US2686040A

US2686040A - Multiple drill mounting

Info

Publication number: US2686040A
Application number: US172340A
Authority: US
Inventors: Earl B Lear
Original assignee: Chicago Pneumatic Tool Co LLC
Current assignee: Chicago Pneumatic Tool Co LLC
Priority date: 1950-07-06
Filing date: 1950-07-06
Publication date: 1954-08-10
Anticipated expiration: 1971-08-10

Description

Aug. 10,1954

' E. B. LEAR MULTIPLE DRILL MOUNTING sheets-sheet 1 Filed July e, 195o y wa lfm?.

ATTORNEY Aug. 10, 1954 E. B. LEAR 2,586,040

MULTIPLE DRILL MOUNTING Filed July e, 195o 's sheets-sheet 2 lNvENToR f4/Pz .5. f4/4. BY M WTORNEY LUL.

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E. B. LEAR MULTIPLE DRILL MOUNTING Aug. l0, 1954 I s sheets-'sheet 3 Filed July 6. '1950 m QQ *im Sra. QQ SS QM, mm. N

BY M5L@ w TTORNEY` Aug' 10, 1954 E. B. LEAR 2,686,040

MULTIPLE DRILL MOUNTING Filed July 6, 1950 `S Sheets-Sheet 4 INVENTOR ch/a4 5. s4/.

Q-VMMBY ML ATToiIQNEY All@ 10, 1954 l E. B. LEAR 2,686,040

MULTIPLE DRILL MOUNTING Filed July 6, 1950 A 6 -SheetS-SheV-et 5 Tuzlll. -rlc'lh T:LCIJ. \\\Q\ i 77 04. 9

ATTORNEY Aug. 10, 1954 E. B. LEAR 2,686,040

MULTIPLE DRILL MOUNTING Filed July e, 195o s sheets-sheet e lNvr-:NTOR fev/a f4/P. BYVMM/ m i ATTORNEY Patented Aug. 10, 1954 MULTIPLE DRILL MOUNTING Earl B. Lear, Detroit, Mich., assignor to Chicago Pneumatic Tool Company, New York, N. Y., a corporation of New Jersey Application July 6, 1950, Serial No. 172,340 7 Claims. (Cl. Z55-51) This invention relates to rock drilling equipment and more particularly to improvements in a portable multiple drill supporting apparatus.

It is common practice in quarry and mining operations, especially in tunnelling operations, to employ a track mounted carrier having adjustable drill supporting means whereby one or more drills may be readily positioned and maintained in operative position with respect to the work surface. Such equipment is generally known in the industry as a jumbo drill mounting, and usually includes one or more power operated booms, each of which supports a drill aiiixed thereto by some form of swivel arrangement. The use of the jumbo drill mounting permits the convenient drilling of any work surface, or of any tunnel area as the case may be,

During the actual drilling operations, it is important that the drill be rigidly maintained in operative position. To this end, various means for anchoring the carrier, as well as means for locking the boom and swivel arrangement, have been designed. However, the arrangements of the prior art structures are not always successful in maintaining the drill in fixed position during drilling, due to the great weight of the boom and drill, together with the excessive vibrations which are set up during drilling. In such cases the drill steel very shortly settles, or rides, on the lower radius of the drill hole, thereby causing increased friction with a reduction in drilling speed. Furthermore, any tendency of the carriage anchoring means to lose grip, likewise contributes to a reduction in operating efiiciency. Such conditions are undesirable since frequent readjustment of the boom and/or the anchoring means is required to maintain proper alignment of the drill with the hole being drilled.

It is the object of the present invention to provide a jumbo drill mount with an improved drill supporting means, which maintains proper alignment of the drill with the hole being drilled. Another object is to provide an improved drill supporting means having a boom which is automatically locked in position after adjustment, to avoid downward movement or sagging thereof. A further object is to provide an improved anchoring means for the carriage which can be quickly and conveniently set up and knocked down, and which is rigid and reliable in use. Another object is to provide means on the carriage to counterbalance theweight of the booms and drills when the carriage is being moved from one location to another in the mine. A further object is to provide an improved internal construction of the boom whereby lubricant will not vthe arrows 4-4 in Fig.

