US2296819A

US2296819A - Rock drill

Info

Publication number: US2296819A
Application number: US304794A
Authority: US
Inventors: Charles F Osgood
Original assignee: Sullivan Machinery Co
Current assignee: Sullivan Machinery Co
Priority date: 1939-11-16
Filing date: 1939-11-16
Publication date: 1942-09-22
Anticipated expiration: 1959-09-22

Description

Sept. 22, 1942. c. F. OsGooD ROCK DRILL Filed Nov. 16, 1959 5 Sheets-Sheet l Sept. 22, 1942. C, F. OSGOQD 2,296,819

. ROCK DRILL v Filed Nov. 16, 1959 5 Sheets-Sheet 2 5.a EZ 'j 6' v0 9 j Mg. 5.

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Filed Nv. 16, 17939 C. F. OSGOOD ROCK DRILL 3 Sheets-Sheet 3 Patented Sept. 22, 1942 ROCK DRILL Charles F. Osgood, Claremont, N. H., assigner to Sullivan Machinery Company, a corporation of Massachusetts Application November 16, 1939, Serial No. 304,794

8 Claims. (Cl. Z55-52) This invention relates to rock drills, and more particularly to improvements in a hammer rock drill of the self-supporting stoper type.

An object of this invention is to provide an improved hammer rock drill having improved means for supporting the drill with respect to the work. Another object is to provide improved means for supporting and guiding the drill hammer motor of a stoper rock drill. A further object is to provide an improved stoper rock drill of the self-supporting type having improved means for supporting the drill at the working face as well as at its rear end abutment, whereby the drill may be supported with respect to the work wholly without manual aid. Yet another object is to provide an improved fluid actuated, extensible supporting means for supporting a stoper rock drilll at its remote extremities with respect to the working face. A still further object is to provide an improved reversible feeding' means for a stoper rock drill of the self-supporting type whereby the drill hammer motor may be fed rearwardly as well as forwardly with respect to the work while the drill is at all times maintained supported at its remote extremities. Another object is to provide an improved feeding and supporting mechanism for a hammer drill. vention will, however, hereinafter more fully appear.

In the accompanying drawings there are shown for purposes of illustration several forms and modifications which the invention may assume in practice.

In these drawings:

Fig. l is a side elevational view of an illustrative embodiment of the improved stoper rock drill.

Fig. 2 is a view in longitudinal vertical section taken through the rock drill shown in-Fig. 1, the drill hammer motor being shown in side elevation.

Fig. 3 is a fragmentary sectional view taken in the plane of Fig. 2, showing a modified form of construction.

Fig. 4 is a view similar to Fig. 3, showing a further modified form of construction.

Fig. 'lu is an enlarged, fragmentary, sectional view on the same plane as Fig. 4.

Fig. 5 is an enlarged cross sectional view taken substantially on line 5-5 of Fig. 1.

Fig. 6 is a vertical sectional viewtaken substantially on line 6-6 .of Fig. 5.

Other objects and advantages of the in- Fig. 7 is a fragmentary view taken in the 55 plane of Fig. 6, showing the support control valve in a different position.

Fig. 8 is an enlarged detail sectional view taken substantially on line 8-8 of Fig. 6.

Fig. 9 is a side elevational view showing the improved rock drill mounted in horizontal drilling position on a mine column.

Fig. 10 is a view in longitudinal vertical sec. tion taken in the plane of Fig. 2, showing another illustrative embodiment of the invention.

Fig. 11 is a view similar to Fig. 10, showing a further embodiment of the invention.

Fig. 12 is a view similar to Fig. 2, on a somewhat reduced scale, showing still another illustrative embodiment of the invention.

In the illustrative embodiments of the invention shown in Figs. 1 to 8, inclusive, which include one form and two modifications of structural details, the drill hammer motor is generally designated I and the improved supporting, guiding and feeding structure is generally designated 2. The rock drill disclosed is of the kstoper type, although it will be evident that various features of the invention may be embodied in rock drills of various other types.

The drill hammer motor l is of a conventional design and comprises a cylinder 3 containing a reciprocatory hammer piston (not shown) for delivering impact blows to the shank of a drill steel 4, the latter suitably supported within the vfront chuck housing 5 of the hammer motor.

