US2336965A - Folding crane - Google Patents

Description

Dec.` 14, 1943.

R. c. 'sHEMAKER f 2,336,965

FOLDING CRANE Filed May 12, 1942 3 SheetS-Sh'eet lr /N//EN TUR RCBERT C.. SHQENAKER 7- TURA/5V Dec. 14, 1943. n. c. sHoEMAKl-:R

FOLDING' CRANE Filed May l2, 1942 3 Sheets-Sheet 2- Dec. 14, 943. R, C. SHOEMAKER 2,336,965

FOLDING CRANE Filed May l2, 1942 3 Sheets-Sheet 3 R y AKER.

/Nz//v TU OB RT C. SHOE Patented Dec. 14, 1943 Robert C. Shoemaker, Portland, O'reg.,'assignor to Willamette Hyster Company, Portland, Oreg., a corporation of Oregon Application May 12, 1942, Serial No. 442,613

.14 Claims.

This inventionrelates to portable cranes, and

more particularly to a'crane structure adapted to be mounted on a vehicle and having a boom which may be transported in a generally horizontal position overlying the vehicle and which is readily erected to operative positions.

It is frequently desirable to mount a crane on a vehicle in such a manner that it may be folded down over the vehicle Awhen its `use is not required, to facilitate movement ofthe vehicle during such periods. In the case of'a generalutility tractor, that is, one which may be adapted-at will for hauling, pushing,` or hoisting loads, it is a problem to so mount the boom-that in theinoperative position thereof it will not seriously interferey with the use of the tractor for other purposes without requiring the removalof the crane. While the boom may be carried upon a. supporting structure in a generally horizontal overlying position above the head of the operator so as not substantially to interfere witli his control of thevehicle, it is a difficult matter to so mount the crane that the boom can readily be flowered to such a position and also" readily be erected to operative postions,.and, at the same ing a boom adapted to be carried thereby in a substantially horizontal inoperative position overlyingthe tractor and to be readily elevated to operative positions, in which latter positions it is `so supported upon the tractor and backstayed thereto as to maintain a uniform and safe distributionpf load upon the various parts of the tractor. l f

In the illustrated embodiment of the invention, a track type tractor is provided with a folding crane arrangement comprising an upright structure xedly attached to one end of the tractor body, and having a boom which is adapted to be time, provide an anchorage for the crane to enable it to handle relatively heavy loads without exerting excessive stresses upon various elements of the vehicle itself.

It is an object of the present invention, therefore, to provide a new and improved crane ar'- rangement adapted to be mounted on a vehicle such as a tractor.

Another object of the invention-iste provide a new and improved crane arrangement which is adapted to be mounted upon a vehicle, and

supportedin agenerally horizontal. position overlying the /tractor body by means including the upright structure. The boom is carried in the inoperative position at a suitable heightv above the head of the operator seated on the tractor body so that it does not interfere wih his normal line of vision during control of the vehicle, or with the normal use of the tractor in operations not requiring the crane. ',Ifhe boom is pivotally movable about the upper end of the upright-structure by means including the power driven winch providedv on the tractor. Upon elevation, the lower endof the boom engages with supporting means positioned relatively low carried thereby in a substantiallyl horizontal position overlying the vehicle at such a height as not substantially to interfere with the operation V,of

the vehicle for normal uses, and which may readily be erected to operative positions in a short "length of time. v A

rAnother object of the invention is to provide a new and improved mounting arrangement for-a crane upon a vehicle whereby the crane may be lowered to an inoperative position at a suitable height above the head of van operator seated on the lvehicle and readilybe erected to an on the tractor body, about which support means the boom is pivotally movable to various angularV operative positions extending rearwardly from the tractor., The upper end of the boom, when in the operative positions, is backstayed by a cable arrangement extending to the forward ends of the crawler units, provision being made for equalizing the stress between the two crawler units and for maintaining the line of pull through the cable connections insuch directions as not to exert excessive strains thereupon. While the boom` in the inoperative position is supported vat a relatively great height above the tractor body, in the operative positions the lower end of the boom is anchored at a point on the tractor operative position, in which latter position the crane will be capable of handlingrelatively heavy loads without unduly stressing they various elements of the vehicle.