. 2 collect therein and Iiood the boom actuating motor when the boom is lowered. These and other objects and features of the invention will become more apparent when viewed in the light of the following specification and accompanying drawings wherein:

Fig. 1 is a side view of a rock drill machine embodying the invention;

Fig. 2 is an incomplete front view of the machine of Fig. 1 with some parts in section;

y Fig. 3a is a fragmentary sectional view of one V end of the boom;

Fig. 3b is a fragmentary sectional view of the other end of the boom;

Fig. 4 is a section of the boom as seen from Fig. 5 is a longitudinal section view of the boom actuating motor including the boom locking arrangement and a portion of the boom screw;

Fig. 6 is a sectional view of the boom actuating motor as seen from the arrows 6-6 in Fig. 5;

Fig. 7 is a sectional view of the boom locking arrangement as seen from the arrows 1 1 in Fig. 5; v

Fig. 8 is an exterior view of a portion of the boom in the region of the boom control motor valve;

Fig. 9 is a sectional View as seen from the arrows 9 9 in Fig. 8;

Fig. 10 is a sectional view .of the boom motor control valve arrangement as seen from the arrows lU-IU in Fig. 8;

Figs. 11, 12 and 13 are sectional views of the boom motor control valve arrangement taken as indicated by the respective arrows in Fig. 9;

Fig. 14 is a plan view of the boom motor control valve;

Fig. l5 is a partial section view of the boom motor control valve viewed as indicated by arrows I5|5inFig.14;

Figs. 16 and 17 are sectional views of the boom motor control valve taken as indicated by the respective arrows in Fig. 15;

Fig- 18 is an exterior portion of the control valve viewed as indicated by arrows Iii-I8 in Fig. 17;

Fig. 19 is a longitudinal view, partly in section, of a jack used in the anchoring assembly;

Fig. 20 is a section view as seen from lines 2li-2E! in Fig. 19;

Fig. 21 is a section view as seen from lines 2I-2I in Fig. 19; and

Fig. 22 is a partial view of the jack base arrangement.

The scale used in the drawings is not alike for all gures: Figs. 1 and 2 are alike in scale; Figs.

3a and 3b are alike in scale but larger than Fig. 1; the scale of Fig. 4 is greater than that of Fig` 3ra; Figs. 5 to 13 inclusive are alike in scale but larger than Fig. 4; Figs. 14 to 18 inclusive are alike (and are approximately full scale) but larger than Fig. 5; Figs 19 to 22 are alike in scale but smaller than Fig. 14.

Referring now to Fig. 1 a jumbo drill mounting illustrative of the invention comprises, a carrier 30 arranged to ride upon trackway 3i, which is laid in advance of the carrier as the work or tunnelling progresses; one or more swivel heads 32 mounted upon the carrier and arranged for rotation about a vertical post 33; a boom arrangement 3i pivotally afhxed to the swivel head for movement in any vertical plane bisecting the axis of the swivel head; an anchoring assembly including three jacks 35 which are each mounted by a universal joint arrangement to the carrier; and a ballast box 36 projecting in overhanging manner from the rear end of the carrier.

The carrier 36 comprises a platform 31 mounted upon two pairs of wheels 38, which are designed to ride upon trackway 3l. Swivel head posts 33 are symmetrically arranged about the longitudinal axis of platform 31, and at a short distance rearward of the front pair of wheels 38. Each swivel head 32 has a clamping means 39, such as the well known block and bolt type, by means of which the swivel head can be manually locked in position on the swivel head post 33.