The motor cylinder has a rear head block 6 containing a throttle valve mechanism generally designated 1 for controlling .the supply of pressure fluid to the motor cylinder. 'I'he rear head block and front chuck housing are secured to the motor cylinder in any conventional manner, as by side rods 8. As the internal structure of the drill hammer motors and the mode of operation thereof are well known to those skilled in the art, and as the present invention is not dependent upon the use of any particular motor, further detailed description and illustration of the hammer motor are unnecessary.

Now referring to. the supporting, guiding and feeding structure 2, it will be noted that a stationary feed cylinder Ill has its rear head I I provided with an abutment-engaging point l2. Contained in the feed cylinder I0 is a reciprocable feed piston I3 having its piston rod I4 extending fcrwardly through the fronthead' l5 of the feed cylinder I0. The forward end of the feed cylinder bore at the forward side of the feed piston is vented to atmospherey through a vent port I6. The feed piston rod M is of tubular form and has a. bore I1, and the feed piston I3 constitutes the rear head for the cylinder bore I1. Contained in the bore I1 is a reciprocable piston I8 carrying a cup leather I8 sealingly engaging the walls of the bore I1 for precluding leakage of fluid from the bore at the lower side of the piston past the piston. The piston I8 has a tubular piston rod 20 extending forwardly through a front head 2I integral with the feed piston rod I4, and secured to the outer end of the piston rod 28 is an abutment-engaging point 22. The forward end of the cylinder bore I1 at the forward side of the piston I8 is vented to atmosphere through a vent port 28. Fixed at 24 to the rear head II of the feed cylinder is a reaction rod 25, the latter arranged centrally within the feed cylinder and extending forwardly axially through a central opening 26 in the feed piston I8 and telescopically arranged within the piston rod 28. 'I'he feed` pisthe tubular piston rod 26, and this head has external grooves 28 for conducting pressure fluid from the bore I1 at the lower side of the piston I8 and through the tubular piston rod 28, alongthe rod past the piston head 28, to the bore in the piston rod 28 in advance of the piston head. The abutment-engaging points I2 and 22 are in alinement and constitute the sole supporting means for the drill, the point 22 being engageable with the working face while the point I2 is engageable with a rearwardly located extraneous abutment. It will thus be seen that when pressure fluid is supplied to the bore I1 0f the feed piston rod I4, the pressure fluid flows along the rod through the bore of the piston rod 20 and through the grooves 28, past the piston head 28, to the piston rod bore in advance of the piston head 28, and as a result the pressure uid acts on the lower surface of the pistonV I8 and the surface 30 at the forward end of the bore of the piston rod 20, thereby moving the front point 22 into firm engagement with the working face, while at the same time the pressure fluid in the bore of the piston rod 20 acts on the upper surface of the piston head 28 of the reaction rod to hold the rear point I2 rmly against its abutment.

The drill hammer motor I is mounted feed pistonrod I4, with its longitudinal axis in parallelism with the longitudinal axis of the supporting and guiding means 2, and in this instance on the l the front chuck housing 5 has a laterally located integral boss-like projection 8l having a bore 32 receiving the forward portion of the feed piston rod I4. The projection 3| is held in position on the feed piston rod against a shoulder 33 by a retaining nut 34 threaded on the rod. Suitable means, such as a dowel, may be provided for preventing relative rotation between the projection 3l and the feed piston rod I4. It will thus be seen that the drill hammer motor I is entirely supported by the feed piston rod I4 of the feeding means and is guided during its feeding movement by the feed cylinder and the rods I4, 28 and 25.

