US2035385A - Power crane, shovel, and the like - Google Patents

Description

March 24, 1936.

POWER CRANE, SHOVEL AND THE LIKE 5 Sheets-Sheef l Filed March l5, 1954 4 1 4 .H i @W x@ @y NN QN QN NN March 24, -1936. o MCLEAN POWER CRANE, SHOVEL AND THEV LIKE Filed March 15, 1934 5 Sheets-Sheet 2 March 24, 1.936. M0 MOLEAN 2,035,385

- POWER CRANE, sHoVEL AND THE LIKE Filed March 1,5, 1934 5 Sheets-Sheet 3 March 24, 1936. o. MCLEAN POWER CRANE,

SHOVEL AND THE LIKE Filed March l5, 1954 5 Sheets-Sheet 4 INVENTOR March 24, 1936. L, Q, MCLEAN 2,035,385

.POWER CRANE, VsHox/ELl AND THE LIKE Filed March l5, 1934 5 Sheets-Sheet 5 zzz 9.

Patented Mar. 24, 1936 UNITED STATES P Arlzlv'rA OFFICE4 A I 3 Claims.

.My invention relates to shovels, cranes, excavating apparatus and the like, and more particularly to such power machines that are in themselves a, complete operable unit.

The general practice in the design of cranes, shovels, drag lines, trench hoes and similar mechanism is to provide achassis with a revolving table supported thereon by rollers which is arranged to carry the` operator, the boom and the cable-Winding apparatus.

In the stationary power plant type of machine the motor is carried by the chassis inthe Arear of the revolving table and the operating power andsome of the controls for the boom and its associated parts are transmitted from the' motor to the apparatus on the revolving table throughthe center thereof. When the operator Wishes to maneuver this type of machine he is required to turn from the controls of his normal working positionto operate the necessary levers on the chassis. Thus moving or turning. of the whole machine involves a considerable loss of operating time. Again it is difficult to load and impossible to dig at the rear of this shovel, as the stationary motor is in the way, which is an undesirable feature of this type of machine.

'I'he other general type of machine is known as the full revolving machine. The power plant of this type of machine is on the revolving table and the locomotive power is transmitted down through its pivotal axis to the chassis and the driving mechanism.l The revolving table in this type of machine is ordinarily rectangular in shape, the axis of rotation not being at the center but approximately one-fourth of the length of the table from the forward `end thereof.

The motor is located on the rear end of the table so that its weighthelps to counterbalance the boom mechanism. When the table is rotated the rear end swings out over the chassis and the' propelling mechanism. rI'his feature is termed the tail swing of the machine.

Tail swing is a very undesirable feature especially if the operator of the shovel does not have full vision from his cab. He is unable to work in narrow'v or confined places owing to the large clearance required for the rear of his machine l which might strike objects such as the trucks crane, shovel or similar mechanism that is' full revolving and does not have any parts projecting beyond the propelling base.

I attain' this purpose by providing the machine with a rotary table arranged to carry the power plant, the hoisting mechanism, and the operator, which table does not extend beyond the propelling base regardless of the position it may be in.

"'Ihis'impr'ovement is made possible by the a1'- rangement and design of the parts of the ma` chine and which lowerA the center of gravity of table assembly.

I attain this feature by eliminating the ordinary table rollers thus lowering the center of gravity of the machine and rendering it more stable obviating the necessity of counterbalancing the boom mechanism by a weight which would have to extend a considerable distance from the center of rotation of the table.

To this purpose I employ a plurality of novel hook rollers adapted to operate in a horizontal groove, or channel in the base of the mechanism and arranged to rotatably supportA the table against working thrusts, preventing it from tilting with respect to the base casting.

The hookrollers which support the table on the base casting are disposed in the same substantially horizontal plane as the central spindle bearing of the table.

ers ride has inwardly converging walls and the rollers are tapered or frustro-conical, so that by properly adjusting the rollers axially the table is eifectually prevented from tipping. The location of. the hook4 rollers in the same` plane as that swing, also permits full vision of the operator` around the shovel so that he may quickly and advantageously operate the machine, something which has not been practical heretofore on a full revolving shovel.