A further object of the 'invention' is to provide a new and improved arrangementof a folding crane mounted on the end of a tractor and havpended claims.

f In the drawings, Figure 1 is a side elevation illustrating a crane and tractor mounting ar-I body which is suiiiciently low that loading of the crane will not exert excessive rotational components of force about the rear axle of the tractor which might cause harmful stressing of the tractor spring. l

Further objects and advantages of the rinvention will appear-from the following description, taken in connection with the accompanying drawings, while the features of novelty will be pointed out with greater particularity in the aprangement therefor constructed in accordance with an embodiment of the invention, the crane -being shown 'folded down into a horizontal inoperative position; Figure 2 is a plan view of the arrangement shown vin Figure 1; Figure 3 `,is av side elevational view illustrating the crane in an elevated position; Figure 4 is a side elevaltional view ofthe arrangement, illustrating the crane in an `operative kposition extendingrearwardly from the tractor; Figure 5isv an enlarged fragmentary end view illustrating the. lower end of the crane and mounting arrangement in the position corresponding to that of Figure 3; Figure 6 is an enlarged fragmentary view iilustrat" ing one detail of the cranesupporting arrangement; Figure 'l is an enlargedfragmentary cross sectional view illustratingone detail of the boom anchoring arrangement; Figure 81s a front ele- I vation of the tractor and crane Aarrangement illustrating particularly the details of theanchor-k ing arrangement and front crane support; Figure"9jis an enlarged fragmentary cross sectional f view illustrating-the springvsuspension for the front end of `the `tractor body; .and Figure 10 vis a Adiagrammatic: sketch illustrating functional y features of the `arrangement of the invention.

` In the drawingsthe crane 'and 4mounting arrangement therefor will be described as itmay particularly be adapted for use in conjunction with a tractorof thecrawlertype. While the various features of -the invention will be devscribed with particular reference to such'a vehicle, it will become 'apparent as the description proceeds that the invention is'not to'be necesy l 'Asarily so limited. -Thusin its broader aspects,

the y crane and mounting arrangementv thereforv is suitable for use in conjunction with any suit- `gable vehicle which, in this particularinstance..

is represented `by the tractorv indicated generally AiB/falli" Y I'teferring'to thezdrawingathe tractorfIIl, as shown; comprises a body 4I I having'a prime mover engineinot'shown) `vmounted in the forward end f' ,thereof-andjl'iavingv an'operator'sseat I2on the i' rearend from which the 'operation ofthe tractor v may be'controlled. A cable winch drum I8 is mounted upon the rear end of the tractorbody,

being suitably'connected with'Y the primemover -eng'ine for foperation'thereby. The tractor body. Il is y.supported upon a pair'of crawler units I3 arranged on theopposite sides thereof, thebody being pivotallymountedat therear end relative tothe crawler units about an axle unit I4 through which driving 'connection is made between the prime A`mover `engineyand crawler treads. `The crawler units I3 include longitudinal frame members I5 extendingbetween the 'frontand rear carrier wheels `(notshown) Afor the tractor treads.

' They front end kof the tractorbody is resiliently `supported upon the corresponding adjacent ends of the vframework of the crawler units` in some such manner as illustrated more' clearly in the enlarged fragmentary view -of l.Figure 9. l The resilient supporting arrangement illustrated in-` kcludesa compression leaf spring I6 extending transversely ofthe tractorfthe opposite ends thereof being supported upon saddles I1 provided upon the upper surface of theifram'e members, -I5 of the crawlerfunits. The body vI I is suitably attached to the central portion of the spring I6 i ywhereby the `weight er the forward vena thereof l 1. is transmittedtothe forward ends of the crawler units. The tractor thusfar describedisof more` l or less conventional design adapted` for` general` 76 utility,lthe crawleru'nits being flexibly mounted relative tothe body.

Referring more particularly to the plan view of Figure 2, the boom 20 comprises a pair of side rails 2| which, at their lower extremities, extend generally parallel with each other for a considerable distance and then converge toward the tip end 23 where they are rigidly united together.