The throttle valve mechanism 1 comprises a throttle valve 35 (Fig. 5) `rotatably mounted in a bore 36 in the rear head block 8. The valve has a stem 31 to which is secured an operating handle 3B. The throttle valve has a hollow interior at 38, and pressure fluid may be supplied to the throttle valve interior through a supply connection 40 leading to any suitable source of pressure fluid supply. Pressure huid may be supplied to the rear end of the feed cylinder at the lower side of the feed piston under the control of the throttle valve 35 through a port 4I in the valve communicable with a passage 42 connected through a flexible conduit 43 to a passage 44 (Fig. 2) in the rear head II of the feed cylinder. The throttle valve has ports 45 for supplying pressure fluid to the supply passages of the drill hammer motor in a well known manner. Pressure fluid may ow to the rear end of the bore I1 of the feed piston rod I4 below the piston I8 through a passage 46 (indicated in dotted lines in Fig. 5) communicating with the supply connection 40. Arranged in a bore 41 in the head block 6 is a separate, rotary, support control valve 48 provided with a valve stem to which is secured a manual control handle 49. The support control valve 48 has a bore 5I) communicable through a port 5I with the passage 46. Seating against a seat surrounding the bore 58 is a spring-pressed check valve 52 for controlling the flow of fluid from the bore 50 to a groove 53 in the control valve.

Passages

54 and 55 in the check valve 52 conduct pressure fluid, when the check valve is unseated, from the bore 58 past the valve seat and through the groove 53 to a chamber 56 at one end of the valve bore 41. A groove 51 in the control valve connects the chamber 56 with a passage 58 in the head block (see also Fig. 6) in one position of the valve 48. A circumferentially extending groove 59 on the throttle valve 35 connects the passage 58 with a passage 60, the latter extending longitudinally through the motor cylinder `3 and front chuck housing and communicating with a passage 6 I. As shown in Fig. 2, the passage 6I is connected by a longitudinal passage 62 in the feed piston rod I4 to a lateral port 63, the latter communicating with the rear end of the piston rod bore I1 at the lower side of the piston I8 in the manner shown. When the throttle valve 435 and the support control valve 48 are in the position shown in Fig. 6 pressure fluid may flow from the supply connection '48 through the passage 46, port 5I, past the check valve 52, through

passages

54, 55, chamber 56, groove 51, passage 58, groove 59 on lthe throttle valve, passage 60, port 6I, passage 62 and port 63, to the piston rod bore I1v at the lower side of the piston I8 to move the latter upwardly and forwardly within its bore in the feed piston rod. Concurrently, pressure fluid ows from the bore I1 through the bore of the piston rod 28, through the grooves 28 in the piston head 28 of the reaction rod 25, to the upper end of the piston rod bore, to move the reaction rod in a rearward direction. When the valve 48 is turned in the position shown in Fig. 7, the bore I1 at the lower side of the piston I8 is vented to atmosphere through port 63, passage 62, port 6I, passage 68, groove 59 on the throttle valve, passage 58, a groove 64 on the valve 48, and an exhaust passage 65 in the valve. The throttle valve 35 is provided with an exhaust groove 66, and when the throttle valve is rotated to bring the groove 86 into communication with the passage 42. the rear end of the feed cylinder at the lower side of the feed piston is vented to atmosphere. Pressure fluid may also flow from the interior of the throttle valve 35 through the port 4I, passage 42, conduit 43, and passage 44, to the lower end assumo of the feed cylinder at'the lower side ofthe feed piston I3. Pressure fluid flowing through the passage 62 and port 88 to the bore I1 acts on the lower side of the piston-I8 to'move the front point 22 firmly against the working face and.

concurrently, the pressure fluid flowing -through the piston rodbore past the reaction rod 28 and through the grooves 29 in the piston head 28 to the bore of the piston rod 28 atthe upper side of the piston Lead, acts on the upper surface of the piston head to hold the rear point I2 at the rear ,end of the drill' firmly against its extraneous abutment. When the abutment-engaging points I2 and 22 are in extended position against their extraneous abutments, the supporting and guiding and guiding structure toward the work.

When the feed cylinder bore at the lower side of the feed piston I3 is vented to atmosphere, the pressure fiuid'in the piston'rod bore I1 acts on the upper surface of the piston to effect rearward movement of the latter with respect to the piston I8, and as a result the drill hammer motor 'is moved along the supporting and guiding structure in a rearward direction. In the event that the fluid supply should fail for any reason,.t he check valve 52 automatically closes to trap the fluid in the piston rod bore I1 at the lower side of the piston I8 and at the upper side of the piston head 28, so that the abutment-engaging points are held firmly in place, thereby to prevent inadvertent falling of the drill away from the work. It should be noted that the valve 35 can be manipulated to supply pressure to or to vent the port 42 without interrupting communication of groove 59 with passages 58 and 68.