Again, the turntable is supported closely adjacent to the ba'se casting which permits theA buse of a short heavy spindle or stub shaft for centering the turntable, making the mechanism stronger and more rigid. l

This feature also permits the use of a short vertical swing shaft which eliminates the tendency for the swing shaft pinion to bind in the circle gear track.

All of these features are not attainable on the present design of full revolving machines of this nature because of the difference in the elevation of the supporting rollers and the spindle or stub shaft mechanism.

A further object of my invention is the provision of a combination crowding mechanism which is efficient and universal in its use on a shovel mechanism.

To complete the efficiency of operating the machine to the best advantage of the novel features therein I provide a pneumatic trip for the dipper bottom controlled by the control levers making up a control system which is novel in my machine.

Other objects, and also other novel features of construction, and also of arrangement of parts, will appear from the following description.

In the accompanying drawings, wherein I have illustrated a practical embodiment of the principles of my invention, Fig. 1 is a side elevation partly in section illustrating some of the novel features of my invention.

Fig. 2 is a plan View of the same with the housing and cab cut away to show parts.

Fig. 3 is an end view from the rear with the power plant removed and the housing and cab in section.

Figs. 4 and 5 are sectional views on enlarged scale showing in detail the structure of the hook rollers and their associated parts.

Fig. 6 is a side elevation showing the boom assembly.

Fig. 7 is a sectional View of the shipper shaft mechanism taken on the line 1-1 of Fig. 6.

Fig. 8 is a sectional view of the pneumatic tripper drum mechanism and its associated parts taken on the line 8-8 of Fig. 6.

Fig. 9 is a plan view of the turntable, parts of which are broken away, showing a modification of the shaft assembly.

Fig. 10 is a side elevation looking from the right in Fig. 9.

Fig. 11 is a side elevation, partly in section, looking from the left in Fig. 9.

Referring to the drawings, I0 represents a standard propelling base or crawler mechanism consisting of the frames which extend longitudinally of the crawler mechanism and are arranged Ato rotatably support the crawler link belts I2 by means of the end driving sprocket gears I3 and the opposite end idler sprockets I4.

The under sides of the frames are provided with a series of idler load-carrying rollers I5 which are arranged to ride on the interior of the crawler belt I2 as it passes beneath the frame between the end sprockets, thus carrying the load of the mechanism. 'Ihe top idler rollers I6 are provided to carry the weight of the crawler belt I2 oid prevent it from sagging between the end sprockets.

The alined shafts I1 support the belt-driving sprockets I3 and are provided with the chain sprockets I8.

The frames I I of the propelling base are rigidly connected by the cross beams or members I9,

which are arranged to carry the entire shovel mechanism.

arranged to be secured to the beams I9 by means of the bolts 22. The circular perimetral surface of the base casting is provided with an annular groove or channel track 23, the upper and lower surfaces or sides 24 and 24' of which converge inwardly to receive a conical roller.

25 represents an internal annular gear track cut on the upper internal face of the casting and arranged to receive a rotating pinion. The base casting 20 is provided with the radial spokes 26 terminating in the hollow hub or spindle 21, said spokes being below the gear track, as shown in Fig. 3.

28 represents a pair of brackets depending from the casting 20 at each side thereof and arranged to support the housing of the lower horizontal propelling shaft mechanism. The outer ends of the propelling shafts are provided with the chain sprocket gears 29 arranged for driving the sprocket gears I3 of the propelling base by means of the chains 30. l

The propelling shafts are provided with the brakes 3|, inwardly adjacent to the brackets 28, which brakes are arranged to be separately operated to prevent the rotation of either or both of the propelling shafts for steering the machine vwhen traveling or for locking both propelling shafts to prevent movement of the propelling base.