. Suitable crossibracing is provided between the 'side members 2I for imparting desired rigidity to the boom structure:

Fixedly attached tothe rear end of the tractor bodyis an upright structure comprising a pair of vertically disposed members 25, the lower ends' of whichv may, for example, be secured to the oppositesides of the housing of the winch unit I8 rigidly mounted on the rear end of the tractor body. The uprights 25 may suitably be braced by transverse members v26 and' 21 extending 0l therebetween adjacent the upper end thereof. v Thevuppermost ends ofthe uprights 25 extend vto a point substantially higher than the head of an operator seated upon the tractor seat I2 for 25,.'while `the forward end of the boom is supportedat substantially the same height as the lopposite end by means including uprights 29 extending upwardly from the opposite sides of the front end of the tractor body, the uprights 29 being secured together adjacent their `opposite `endsby a cross member 30 which provides a cradle support for theupper end of the boom z* when in the lowered, or inoperative position. In v this position the lower extremities of the boom side members `2| extend somewhat beyond the upper ends of the uprights 25so that, broadly speaking, the boom 20, in `thehorizontal position thereof, is supported intermediate its opposite ends upon the upper ends of the upright members 25.v The'supportingarrangement for the boom on the upright structure includes U-shaped saddles 32 secured tothe'lower edges of the boom uside members 2|, as shown more clearly in the fragmentary view of Figure 6, and which saddles are adapted `cooperatively to engage with pins 33 extending outwardly from the outer surfaces of the'upright members 25 adjacentthe upper extremities thereof, about which the boom 20 pivots during movement between operative and v, inoperative positions. The lowermost ends of the boom side members 2I and 22 are connected by links-34 to the outermost ends of the pins 33.

Extending upwardly and rearwardly from the upper ends of uprights 25, at a substantially 45 degree angie, is a bracket arm 31 having an idler roller or pulley 38 arranged between the extremities thereof. The bracket arms 31 may be suitably braced by means of upright members 39, the lower ends of which are also fixedly attached to thehousing of the winehunit I8. For raising the boom 20 from the horizontal or inoperative 'position to the elevated position as illustrated in Figure 3, thehook 40 at the end of the cable 4I is suitably anchored to a part of the upright structure, indicated at 42. The cable 4I extends 4rthrough the -block 43 attached to the tip 23 of the boom, and is then trained over the idler roller 38Y.and-exten'ds downwardly to the .drum of the winch-unit. I8. rUpon energization of the winch unit the cable is reeled in to effect pivotal movement of the boem te the elevated position. since the upper ends of the bracket arms 31 supporting the idler roller38 extend .somewhat above the pins 33, a pull` may be had in a proper angularV v direction uponthe upper end of the'boom forr effecting pivotal movement thereof to the eley vated position.

As `the boom approaches the vertical position the lower end of the boom side members 2| are cooperatively engaged bysupport means provided therefor at a relatively low point upontlie'tractor body, As shown in the specific illustrated embodiment, this support means is provided upon the upright members 25 by brackets 45 rigidly attached thereto and defining sockets 46 for co-4V operativelyreceiving the ends of the pins 41 prop' vided in the lower extremities lof theA boom side arms 2|. The sockets 46 are spaced below the to guide the pins 41 into the 'sockets 46, arcuate guide plates 49 are provided, these beingsecured at one end to the outer surface of the upright members near the brackets 45 and extending upwardly therefrom in the path of-travel of the extremities of the boom side arms. After the pins l1 have become seated in their respective sockets 46, theymay be secured in lplace by means f locking pins 5| dropped through cooperative openings in the outer ears of the bracket arm portions defining the sockets 46 as shown more clearly'in the enlarged sectional View of Figure 7.

