US2811335A

US2811335A - Mobile roof drill

Info

Publication number: US2811335A
Application number: US321344A
Authority: US
Inventors: Fletcher James Robert; William F Fletcher
Original assignee: JH Fletcher and Co
Current assignee: JH Fletcher and Co
Priority date: 1952-11-19
Filing date: 1952-11-19
Publication date: 1957-10-29
Anticipated expiration: 1974-10-29

Description

Oct. 29, 1957 J. R. FLETCHER ETAL 2,811,335

MOBILE ROOF DRILL Filed Nov. 19. 1952 5 Sheets-Sheet 1 INVENTORS. James Faber! F/e faker Wd/iam Fara/e7! Tlezcke: Ida/4.5 Z T E Oct 1957 J. R. FLETCHER ETAL' 2,811,335

MOBILE ROOF DRILL Filed Nov. 19, 1952 5 Sheets-Sheet 2 6] 63 o L W" 45 :91 IO 53 41 I07 w I ll INVENTORS. James Faberf F/e tC/Iez 'lliam Tara/ell Fletcher b Q HZ Z HE Oct. 29, 1957 J. R. FLETCHER ETAL MOBILE ROOF DRILL 5 Sheets-Sheet 5 Filed NOV. 19, 1952 a 5 M H M U m H w m Oct. 29, 1957 J, FLETCHER E 2,811,335

MOBILE ROOF DRILL Filed Nov. 19, 1952 5 Sheets-Sheet 4 INVENTORS. limes Ebert Fletcher 1T. 3 mm Fame/l Wezc/zer Oct. 29, 1957 Filed Nov. 19, 1952 MOBILE ROOF DRILL 5 Sheets-Sheet 5 no I09 Iig-El 97 94 L ,INVENTORS.

Hla

& H am Fara/e]! Fletcher E Z 2 H5 United States Patent Office 2,811,335 Patented Oct. 29, 1957 MOBILE ROOF DRILL James Robert Fletcher and William F. Fletcher, Huntington, W. Va., assignors to J. H. Fletcher & Co., Chicago, 11]., a corporation of Illinois Application November 19, 1952, Serial No. 321,344

10 Claims. (Cl. 255-51) This invention relates to improvements in mobile roof drills and more particularly relates to such a drill having a drop mast taking the drilling reaction on the ground.

A principal object of our invention is to provide a mobile roof drill for drilling holes directly in the mine roof to receive roof bolts, in a more expeditious manner than formerly.

Another object of our invention is to provide a novel and improved form of mobile roof drill for drilling vertical holes in a mine roof particularly adapted for operation in thin seams of coal.

A further object of our invention is to provide a novel and improved form of roof drill having a drilling carriage supported for vertical movement against a drop mast reacting against the mine floor during vertical feeding movement of the carriage for drilling in a mine roof.

A still further object of our invention is to provide a novel and improved form of self-propelled drilling apparatus for drilling holes upwardly in the mine roof, arranged with a view toward providing a firm support for the drilling mechanism during the entire drilling operation and increasing the travel of the drill carriage and making it unnecessary to change drill during the normal operation of drilling in the roof, to receive a roof-supporting bolt.

A further object of the invention is to provide stability for the mast, so that after the hole is drilled and the bolt inserted, the drill chuck may be maintained in alignment with the bolt head and be used to tighten the bolt.

A still further object of our invention is to provide a mobile roof drill, particularly adapted to drill holes for roof bolts in mines underground wherein a drop mast forms a support for the drill and drill carriage and the mast is so arranged as to take the drilling reaction against the ground and to accommodate the drill carriage to first travel the height of the collapsed mast and then to travel a further distance equal to the length of extensible movement of the mast.

A further and more detailed object of our invention is to provide a self-propelled roof drill wherein a mast assembly is guided on a mobile frame for vertical movement with respect thereto and has a drill guided for vertical movement therealong and in which a cylinder and piston unit sets the mast assembly on the floor and an additional two stage cylinder and piston unit moves the drill carriage along the mast assembly during one stage of extensible movement thereof and then moves the assembly and carriage a further distance during a second stage of extensible movement thereof.