32 represents the differential housing ar.

ranged for carrying the differential mechanism of the lower horizontal propelling shafts. The differential housing 32 is secured to the under side of the base casting 20 at the center thereof. The differential mechanism is of a design similar to those used on motor vehicles and is not therefore shown in detail. The beveled pinion of the differential is secured to the lower end of the tubular drive shaft 33.

The drive shaft 33 is hollowed to permit the passage of a plurality of coaxially arranged air lines (not shown) therethrough for operating the pneumatic brakes 3| or other means for operating the brakes.

The drive shaft 33 extends up through the spindle 21 and is supported therein at its upper end by the antifriction bearings 34.

35 represents a. circular revolving table of the -shovel mechanism which is arranged to carry the power plant and all the mechanism and controls for operating the shovel. 'Ihe center of the under side of the revolving table is provided with the hub 36 having the bearing bushing 36 which is arranged to rotatably engage the exterior surface of the Spindle 21, thereby maintaining the table on its centered pivoted connection. The hub 36 is adequately strengthened or braced by the radial ribs 31 which terminate in the annular depending flange member 38 of the rotary able.

39 represents an end plate secured to the upper surface of the gentler of the table and which is arranged to carry thm end thrust bearing of the beveled pinion 4|) secured on the upper end of the drive shaft 33. 5| represents a pressure grease fitting screwed into the plate 39 for admitting lubricant to the bearing 34.

The rotary table 35 is supported by a plurality of oppositely disposed and arcuately arranged tapered or conical rollers 42 which ride in the track 23 and are arranged to engage the surfaces 24 and 24' thereof. The term channel track is employed to indicate a track having upper and lower engaging surfaces. -Said rollers are rotatably supported by means of the brackets i3 depending from the table 35 and radially adjustable therewith.' 'Ihe brackets may be provided with a horizontal T-shapedy portion as at 44 arranged to slide in a complementary T-shaped slot 45 in the box-like structure 46 which may be integral with or secured in any suitable manner to the underside of the table 35. 'Ihe underside of the box has fastened thereto the back-up plate 41 as by the bolts 48,v which plate is arranged to clamp and receive with the T- shaped slot of the box any upward thrusts froml the brackets 43. The table is slotted as at 49 to receive the bolts 5I! which screw into and lock the brackets 43 in position after they have been adjusted in the annular groove 23.

5| represents lugs depending from the table 35 at a point radially beyond the brackets 43 and the box structure 46. These lugs are provided with threaded holes for receiving the radial adjusting screws 52. The inner end of the adjusting screws 52 are arranged to move the brackets 43 radially and are provided with lock nuts to hold them in place after the adjustment is made.

The depending portion 53 of the brackets 43 is provided with the non-rotatable shaft 54 which carries the conical rollers 42 on the antifriction bearings 55. Fig. 2 of the drawings shows the preferred arrangement of these supporting rollers and their radial adjusting mechanism wherein four rollers are each radially e positioned about the table at an angle' of approximately twenty degrees from a plane bisecting the circular table and the boom of the shovel. When lthemshovel is working or digging the fore i rollers support the downward thrust by riding on the lower side 24' of the track 23 while the aft rollers take the upward thrust, or vice versa when the thrusts are reversed, thus relieving the spindle 21 from bending strains. Therefore the revolving table is rotatably supported by the rollers 42 and the conventional Vturntable rollers which in common practice are interposed between the base casting andthe turntable are eliminated. y

It will be noted that the construction described enables the center bearing of the turntable to be lowered so that the plane of the axes of the rollers 42 will intersect said bearing, thus reducing the bending stresses effective on the spindle 21 to aminmum. d

56 represents the motor or power plant which is secured on the rear of the table and transversely thereof. The radiator 51 and the crank 58 extend beyond the covering or hood 59. The other end of the motor is provided with the transmission as indicated at 60 which 'has the usual gear shifting lever and `clutch mechanism (not shown).