The provision of the reverse feed' for the drill hammar motor is of particular importance when the drill is in horizontal drilling position, as shown in Fig. 9, so that the hammer motor can be readily retracted from the work. In this instance the rear abutment-engaging point I2 of the drill is seated within a socket member 18, in turn pivotally mounted at 1I on a clamp 12, the latter being secured to an upright mine column 13. 'This mine column has a bottom abutmentengaging point14 and a top abutment-engaging point 15, the latter being secured to an extensible member 16. The mine column is preferably of the duid-actuated type, and the extensible member 16 is extended under the action of pressure fluid so that the abutment-engaging points at the opposite extremities of the column are held firmly in position. The supply connection 40 of the drill hammer motor is connected through a hose 11 to a main supply line 18, and also connected to this supply line through a hose 19 under the control of a valve 88 is the fluid supply for the mine column. When the parts are in the position shown in Fig. 9, the drill is supported at the working face by the abutment-engaging point 22, and at its rear end by the mine column. When pressure fluid is supplied to the rear end of the feed cylinder I8 at the rear side of the feed piston I3, the drill hammer motor may be fed forwardly along the supporting and guiding structure 2, and

when the rear end of the feed cylinder I8 is vented to atmosphere in the manner above described, the pressure in the piston rod bore I1, due to the differential pressure areas on the feed piston acts on the feed piston head to feed the may be retracted by power.

portfngand-guiding structure. This reverse feed feature eliminates, during horizontal drilling, the necessity` of manually moving the drill hammer motor in a'rearward direction, as would be necessary If the reverse feedfeature were omitted.- In

a drill ofthe stoper type. as shown in Fig. 1,k

the reversefeedfeature is not so essential since the weight of the drill hammer motor, when the rear end of the/feed cylinder is vented to atmosphere, causes the hammer motor to move rearwardly by gravity.

In Fig. 3 a modified form of construction 'is disclosed. In this instance the piston I8 assumes the form of a piston head8I fitting the bore I1 of the feed-piston rod I4, and this piston head has a series -of longitudinal external grooves packings and the fluid supply passage in the walls of the piston rod I4, as in the construction disclosed in Fig. 2. As illustrated, the fluid supply passage 6I is connected by a passage'83 in the front head 2I of the piston rod with a passage 84 communicating `with the upper end of the piston rod bore I 1. When pressure fluid is supplied to the passage 8|, it flows through passages 83 and 84 to the upper end of the piston rod bore I1, past the piston head 8I, through the grooves 82, to the piston rod bore at the lower side of the piston, the pressure fluid acting on the lower pressure area kof the piston head'8l to move the latter upwardly within its bore to effect engagement of the abutment-engaging ppint 22 with the working face. Concurrently, pressure fluid ows through the bore of the piston rod 28,.past the grooved head 28 on the reaction rod 25, to the bore of the piston rod 28 above the piston head 28, the pressure fluid acting on the upper pressure area of thev reaction rod head to hold the rear abutment-engaging point I2 iinnly against its extraneous abutment. The retaining nut 34 is provided with a forward enlargement 85 carrying a packing 86 sealingly engaging the exterior surface of the piston rod 20 to prevent leakage of pressure fluid from the upper end of the piston rod bore I1 past this piston rod. Otherwise this modified structure is the same as that disclosedin Fig. 2.