These and other objects of our invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawings wherein:

Figure l is a top plan view of a mobile roof drill constructed in accordance with our invention;

Figure 2 is a view in side elevation of the drill shown in Figure 1 Figure 3 is a front end view of the drill shown in Figures 1 and 2;

Figure 4 is a fragmentary view in side elevation of the forward end portion of the drill frame and mast, showing the drop mast and drill carriage in engagement with the ground;

Figure 5 is a view somewhat similar to Figure 4, but showing the drop mast and drill carriage in a fully extended position;

Figure 6 is a front end View of the drop mast and drill carriage showing the drop mast and carriage in the extended position shown in Figure 5;

Figure 7 is an enlarged fragmentary plan view of the front end of the drilling apparatus showing certain details of the mast and support therefor, not shown in Figure 1;

Figure 8 is a diagrammatic view showing the fluid diagram for operating the drill and extending and tilting the drop mast and drill carriage; and

Figure 9 is a transverse sectional view taken through the two stage fluid pressure cylinder and piston for feeding the drill carriage along the drop mast and then extending the mast and carriage therewith.

In the embodiment of our invention illustrated in the drawings a truck 10 is shown as including a main frame 11 mounted on

front traction wheels

12, 12 and a rear steering wheel 13.

The frame 11 is shown as having an operators compartment 14 at one side thereof having a steering wheel 15 therein operatively connected with the rear steering wheel 13 for turning the same and steering the vehicle through a chain and sprocket drive 16.

A motor 17 is also shown as being mounted on the main frame 11 and as having driving connection with a pump 19 through a flexible coupling 2%. The motor 17 may be controlled by a controller 21 on the opposite side of the frame from the operators compartment 14, which may be operated from the operators compartment in a suitable manner. The motor 17 may also be connected with the

front traction wheels

12, 12 for driving the same in any well known manner, and not herein shown or described since it forms no part of our present invention.

At the front end of the main frame 11 and extending transversely thereof between the

wheels

12, 12 is a vertical support plate 22 for a drop mast 23. The drop mast 23 is herein shown as comprising a channelled guide 24 mounted on and extending forwardly from a tiltable plate 25, shown as being pivotally mounted on the plate 22 adjacent the lower end thereof on a pivot pin 27 extending longitudinally of the frame 11. The plate 25 is shown as having an arcuate slot 26 adjacent its upper end within which extends a headed pin or bolt 30, mounted on and extending outwardly from the plate 25. A collar may encircle said pin and be interposed between said plates and a nut may be threaded on the inner end of the pin 30, to hold the outer plate 25 in parallel relation with respect to the plate 22. The outer plate 25 is shown as being tiltable about the axis of the pin 27 by means of a fluid pressure cylinder 31 having a piston (not shown) movable therein and a piston rod 33 extensible therefrom. The cylinder 31 is shown as having an ear 34 projecting outwardly from its head end, which is pivotally connected to the left-hand upper corner of the support plate 22 on a pivot pin 35. The piston rod 33 is shown as being connected with the plate 25 for pivoting the same about the axis of the shaft 27 on a pivot pin 36 secured to and extending inwardly from the plate 25. Fluid under pressure may be admitted to and released from the head and piston rod ends of the cylinder 31, and may be held therein to hold the plate 25 in the desired position of adjustment under the control of a valve 37 in a valve bank 38. Pressure lines 39 and 40 leading from the valve 37 are shown as being connected to the head and piston rod ends of the cylinder 31, respectively (see Fig. 8) to sup- J ply and release fluid therefrom and to hold fluid under pressure therein under control of the valve 37, in an obvious manner.

The channelled guide 24 on the plate 25 is shown in Figure 7 as comprising two spaced, inwardly facing

angles

41, 41 extending vertically along said plate and suitably secured thereto as by welding. Spaced blocks 42, 42, extend along the plate 25 and a leg of each angle to form the inner guide of the channelled guide. Said blocks terminate short of the arcuate slot 26 and space the drop mast outwardly from the head of the pin 30.

Slidably guided within the channelled guide 24 is the drop mast 23. Said drop mast is shown as having a drill carriage 44 slidably guided therein for vertical movement therealong. The drop mast 23, as herein shown, comprises two facing channels 45, 4S guided for vertical movement along the channelled guide 24. The drop mast 23 also includes two facing

channels

47, 47 slidably guided within the

channels

45, 45 for extensible movement therefrom. The

channels

45, 45 are shown as being connected together at their lower ends by a base plate 49 engageable with the ground and reacting thereagainst during the drilling operation.