The drive shaft 6| extends beyond the transmission 66 and is provided with the sprocket gear 62 which rotates counterclockwise in Fig. 1,

and is arranged to drive the sprocket gear 63 of the first intermediate drive shaft 64 by the chain 65. The shaft 64 is journaled in suitable bearings on the table 35. The sprocket gear 62 is of smaller diameter than the sprocket gear 63 and eects a reduction in speed of the rst intermediate driven shaft 64.

The shaft 64 is provided with the multiple belt drive pulley 66 arranged to drive the air compressor 61 mounted on the table 35, by means of the belt 68.

69 represents a sprocket gear on the shaft 64 for driving, through the medium of the chain 1|l, the sprocket gearsl 1|, 12, and 13 of the Vupper horizontal propelling shaft14, the horizontal n 3 swing shaft 15, and the mam hoisting shaft 1s.

' respectively, all of which shafts are arranged .inwardly and oppositely disposed flange members 11 arranged to support brake band mechanism applicable to operate on the drum mechanisms carried by the shaft 16.

The upper horizontal propelling shaft 14 is positioned directly over the center of the table 35 and rotatably carries the beveled gear 18 arranged to mesh with the pinion 40 on the upper end of the shaft 33. Upon engaging the mechanical clutch 19, xed to the shaft 14, with its complementary part in the beveled gear 18, power may be transmitted from the shaft 14 to the shaft 33 and the differential mechanism, thereby operating the lower horizontal propelling shafts for driving the sprocket vgears of the crawlers to.

effect vpropulsion oi:`- the mechanism. Thedirection of travel of the crawlers may be effected by the shifting of the usual gears in transmission 60.

The rotary shaft 14 is also employed as second intermediate drive shaft for operating the boom hoist drum 80. This is effected by engaging the mechanical clutch 8|, fixed to the shaft 14, with its complementary part in the beveled gear 82 lrotatably mounted on the shaftv 14 and which meshes with the beveled pinion 83 keyed to one end of the inclined shaft 84 suitably journaled from the table 35. The other end of the shaft 84 is provided with a worm pinion 85 in mesh with the worm gear 86 on the horizontal boom hoist shaft 81 which carries the drum 80 and is journaled on the underside of the table 35. The drum 80 is provided with the cable 88 which is employed to raise and lower the boom and extends up through the table 35. lSince the boom hoist drive mechanism includes a meshing worm pinion and gear it is necessary that it be positively driven in both directions. This movement is accomplished by shifting the gears in the transmission 60 as in the case of. reversing the direction of the propulsion crawlers.

89 represents a sprocket rotatably mounted on the shaft 14 and which may be caused to rotate therewith by engaging the pneumatic clutch 90, the latter being operable by means of the air ram 9|. The sprocket4 89 is arranged to drive the sprocket 92 mounted on the crowd spool 93 by means of the chain 94.' The Aspool 93 is rotatably mounted on the shaft 16 but may be caused to rotate with said shaft by.energizing the pneumatic ram9| to engage the clutch 90. The horizontal swing shaft 15 is provided with `the opposed air rams 95 and 96 which operate Awill drive the beveled gear Illl counterclockwise in Fig. 2, thereby swinging the table 35 clockwise in Fig. 2. Similarly if the pneumatic ram 96 is 'energized the table 35 is caused to rotate counterclockwise.

The pneumatic rams 95 and 96 are controlled by operating a single lever in opposite directions so that only one ram may be energized at a. time.

Referring now to the main hoist drum shaft 16, which is at' the apex 'of the operating shaft assembly, |04 represents a pneumatic ram arranged to operate the clutch |05 which imparts rotary movement to the main hoist drum |06 rotatably mounted on the shaft 16 for winding the hoist cable |01 thereon.

|08 represents a pneumatic ram arranged tov operate the clutch |09 for driving the crowd spool 93 in a counterclockwise direction in Fig. 1 on the shaft 16. Thus by means of the clutch 90 the crowd spool 93 may be rotated in a clockwise direction in Fig. l, while by means of the clutch |09 a reverse rotation of the crowd spool may be effected.