For guying the upper end of the boom 20 inv i the elevated positions thereof,` a cable' 52'is provided, the opposite ends of which are secured to the upper ends of posts 53 secured to the frame members I5 of the crawler units adjacent their jboonito the rearwardlyfextending position it is foremost ends. The posts 53 are suitably braced f against deflection in the rearward direction by means of braces 55, and further steadied against deflections' laterally of the tractor by additional braces 56 as shown more clearly in the front view of Figure `8. The cable 52 extends through an equalizer block `51 which in turn is secured through suitable tackle 58 to the tip of the boom 26, the tackle cable 59 being attached to a hand operated drum 6|) secured to the upright structure. For preventing the pull on the cable 52 from drawing the upper ends of the posts 53 together and thus exerting a lateral twist upon'the crawler units, a spreader bar 62 is provided be-4 tween the opposite sides of the cable 52; as shown more clearly in Figure 8. By virtue of the fact that the cable is trained through the equalizerv block 51, the load is uniformly distributed between the two crawler units throughthe cable 52, irrespective of the relative positions of the two units. Assuming that the forward ends of the two crawler units are positioned at different elevations,l due to the uneven ground :condition indicated by the dotted lines 63, the cable 52 will run through the block 51 to automatically adjust the length of the opposite sides thereof in accordance with the distance from the boom tip to the upper ends of the posts 53, as indicated by the dotted line position 62 of the spreader bar 62. i

It will be observed 'that the backstay cable 52 is anchored to the foremost ends of the crawler units rather than to the forward end of the tractor body. If the cable 52 were anchored to the forward end of the tractor body,V itv would be obvious that upon loading of the crane the trac-v tor body would tend to rotate backwardly about the rear axle I4, unstressing the front spring I 6 and tending to raise' its opposite ends from the saddles provided therefor on the crawler frames. If the'ends of the springs were secuiely'attached to the crawler frames, then the spring I6 would be stressed in the reverse direction with the entire weight of the forward ends of the crawler unitsv being supported bythe lowermost leaf ot' vthe spring I6.

spring I6 vmight readily breakthe spring, even when *attempting to raise a relatively light load bythe crane.v On the other hand, by anchoring` the backstayl cable'to the forward ends' of the crawler units themselves, the weight of the forward ends of the crawler units, aswell as that of'the tractor body, is availed of for counter- Abalancing the-load transmitted'through the backstay. If y necessary, additional counter- .weights such as are indicated at 6|, may be mounted upon the forward end of the 'crawler `frames in any vsuitable manner.

In the usual operation of the crane the boom islowered rearwardly 'tonsomesuclr position as indicated in Figure 4. In pivoting -from the vertical position tothe rearwardly extending angular position lofiguregl, the saddles 32 move freely away from the pins 33 onthel uppermost ends of the upright'members 25. -In moving the necessary only to unwind the'hand vdrum 60 to permit slack in the tackle 58 as the powerdriven winch unit I8, acting through the cable 4|, pulls the boom over the dead center position. From p that point on, the angular position of the boom may be determined entirely by manipulation of the handA drum 60. In ythe operative position of the boom 42li the backstay cable 59 is trained over roller B6 provided upon the upper end of the upright structure.-

It will be observed that as soon as the boom has been moved to an elevated operative position, the position of the boom is controlled by Athe backstayycables 52 and 59, and the hook 40 For lowering the boom from an initial operative position, such asshown in Figure 4, to the horizontal position as shown in Figure 1, the boom is first lifted by means of thehnand drum l 6U to the vertical position as shownin Figure 3. The hook 4|] at the end of the cable 4| extending from the winch unit lI8 is then anchored to the fixed frame portion 42. The pins 5| are then removed from the brackets 45 to permit the pins' 41 at the lower extremity ofthe boom side rails 2| to` shift fromthe socketsl 46 upon further tightening of the backstay line-59, thus` rocking the upper end of the boom over dead center and transferring theloacl thereof onto the cable 4I. By gradually easing out the cable 4| from the winch unit I8, the boom may be pivoted about i the pins 33 atthe upper end of the upright members 25 until the tip of the boom cornes to rest upon the cross bar 30 of .the forward supporting structure 29. As the boom 20 is lowered to the horizontal position, the spreader bar 62 is hooked under the clips 10 provided upon the forward,

sides ofthe opposite side rails 2| of the boom, and the hand drum 60 is rotated so as to wind up the slack of theV backstayline 59, thereby Such unnatural'stressing of the- Y holding'f-the tackle snugly against the under-f uses ofthe tractor.`

considerable distance. ie -,f rom the'standpoint of operation andcontrol ofthe tractor withfthe boom in thefinoperativeor lowered position to` supportthe boomin such'positionat a considerfrom theaxle I4 to the spring I6 supporting the forward end ofthe body is representediby s, and