The boom arrangement 34 basicallyrcomprises a boom 4i, an arm 42, and a boom actuating means 43. r)The boom 4l has a yoke member lillv at one end by means of which the boom is pivotally affixed to the upper end of the swivel head 32. Arm 42 is located at the other end of boom il and is connected thereto, by swivel means 45, for movement oi approximately 180 in a plane parallel to the pivot axis of yoke 44. The swivel means i5 consists of a tapered or rusto-conical member 46 (Fig. 3b) forming a portion of a casting 41 secured to the end of the boom di as shown, anda cup member 48 which is secured to the arm 42, and whichhas an internal tapered surface engageable. with the member 4E. By means of a draw bolt E9, the cup member d8 can be Vdrawn snugly down upon the frusto-conical member d6, to lock arm 42 in position. Arm 42 is made up of an inner shaft (not shown) which is integral withthe cupmember 48, and a cylindrical outer member 5i which is positioned for rotational movement about the inner shaft. A draw .bolt 52 is arranged to provide looking of the outer member 5l against movement relative to the inner shaft. Near the free end of the arm t2 is a clamping head 53 for supporting and clamp'- ingv a swivel base 54 of a drill 55, the illustrative type shown being. known to the trade as a driften The boom actuating means 43 comprises an actuating motor 56 (Figs. 1 and 5) a screw member 51 having a single right-hand square thread, and. a sleeve member 58 which has internal thread means to receive the screw member. One end of the sleeve member is enclosed by a yoke Eil-(Figs. 1 and 2), which is pivotally affixed to a lower portion of the swivel head 32, while the other end encompasses the screw member 51. The actuating motor 56 is drivingly connected to the screw member at one end and is pivotally connected at the other end to a yoke bracket 6| which is attached to the lower side of the boom 4l. Slightly forward of the motor 56 an actuating motor control valve assembly 62 is aixed to 4 the underside of the boom 4I by means of bolts 63 which hang from a saddle clamp 64. It will be seen that the structure of the boom arrangement as described, permits the positioning of the drill at any angle with respect to the work surface. The screw 51 has a relief 51a which in turn has two :dats 51h for turning the screw with a wrench, when compressed air is not available for running the motor 56.

Turning now to the consideration of certain elements of the boom arrangement 34 in greater detail, the boom 4I comprises in part an outer tubular member 65 (Figs. 1, 3a and 3b), and an inner tubular member 56, for delivery of live air to the drill and actuating motor, which is maintained in spaced relation to the member 65 by spacer blocks 61 and a distributing block 68, the latter of. which are welded in place within member 65. The inner member 66 is slidably fitted to the

blocks

61 and 63, and when assembled is maintained in position by a spring 69 which is held in compression between the end of member @6 and a cap 1l, threadably axed to the yoke member 4d. Athreaded portion 12, located in the end of member 66, is provided for the convenient removal of the inner member 66 from the outer member 65. The distributing block 'is bored to receive the front end of the tubular member BE, and has a passageway 13 which leads upwards, connecting with a hole 1li formed in the outer member 65, the hole 15 being surrounded by a boss member 15 tapped to receive a pipe connection. A circumferential groove 16 is formed on the periphery of the block 6i), which intersects with the passageway 13, and which is aligned with a hole 11, formed in the lower surface of the member 65. A threaded hole 18 is provided in yoke member l5 to receive a pipe coupling for the flow of live air to the inner member 66. It will be apparent that air iiow through the inner member 65 leaves the boom 4i by wayl of hole 1li and also hole 11. It is further seen that the arrangement of the boom, viz., the smaller diameter inner member 66 supported within a relatively large diameter outer member 65, provides a smaller passageway for the conduction of air through the boom, thereby reducing the possibility of lubricant condensation to a degree which could flood the actuator motor when the boom is lowered.

Control valve assembly 62, as shown in Figs. 9 and 10,' comprises a housing 1S, formed with lugs 8i tapped to receive bolts 63, and having a transverse bore 82 for reception of a valve 83. The valve {i3-has two control handles B and 85 on opposite sides of the boom 4I, the rst of which is cast integral with the body of valve 63, the latter of which is maintained in alignment thereon by a Woodrui key 86 or equivalent, and a nut 81. An alignment bushing 88, fitted to the housing 19, projects into hole 11 in the boom outer member 65.

