US2718379A

US2718379A - Drilling machine

Info

Publication number: US2718379A
Authority: US
Publication date: 1955-09-20
Anticipated expiration: 1972-09-20

Description

Sept. 20, 1955 J. A. MxLLER DRILLING MACHINE NHSB IIA' :3.

Filed June `15, 1954 nited States Patent O DRILLING MACHINE .lohn A. Miller, Fremont, Ohio Application .inne 15, 1954, Serial No. 436,776

Claims. (Cl. Z55-4.4)

This invention relates to rock drilling devices such as are used in quarrying for drilling holes into which explosives are to be packed for blasting. Such holes may be from a few feet deep to as much as or more than sixty feet deep.

lt is a general object of this invention to provide a drilling device which will function electively at any depth.

More specifically it is an object of this invention to provide a drilling machine in which mass of reciprocating parts, rapidity of reciprocation, length of stroke, resiliency and other characteristics are so coordinated that rapidly repeated reactions substantially counterbalance gravity to keep the body of the machine spaced above the rock being drilled at a substantially constant distance from which a piston repeatedly plunges a bit against the rock.

Ancillary objects are to provide a drilling machine of simple and sturdy construction which will continue to operate reliably under abusive hammering conditions and in atmospheres loaded with abrasive particles.

Other objects and advantages will be apparent upon perusal of the following description illustrated by the accompanying drawings in which:

Fig. I is an elevational view of a drilling machine embodying the instant invention, an outer casing and a cylinder and chest being shown in section and a part of a piston rod being broken out;

Fig. II is an enlarged sectional view of parts of the outer casing and the cylinder and chest and parts contained therein;

Fig. III is a plan view of an upper cylinder head.

Fig. 1V is an elevational view of the upper cylinder head certain interior details being shown in dash lines.

Fig. V is an elevational view of a lower cylinder head.

The mechanism of the drilling machine is mounted within a tubular shell 8, which may be of any desired dimensions e. g., four to six inches in diameter and five to ten feet long.

Mounted within the lower end of the shell 8 and retained therein by a pair of pins 9 and a threaded ring 1t) is a composite engine casing comprising an upper tubular chest 11, an intermediate cylinder 12, and a lower tubular section 13.

Screwed into the upper end of the tubular chest 11is a threaded plug 14 having a threaded opening into which is screwed a pipe or nipple 15 adapted to conduct an expansive fluid such as steam or compressed air into the tubular chest 11. The expansive fluid may be supplied by a hose which extends to a source of supply outside of the hole being drilled.

Interposed between the tubular chest 11 of the composite engine casing and the intermediate cylinder 12 is an upper cylinder head 16 having arcuate sides that t ing reduced

threaded ends

20 and 21 upon which internally threaded ends of the intermediate cylinder 12 and the lower section 13 are screwed.

From the tubular chest 11 expansive fluid such as steam or compressed air is conducted by a conduit 22 to the upper cylinder head 16 and to the lower cylinder head 19.

Within the intermediate cylinder 12 reciprocates a piston 24. Fixed to the piston 24 is a piston rod 25 which passes through a bearing plug 26 tting within the lower end of the shell 8 and has a reduced threaded part that is screwed into the lower end of the lower section 13. The lower section thus serves as a holder which spaces the bearing plug 26 far enough from the lower cylinder head 19 to insure against binding or jamming of the piston or piston rod.

The upper cylinder head 16 is provided with an inlet passage 27 leading from the conduit 22 to the space in the cylinder 12 above the piston 24. Interposed in the inlet passage 27 is an inlet valve 28 which is opened by an inlet valve tappet during the final part of the upward stroke of the piston 24. The inlet valve tappet consists essentially of a tappet rod 29 which is slidable through the upper cylinder head 16 and which is protected against peening by cushioning springs 30 interposed between the tappet rod and its tips 31. Fixed to the tappet rod 29 is a block 32 which is located within the passage 27 and is secured to the stern 33 of the inlet valve 28, the stem 33 also being slidably mounted in the upper cylinder head 16. Thus when the piston 24 strikes the lower tip 31 of the tappet rod 29 the tappet rod 29, the block 32 and the inlet valve stern 33 will be pushed up as a unit to open the inlet valve 28.

The upper cylinder head 16 is provided also with an exhaust passage 34 leading from the space in the cylinder 12 above the piston 24 to an exhaust pipe 35. The exhaust passage 34 is closed and opened by an exhaust valve 36 whose stem 37 is slidably mounted in the upper cylinder head 16 and is fixed to a block 38 that is located within the exhaust passage 34. An exhaust valve tappet rod 39 is slidably mounted in the cylinder head 16 and is xed to the block 38. The exhaust valve tappet rod 39 is equipped with spring cushioned tips 31 identical with those on the inlet valve tappet rod 29. When the piston 24 strikes the lower tip of the exhaust valve tappet rod 39 it will push the exhaust valve tappet rod 39, the block 38 and the valve stem 37 up as a unit thus closing the exhaust valve 36.