. the y.reaction of the spring against the rotational Solving Equation lInasmuch as `s` is constant, it is'th parent that the stress S inthe spring I6 is directly proportional to themoment arm JA ofthe.

neathside of the boom as shown in Figure` l, and v Aoutcf the line of vision of the operator. y

, In Ythe noriz'ontal'lposition ,the boom. is substantiallyV entirely supported above thehead of the operator so as not tointerfere with his line of vision. Theboom is, furthermore, supported' so aS-vn'ot to interfere,.with'othe r conventional- Once the boom haslbeeng.

lowered tothe horizontal position, the cable exev .v tending from the winch drum vlilma'y'be disconnected therefrom and hookedfonto any load which does ynot require use` of the'cra'nel" Itwill f tractor spring.` which'is not normally designed.

be understood thatin certain locations overhead clearances might not tolerate the erection of the boom, adthat theload can,satisfactorilyV be handled byuuse vof the winch drum alone and i with thefcabley trained` over the roller 38 ,pro- .l r vided onthe upperfend of ,the bracketyarm 31,l

d lift on the cable of" thus providing an upwar `While it, is y desirab able:` height abovey the tractor body, it is undesirable for numerousreasons to pivotally support the lower endof the boom at such aheightr abovey i the tractor body when handlingloads therewith.

- When ,operating the crane', that is, for handling loads therewith, it is desirable-to support the Y lower end of the boom reasonably low upon the Vtractorbody so as to simplify the backstaying off the Vboom and also so as to minimize stresses which may otherwise be transmitted` to. certain parts ofthe tractorbody through unduly long.

lever arm reactions.' Referring to the `diagrammatic sketch of Figure 10, assume rst that the boom is pivotally supportedatsome point 331 which is located at a considerable distance aboveV the axle l4, and that 5,the boom is "adjusted to some such rearwardly extending position` as indicated bythe arrow F. Now assumenthat a load is applied to the end ofthe boom and that a force f F is transmitted.longitudinally of the boom to the tractor body through vthe point 33?.: Theforce F acting in the direction indicated Vhas a moment armj about the rear axle vI4 of the tractor, the moment Ff tending to rotate the main body ofthe tractor about the axle-i4. Thefdistance force' due to loading of thecrane is represented by the Vforce vector S.` The moment ofthe spring,

which will be -`cal1ed-the resisting momenhmay,

` i therefore, be represented as Ss. For equilibrium `the resisting moment must equal, the applied moment and, therefore,

(Equation A) erefore apboom thrust. Now, byfloweringlthepivotal support fory the heel of the boom from the'position 33"to a pointsuch as 46', it is apparent-that the tionately reduced to some much smaller. value such as f.

of the boomin the operative Vpositions therefor. In the diagrammatic representation of Figure 10,

` v tion in what is considered to be a preferred empermanently damaged.,

this is visually illustratedby a comparison of the lengths of the' moment arms f and f. The magnitude or the forcesV involved is such that the for the application of external loads other than those due tothe weightand inertia of the for- Ward vportion lof the main tractor body. would, by application ofy a normal capacity load on the boom, be stressed beyond its safe limit and would not only be undesirably deflected, but may actually be stressed beyond its elastic limit and be 'IheaboveA discussion assumes that the force F is equal tothe force F, whereas, by a rigorous analysis it can be shown that the force F is considerably greater thanforce F', particularly on low' boom operations. This can'readily be understood by reference to Figure 4 and imagining that the crane be pivoted at'the point 33' rather thanat the point 46. If such were the case, it will readily be seen that guy `cable 52 passes such a small distance above the point`33 that any appreciable load applied to the endy of the boom would induce extremely high stresses in the guy cablewith an accompanying boomA thrust far in excess o'f that which would be developed by the same loading-if the boom were supported at point 46,.in1a lowerposition; If vthe stress reduction due to the short load? moment arm, as first discussed above, is multiplied ,by the reduction effected by increasing the angle between the backstay cable and the boom, it is apparent that the stresses in the tractor spring are decreased in geometric progression as the yboom pivot point is lowered from apoint adjacent the upper extremitiesyof the uprightmembers 25 toward some lower point-l positioned near the rear axle of the tractor.` Just whatl the distance should be between the axle and the' pivotal supportfor the heel of the boommay dependupon various factors. l In anyevent, the pivotal support 'for the heel of the` boom should be low en'oughin order thatwlien the boom isrr lowered to the lowest normal operative position and loaded with a normal rated capacity load, the lever arm of the force acting about the rear yaxle of the tractor ls so short that the resultantmoment imposes a load on the front spring of the tractor which is safely within its maximum capacity.