'I'he spool 93 is provided with the sprocket ||0 arranged to drive the sprocket by means of the chain ||2. The sprocket is fixed to the sleeve ||3 which is rotatably mounted on the stationary boom hinge pin H4. It is obvious that the direction of rotation of the sprocket is determined by the selective energization of the pneumatic rams 9| and |08 which are controlled by a single lever operated in opposite directions as previously explained.

||5 and ||6 represent air pistons mounted on the brackets 11 and which are arranged to operate the brake bands ||1 and ||8 of the main hoist drum |06 and the crowd spool 93 respectively. These brake bands are arranged to retard the movement of their respective drum and spool or to lock the same against movement.

The stationary boom hinge pin ||4 is supported on the table 35 and in the front thereof by means of the upstandng lugs ||9. The ends of the pin I |4 carry the base sockets |20 arranged to receive the compression or front legs |2| of the boom hoist mast |22. The table 35 is provided with the upstanding lugs |23 between which is attached the lower end of the tension or rear leg |24 of the mast' |22. The three legs of the mast |22 converge at their upper ends in the mast head |25 which is usually provided with a pair of idler pulleys or sheaves |26 arranged to carry the boom lmist cable 88 which starts from the boom hoist drum and passes over one of the mast sheaves |26 to a pulley at the outer end of the boom and returns to dead end the other mast sheave |26 as shown in Fig. 1.

|21 represents a box type boom whose inner end is provided with the boom base castings |28 which are hingedly attached as at |29 to the boom hinge pin ||4 between the lugs I9. The other end of the boom is provided with the boom cap casting |30 for supporting the idler boom hoist sheave |3| and the main hoist sheaves |32. The former carries the boom hoist cable 88 while the latter sheaves carry the main hoist cable |01.

Intermediate of its ends and on the upper surface thereof the boom has adjustably secured thereto the shipper shaft assembly |34, a sectional view of which is shown in Fig. '1. This assembly includes a shaft |35 journaled in the bearings |36 secured to the upper surface of the boom. The pinions |31 which are securedto the shaft |35 on each side of the boom movably support the dipper sticks or handles |38 whose under sides are provided with the racks `|39 arranged to mesh with and be driven by the pinions |31. The outer ends of the shaft |35 rotatably support the brackets or guides |40 in which the dipper sticks slide and which extend up along the outer sides of the sticks and project inwardly over the top and ride upon the upper surface thereof.

|4| represents a spool'or cable drum keyed to the middle of the shaft |35 between the bearings |36. The boom is cut away to receive the flanges |42 and |43 of the drum 4|. The perimeter of the flange |43 is provided with sprocket teeth to receive the crowd chain |44 which is driven by the sprocket |45 secured to the sleeve ||3 Aon the hinge pin ||4.

'Ihus the dipper sticks |38 may be moved in by energizing the pneumatic ram |08 which engages the clutch |09, driving the crowd spool 93 counterclockwise in Fig. 1, thereby driving the chain ||2the sprocket the sleeve ||3, the sprocket |45, the chain H4, causing the shipper shaft |35 to move the dipper towards the boom. Again if the pneumatic ram 9| be energized to engage the clutch 90 for driving the sprocket 89 from the shaft 14 thereby rotating the crowd spool 93 in the opposite or clockwise direction, the dipper is moved out or away from the boom. The pneumatic rams 9| and |08 are operated by the movement of a control lever in opposite directions. 'I'hus it is impossible to create an interference between these movements by energizing both rams simultaneously.

The outer end of the dipper sticks |38 are connected by the casting |38 to which is hinged the dipper, shovel or bucket |48 which is provided with the dipper hoisting block assembly |41 arranged to receive the hoisting cable |01.