As best seen in Figs. 14 to 17 inclusive, the valve 83 has a circumferential groove 89, which connects with two grooves Si, and 92 running in the direction of the longitudinal axis, groove 9i extending toward control handle 84, while groove 92 extends in the opposite direction and is' displaced'approximately 165 froml groove 9|. A longitudinal passageway 93 formed within the valve 83, has an opening 94 adjacent a flange 95,

which is cast integral with the valve 83, as best l seen in Fig. l5. A radial hole 96 is formed in the valve in a plane coincident with the axis of groove 32, and connectswith passageway 93.-

While another ,radial hole 91 is formed in the valve in a plane coincident with the axis of groove 9|, and also connects with passageway 93. A groove 98, connecting with groove 92, and of somewhat less width, extends a short distance about the periphery of valve 83, in a direction as shown in Fig. 18. Two radial holes 99 and in the same plane as hole 91, are arranged to connect passageway 93 to the periphery of the valve 83. The end of the valve 83 has a threaded portion |03 to receive the nut 81.

A passageway |04, formed in part by the bore of alignment bushing 88, connects groove 16 of the distributing block 68 with groove 89 of the valve 83. Passing through a wall surrounding in part the bore 82 of housing 19, are two holes |05, |06, the rst of which is located, as shown in Fig. 13, for possible alignment with groove 9|, or hole 96, the latter of which is located for alignment, as shown in Fig. 11, with

grooves

92 and 98 or

holes

grooves

92 and 98, or holes 91, 99 and |0|, as will be more fully explained. The handle 85 has a groove |09 formed on an inner corner of its Yflange portion, which extends for a distance of a little more than 180, and has three equispaced detents 2, and ||3, as best seen in Fig. 8. An indexing pin ||4, which is slidably mounted within the housing 19, is spring loaded to bear against a side of groove |09 and has a pointed end for engaging any one of the detents ||2, and 3 to hold the valve in position. As will be seen, the pin 4 engages detent ||2 when the valve 83 is in normal or non-operative position, engages detent when the boom is being lowered, and engages detent ||3 when the boom is being raised. In event an auxiliary air outlet is desired for operation of a blow gun, etc., a hole |0 is provided in the housing 19 in alignment with groove 89 of the valve; when not in use the hole ||0 is plugged with a pipe plug, as shown.

The exterior structure of the actuating motor 56 comprises a motor housing ||5 and a ratchet housing I6 which are secured in fixed relation by bolt means (not shown). At the exterior end portion of housing is formed a lug |1 which is bored to receive a pin I I8 for pivotally afxing the motor 56 to the yoke bracket 6|, as heretofore explained. The pin |8 is grooved about its midsection to receive a set screw H9, positioned in the lug I |1, whereby lateral movement of the pin ||8 is prevented. Supported within the motor housing, is a cylindrical liner |2|, the ends of which abut against end plates |22, each of which has a iiange |23, on the outer wall, which surrounds and supports a ball bearing i 24. The ball bearings |24 support front and rear shafts |25 and 26 which project from, and are integral with, a rotor |21. The rotor is of cylindrical shape and is arranged coaxially with the shafts |25, |26 and with the motor and ratchet housings, but is eccentric with respect to the cylinder liner |2| to provide a crescent shaped chamber between the rotor and cylinder liner. The rotor is provided with a plurality of radial slots in which blades |28 are slidably mounted for movement with their outer edges in scraping contact with the cylinder to divide the crescent shaped chamber into a series of pockets.

Arranged toward the lower portion ofthe cylinder liner |2| and on each side of the center are sets of air intake ports |29 and |30, while near the top portion of the cylinder liner, are a plurality of exhaust slots |3|. The exhaust slots |3| are covered by a hood |32, which is formed integral with the motor housing ||5, and is arranged to deect exhaust air downwardly about the motor. Air inlet passages |33 and |34, having threaded openings, are provided in the lower portion of the motor housing H5, for the passage of air tothe exterior of cylinder liner |2| and to intake ports |29 and |30 respective1y. A ilexible hose |35 connects inlet passage |34 with the hole 06 of control housing 19, while another ilexible hose |36 connects inlet passage |33 with hole |05 of the control housing.