Having described the principles of my invenbodiment thereof, it isdesired that it be under- 1 are mer vmoment armff of the'boom thrustl is proper Thus' itis obvious that the stress S --in the tractor springl is ,veryqmateriall'y reduced by the lowering of the support for' the heel great distance above said vehicle, and means for' transferring the point of application of boom thrust from said relativeiy high position to a relatively low position adjacent the vehicle axle upon erection'of said boom from inoperative to operative positions, said boo-m being pivotally movable from said inoperative position to various angular operativepositions extending rearwardly from thetractor.

, 2. A tractor comprising a body, a rigid upright structure attached to said body, a boom mounted on said' tractorand adapted to be carried thereby in a generally horizontal inoperative position overlying said body and being further adapted to be elevated to an upstanding` operative position,

means for pivotally supporting said boomfupon the upper end of said upright structure so as to be movable thereabout to said operative position,

means mounted adjacent the lower end of said 3; A tractor comprising a body, an upright structure mounted onV said body, al boom, means including said upright structure for supporting `said boom in a generally horizontal inoperative position overlying said tractorr body and in a plane `substantially above the head of an operator seated on said tractor, said boom being pivotally movable about a point intermediateits ends adjacent the upper end of said upright from said horizontal inoperative position to an upstandirlf,r

operative position, and support means positioned below the upperend of said upright for engaging and pivotally supporting the lowermost end of said boom in said operative position. said boom in said operative position being movablefree of the uppermost end of said upright structure;

4-A tractor comprising a body, an upright structure mounted on said body, a boom, means including said upright structure for supporting said boom in a generally horizontal inoperative position overlying said .body and in a planesubstantially above the head of an operator seated on said tractor, said boom being pivotally supported intermediate its ends upon said upright structure4 for pivotal movementr between said horizontal inoperative position and a substantially vertical operative position, Vand support means xedly secured relative to said body for engaging and pivotally supporting the lowermost end of said boom in said operative position.

5. A tractor comprising a body, track type crawler units on theopposite sides of said body, said body being pivotally supported at the rear end on said crawler units, said body being resil-v ientiy supported at the forward end on said crawler units, a boommounted on` said tractor body andadapted to be carried in a substantially horizontal Iinoperative position overlying said body and to be elevated to an upstanding operative position, means for supporting the lower end portion of said boom for pivotal movement between said inoperative and operative position,

and means mounted below said first meansv for engaging and pivotally supporting the lowermost end of said boom in the` operative "positions thereof. n

6. A tractor comprising a body', ltrack type crawler units on the opposite sides of said body, said body being pivotally supported at one end on said crawler units, said body being resiliently supported at the opposite end on said crawler units, an operators seat on said body, an upright structure fixedly attached to said body adjacent the said one end thereof and extending upwardly to a point above the head of'an operator on said seat, a boom mounted on said tractor adapted to be carried in a generally horizontal inoperative position overlying said body, means for elevating said boom to a vertical operative position, said boom being pivotally supported intermediate its ends adjacent the upper end of said upright.

structure when in the horizontal position, said boom pivoting about the upper end of said'upright structure in movement from horizontal to vertical positions, and supporting means adjacent the lower end of said uprightstructure adapted to be pivotally engaged ,by the heel of said boom when said boom is in the operative position.