In the modified construction shown in Fig. 4, the piston rod 20 supporting the abutment-engaging point 22 is actuated by pressure fluid in a reverse direction, as well as in a forward direction, so that the abutment-engaging point 22 In this construction, the piston I8 carries packings 81 for preventing leakage of pressure fluid from the opposite ends of the piston rod bore I1 past the piston I8. Arranged in a bore 88 in the bossdrill hammer motor, isa rotary reverse' valve 89. Communicating with the valve bore is a passage 90 connected-to a passage 9I communieating with the upper end of the piston rod bore I1 at the upper side of the piston I8. Also'communicating with the valve bore is a passage 92 connected to a passage` 93 extending longitudinally through the side wall of the feed piston rod I4, the passage 93 being connected through a lateral port 94 with the piston rod bore I1 at the lower side of the piston I8. Also communicating with the valve bore is a vent passage 95. The valve 89 has a central supply chamber drill hammer motor rearwardly along the suppressure area of the piston I8 to move the latter forwardly within the piston rod bore, thereby moving the abutment-engaging point 22 forwardly against the working face. When pressure fluid is supplied to the lowerv end of the piston rod bore at the lower side of the piston I0, the upper end of the piston rod bore is concurrently vented to atmosphere through passages 9I, 90 and exhaust groove 99 communicating with the exhaust passage 95. When the valve 09 is rotated to bring the supply groove 98 into communication with the passage 90, pressure uid may flow through the passage 9| to the upper end of the piston rod bore |1 at the upper side of the piston |8, the pressure fluid acting on the upper pressure area of the piston to effect rearward movement of the latter in the piston rod bore, and as a result the abutment-engaging point 22 is retracted from the working face. As pressure uid flows to the upper end of the piston rod bore, the piston rod bore at the lower side of the piston is concurrently vented to atmosphere through port 94, passage 93, passage 92 and exhaust groove 99 communicating with the exhaust passage 95. Otherwise this modied form of construction is the same as that disclosed in Fig. 2.

In the illustrative embodiment of the invention disclosed in Fig. l0, the drill hammer motor is supported by a reciproeable feed cylinder |05, the boss-like `projection 3| on the chuck housing 5 of the drill hammer motor `being secured at |06 to the forward end of the reciprocable feed cylinder. Contained in the feed cylinder is a stationary feed piston l? having a tubular piston rod |08 extending rearwardly through the packed rear head |09 of the feed cylinder. Secured to the rear end of the feed piston rod |08 is a head member 0 carrying an abutment-engaging point I. The rear feed cylinder head carries a packing H2 sealingly engaging the exterior periphery of the piston rod |08 to prevent leakage of pressure uid from the feed cylinder. Secured at H3 to the upper head H4 of the feed cylinder is a tubular member H5 extending centrally through the feed cylinder bore and telescopically arranged with the tubular piston rod |08. The feed piston |01 carries packings H6 sealingly engaging the exterior periphery of the tubular member H5 to prevent leakage of pressure fluid in opposite directions past the piston. The rear end of the tubular member H5 has an integral piston head I I1 guided within the bore of the piston rod |08 and having longitudinal external grooves H8 to permit the flow of pressure fluid past the same. 'I'he bore of the feed piston rod |08 is connected, through ports H9 in the tubular member H5, with the lower end of the bore |20 of this tubular member. The bore of the feed piston rod |08 is connected through ports |2| with the feed cylinder bore at the lower side of the feed piston. Reciprocably mounted in the bore |20 of the tubular member H5 is a packed piston |22 having its piston rod |23 extending forwardly through the upper head of the feed cylinder and carrying' at its upper end an abutment-engaging point |24. AConnected to the head member III is a fluid supply connection |25 mmunicating through a passage |25 with the lower end of the bore of the feed p|ston rod |05. When pressure ilid is supplied through the connection |25 and passage |25 to the bore of the feed piston rod |00, it flows' through the grooves H8 past the piston' head ||1 and through ports H9 to the bore |20 of the tubu- Alar member H5, the pressure fluid acting on the lower pressure area of the piston I 22 to move the latter upwardly within its bore; and as itv result the abutment-engaging point |24 is moved against the working face. When it is desired to effect-forward feed of lthe drill hammer motor,

pressure fluid may be supplied through a supply.