The base plate 49 of the drop mast 23 is herein shown as being moved into and out of engagement with the ground by means of a fluid pressure cylinder 50 having a piston (not shown) movable therein and a piston rod 51 extensible therefrom. The cylinder 50 is shown as having a lug 53 extending from its head end, pivotally connected to the left-hand angle 41 adjacent the upper end thereof on a pivot pin 54. The free end of the piston rod 51 is shown as being pivotally connected to the lower end of the left-hand channel 45 of the drop mast 23 on a pivot pin 55. Fluid under pressure may be admitted to the head and piston rod ends of the cylinder 58 to raise and lower the

channels

45, 45 and base plate 49 of the drop mast 23, and engage the base plate 49 with the ground, by means of a valve 56 in the valve bank 38 and pressure lines 57 and 58 leading from said valve to head and piston rod ends of the cylinder 50 (see Fig. 8).

The

channels

47, 47 slidably guided within the

channels

45, 45, are shown as being connected together adjacent their upper ends by a tie plate 61. A drill guide 63 is shown as extending forwardly therefrom and forming a guide for a drill 65, carried at its lowered end in a chuck 66 in the drill carriage 44. The drill guide 63 may be of any well known form and is not herein shown or described in detail since it forms no part of our present invention.

Slidably supported and guided within the

channels

47,47 is the drill carriage .4. Said drill carriage is shown as comprising two

frame members

67, 67 each of which has spaced

rollers

69, 69 rotatably mounted thereon and fitting within the

channels

47, 47 and riding along the flanges thereof. The

frame members

67, 67 are shown as being connected together by a vertical plate 70 spaced forwardly of the

channels

47, 47. Attached to the plate 79 and extending forwardly therefrom is a base plate 71 having a fluid motor 73 mounted thereon and also having a housing 74 mounted thereon and forming a housing and bearing support for the chuck 66 and the drive mechanism therefor.

The fluid motor 73 is shown in Figure 7 as driving the chuck 66 through a chain and sprocket drive 75 and spur reduction gearing 76 driven thereby. A clutch (not shown) operated by a hand lever 78 may be provided to selectively connect the chain and sprocket drive 75 with the gearing 76. The fluid motor 73 may be operated in reverse directions under the control of a valve 77, which may be mounted on a support plate 79 extending outwardly from the right channel 45 adjacent the right-hand end thereof (see Figures and 8). Fluid under pressure may be supplied to said valve from the pump 19 through a pressure line 80 connected from said pump to said valve, the return from said valve being through re- 4 I turn lines 81 and 82 leading to a tank (not shown). The valve 77 is connected with opposite sides of the drill motor 73 to supply fluid under pressure to either end thereof by means of pressure lines 83 and 84, it being understood that when fluid under pressure is supplied to one end of the drill motor 73 through one pressure line that it is released from the opposite end of said drill motor through the other pressure line.

The pump 19 is shown in Figure 8 as being a dual pump driven by an electric motor 116. One section 117 of the pump 19 receives fluid from fluid storage tank 119 and serves to supply fluid to the pressure line and the drill motor 73. Another section 120 of the pump 19 is connected with a fluid storage tank 121 and delivers fluid to the valve bank 38 through a pressure line 122. A flow control valve 123 is connected in said pressure line and also serves as a relief valve.

The means for feeding the drill carriage 44 along the

channels

47, 47 and then extending the

channels

47, 47 from the

channels

45, 45 is shown as comprising a two stage fluid pressure cylinder 85, which may be double acting, and has a piston rod 86 extending downwardly therefrom into engagement with a socket and fitting 87 on the base plate 49 (see Figure 6).

As shown in Figure 9, the two stage cylinder has an outer casing or shell 89 having an inner casing or cylindrical shell 90 spaced inwardly therefrom and sealed to the wall thereof and extensible therefrom.