It will be seen that when the live air is admitted to the motor housing ||5 by way of passage |33, it will enter ports |29 and, ina well known manner, cause the rotor |21 to turn in clockwise direction (as viewed in Fig. 6), ex-

hausting by way of exhaust slots |3|. Any air that is entrapped between the blades |28 afterv the exhaust slots 3| are passed, ,will be forced out of the ports |30. Likewise when live air isv admitted to the motor housing I5 by way of passage |34, it will enter ports |30 and will cause the rotor 21 to turn in a counter-clockwise direction (as again viewed in Fig. 6), exhausting by way of exhaust slots |3I. Any air that is entrapped between the blades |28 after the exhaust `slots 3| are passed, will be forced out of the ports |29.

The gear retainer |39 has a diametrical slot to receive a tongue |49a at one end of a iiexible coupling element |49 whose opposite end has a tonguer 5| which engages a cross slot |52 arlatter by means of a bushing |55 which engages I arsmooth-portion of the screw member. Aspring actuated plunger |56 is slidably arranged inr a bore |51 formed in the ratchet housing IIB, and constantly bears against theside of the pawl 51| tomaintain an end corner of thev pawl in full engagement with the teeth of the ratchet-ringv |53.I A trunnion member |58 is threadably aixed to the ratchet housingv H6 to support the pawl in operative position as shown. It will be seen (Fig. 7) that the pawl, when so engaged, restricts rotationof the screw member 51 in clockwise direction but vwill not restrict rotation of the screw member in counterclockwise direction.

In an enlarged portion of 'the ratchet housing IIS, a bore |59 is formed which slidably maintains a piston means comprising a head portion ISL-and a rod. |62, the `free end vof which is in alignment with the side ofthe pawl |54 opposite that in contact with plunger |56. Surrounding the rod |62 is a spring |63 which is-'under compression to urge the head portion and rod in a direction away from the pawl. A cap |64, axed to the ratchet housing to cover bore i59, engages the head portion |6| of the piston means to limit maximum movement thereof in one direction in the bore |59. An air passageway |65 formed in the cap |64, is arranged to admit air to bore |59 to move the piston means so that the rod |62 engages the pawl to disengage the pawl from the teeth of ratchet ring |53; A passageway |66 vents the chamber formed in bore |59 underneath the head 16| ofr the'piston means. A hose |61 is threadably amxed to the open end of pas-V sageway |65 to connect same with the hole |51 in vcontrol valve housing 19.

Surrounding the end of sleeve member 58 and aillxed thereto, is a casing |68, which is coupled by bolt means |69 to an internally threadedbushing |1|, which engages the threads of the screw member 51. member is caused to rotate in counter-clockwise direction (Fig. '1), the actuating motor 56 will move away from bushing |`i l, with the result that the boom 4| will be raised, whereas when the screw member is caused to rotate in clockwise direction, the actuating motor will move toward bushing |1I, with the result that the boom will be lowered.

Considering nowy the over-all picture of the boom actuating arrangement, and assuming that the boom is rto be raised, the control valve handle 85 (or 84) is rotated counter-clockwise (Fig. 8) thereby causing groove 9i, of the valve 83, to lineup with hole |65 in housing 19. Live air will then flow through hose ii-to passageway |33, enter ports |29, and turn the rotor |21 in counter-clockwise direction (looking toward screw member 51), thereby causing movement of the actuating motor in. a direction to raise the boom, as explained above.r The valve 83 is maintained in boom raising position by .means ofV pin ||4 being in engagement withdetent-||3 With the valve in this position, it istobenoted that hole 91 thereof is in alignment with hole |05 in housing 19, so that exhaust air entrappedbetween the blades |28 of the rotor` |21, is afforded exit to the atmosphere via ports |39 andpassageway |34, through hose |35, andholeslo and91, throughpassageway 93 in the valve,..and. opening 94. Further, as the screw member 51 is rotating, the pawl |51.'I successively engages the teeth on the ratchet ring |53 so that when the control.

valve handle is moved back to normal or nonoperative position and the power to the actuating..

motor 5B is cut-oli, the screw member 51 is auto- It will be seen that as the screwV 8. matically locked against rotation sothat the boom is vrigidly maintained in the new position of adjustment.