In Figs. II and IV the parts are shown in their relationship just as the piston 24 reaches the lower tips 31 of the

tappet rods

29 and 39 while the inlet valve 28 still is closed and the exhaust valve 36 still is open. The

. linal upward movement of the piston through a fraction enter the upper end of the cylinder 12 as long as the within the shell 8 and having reduced threaded ends 17 inlet valve remains open.

Fixed to the piston 24 and extending upwardly therefrom through iluid tight packing in the cylinder head 16 is an auxiliary rod 40 which carries a plate 41. When the piston 24 comes within a small fraction of an inch of the end of its downward stroke the plate 41 will strike the spring cushioned upper tips of the

tappet rods

29 and 39 and thus close `the inlet valve 28 and open the exhaust valve 36 so that the piston 24 can be driven upwardly. Admission of expansive fluid into the space in the cylinder 12 below .the piston 24 .and exhaust .0f eX- pansive uid from such space is accomplished by mechanism mounted in the lower cylinder head. This mechanism diters from that inthe upper cylinder head principally in that pairs of :small valves are employed in the lower cylinder head rather than .single large valves such as are yemployed in the .upper cylinder head.

The lower cylinder head 19 .is provided with :an inlet passage 42 leading from the conduit 22 .to .the space in the cylinder 12 beneath the piston 24. interposed in the inlet passage 42 is a pair .of inlet valves .43 which are opened by a lower inlet valve tappet .during the -inal part of =the vdownward stroke .of the piston 24. The lower inlet valve tappet consists essentially .of a tappet rod 44 which is -slidable through the lower .cylinder head 19 and which is protected against peening by cushioning springs 30 interposed lbetween the tappet rod and its tips 31. Fixed to the tappet rod 44 is a block 45 which is loca-ted within Athe inlet passage 42 and .is secured to the stems 46 of the inlet valves 43, the stems 46 `also being slidably mounted in @the lower :cylinder head 19. Thus when the piston 24 strikes the upper tip 31 of the tappet rod 44.1the tappet rod 44, the 'block 45 and the inlet valve stems 46 are pushed down as a unit to open the inlet valves43.

The lower cylinder .head 19 is Vprovided also with an exhaust passage 47 leading from the space in the cylinder 12 beneath the piston 24 to the exhaust pipe 35. The exhaust passage 47 is closed and opened by a pair of exhaust valves 48 whose stems 49 are slidably mounted in the lower cylinder head 19 and are fixed to a block 50 that is located within the exhaust passage 47. An exhaust valve tappet rod S1 is slidably mounted in the lower cylinder head 19 and is fixed to the block 50. The exhaust valve tappet rod -is equipped with spring cushioned tips 31.

When the piston 24 strikes the upper tip of the lower exhaust valve tappet rod 51 -it pushes the tappet rod 51, the block 50 .and the valve stems 49 down as a unit thus closing Vthe exhaust valves 48.

Fixed to the piston -rod 25 -is an -annulus 52. When the piston 24 comes to within a fraction of an inch of its upward stroke the annnlus 52 will strike the lower spring Acushioned tips of the

tappet rods

44 and 51 and thus push -the vtappet rods up to close the inlet valves 43 and open the -exhaust valves 48, so that the piston 24 again jcan be driven downwardly.

Accidental partial or full opening or closing of any of the valves of the lapparatus is prevented i-n each case by a pair of balls 53 which are pressed by expansive springs 54 into a pair of sockets in the block -xed xto the tappet rod when the valve is closed and ywhich cam out yof those sockets and snap into another pair of sockets when the valve is ypushed open by the impact of the piston 24, the plate 41, -or the an-nulus 52 on the -tip of the tappet rod. `Such balls and -springs are shown in dash lines in Figs. IV and V.

LlFig. II yshows the condition ofthe mechanism of the lower cylinder head 19 just as `the annulus 52 engages the lower spring cushioned tips 31 of the tappet rods v44 and 51 near the end of the up stroke of the piston 2'4. Inthis condition `the inlet valves 43 still are open and the exhaust valves 48 are closed. Continued upward movement of the piston 24, piston rod 25 and annulus 52 ythrough a small fraction of an inch will close the inlet valves 43 and open the exhaust valves 48 so that the piston again can descend.