The piston rod 86 in turn is shown as being hollow and as being slidably movable within a cylinder 91. The cylinder 91 is secured at its inner end to a retainer 93 threaded within the outer shell 89. The retainer 93 is shown as having a sealing member 94 threaded therein, having slidable engagement with the piston rod 86 and forming a seal and slidable guide therefor. The end of the cylinder 91 opposite from the retainer 93 or end closure for the cylinder 89 is shown as being closed by an end closure cap 95 threaded therein and sealed thereto. The cylinder 91 is shown as being connected at its upper end on the end closure cap 95 to the tie plate 61 connecting the channels together at their upper ends and as having abutting engagement with the bottom of said tie plate. A pressure line 98 leading from a valve 96 shown as being in the same valve bank as the valves 37 and 56, is connected with a port 97 leading through the cylinder 89, and is also connected with the upper end of the cylinder 91 through a port 99 leading through the cap 95 to the interior of said cylinder. When the valve 96 is in position to supply fluid under pressure to the

ports

97 and 99, due to the increased surface area within the cylinder 89, fluid will first act on the inner cylinder 90 and move said cylinder upwardly along the cylinder 89 for the length of stroke thereof. Fluid under pressure also entering the interior of the cylinder 91 will then react against a piston 101 within said cylinder and on the upper end of the piston rod 89, bodily moving the cylinder 91 and the

cylinders

89 and 90 along the piston rod 86 as a unit. A port 103 enters the cylinder 89 at a point spaced above the bottom thereof and is connected with the valve 96 through a pipe 104. The pipe 104 is also connected with a port 105 at the lower end of the piston rod 86 admitting fluid under pressure to the hollow interior of said piston rod. When the valve 96 is in position to admit fluid under pressure through the pipe 104, fluid under pressure entering the port 103 will first move the cylinder 90 downwardly within the cylinder 89. Fluid entering the interior of the cylinder 91, through the port 105, will then react against said piston in a direction to retract the cylinder 91 along the piston rod 86 and retractably move the cylinder 89 therewith.

The connection between the cylinder and piston unit 85 and the drill carriage 44 is shown as including two flexible devices, such as

chains

107, 107. The

chains

107, 107 are shown as being secured to the outer end of the cylinder 89 at one of their ends on

connectors

108, 108 and as extending upwardly therefrom over

rollers

109, 109 rotatably journaled on a collar 110. The opposite ends of the

chains

107, 107 are suitably connected to the drill carriage 44 to effect movement of said drill carriage along the

channels

47, 47 upon extension of the inner casing 90 from the outer casing 89. The collar 110 is shown as encircling the cylinder 90 and as resting on the upper end thereof. Since the pull of the chains 107 are always in a downward direction with respect to the

rollers

109, 109 and since said chains take the weight of the carriage 44, the collar 110 will be retained in engagement with the upper portion of the cylinder 90 by the weight of the drill carriage 44. A snap ring 111 which may be snapped within the collar 110 and engage a recessed portion 111a of the cylinder 90 is provided to retain the collar 110 from upward lifting movement with respect to the cylinder 90.

Thus, when the reaction plate 49 is in engagement with the ground and the valve 96 is in position to admit fluid under pressure to the

ports

97 and 99, the collar 110 and

rollers

109, 109 will first move upwardly relative to the cylinder 89, moving the drill carriage 44 upwardly therewith. When the cylinder 91 reaches the upper limit of its travel, as when a sealing ring collar 114 abuts a shouldered surface 115 on the inner periphery of the cylinder 89, fluid pressure entering the cylinder 91 through the port 99 will act on the piston 101 and extend the cylinder 91 along the piston 86 for the limit of travel thereof, moving the

cylinders

90 and 89 and drill carriage 44 and drill 65 therewith.

Upon movement of the valve 96 into a position to admit fluid under pressure to the

ports

103 and 105 the entire drill carriage will be lowered, withdrawing the drill carriage and drill from the roof in an obvious manner.

It may be seen from the foregoing that we have provided a novel and improved form of drill, particularly adapted to drill holes in a mine roof for roof bolts with expansion shields to hold the weaker rock strata to the firmer rock, which is so arranged that the reaction to drilling is taken on the mine floor, permitting high pressures to be applied against the rock roof when drilling, and thus enabling harder rock to be drilled faster than formerly, with a resultant increase in life of the drill bit.

It may further be seen that the device of our invention is of a simple form, utilizing a telescopic drop mast movable into engagement with the ground and then feeding the drill upwardly in two stages, with a resultant increased length of drill travel, enabling the use of relative ly long drills, and reducing the number of drill changes during a drilling operation.