passage |21 in the boss-like projection 3| and through port |28 to the feed cylinder bore at the upper side of the feed piston, the pressure uid acting on the forwardly acting pressure area |29 of the front cylinder head ||4 to effect forward feeding movement of the feed cylinder relative to the feed piston; and as a result the drill hammer motor is moved forwardly toward the Y work. During the forward feeding operation the pressure fluid acting on the front cylinder head 4 is supplemented by the pressure fluid acting on the effective rear pressure area |30 of' the piston head ||1 of the tubular member |I5. Concurrently, pressure fluid flows from the bore of the feed piston rod |08 through ports |2| to the feed cylinder bore at the rear side of the feed piston |01. When the forward end of the feed cylinder bore at the upper side of the feed piston is vented to atmosphere, the pressure fluid flowing to the rear end of the feed cylinder bore acts on the rearwardly acting pressure area |3| of the rear cylinder head |09 to effect rearward movement of the feed cylinder relative to the stationary feed piston; and as a. result the drill hammer motor is fed rearwardly with respect to the work. It is evident that the combined effective pressure areas |30, |29 on the head ||1 and the front cylinder head are substantially greater than the rearwardly acting pressure area. |3| on the rear cylinder head |09, so that when pressure fluid is supplied to the forward end of the feed cylinder bore forward feed is effected. Also, the rearwardly acting pressure area. |3| on the rear feed cylinder head |09 is somewhat larger than the effective rear pressure area |30 on the piston head I I1, so that when the upper end of the feed cylinder bore is vented to atmosphere, reverse feed is effected. Obviously any suitable control means for the selective supply and venting of fluid relative to the passages |21 and |25 may be used. For example the control means for port 42 can be utilized through a suitable conduit to govern the connection |21, and the control for passage 60 can be utilized through suitable conduits to control passage |25.l

In the illustrative embodiment of the invention shown in Fig. ll, the feed cylinder structure is essentially the same as that disclosed in Fig. l0, in that the feed cylinder is reciprocable and the drill hammer motor is supported by the feed cylinder. In this construction, the reciprocable feed cylinder |32 contains a feed piston |33 stationary in normal use and having a tubular piston rod |34 extending rearwardly through the packed rear head |35 of the feed cylinder. Secured to the rear end of the feed piston rodis a head member |36 carrying an abutment-engaging point |31. Reciprocable in the bore 38 of the feed piston rod |34 is a piston head |39 having itsv piston rod |40 telescopically arranged within the feed piston rod and extending forwardly through the packed bore |4| of the feed piston and upwardly through the packed upper head I 42 of the feed cylinder. Carried at the upper end of the piston rod |40 is an abutment-engaging point |43. The feed piston carries packings |44 sealingly engaging the piston rod |40 for preventing leakage of pressure fluid through the bore I4| past the feed piston in opposite directions. head member |36 is a supply connection |45 communicating through a passage |46 with the bore |38 of the feed piston rod. A fluid supply passage |41 communicates through a port |48 with the feed cylinder bore at the upper side L the feed piston. Any suitable supply and exhaust controls for connections |45 and |41 may, as noted with connections |25 and |21, be used. The bore |38 in the feed piston rod is connected through ports |49 with the feed cylinder bore at the lower side of the feed piston. The piston head |39 is provided with longitudinal external grooves |50 to permit flow of pressure fluid through the piston rod bore past the piston head. When pressure fluid is supplied through the supply connection |45 and passage |46 to the bore |38 of the feed piston rod, the pressure fluid acts on the effectiverear pressure area of the piston head |39 to move the latter forwardly within the piston rod bore; andas a result the abutment-engaging point |43 is moved into engagement with the working face. At the same time pressure fluid flows through the grooves |50, through the piston rod bore, along the piston rod |40, and through ports |49, to the feed cylinder bore at the rear side of the feed piston. When pressure fluid is supplied through the passage |41 and port |48 to the feed cylinder bore at the upper side of the feed piston, the pressure fluid acts on the forwardly acting pressure area |52 of the front cylinder head to move the feed cylinder forwardly; and as a result the drill hammer motor is fed toward the work. When the passage |41 is vented to atmosphere, pressure in the upper end of the feed cylinder bore is exhausted, and as a result the pressure fluid flowing through the ports |49 to the rear end of the feed cylinder bore acts on the rearwardly acting pressure area |53 of the rear feed cylinder head to move the feed cylinder rearwardly, thereby retracting the drill hammer motor from the work.