The piston rod 25 terminates in a replaceable bit 55 which as the piston reciprocates chisels the rocky away with rapidly repeated blows. The piston and piston Arod are free to rotate about their axis so the bit 'bores a hole that is approximately round and as the entire machine dances about, ythe hole is larger in diameter than the width of the bit. The exhaust blast is directed vby the exhaust pipe 35 through a port 56 in the ring 10 into the .hole .around .the bit 55 to sweep away .the debris and carry it up along the outside of the shell 8.

Friction reducing bushings of oil impregnated metal, piston rings, gaskets and suitable packing to minimize leakage are employed in the machine wherever their employment is advantageous. By unscrewing the ring 10 the engine can be withdrawn from the shell for cleaning, repair or adjustment.

Following are approximate statistics of a typical machine:

yOuter shell .8: outside diameter 41/2 inches; length 7 feet. Cylinder 12: inside diameter 3 inches; length 61/2 inches. Piston stroke: 41/2 inches.

Expansive fluid pressure: 200 pounds per square inch. Total pressure on cylinder: 1400 pounds.

Strokes per minute: 1200 to 1400.

Dimensions, pressures etc. can be varied as desired.

When the machine is in action the bit attacks the rock with high kinetic energy. The Hforce of the rapidly repeated Oppositely directed reactions or kicks against the cylinder heads is so great that the eiect of gravity on the lmass o f the machine is comparatively negligible. The intervals between oppositely directed kicks are so short the inertia of lthe machine is s o great that the machine hovers practially motionless at about the level at which it would stand on the bit 55 if the piston 24 were stopped at the bottom of its stroke. As the drilling progresses the machine gradually descends. When the hole to be drilled -is so deep that the entire shell 8 may descend into it, a cable or rope is attached to the shell for .use when the machine is to be pulled out `of lthe hole.

It is to be understood that the foregoing description and the accompanying drawings are yexemplary only and that the invention is susceptible to variation and modification within the spirit and scope of the subjoined claims.

Having described the invention, I claim:

l. In a drilling machine, in combination, an outer tubular shell, a composite engine casing removably mounted within said outer tubular shell, said composite yengine casing comprising a tubular chest, a tubular cylinder and a tubular bearing supporting section, there being ,an upper cylinder head interposed between said chest and said `-cylinder and Va lower cylinder head interposed between said cylinder and said tubular bearing supporting section, a bearing supported in spaced relation to said lower cylinder head by said tubular bearing supporting section, a reciprocatory piston within said cylinder, a piston rod fixed to said piston and slidable through said lower cylinder head and said bearing, an annulus Vxed to said piston rod and located within said tubular bearing Vsupporting section, a chisel like bit secured to the lower extremity of said piston rod, an auxiliary -rod 4iixed to said piston .and slidable through said upper cylinder head, a plate tixed to said auxiliary rod and located within said chest, means for continuously supplying 4,expansive fluid to said chest, a conduit for conducting such iluid to said upper cylinder head and said -lower `cylinder head, there being an inlet passage in said ,upper cylinder head leading from said conduit .to space `in said cylinder above said piston, an inlet valve for closing `and opening said inlet passage, an inlet ltappet rod rigidly connected with said inlet valve and having its lower end extending into said cylinder and its upper end extending into said chest, said inlet tappet .rod having spring cushioned vupper land lower tips the lower tip being so located as to be engaged by said reciprocatory ypiston .fas said piston nears the upper limit of its reciprocatory movement whereby said inlet tappet rod is -pushed up to open said inlet valve, the upper tip being so located as to vbe lengaged by said plate as said reciprocatory vpiston nears the lower limit of its reciprocator'y movement whereby said inlet tappet rod is pushed down to close said inlet valve, anexhaust channel extending from said upper cylinder head and said lower cylinder head to discharge exhaust iluid adjacent said bit, there being an exhaust passage in said upper cylinder head leading from the space in said cylinder above said piston to said exhaust channel, an exhaust valve for closing and opening said exhaust passage, an exhaust tappet rod rigidly connected with said exhaust Valve and having its lower end extending into said cylinder and its upper end extending into said chest, said exhaust tappet rod having spring cushioned tips, the lower tip being so located as to be engaged by said reciprocatory piston as said reciprocatory piston nears the upper limit of its reciprocatory movement whereby said exhaust tappet rod is pushed up to close said exhaust valve, the upper tip being so located as t0 be engaged by said plate as said reciprocatory piston nears the lower limit of its reciprocatory movement whereby said exhaust tappet rod is pushed down to open said exhaust valve, said lower piston head having inlet and exhaust passages, inlet and exhaust valves and inlet and exhaust tappet rods corresponding in relationship to each other and in function to the similarly denominated elements in said upper cylinder head, the tappet rods of said lower cylinder head being pushed down by said reciprocatory piston to open the inlet Valve and close the exhaust valve in said lower cylinder head when said reciprocatory piston nears the lower limit of its reciprocatory movement and being pushed up by said annulus xed to said piston rod to close the inlet valve and open the exhaust vaive in said lower cylinder head when said reciprocatory piston nears the upper limit of its reciprocatory movement, whereby said bit is caused to attack the substance being drilled with a rapid succession of chiseling blows and the machine is caused to hover at such an elevation above the substance being so attacked that such blows are delivered with high kinetic energy.