It may still further be seen that as a result of the added drill travel obtained by lowering the mast and drill carriage into engagement with the ground, the drill of our invention is particularly adapted for use in thin seams of coal, since the required depth of hole may be drilled with longer drills and fewer drill changes than formerly.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

We claim as our invention:

1. A mobile roof drill comprising a wheel mounted frame, guide means at one end of said frame having a vertical guideway extending therealong, a first guide track guided in said guideway for vertical movement therealong, a second guide track guided in said first guide track for vertical movement along said first guide track, said first guide track having a bearing plate at the lower end thereof engageable With the ground, a drill carriage having a vertical drill therein, means guiding said drill carriage for movement along said second guide track, fluid pressure means mounted on said bearing plate and extending upwardly therefrom and having connection at its upper end with said second guide track for moving said second guide track vertically along said first guide track, other fluid pressure means encircling said first mentioned fluid pressure means and having connection with said carriage and with said first fluid pressure means and being movable along said first fluid pressure means, for moving said carriage upwardly along said second mentioned guide track, and a drill guide on the upper end of said second guide track having guiding engagement with said drill.

2. A roof drill comprising a mobile frame, a stationary vertical guide at one end of said frame comprising a pair of facing vertically extending guideways, a telescopic guide track guided for movement along said guideways and having a bearing plate at the lower end thereof engageable with the ground, a fluid pressure cylinder and piston unit having a piston rod mounted on said bearing plate and having a first cylinder connected with said guide track for extensibly and retractibly moving the same, a second fluid pressure cylinder and piston unit encircling said first cylinder, said second mentioned cylinder and piston unit having a piston unit encircling said first cylinder and being movable therealong, a drill carriage guided for movement along said guide track, and an operative connection between said fluid pressure cylinder and piston unit and said carriage for effecting movement of said carriage along said guide track upon movement of said piston unit with respect to said cylinder, and for effecting movement of said carriage with said telescopic guide track upon extension thereof by extension of said first cylinder along said piston rod.

3. A self-propelled roof drill comprising a mobile frame, a stationary guide at one end of said frame comprising a support plate pivoted on said frame for movement about a horizontal axis and having a pair of facing guideways mounted thereon, an outer guide track guided in said guideways for movement therealong, a bearing plate carried by said outer guide track for engagement with the ground, an inner guide track guided for telescopic movement along said outer guide track, a drill carriage guided in said inner guide track for movement therealong and for movement therewith, a fluid pressure cylinder and piston unit comprising a first cylinder having connection with the inner of said guide tracks at its upper end and having a piston rod extensible therefrom mounted on and extending upwardly from said bearing plate, a second cylinder and piston unit encircling said first cylinder and piston unit and comprising an outer cylinder encircling said first mentioned cylinder and secured thereto, and an intermediate piston unit extensible with respect to said outer cylinder and movable along said first cylinder, and a flexible feeding member connecting said intermediate piston unit with said carriage for feeding said carriage along the inner of said guide tracks upon extensible movement of said intermediate piston unit with respect to said outer cylinder, and holding said carriage to eifect movement of said carriage with the inner of said guide tracks upon extensible movement of said first cylinder along said piston rod.

4. In a drilling apparatus of the class described, a wheel mounted frame, a channelled guide at one end of said frame, a channelled guide track guided in said channelled guide for vertical movement therealong and having a bearing plate at one end thereof engageable with the ground, a second channelled guide track guided in said first channelled guide track for extensible movement with respect thereto, a drill carriage guided for movement along said second channelled guide track, a two stage cylinder and piston unit mounted on and extending upwardly from said bearing plate and operatively connected with said second channelled guide for extending said second channelled guide with respect to said first channelled guide, said two stage cylinder and piston unit including a piston rod engaging said bearing plate, a cylinder movable therealong and connected With said second channelled guide, an outer cylinder connected with said first mentioned cylinder and encircling the same and extending th'erealong for a part of the length thereof, an intermediate piston unit movable along said first mentioned cylinder and extensible from said outer cylinder, means limiting extensible movement of said intermediate piston unit with respect to said outer cylinder, a flexible feeding member connected with said intermediate piston unit and having connection with said carriage for vertically moving said carriage along said guide track upon extensible movement of said intermediate piston unit with respect to said outer cylinder, and said outer cylinder and intermediate piston units being extensible together along said piston rod at the limit of travel of said intermediate piston unit, for effecting movement of said carriage with said second guide track upon extensible movement thereof. i