In the illustrative embodiment of the invention disclosed in Fig. 12,'the supporting, guiding and feeding structure 2 is, except as will be noted, the same as that disclosed in Fig. 2 and the drill hammer motor is carried by the piston rod I4 of the feed piston I3. The feed piston is reciprocable in the stationary feed cylinder I0, the latter having a rear abutment-engaging point I2. In this construction, the feed A piston rod I4 has a bore |54, and reciprocable in the piston rod bore is a piston head |55 having its piston rod |56 extending forwardly through a packing |51 carried at the forward end of the feed piston rod. Secured to the forward end of the piston rod |56 is the abutmentengaging point 22. The piston head |55 is provided with longitudinal external grooves |58 to permit flow of pressure fluid past the piston head. In this instance the reaction rod 25 is omitted and the rear end of the piston rod bore |54 is Connected to the eating with the piston rod bore |54 at the upper side of the piston head |55 is a fluid supply passage |60. When pressure fluid is supplied through the passage |60 to the piston rod bore |54, pressure fluid flows rearwardly through the bore |54, along the piston rod |56, and through the grooves |58 on the piston head |55, to the piston rod bore |54 at the rear side of the piston head, the pressure fluid acting on the rear pressure area ISI of the piston head to move the latter forwardly within the piston rod bore |54; and as a. result the abutment-engaging point 22 is moved forwardly against the working face. When pressure fluid is supplied to the rear end of the feed cylinder I4 at the rear side of the feed piston, the pressure fluid acts on the rear pressure area |62 of the feed piston to move the latter forwardly within the feed cylinder bore, and as a result the drill hammer motor is fed toward the work. When the rear end of the feed cylinder bore is vented to atmosphere, pressure fluid in the piston rod bore |54 acts on the forward pressure area. |63 of the piston head- |59 to effect rearward movement of the feed piston I3, and as a result the drill hammer motor is retracted fromnthe Work. Otherwise this embodiment of the invention is the same as that disclosed in Fig. 2.

As a result of this invention, it will be noted than an improved supporting structure is provided for a stoper rock drill whereby the rock drill may be supported with respect to the work wholly without manual aid. It will further be noted that by the provision of the front abutment-engagmg point engageable with `the work-l ing face and actuated by pressure fluid, the stoper rock drill is held firmly against'the work. It will further be evident that by the provision of the reverse feeding means the drill hammer motor may not only be fed forwardly toward the work under the action of pressure fluid, but may be also retracted from the work under the action of pressure fluid, in a simplified manner, the drill hammer motor being supported and guided by the improved supporting and guiding means during both its forward and reverse feeding movements. Other uses and advantages of the improved rock drill will be clearly apparent to those skilled in the art.

While there are in this application specifically described several forms and modifications which the invention 'may assume in practice, it will be understood that these are shown for purposes of illustration and that the invention may be further 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:

l. In a rock drill, relatively reciprocable feed cylinder and feed piston elements, fluid actuated means coaxial with said cylinder and piston elements for supporting the drill on the working face and including oppositely acting fluid actuated supporting elements, one of which is a stationary reaction element, a drill hammer motor operatively connected to the piston element for feeding thereby, said feed piston element having differential pressure areas, the larger one of said piston areas acting in the forward-feed-effecting direction and the smaller pressure area acting in the reverse-feed-effecting direction, means for supplying pressure fluid concurrently to said fluid actuated supporting means and said smaller closed by a rear head member |59. Communipiston area, and means for supplying pressure iiuid to and exhausting fluid from said larger piston area without interrupting the flow of pressure uid to said smaller pressure area, the pressure fluid acting on said larger pressure area overcoming the pressure of the uid acting on said smaller pressure area to effect forward feed of the drill hammer motor and the pressure fluid acting on said smaller pistonarea effecting reverse feed of the drill hammer motor when said larger piston area is connected to exhaust.