2. In a drilling machine, in combination, an outer tubular shell, a composite engine casing removably mounted within said outer tubular shell, said composite engine casing comprising a tubular chest, a tubular cylinder, an upper cylinder head and a lower cylinder head, a bearing supported in spaced relation to said lower cylinder head, a reciprocatory piston within said cylinder, a piston rod fixed to said piston and slidable through said lower cylinder head and said bearing, an annulus fixed to said piston rod, a chisel like bit secured to the lower extremity of said piston rod, an auxiliary rod iixed to said piston and slidable through said upper cylinder head, a plate fixed to said auxiliary rod and located within said chest, means for continuously supplying expansive fluid to said chest, a conduit for conducting such fluid to said upper cylinder head and said lower cylinder head, there being an inlet passage in said upper cylinder head leading from said conduit to space in said cylinder above said piston, an inlet valve for closing and opening said inlet passage, an inlet tappet rod rigidly connected with said inlet valve and having its lower end extending into said cylinder and its upper end extending into said chest, said inlet tappet rod having spring cushioned upper and lower tips the lower tip being so located as to be engaged by said reciprocatory piston as said piston nears the upper limit of its reciprocatory movement whereby said inlet tappet rod is pushed up to open said inlet valve, the upper tip being so located as to be engaged by said plate as said reciprocatory piston nears the lower limit of its reciprocatory movement whereby said inlet tappet rod is pushed down to close said inlet valve, an exhaust channel extending from said upper cylinder head and said lower cylinder head., there being an exhaust passage in said upper cylinder head leading from the space in said cylinder above said piston to said exhaust channel, an exhaust valve for closing and opening said exhaust passage, an exhaust tappet rod rigidly connected with said exhaust Valve and having its lower end extending into said cylinder and its upper end extending into said chest, said exhaust tappet rod having spring cushioned tips, the lower tip being so located as to be engaged by said reciprocatory piston as said reciprocatory piston nears the upper limit of its reciprocatory movement whereby said exhaust tappet rod is pushed up to close said exhaust valve, the upper tip being so located as to be engaged by said plate as said reciprocatory piston nears the lower limit of its reciprocatory movement whereby said exhaust tappet rod is pushed down to open said exhaust valve, said lower piston head having inlet and exhaust passages, inlet and exhaust valves and inlet and exhaust tappet rods corresponding in relationship to each other and in function to the similarly denominated elements in said upper cylinder head, the tappet rods of said lower cylinder head being pushed down by said reciprocatory piston to open the inlet valve and close the exhaust valve in said lower cylinder head when said reciprocatory piston nears the lower limit of its reciprocatory movement and being pushed up by said annulus fixed to said piston rod to close the inlet valve and open the exhaust valve in said lower cylinder head when said reciprocatory piston nears the upper limit of its reciprocatory movement, whereby said bit is caused to attack the substance being drilled with a rapid succession of chiseling blows and the machine is caused to hover at such an elevation above the substance being so attacked that such blows are delivered with high kinetic energy.