5. In a drilling apparatus of the class described, a wheel mounted frame, a guide on said frame having a guideway extending vertically therealong, a guide track guided in said guideway for vertical movement therealong and having a bearing plate at one end thereof for engagement with the ground, a second guide track guided for movement along said first guide track, a drill carriage having a vertical upwardly facing power driven drill guided for movement along said second guide track, a two stage hydraulic cylinder and piston unit including a cylinde'r having'connection with said second guide track, a piston rod extensible from said cylinder and mounted on and extending upwardly from said bearing plate, an outer cylinder extending along said first mentioned cylinder for a portion of the length thereof and connected with said first mentioned cylinder for movement therewith, an intermediate piston unit within said outer cylinder and movable along said outer cylinder and extensible therefrom, a stop limiting movement of said intermediate piston unit along said outer cylinder said intermediate piston unit having a direction changing roller mounted thereon for movement therewith and spaced vertically from said outer cylinder, and a flexible feeding member connected at one end with said outer cylinder and trained about said direction changing roller and connected at its other end with said carriage, for moving said carriage along said second guide track upon extensible movement of said intermediate piston unit from said outer piston unit, and then effecting movement of said carriage with said second guide track upon engagement of said intermediate piston unit with said stop and movement of said intermediate piston unit and said outer cylinder with respect to said piston rod upon extensible movement of said first mentioned cylinder along said piston rod.

6. In a drilling apparatus particularly adapted to drill holes in a mine roof to set roof bolts therein, a frame, an upright guide track, a generally vertically extending guide means on said frame guiding said track for vertical movement with respect to said frame, a drill carriage guided for movement along said track and having a rotatably driven drill chuck, fluid pressure operated means mounted on said guide means and having operative connection with said guide tracks for moving said guide track relative to said frame to a position adjacent the ground and for holding said guide track in engagement with the ground to take the reaction of drilling on the ground, and other fluid pressure means connected with said carriage for moving said carriage vertically along said guide track to effect vertical feeding movement thereof.

7. In a drilling apparatus of the class described, a Wheel mounted frame, a channelled guide at one end of said frame adapted to extend in a vertical direction, a telescopic guide track guided in said channelled guide for vertical movement therealong, said telescopic guide track having inner and outer guides having a bearing plate at one end of the outer of said guides and adapted to engage the ground, a hydraulic cylinder and piston unit connected with the outer of said guides and operable to engage said bearing plate with the ground and lift the same above the ground, a drill carriage guided for movement along the inner of said guides of said telescopic guide track, a two-stage hydraulic cylinder and piston unit supported on said bearing plate at one end and connected with the innertof said guides of said telescopic guide track for extending the same upon the admission of fluid under pressure thereto, said two-stage hydraulic cylinder and piston unit: including an outer cylinder, an intermediate piston unit extensibly movable with respect to said outer cylinder,.means limiting extensible movement of said intermediate piston unit with respect to said outer cylinder, and an inner cylinder and piston unit within said intermediate piston unit, a flexible feeding member operated by said intermediate piston unit and having engaging connection therewith and having fixed connection with said carriage for vertically moving said carriage along said guide track upon extensible movement of said intermediate piston unit, and said outer cylinder and said intermediate piston unit being movable together along said inner'cylinder and pistonunit upon engagement of said intermediate piston unit with said means limiting extensible movement of said intermediate piston unit with respect to said outer cylinder, for extending said guide track and carriage therewith.