2. In a rock drill, relatively reciprocable feed cylinder and feed piston elements, said piston element having a piston rod provided with a bore. uid actuated means coaxial with said cylinder and piston elements for supporting the drill on the working face and including a fluid actuated supporting piston reciprocably mounted in saidpiston rod bore and extending forwardly through the forward end of said feed piston rod, said piston rod of said supporting piston having a bore, a reaction rod secured to and extending centrally through said feed cylinder element and having a piston head received in said bore of said supporting piston rod, a drill hammer motor operatively connected to .the piston element for feedingv thereby, said feed piston element having differential pressure areas, the larger one of said piston areas acting in the forward-feed-eifecting direction and the smaller pressure area acting in the reverse-feed-effecting direction, means for supplying pressure uid concurrently to said uid actuated supporting means and said smaller piston area without interrupting the fiow of pressure iiuid to said smaller pressure area, and means for supplying pressure fluid to and exhausting uid from said larger piston area, the pressure fluid acting on said larger pressure area overcoming the pressure of the fluid acting on said smaller pressure area to effect forward feed of the drill hammer motor and the pressure uid acting on said smaller piston area effecting reverse feed of the drill hammer motor when said larger piston area is connected to exhaust.

3. In a rock drill, a stationary feed cylinder having a rear abutment-engaging point, a feed piston reciprocable in said feed cylinder and having its piston rod extending forwardly through the front cylinder head, said feed piston rod having a bore, a drill hammer motor carried by said feed piston rod, a piston reciprocable in said piston rod bore and having its piston rod extending forwardly through the forward end of said feed piston rod, an abutment-engaging point carried at the forward end of said last-recited piston rod, andv relatively stationary reaction means for said last mentioned piston. l

.4. In a rock drill, a stationary feed cylinder having a rear abutment-engaging point, a feed piston reciprocable in said -feed cylinder and having its piston rod extending forwardly through the front cylinder head, said feed piston rod having a bore, a drill hammer motor carried by said feed piston rod, a piston reciprocable in said pis ing, oppositely extending, telescopically arranged piston rods, each having a piston head contained in a cylinder, said rods at their remote extremities adapted to react against extraneous abutments, the face. of the work constituting the forward. abutment, means for supplying pressure fluid to the cylinders to effect opposite relativrI movement of said rods to move the same into firm engagement with their extraneous abutments, a feed cylinder stationary with respect to one of said rods and containing a reciprocable feed piston, anda drill hammer motor operatively connected to said feed piston for feeding thereby.

6. In a rock drill, an elongated extensible supporting structure comprising a pair of cooperating, oppositely extending, telescopically arranged piston rods each having a piston head contained in a cylinder, said rods at their remote extremities adapted to react against extraneous abutments, means for supplying pressure fluid to the cylinders to effect opposite relative movement of said rods to move the same into firm engagement with their extraneous abutments, a feed cylinder stationary and coaxial withrespect to one of said rods and containing a reciprocable feed piston, said feed piston having a tubular piston rod providing a cylinder in which one of said pistonsof said telescopically arranged piston rods is contained, and a drill hammer motor operatively connected to said feed piston for feeding thereby.

7. In a rock drill, an elongated, extensible supporting structure comprising a pair of cooperating, oppositely extending, telescopically arranged piston rods each having a piston head contained in a cylinder, said rods at their remote extremities adapted to react against extraneous abutments at the opposite extremities of the drill, means for supplying pressure fluid to the cylinders to effect opposite relative movement of said rods to move the same into firm engagement with their extraneous abutments, relatively reciprocable feed cylinder andv piston elements coaxial with said supporting structure, and a drill hammer motor operatively connected to said reciprocable feed piston element for feeding thereby.

8. In a rock drill, an elongated, extensible supporting structure actuated by pressure fluid and at its remote extremities adapted to react against extraneous abutments whereby the drill is supported solely at its remote extremities, a drill hammer motor, and fluid actuated feeding means for said hammer motor including relatively reciprocable feed cylinder and piston elements arranged coaxially with said supporting structure, said feed piston element having differential pressure' areas, means for supplying pressure fluid concurrently to said supporting means and the smaller pressure area of said feed piston, and means for supplying pressure fluid to and exhausing fluid from the larger pressure area of said feed piston without interrupting the flow of pressure fluid to said smaller pressure area, the pressure fluid acting on said larger pressure area overcoming the pressure of the uid acting on said smaller pressure area to cause said piston to effect forward feed of said drill hammer motor and the pressure fluid acting on the smaller pressure area of said feed piston effecting reverse feed of said drill hammer motor when said larger pressure area is vented to atmosphere.

CHARLES F. osGooD.