3. In a drilling machine, in combination, an outer tubular shell, a composite engine casing removably mounted within said outer tubular shell, said composite engine casing comprising a tubular chest, a tubular cylinder, an upper cylinder head and a lower cylinder head, a bearing supported in spaced relation to said lower cylinder head, a reciprocatory piston within said cylinder, a piston rod fixed to said piston and slidable through said lower cylinder head and said bearing, an annulus ixed to said piston rod, a chisel like bit secured to the lower extremity of said piston rod, an auxiliary rod xed to said piston and slidable through said upper cylinder head, a plate xed to said auxiliary rod and located within said chest, means for continuously supplying expansive fluid to said chest, a conduit for conducting such fluid to said upper cylinder head and said lower cylinder head, there being an inlet passage in said upper cylinder head leading from said conduit to space in said cylinder above said piston, an inlet valve for closing and opening said inlet passage, an inlet tappet rod rigidly connected with said inlet valve and having its lower end extending into said cylinder and its upper end extending into said chest the lower end being so located as to be engaged by said reciprocatory piston as said piston nears the upper limit of its reciprocatory movement whereb said inlet tappet rod is pushed up to open said inlet valve, the upper end being so located as to be engaged by said plate as said reciprocatory piston nears the lower limit of its reciprocatory movement whereby said inlet tappet rod is pushed down to close said inlet valve, an exhaust channel extending from said upper cylinder head and said lower cylinder head, there being an exhaust passage in said upper cylinder head leading from the space in said cylinder above said piston to said exhaust channel, an exhaust valve for closing and opening said exhaust passage, an exhaust tappet rod rigidly connected with said exhaust valve and having its lower end extending into said cylinder and its upper end extending into said chest, the lower end being so located as to be engaged by said reciprocatory piston as said reciprocatory piston nears therupp'er limit of its reciprocatory movement whereby said exhaust tappet rod is pushed up to close said exhaust valve, the upper end being so located as to be engaged by said plate as said reciprocatory piston nears the lower limit of its reamat-W9 ciprocatory movement whereby said exhaust tappet rod is pushed down to open said exhaust valve, said lower piston head having inlet and exhaust passages, inlet and exhaust valves and inlet and exhaust tappet rods corresponding in relationship to each other and in function to the similarly denominated elements in said upper cylinder head, the Vtappet rods of said lower cylinder head being pushed down by said reciprocatory piston to open the inlet valve and close the exhaust valve in said lower cylinder head when said reciprocatory piston nears the lower limit of its reciprocatory movement and being pushed up by said annulus xed to said piston rod to close the inlet valve and open the exhaust valve in said lower cylinder head when said reciprocatory piston nears the upper limit of its reciprocatory movement, whereby said bit is caused to attack the substance being drilled with a rapid succession of chiseling blows and the machine is caused to hover at such an elevation above the substance being so attacked that such blows are delivered with high kinetic energy.

4. In a drilling machine, in combination, an outer tubular shell, a composite engine casing removably mounted within said outer tubular shell, said composite engine casing comprising a tubular chest, a tubular .cylinder and a tubular bearing supporting section, there being an upper cylinder head interposed between said chest and said cylinder and a lower cylinder head interposed between said cylinder and said tubular bearing supporting section, a bearing supported in spaced relation to said lower cylinder head by said tubular bearing supporting section, a reciprocatory piston within said cylinder, a piston rod lixed to said piston and slidable through said lower cylinder head and said bearing, an annulus fixed to said piston rod and located within said tubular bearing supporting section, a chisel like bit secured to the lower extremity of said piston rod, an auxiliary rod lixed to said piston and slidable through said upper cylinder head, a plate lixed to said auxiliary rod and located within said chest, means for continuously supplying expansive fluid to said chest, a conduit for conducting suchfluid to said upper cylinder head and said lower cylinder head, there being an inlet passage in said upper cylinder -head leading from said conduit to space in said cylinder above ysaid piston, an inlet valve for closing and opening said inlet passage, means operative as said pistou nears the upper limit of its reciprocatory movement to open said inlet valve, means operative as said reciprocatory pis-ton nears the lower limit of its reciprocatory movement to close said inlet valve, an exhaust channel extending from said upper cylinder head and said lower cylinder head to ldischarge exhaust fluid adjacent said bit, there being an exhaust passage in said upper cylinder head leading from the space in said cylinder above said piston yto said exhaust channel, an exhaust valve for closing and opening said exhaust passage, means operative as said reciprocatory piston nears the upper limit of its reciprocatory movement to close said exhaust valve, means operative as said reciprocatory piston nears the lower limit of its reciprocatory movement to open said exhaust valve, said lower piston head having inlet and exhaust passages, and inlet and exhaust valves and valve actuating means all corresponding in relationship to each other and in function to the similarly denominated elements in said upper cylinder head, whereby said bit is caused to attack the substance being drilled with a rapid succession of chiseling blows and the machine is caused to hover at such an elevation above the substance being so attacked that such blows are delivered with high kinetic energy.