8. In a drilling apparatus of the class described, a wheel mounted frame, a channelled guide at one end of said frame and extending in a generally vertical direction, a telescopic guide track guided in said channelled guide for vertical movement therealong, said telescopic guide track having inner and outer guides, a bearing plate connected with one end of the outer of said guides for engagement with the ground, a hydraulic cylinder and piston unit connected between said channelled guide and the outer of said guides for engaging said bearing plate with the ground and lifting said bearing plate above the ground, a drill carriage guided for movement along the inner of said guides of said telescopic guide track, a two-stagehydraulic cylinder and piston unit mounted on said bearing plate at one end and connected with the inner of said guides of said telescopic guide track at its opposite end, said twostage hydraulic cylinder and piston unit including an outer cylinder, an intermediate piston unit extensibly movable relative to said outer cylinder, mean'siimiting the extensible movement of said intermediate piston unit with respect to said outer cylinder, and an inner cylinder and piston unit Within said intermediate piston unit, said intermediate piston unit having a-direction changing roller mounted thereon in vertically spaced relation with respect to said outer cylinder, and a flexible'feeding member connected at one end with said outer cylinder and trained about said direction changing roller and connected at its other end with said carriage, for moving said carriage along said telescopic guide track upon the admission of fluid under pressure to said outer cylinder to extend said intermediate piston unit along said outer cylinder and moving said carriage with said guide track upon engagement of said intermediate piston unit with said means limiting movement of said intermediate piston unit with respect to said outer cylinder effected by movement of said intermediate piston unit and said outer cylinder along said inner cylinder and piston unit.

1 9 A self-propelled roof drill comprising a mobile frame, a stationary guide at one end of said frame comprising a support plate pivoted on said frame for movement about a horizontal axis and having a pair of facing guide members mounted thereon forming a guideway positionable to extend in a vertical direction, a telescopic guidetrack having an outer guide track guided for move ment along said guideway and an inner guide track guidediin said outer guide'track for extensible movement with respect thereto, a bearing plate connected to one, end of said outer guide track and adapted to engage the ground, a fluid pressure cylinder and piston unit' connected between said frame and support plate for tiltingsaid support plate and guideway about a horizontal axis, a second fluid pressure cylinder and piston unit connected between said support plate and the outer of said guide tracks for moving said guide track in a direction to engage said bearing plate with the ground, a drill carriage guided in the inner of said guide tracks for movement therealong, a two-stage cylinder and piston unit mounted on said bearing plate and having connection with the inner of said guide tracks for extensibly moving the same with respect to the outer of said guide tracks, said two-stage cylinder and piston unit including an outer cylinder, an intermediate piston unit mounted for extensible movement with respect to said outer cylinder, means limiting extensible movement of said intermediate piston unit with respect to said outer cylinder, and an inner cylinder within said intermediate piston unit and having a piston rod extensible therefrom and carried on said bearing plate, a flexible feeding member fixedly connected with said outer cylinder at one end and With said carriage at its opposite end, a direction changing member on said intermediate piston unit spaced vertically from said outer cylinder and having said flexible feeding member trained thereabout, for moving said carriage along said inner guide track upon extensible movement of said intermediate piston unit into an engagement with said means limiting extensible movement thereof, said outer cylinder and intermediate piston unit then moving with said inner cylinder along said piston rod and moving said inner guide track and carriage as a unit.

10. A roof drill comprising a mobile frame, a telescopic guide track at one end of said frame and including facing outer and inner guide tracks normally extending in a vertical direction, one of which is telescopically movable with respect to the other, guide means on said frame having a vertically extending guideway extending therealong having guiding engagement with the outer of said guide tracks and guiding said guide tracks for vertical movement with respect to said frame, a bearing plate at one end of one of said guide tracks engageable with the ground, a drill carriage having a drill chuck and a motor for rotatably driving said chuck, means guiding said carriage for movement along the inner of said guide tracks, fluid pressure means mounted on said guideway and having operative connection with the outer of said guide tracks for moving said bearing plate into engagement with the ground, other fluid pressure means supported on said bearing plate and having connection With the inner of said guide tracks for raising and lowering said guide track along the outer of said guide tracks, and means connecting said other fluid pressure means with said drill carriage for moving said drill carriage upwardly along the inner of said guide tracks.

References Cited in the file of this patent UNITED STATES PATENTS 1,834,701 Gustafson Dec. 1, 1931 2,055,520 Curtis Sept. 29, 1936 2,168,522 Hart et a1. Aug. 8, 1939 2,296,819 Osgood Sept. 22, 1942 2,362,161 Sellars Nov. 7, 1944 2,409,843 Feucht Oct. 22, 1946 2,634,587 Ptak Apr. 14, 1953 2,670,931 Curtis Mar. 2, 1954 2,673,452 Glaze Mar. 30,