The outer or remote end of the hoisting cable is attached to the drum I 4| of the shipper shaft assembly and is wound several times therearound. The cable is then carried over one of the sheaves or idler pulleys |32 in the boom cap casting, thence to the dipper hoisting block assembly |41 and back to the other sheave |32 of the boom can casting and thence to the main hoisting drum |06. Thus lf the crowd chain assembly is permitted to freely rotate by releasing the brake |'8 on the crowd spool 43 the hoist cable |01 may be used for crowding out the dipper. Ihe weight of the dipper at the end of the dipper sticks is then suicient to cause the dipper to drop unreeling the hoist cable that is wound around the shipper shaft drum |4|. During this action the main hoist drum |06 is locked so the movement of the dipper 1s out and slightly downward. Before the sticks are run completely out the main hoist drum is released and the cable |01 is permitted to unreel therefrom. 'I'he dipper would then swing in an arc back towards the base of the boom and in the position to dig, the sticks being almost all the way out. The pneumatic ram |04 is then energized, which actuates the clutch |05, caus ing the main hoist drum |06 to reel-in the hoisting cable |01. The weight and the resistance to movement of the material scooped up by the dipper is then divided into two forces by the pull on the hoist cable |01. Part of the energy will be used in pulling the dipper forwardly and the rest will be used in unreeling the cable |01 from the shipper shaft drum 4| which forces the dipper sticks away froxnvthe boom, causing the dipper to crowd further into the soil or material to be removed. When the resistance of the material to the downward movement of the dipper becomes greater than the resistance of the matcrial to the forward pull on the dipper the cable |01 will stop unreeling on the drum |4| andthe dipper will be raised as it is drawn forwardly. When the resistance to the downward movement of the dipper becomes les,\the sticks tend to rles ' provided with windows softhat the Ioperatorhas a 4 clear vision in all directions.

crow'd thedipper down to equalize'zthe load until the sticks are all the way out. termed the cable crowd out, "anddswveryfsuccessful because vof its uniformly eiiicient method 4of digging.

` The other method'for crowding out is by means of a positive drive, as -by driving out the dipper sticks by rotating movement -in Fig. 4as previously described. This method is not as efiicient as the rope crowd as the operator must divide the ,power between the hoisting and crowding out actions at the operating shaft mechanism, and the result is that he is never able to balance the loads as automatically occurs with the "rope crowd method.

However the positive chain crowd is more satisfactory to draw the dipper sticks in and I have.

therefore employed the best features of both methods to obtain what I term as a rope-chain crowd and the rope crowd feature must necessarily employ the chain crown-in feature to obtain a complete crowd function.

To complete` the operation of digging with a shovel I have provided the dipper with a pneumatic tripper mechanism for releasing the door of the dipper to permit the material to fall therefrom. Referring especially to Fig. 8 to accomplish this function I employ a reel |48 journaled Y on the hollow shaft above theshipper-shaft mechanism. Compressed,

|49 xed within the boom |21 air is fed from the table 35 to the shaft |49 by the tubing |50 which is connected therewith so as to open into the hollow portion |5| vof the shaft |49. The shaft |49 is provided with the ports |52 which form a communication between the hollow portion 5| of the shaftand the annular recess |53 in the bore of the reel |48 which in turn is provided with a hose connection as shown at |54. 'I'he recess |53 is properly'sealed against the escapel of air by the annular sealing rings |55 and' is provided with adequate lubricating appliances. |56 represents a helical spring secured at one end to the boom and at the other end to the reel |48.

This permits the unreeling of the hose- |51 from the reel as the dipper is moved out from the boom and draws the hose back onto the reel as the dipper is retracted.

|58 represents two pulleys mounted in the un'- der side of the boom for guiding the hose |51 therethrough.