5. In a drilling machine, in combination, an outer tubular shell, a composite engine casing removably mounted within said outer tubular shell, said composite engine casing comprising a tubular chest, a tubular cylinder, an upper cylinder head and a lower cylinder head, a bearing supported in spaced relation to said Vlower cylinder head, a lreciprocatory piston within said cylinder, a piston rod lixed to said piston and Vslidable through said lower cylinder head and said bearing, an annulus lixed to said piston rod, a chisel like bit secured to the lower extremity of said piston rod, an auxiliary rod xed to said piston and slidable through said upper cylinder head, a plate fixed to said auxiliary rod and located within said chest, means for continuously supplying expansive uid to said chest, a conduit for conducting such liuid to said upper cylinder head and said lower cylinder head, there being an inlet passage in said upper cylinder head leading from said conduit to space in said cylinder 'above said piston, an inlet valve for closing and opening said inlet passage, means operative as said piston nears the upper limit of its reciprocatory movement to open said inlet valve, means operative as said reciprocatory piston nears the lower limit of its reciprocatory movement to close said inlet valve, an exhaust channel extending from said upper cylinder head and said lower cylinder head, there being an exhaust passage in said upper cylinder head leading from the space in said cylinder above said piston to said exhaust channel, an exhaust valve for closing and opening said exhaust passage, means operative as said reciprocatory piston nears the upper limit of its reciprocatory movement to close said exhaust valve, means operative as said reciprocatory piston nears the lower limit of its reciprocatory movement to open said exhaust valve, said lower piston head having inlet and exhaust passages, and inlet and exhaust valves and valve actuating means all corresponding in relationship to each other and in function to the similarly denominated elements in said upper cylinder head, whereby said bit is caused to attack the substance being drilled with a rapid succession of chiseling blows and the machine is caused to hover at such an elevation above the substance being so attacked that such blows are delivered with high kinetic energy.

6. A drilling machine comprising, in combination, a tubular chest, a tubular cylinder and a tubular bearing supporting section, there being an upper cylinder head interposed between said chest and said cylinder and a lower cylinder head interposed between said cylinder and said tubular bearing supporting section, a bearing supported in spaced relation to said lower cylinder head by said tubular bearing supporting section, a reciprocatory piston within said cylinder, a piston rod iixed to said piston and slidable through said lower cylinder head and said bea-ring, an annulus xed to said piston rod and located within said tubular bearing supporting section, a chisel like bit secured to the lower extremity of said piston rod, an auxiliary rod fixed to said piston and slidable through said upper cylinder head, a plate iixed to said auxiliary rod and located within said chest, means for continuously supplying expansive fluid to said chest, a Aconduit for conducting such uid to said upper cylinder head and said lower cylinder head, there being an inlet passage in said upper cylinder head leading from said conduit to space in said cylinder above said piston, an inlet valve for closing and Opening said inlet passage, an inlet tappet rod rigidly connected with said inlet valve and having its lower end extending into said cylinder and its upper end extending into said chest, said inlet tappet rod having spring cushioned upper and lower tips theV lower tip being so located as to be engaged by said reciprocatory piston as said piston nears the upper limit of its reciprocatory movement whereby said inlet tappet rod is pushed up to open said inlet valve, the uppertip being so located as to be engaged by said plate as said reciprocatory piston nears the lower limit of its reciprocatory movement whereby said inlet tappet rod is pushed down to close said inlet valve, an exhaust channel extending from said upper cylinder head and said lower cylinder head to discharge exhaust iluid adjacent said bit, there being an exhaust passage in said upper cylinder head leading from the space in said cylinder above said piston to said exhaust channel, an exhaust valve vfor closing and opening said exhaust passage, an exhaust tappet rod rigidly connected with said exhaust valve and having its lower end extending into said cylinder and its upper end extending into said chest, said exhaust tappet rod having spring cushioned tips, the lower tip being so located as to be engaged by said reciprocatory piston as said reciprocatory piston nears the upper limit of its reciprocatory movement whereby said exhaust tappet rod is pushed up to close said exhaust valve, the upper tip being so located as to be engaged by said plate as said reciprocatory piston nears the lower limit of its reciprocatory movement whereby said exhaust tappet rod is pushed down to open said exhaust valve, said lower piston head having inlet and exhaust passages, inlet and exhaust valves and inlet and exhaust tappet rods corresponding in relationship to each other and in function to the similarly denominated elements in said upper cylinder head, the tappet rods of said lower cylinder head being pushed down by said reciprocatory piston to open the inlet valve and close the exhaust valve in said lower cylinder head when said reciprocatory piston nears the lower limit of its reciprocatory movement and being pushed up by said annulus fixed to said piston rod to close the inlet valve and open the exhaust valve in said lower cylinder head when said reciprocatory piston nears the upper limit of its reciprocatory movement, whereby said bit is caused to attack the substance being drilled with a rapid succession of chiseling blows and the machine is caused to hover at such an elevation above the substance being so attacked that such blows are delivered with high kinetic energy.