When the boom is to be lowered, the valve handle (or 84) isrotated clockwise (Fig. 8); As the valve 83 is being rotated, groove 92 'irst uncovers passageway |08 in the. housing, thus allowing live air to flow through hole |01`andhose |61, into passageway |65 in cap |64 andmove the piston means in bore |59 so that the piston rod |62 contactsand forces pawl |54 out'of engagement with' the toothed ratchetvring |53. Screw member 51 is thus conditioned for rotation in clockwise direction (Fig. 7). Continued rota- 'tion ofthe valve causes alignment` of the groove 92 with the hole |95, whereupon live air will ilow through the hose |35,fto passageway |34, enter ports |30, and turn the rotor |21 in clockwise direction (looking toward screw member 51) thereby causing movement of the actuating motor in a direction to lower the boom, as heretofore explained. The valve 83 ismaintained in boom lowering position by means of pin |14 being in engagement with detentvl With the valvev lpassageway |99, as heretofore shown. When the valve handle 85 is rotated tonormal or non-operative position (pin H4 engaging detent H2) the power to the actuating motor is cut-off, and air pressure behind the piston head |6| is released to the atmosphere via hose |61, hole |01 and passageway |68, hole |9| in the valve- 83, to passageway 93 and opening 94, thereby allowing spring |63 to move the piston means to nonoperative position, whereuponv the pawl |54 is -forced back into engagement with the toothed ratchet ring |53, and the screw member is again locked against clockwise rotation. It will be seen that hole 99 in valve 83 prevents any build-up of air pressure in hose |61, due to valve leakage, during the boom raising operation.

For the purposes of supplying water to the drill 55 for use in wet drilling, a pipe |12 is ainxed to the bottomof the boom 5|, the front end of which is connected to a hose |13 leading to the'drill, the lower end of which connects with ahose |14 leading to a distributing manifold |15 affixed to the platform 31, which is connected to a source of water supply, not shown. An air hose |16 cornnects hole '18 of the boom 4| with adistributing block |11, attached to the platform 31,' thedistributing block being supplied by an air hose |18; At the forward end of the boom a hose |19 connects with the tapped hole 18 in boss member 15 for delivery of live air to the drill 55.

The three jacks 35 used in the anchoring' as# sembly are alike in structure and comprise. ai tubular member V59, one end oiv which hasfa pointed end |8| which is swivelled and., turns freely within the tube |19, `theother` endr of which is arranged to telescope into another tubu'- lar member |92. Y At the lower end of the member- |82 is affixed a bushing |83 having aninner. thread portion which engages a screw member |84, me external diameter of whichis somewhat less than that of tubular memberl19.' The upper end ofthe tubular member |82 has ailixed thereto 'a casting |85 which has diametrically disposed lugs |86, to each of which is pivotally aflixed a |81. A spring loaded plunger |88 is two detents |89, |9|, formed in lugs |36, detent |89 being positioned for maintaining the handle |81 in non-operative position, lwhile detent |9| is positioned for maintaining the handle |81 in operative position, or normal to the longitudinal axis of the jack, as shown. A series of holes |92 are formed in member |19 to receive a pin |93, which engages a pair of grooves |94 formed in the end edge of casting |85. The member |82 is locked upon the screw |84 by means of a jam nut |95 which can be rotated in tight engagement with bushing |83. The lower end of screw |84 is formed with an eye lug |96 for pivotal connection to a. universal joint member |97, the lower end of which is pivotally connected to a base casting |98 which is bolted to the platform 37. By means of the universal joint type of connection, any jack 35 can be positioned with its end |3| at any point above the horizontal.

It will be apparent that the structure of the jacks 35 make it extremely convenient for quickly setting them in position to anchor the mining machine. Note that the approximate required length of the jack is achieved by setting the pin |93 in the most appropriate hole |92, thereafter only a minimum of turning of the member |82 is required to screw the jack rmly in position. The handles |87 afford good leverage so vthat the jack can be securely set in place. With the use of three jacks, the mining machine can be quickly anchored in the most convenient position. When the jacks are not in use they may be carried in collapsed condition in the ballast boX 3S.

