding passage means for supplying operating' fluid tothe oppositeends of said cylinder at the opposite ends of said piston respectively, an operating fluidsupply, valve means including a pair of-cooperating, relatively movable lvalve elementsmovable into abutting engagement: and respectively controlling the flow of operating fluid to the opposite ends of said cylinder, for controlling the'communication of said passage means withsaid fluid supply, and valve throwing .means ,for, subjecting said valve elements to valve throwing pressures to move said valve elements intotheir difierent operating positions, said 'valve elements being movable toward one another into abutting relation and from one another out sof -abutting relation and when in their positions away from one another out of abutting relation momentarily concurrently completely cutting off communication of both of said passage means withsaid fluid supply, and said valve elements when so completely cutting ofi communication cooperating in forming. a partition extending in the direction of valve movement and having at one side of said partition said operatingfluid supply andat the other side thereof surfaces intermittently subjectedto pressures to efiect positioning of the valve elements in said non-abutting positions.

'29. A pressure fluid motorcomprisingfincombination, a cylinder, a piston therein-,rand fluid distribution means for the motor "including ED345- sage means for supplying operating fluid to the opposite ends of the cylinder at the opposite ends of the piston respectively, an operating fluid supply, valve means including a pair of cooperating, relatively movable valve elements respectively controlling the flow -'of operating 'fluid to the opposite ends ofsaid cylinder for controlling'the communication of said passage means with said fluid supply, and valve throwing means for subjecting said valve elements to valve throwing pressures to move said valveelements into their different operating positions, said valve throwing means including 'for -each of said valve elements means associated with the latter and subjected to a valve 'closing 'pressure-by"'fluid flowing past said valve element to the cylinder and means subjected toa supplemental valve closing pressure controlledzby the position of: the motor/piston, said valve elen'lentstbeing movable toward and from one another, each of said valves when in'its full open position exerting a force forholding the other closed, and said valve elements movable to effect concurrently interruption of communication of each of said passage means withsaid fluid supply. 7

- 30. In a pressure fluidmotor,vtheicombination comprising a cylinder having a bore, a piston reciprocab-lein said cylinder bore, a valve chest providing a. chamber, fluid distribution passages leading fromsaid valve chamber to the opposite ends of :said cylinder bore, valve means in said chamber for -.controlling thelflow of motive fluid from said chamber to said distribution pass-ages including relatively. movable fluid distributing valve elements,v said .valve elements movable to positions in which. they concurrently interrupt communication, between said chamber and said fluid. distribution passages and simultaneously cooperate iniprovlding a partition which divides saidlchamberfromend to end .andat one side of which. partition ,bothof saiddistribution passages openintothe chamber, asource of operating fluid communicating.withsaidchamber at a point separated by said partition, whenthe same is .formed, from said ,fluid distribution passages,

and. means for ,movingsaid valvelelements into their-.difierent operating positionsincluding. passage means ior, delivering .valvelthrowing fluid to said valve elements to .act..upon. the same at the othervside of said partition. 1

..3l. ,A pressure fluid motor comprising,..in .combination, a cylinder, a. piston-therein, and fluid distribution means for the motor including passagemeans for supplying operating fluidto the opposite ends of the .cylinderlat the opposite ends of,thevpiston.respectivelman operating fluid supply, valve means. including a pair of cooperating, relativelymoving valve elements respectively controlling the flow ,of operatinglfiuid to the opposite ends of .said cylinder for controlling the communication ,ofsaid passage means with said fluidlsupply, and valve throwing means for subjecting said valve elements. to valve. throwing pressures to move said valve elements into their different operating positions including oppositely extending flanges on each of said valve elements respectively.continuouslyand intermittently subjectedto valve closing forces whenlsaid valve element is-in open position, said, valveelements being ,movable toward and from one another, each ofsaidvalve'elements when in its full open position exerting a force for holding the other closed, and said valve elements movable to effect concurrently interruption of communication of each of said passage means with said fluid upp y.

'32; A pressure fluid motorcomprising, incombination, a cylinder, a piston therein, and'fluid distribution means for'the motor including passage meansfo-rsupplying operating fluid to the opposite ends'of the cylinder at the opposite'ends ofthe'piston respectively, an-operating fluid supply valve 'means including a--pair of cooperating, relatively movable valve elements respectively controllingthe' flow of operating fluid to the opposite ends of said cylinder ior'controlling the communication of said passage means with said fluid supply, and valve throwing means forsubjecting said valve-elements to valve throwing pressures to move said valve elements into their diflerent operating positions-including portions on each ofs'aid valveelements-continuously subjected by fluid :flowing past said valve elements to the, cylinder to valve closing forces when said valve elements are in openposition and means providing oppositely facing pressure areas intermittently subjected to valve closing forces to supplement said first mentioned forces and close said valve elements in alternation, said valve elements being movable toward and from one another, each of said valve elements when in its full open position exerting a force for holding the other closed, and said valve elements movable to effect concurrently interruption of communication of each of said passage means with said fluid sup ply.

33. In a pressure fluid motor, the combination comprising a cylinder having a bore, a piston reciprocab le in said cylinder bore, and fluid distribution means for supplying pressure fluid to and exhausting fluid from said cylinder bore to effect reciprocation of said piston comprising means providing a valve chest, a pair of cooperating, relatively movable, fluid distributing valves movably mounted in said Valve chest for controlling the supply of pressure fluid to the opposite ends of said cylinder bore, said valves arranged in coaxial relation and being hollow, and the pressure fluid flowing to the rear end of said cylinder bore through both of said hollow valves, means for effecting movement of said valves relative to one another into their diiierent normal operating positions in said valve chest, and means providing fluid supply passages leading from the opposite ends of said valve chest respectively to the opposite ends of said cylinder bore, said valves respectively controlling the flow of pressure fluid through the ends of said valve chest to said supply passages.

JOHN CLARK CURTIS.

CERTIFICATE OF CORRECTION.

Patent No. 2,22u,859. December 17, 191m, JOHN CLARK CURTIS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, second column, line M1, for "ls" read is-; page 5, second column, line 65- 611., for "pressure" read --pressures; page 8, second column, line 714, claim 21,- for "en" read --ends-; page 9, second column, line 10, claim 2h, after the word "valves" strike out the comma; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this L en day of February, A. D. 19in Henry Van Arsdale,

(Seal) Acting Commissioner of Patents.