7. A drilling machine comprising, in combination, a tubular chest, a tubular cylinder, an upper cylinder head and a lower cylinder head, a bearing supported in spaced relation to said lower cylinder head, a reciprocatory piston within said cylinder, a piston rod fixed to said piston and slidable through said lower cylinder head and said bearing, an annulus xed to said piston rod, a chisel like bit secured to the lower extremity of said piston rod, an auxiliary rod xed to said piston and slidable through said upper cylinder head, a plate fixed to said auxiliary rod and located within said chest, means for continuously supplying expansive fluid to said chest, a conduit for conducting such uid to said upper cylinder head and said lower cylinder head, there being an inlet passage in said upper cylinder head leading from said conduit to space in said cylinder above said piston, an inlet valve for closing and opening said inlet passage, an inlet tappet rod rigidly connected with said inlet valve and having its lower end extending into said cylinder and its upper end extending into said chest, said inlet tappet rod having spring cushioned upper and lower tips the lower tip being so located as to be engaged by said reciprocatory piston as said piston nears the upper limit of its reciprocatory movement whereby said inlet tappet rod is pushed up to open said inlet valve, the upper tip being so located as to be engaged by said plate as said reciprocatory piston nears the lower limit of its reciprocatory movement whereby said inlet tappet rod is pushed down to close said inlet valve, an exhaust channel extending from said upper cylinder head and said lower cylinder head there being an exhaust passage in said upper cylinder head leading from the space in said cylinder above said piston to said exhaust channel, an exhaust valve for closing and opening said exhaust passage, an exhaust tappet rod rigidly connected with said exhaust valve and having its lower end extending into said cylinder and its upper end extending into said chest, said exhaust tappet rod having spring cushioned tips, the lower tip being so located as to be engaged by said reciprocatory piston as said reciprocatory piston nears the upper limit of its reciprocatory movement whereby said exhaust tappet rod is pushed up to close said exhaust valve, the upper tip being so located as to be engaged by said plate as said reciprocatory piston nears the lower limit of its reciprocatory movement whereby said exhaust tappet rod is pushed down to open said exhaust valve, said lower piston head having inlet and exhaust passages, inlet and exhaust valves and inlet andexhaust tappet rods corresponding in relationship to each other and in function to the similarly denominated elements in said upper cylinder head, the tappet rods of said lower cylinder head being pushed down by said reciprocatory piston to open the inlet valve and close the exhaust valve in said lower cylinder head when said reciprocatory piston nears the lower limit of its reciprocatory movement and being pushed up by said annulus xed to said piston rod to close the inlet valve and open the exhaust valve in said lower cylinder head when said reciprocatory piston nears the upper limit of its reciprocatory movement, whereby said bit is caused to attack the substance being drilled with a rapid succession of chiseling blows and the machine is caused to hover at such an elevation above the substance being so attacked that such blows are delivered with high kinetic energy.

8. A drilling machine comprising, in combination, a tubular chest, a tubular cylinder, an upper cylinder head and a lower cylinder head, a bearing supported in spaced relation to said lower cylinder head, a reciprocatory piston within said cylinder, a piston rod fixed to said piston and slidable through said lower cylinder head and said bearing, an annulus fixed to said piston rod, a chisel like bit secured to the lower extremity of said piston rod, an auxiliary rod xed to said piston and slidable through said upper cylinder head, a plate xed to said auxiliary rod and located within said chest, means for continuously supplying expansive fluid to said chest, a conduit for conducting such uid to said upper cylinder head and said lower cylinder head, there being an inlet passage in said upper cylinder head leading from said conduit to space in said cylinder above said piston, an inlet valve for closing and opening said inlet passage, an inlet tappet rod rigidly connected with said inlet valve and having its lower end extending into said cylinder and its upper end extending into said chest, the lower end being so located as to be engaged by said reciprocatory piston as said piston nears the upper limit of its reciprocatory movement whereby said inlet tappet rod is pushed up to open said inlet valve, the upper end being so located as to be engaged by said plate as said reciprocatory piston nears the lower limit of its reciprocatory movement whereby said inlet tappet rod is pushed down to close said inlet valve, an exhaust channel extending from said upper cylinder head and said lower cylinder head, there being an exhaust passage in said upper cylinder head leading from the space in said cylinder above said piston to said exhaust channel, an exhaust valve for closing and opening said exhaust passage, an exhaust tappet rod rigidly connected with said exhaust valve and having its lower end extending into said cylinder and its upper end extending into said chest, the lower end being so located as to be engaged by said reciprocatory piston as said reciprocatory piston nears the upper limit of its reciprocatory movement whereby said exhaust tappet rod is pushed up to close said exhaust Valve, the upper end being so located as to be engaged by said plate as said reciprocatory piston nears the lower limit of its reciprocatory movement whereby said exhaust tappet rod is pushed down to open said exhaust valve, said lower piston head having inlet and exhaust passages, inlet and exhaust valves and inlet and exhaust tappet rods corresponding in relationship to each other and in function to the similarly denominated elements in said upper cylinder head, the tappet rods of said lower cylinder head being pushed down by said reciprocatory piston to open the inlet valve and close the exhaust valve in said lower cylinder head when said reciprocatory piston nears the lower limit of its reciprocatory movement and being pushed up by said annulus fixed to said piston rod to close the inlet valve and open the exhaust valve in said lower cylinder head when said reciprocatory piston nears the upper limit of its reciprocatory movement, whereby said bit is caused to attac-k the substance being drilled with a rapid succession of chiseling blows and the -machine is caused to hover at such an elevation above the substance being so attacked that such blows are delivered w-ith high kinetic energy.