A divisional application, Serial No. 395,345, led December '1, 1953, contains claims to the actuating motor per se as best illustrated in Figs. 5 and 6 of the drawings.

What is claimed is:

1. Rock drill equipment comprising a platform arranged for movement on a trackway, swivel heads mounted on the platform toward one end thereof, counterbalance means aiiixed to the platform at the other end, clamping means for manually locking the swivel heads in xed position relative to the platform, a boom arrangement adjustably mounted on each swivel head for supporting a drill in operative position, said boom arrangement including a boom and a boom actuating means adapted to move and automatically lock the boom in any vertical position of adjustment, and anchoring means swivelly aflixed to the platform between the swivel heads and the counterbalancing means and including a plurality of adjustable jack screws pivoted at one end to a common axis.

2. Rock drill equipment according to claim l wherein the anchoring means comprises three jacks, each of which includes a screw member, an outer tubular member having a threaded bushing for engagement with the screw member, an inner tubular member pointed at one end and telescopically arranged at the other end within the outer tubular member and having an internal diameter less than the diameter of the screw member, said inner tubular member having a plurality of holes for receiving a pin member which projects on each side of the inner tubular member to engage groove means located in the outer tubular member, a pair of handles ailixed to the outer tubular member, a jam nut movable on the screw member to abut the end of the outer tubular member, and a universal type joint arrangement forming a base for the screw v member.

3. A jack according to claim 2, wherein said handles are pivotally aixed to said outer tubular member and have retaining means to maintain either handle vnormal to thelongitudinal Iaxis of the jack or parallel therewith.

4. In drilling mechanism, a boom arrangement comprising a boom having a yoke forming a pivot means at one end and an adjustable cross arm at the other end for supporting a drill, a boom actuating means including an actuating motor, a screw member and a sleeve member, said actuating motor pivotally connected at one end to the under side of the boom and directly connected to the screw member at the other end, said sleeve member having a pivot means at one end and an internally threaded bushing at the other end to receive the screw member, means forming part of the motor to automatically lock the screw member against rotation after cessation of motor operation, a control valve aixed to the boom and arranged for operation of the actuating motor to rotate the screw member for relative movement with respect to the sleeve member, said boom comprising an outer tubular member, an inner tubular member slidably maintained within said outer member by means of spacer blocks, a distributing block within the outer member near an end portion thereof, said distributing block arranged to receive one end of the inner tubular member and further arranged to provide continuous passageways from the inner member to openings on the top and bottom of the outer member, and a compression spring at the other end of the inner member to maintain said inner member in contact with the distributing block.

5. In drilling mechanism, a boom according to claim 4, wherein air inlet means are provided in the yoke for admittance of live air to the inside of the inner tubular member.

6. Rock drill equipment according to claim 4 wherein the control valve is operable to a first position to direct air from the boom to the actuating motor to cause the latter to turn the screw member so that the boom is raised, and operable to a second position to direct air from the boom to the actuating motor to turn the screw member so that the boom is lowered after the locking means of the screw member is unlocked, and positionable in a neutral position wherein live air flow to the actuating motor is cut-off.

7. A control valve according to claim 6 wherein the control valve has a pair of handles located one on each side of the boom so that the control valve may be operated from either side of the boom.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,098,014 Carter May 26, 1914 1,218,149 Wright Mal'. 6, 1917 1,642,355 Avbelj Sept. 13, 1927 1,682,438 Stuthridge et al. Aug. 28, 1928 2,057,832 Jeffrey Oct. 20, 1936 (Other references on following page) Number 11 UNITED STATES PATENTS Name Date Lewis Nov. 17, .1936 Holmes July 19, 1938 Smith Oct. 25, 1938 Feucht June 11, 1940 Smith Oct. '7, '1941 Forker, Jr. Aug. 24, 1943 Fellay et a1 Dec.14, 1948 Manning Aug.A 30, 1949 Number Number Name Date .Lehner Dec. 13, 1949 Curtis et a1 Mar. 21, 1950 Geren June 20, 1950 Hall Feb. 6, 1951 FOREIGN PATENTS Country Date Germany vMay 8, 1934