'I'he other end of the hose terminates at the box |59 mounted on the rear of the casting |38' and arranged to house the piston |60 which is provided with a spring to maintain it in its retracted position. When the compressed air is admitted to the tubing |50 it travels through the recess |53 of the reel and the hose |51 and forces the piston against the lever |6| which vrocks on its fulcrum |62, causing the other end thereof to strike the anged head of the sliding bolt |63 releasing the bolt from the lock slot |64 of the dipper. The door of the dipper then swings away on its hinges |65 pivoted at |66 and the material falls -from the dipper. As the dipper is returned to the clearance for the extension of parts therethrough. f

At the side, the right in Fig. 3, it is stepped down to lform the floor of the cab 59 in which the operator sits or stands. The upper walls of the cab are the chain .|44 a clockwise journaled in the bearings |1I |81 represents the `chain crowd and swing control lever within the cab, which actuates pneumatic valves to zenergize the respective rams for operating the clutches to l engage the selected crowd and swing parts'l fgthe mechanism. Forward movement of the lever operates the dipper to crowd-out andthe rearward movement operates `the pull-in of the dipper; while movement of the lever tor the left causes the turntable to rotate counterclockwise swinging the boom to theleft and movement of the lever Ato the right swinging the boom to the right. When the lever is in its neutral position with respect to the crowd function the crowd brake I I8 is automatically applied.

|88 represents the 'main hoist drum and trip control lever also in=the cab. By moving this lever forward the brake I|1 `of the main hoist drum |08 is released and the weight of thedipper is permitted to unreel the cable therefrom. Moving this lever to the rear operates the ram |04 to reelin the cable |01, and moving it right operates the trip mechanism. The operator thus has full control of the digging operations of the machine through the medium of two small universal levers. The levers |61 and |88 may conveniently be of the general type disclosed in myLetters Patent No. 1,711,896, issued May '1, 1929.

" Referring to Figs. 9 to 11, inclusive, I illustrate the practical embodiments ofmy invention as a modification thereof. The parts similar to those discussed above are being designated by the same reference numerals.

|10 represents the upper horizontal drive shaft and |12, and|13 represents .the main hoist drum shaft journaled in the bearings |14 and |15. These shafts are driven from the first intermediate shaft 64 by means of the sprocket 89, by the chain 10 and the sprockets 12 and 1| on shafts |13 and |10, respectively.

4As shown in Fig; 1`0, the chain 10 runs around the sprocket 12 of the shaft |13, rotating said shaft in a counterclockwise direction, 'and meshes with thel sprocket 1| from below, rotating the shaft |10 in a clockwise direction. l

The shaft |10 is provided with the beveled gear 18 arranged to mesh with the pinion 40 for propeiling -the machine when the toothed clutch member |16 is moved to the left. Moving the clutch |16 to the right drives the beveled gear 82 which is meshed with the beveled pinion 83 on the -inclined shaft 84 for driving the boom hoist drum 80, on the shaft 81 through the meshed worm and gear 85 and 88.

The shaft |10 is provided as before with the chain crown-out mechanism, which comprises the pneumatic ram 9| for operating the clutch 90 to drive the sprocket 92 and the crowd spool 93 in a clockwise direction.

On the other side of the bearing |1|, the shaft |10 is provided with the sprocket |11 which may be made to rotate with the shaft by energizing the pneumatic ram |18 fo'r operating the clutch |19. The sprocket |11 drives the chain |80 in a counterclockwise direction in Fig. 11, which in turn 'drives the sprocket |8| fixed to they horizontal with the beveled gear |0| secured td the upper end of the vertical swing shaft |02. Thus the clutch |19 on the shaft |10 operatesthe vertical 9|, |04 and |08 are fastened to swing shaft 9, revolving clockwise. Y

Similarly, the shaft |13 is provided with the pneumatic ram |84 arranged to operate the clutch |85 to rotate the sprocket |86 in a clockwise direction in Fig. 11, thus driving the chain |80, the sprocket |8|, the horizontal swing shaft |82, and the beveled pinion |00 in a counterclockwise direction. 'I'he vertical swing shaft |02 is thereby rotated in a counter-clockwise directon in Fig. 9 and the table 35 swung to the right.