9. A drilling machine comprising, -in combination, a tubular chest, a tubular cylinder and a tubular bearing supporting section, there being an upper cylinder head interposed between sa-id chest and said cylinder and a lower cylinder head -interposed between said cylinder and said tubular bearing supporting section, -a bearing supported in spaced relation to said lower cylinder head by said tubular bearing support-ing section, -a reciprocatory piston within said cylinder, a piston rod lixed to sa-id piston and slidable through said lower cylinder head and said bearing, an annulus Ifixedl to said piston rod and located within said tubular 'bearing support-ing section, a chisel like bit secured vto the lower extremity of ysaid piston rod, an auxiliary rod iixed to said piston and slidable through said upper cylinder-head, a plate -xed to said auxiliary rod and located within sa-id chest, means tor continuously suppl-ying expansive fluid `to said chest, a conduit for conduct-ing such fluidl to said upper cylinder head and said lower cylinder head, there being an inlet passage in said upper cylinder head leading yfrom said conduit 'to space in -said cylinder above said piston, -a-n inlet vvalve for closing and opening said inlet passage, means operative as said piston nears the upper limit of its reciprocatory movement to open said inlet -v-alve, means operative as said reciprocatory piston nears the lower limit of its reciprocatory movement to close said inlet valve, an exhaust channel extending from said upper cylinder head and said lower cylinder head to discharge exhaust fluid adjacent said bit, there lbein-g an exhaust passage in said upper cylinder head leading from the space in said cylinder above said piston -to said exhaust channel, an exhaust valve for closing and opening said exhaust passage, means operative as sa-id reciprocatory piston nears the upper limit of its reciprocatory movement to close said exhaust valve, means operative as `said reciprocatory piston nears the lower lim-it of its reciprocatory movement to open said exhaust valve, said lower piston head having inlet and exhaust passages, and inlet and exhaust valves and valve actuating means all corresponding in relationship to each other and nin function to the similarly denominated elements `in `said upper cylinder head, whereby said bit is caused to attack the substance being drilled with a rapid succession ,of chiseling blows and the machine is caused to hover ,at such an elevation above the substance being so -attacked that such blows are delivered 4with lhigh kinetic energy.

l0. A drilling machine comprising, in combination, a tubular chest, a tubular cylinder, an upper cylinder head and a lower cylinder head, a bearing supported in spaced relation to said lower cylinder head, a reciprocatory piston within said cylinder, a piston rod xed to said piston and Aslidable through said lower cylinder head and said bearing, an annulus ixed to said piston rod, a chisel like bit secured to the lower extremity of said piston rod, an auxiliar-y rod fixed to said piston and slidable through said upper cylinder head, a plate fixed to said auxiliary rod and located within said chest, means for continuously supplying expansive fluid to said chest, a conduit for conducting such uid to said upper cylinder head and said lower cylinder head, there being an inlet passage in said upper cylinder head leading from said conduit to space in -said cylinder above said piston, an inlet valve for closing and opening said inlet passage, means operative as said pis-ton -nears the upper limit of its reciprocatory movement to open said inlet valve, means operative as said reciprocatory piston nears the lower limit of its reciprocatory movement to close said inlet valve, an exhaust channel lextending from said upper cylinder head and said lower cylinder head, there being an exhaust passage in said upper cylinder head leading from the space in said cylinder above -said piston to said exhaust channel, an exhaust valve lfor closing and opening said exhaust passage, means operative as said reciprocatory piston nears the upper limit of its reciprocatory movement to close said exhaust valve, means operative as said reciprocatory piston nears the lower limit of its reciprocatory movement to open said exhaust valve, said lower piston head having inlet and exhaust passages, and inlet and exhaust v-alves and valve actuating means all corresponding in relationship to each other and in function to the similarly denominated elements in said upper cylinder head, whereby said bit is caused to attack the substance being drilled with a rapid succession of chiseling blows and the machine is caused to hover at such an elevation above the substance -being so attacked that such blows are delivered with high kinetic energy.

References Cited in the tile of this patent 'UNITED STATES PATENTS `860,660 Heldmaier July 23, 1907 96,8016 Williome Aug. 23, 1910 1,569,183 Herman et al. Ian. l2, 1926