'Ille rams |18 and |84 are supported by the brackets |81 which may be bolted or otherwise fastened to the table floor. The other rams, the bearings |1|, |15 and |14, respectively.

The main hoist drum |06 and its operating mechanism is the same as that described above except that it is in the reversed position on the shaft |13.

The crowd spool 93 and the crowd-in mechanism is also the same as before except that it is mounted on the opposite side of the main hoist drum shaft.

The reversal of these parts is due to the pro'- |02 in a clockwise direction in Fig. the table 35 to the left or countervision of the single clutch member |16 which is employed, when moved to, the left, to propel the mechanism and is arranged to lower or raise the boom when moved to the iight.

The modication illustrates a novel method of reducing the shaft assembly to an arrangement in a substantially single plane which provides for better vision for the operator and lowers the center of gravity of the machine:

Fig. 11 also shows a modification in the manner in which the turn-table 35 is journaled toI the base casting 20. |88 represents a hollow stub shaft integral with the table 35 and arranged to be journaled in vertical bearing |89 held by the hub |90 of the base casting 20. The spokes, or ribs, 26 are arranged to support the hub |90 and provide reinforcement for the base casting 20. The internal bearing surface of the bearing |89 may be convex, its walls converging lslightly inwardly from the ends to a circle or zone in the center thereof. 'I'his zone is in the same plane as the axes of the supporting rollers 42. If the table is tipped slightly due to the required clearance of the rollers 42 in the annular track 2'3, the stub shaft |88'will roll about an imaginary horizontal axis, on the internal convex surface of the bearing |89 and thus avoid transmission of any bending strains to the hub |90 of the base casting 20.

The channel track and hook roller construction, provide the important features of my invention, together with the mono-plane table supporting feature which permits the lowering of the center of gravity of the turn-table and the mechanism mounted thereon, eliminating the use of the ordinary turn-table supporting rollers and the long spindles for centering the turn-table.

'I'his invention permits the use of a power plant mounted on a circular Vturn-table, no part of which extends beyond the rim of the table but all within the spread of the ordinary crawler propelling base. Heretofore this feature was impractical, as the supporting rollers for the rotary table positioned the turn-table considerably above the ring gear casting, requiring an extended spindle which was subject to breaking stresses if the boom were not counterweighted by a weight or portion of the apparatus extended from the spindle to form a lever arm much greater than that of the boom. 'I'his feature necessitated considerable tail swing.

My invention permits the assembly of the rotary table in close relation to the ring gear,

which eliminates the strains on the spindle and drops the center of gravity, increasing the efciency of the machine very materially and eliminating any tail swing whatsoever.

I claim:

1. 'I'he combination with a base member, an annular exterior channel track carried by said base member, a turntable member, a plurality of rollers carried by said turntable and engaging said track for supporting the turntable, of universal bearing means between said members to maintain them in coaxial relation, said bearing means comprising a. vertically disposed arcuate bearing surface, the center of the closed-curve contact between the bearing surface being disposed in the plane of the axes of said rollers.

2. The combination with a base member, an annular exterior channel track carried by said base member, a turntable member, a plurality of rollers carried by said turntable and engaging said track for supporting the turntable, of a central bearing element on one of said members, a central stub-shaft on the other of said members arranged to be inserted in the bearing element, an arcuate bearing surface interposed between the bearing element and the stub-shaft to provide for universal movement therebetween, the axes of said rollers being in a plane that intersects the center of the circular-line contact between said arcuate bearing element and said stub-shaft.

3. The combination with a dirigible chassis, a

base member mounted on the chassis, an annular r channel track carried by said base member, a turntable member, a plurality of rollers carried by said turntable and engaging said track for supporting said turntable, of universal bearing means between said members to maintain them in coaxial relation, said 'bearing means comprising a vertically disposed arcuate bearing surface, the center of the closed-curve Contact between the bearing surfaces being disposed in the plane of the axis of the rollers, said bearing means being hollow to provide for the passage of means for guiding and propelling the chassis.

LELAND O. MCLEAN.

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