7.fA tractor comprising a body, an upright structure mounted upon one end of said body, a boom, means including said upright structure for supporting said boom in a generally horizontal inoperative position overlying said body, means for pivoting said boom about the upper end of said upright structure from saidhorizontal inoperative position to an upstanding `operative position, and support means positioned on said body below the upper end of said upright structure for engagingv and pivotally supporting the heel of said boom when elevated to, said operative position,and means connecting the heel ofthe boom and said upright structurefor preventing displacement of said' boom therefrom during movement of said boom vbetween operative and inoperative positions.

8. A tractorcomprising a body, crawler units l on the opposite sides of said body, said bodybeing pivotally supported at the rear end about an axle extending therefrom to said crawler units, a compression spring supporting said body at the forwardend on said crawler units, an upright structure fixedly attached to Vsaid body adjacent one end thereof, a boom, means including said up-v right structure for supporting said boom in a generally horizontal inoperative position and in a plane substantially above the head ofan operator seated on said tractor, means pivotally sup.

porting said boom intermediate its ends adjacent the upper end of said upright structure, means for moving said boom about said pivotal supporting means/frim said horizontal inoperative position to a substantially vertical operative position, support means on said bodyadapted to be pivotally engag d by the lowermost end of said boom when movedp said operative position, said boom being movable upon said support means to angular operative positions extending from `one end of said body, guying means connecting tlietip of 4 said boom when in the4 operative position to the opposite end of rsaid tractor, the height of said support meansabove said axle vbeing such that the component of rotational force about said axle with normal capacity load on said boom when extending outwardly `at an angle from the end of said body is less'than the maximum load capacity of said compression spring.

` 9. kA tractor comprising a body, crawler units on the opposite sides of said body, said body being pivotally supportedat the rear end by an axle extending therefrom to said crawler units, compression spring means supporting the forward end of said body on said crawler units, an operators seat on said body, an upright structure fixedly attached to one end of said body, a boom, means position and in av plane substantially above the T6 I a v f l said body, a guymg cable for' said boom attached to the opposite ends oi vsaid crawler units. saidV 10,A tractor comprisinga body,

ture from said horizontal l ypivotal movementy thereabout from saidfhorizoni t upwardly andvrearwardly therefrom,v afroiler ;on i theQendgofl-said arm,',. a cable. attached to said c "winch extending over 'saidroller and connected "to the upper end of said boom for effecting eleval 'stantially above the head lof anoperator seatedljlr, on 'said tractorfmeanstor pivotallytmovingsaid'vv boom about'the upperfend'vof saidupright struchf position `i .o .\an operative f position, support means positioned onsaidabody below` the ,uppers end of said upright structure adapted ,to be pivot'ellv engaged-by the'lawelnosi' i end of said,boomwhenmovedtofthe voperative oosiioufa` syiag cablforgslailbwmrattachedi tottheH opposite ends oi said '.crawleriunits, j said cable extendingthroughanyequalizerbloclrjse;- V =2"5 cured to the upper end of" said -^;boom,` 'f a spreader bar extending betweenopposite sides lof. saidcable 1 for predeterminingzgthe 1in'e 91;. pull said crawler`4` units therethrough, and means on said boom t for supporting saidspreader bar andsaid Q30 biockitne horizontal patitierror;sind.tintin.;r` *11, A tractor comprising a body-havinga win h" 'attached to; said one-Lend of said bodmfa lfboom means including said uprightv struoturefor supi-135 ,porting `said in a generally ,horizontal finoperative position ov rlying said body,v means pivtf` r otally supportingsaid-boomintermediateits ends- `on the upperend of. said supporting structureren`V 405 tal inoperative position; to' a s ubstantiallyli vere vtical operative position; a1 bracket tachedto'saidupriglit structure and extending#l .tion off said boom Iromwsaid horizontalto v said-'- "verticalposition. U f t 12. Atractorcomprisinga body, a winchfon'. f said body having:a' hoist cablefwound thereon,A f'

an upright structure; iixedly y.attached to one 1 end ofsaid body,=aj bo,om, meansincluding'said f upright structure-for supporting said; boomin a" generally". horizontal 'inoperative `position `over- .v 55

lyingsaid body,'fmeanspivotal1y supporting saidv boomV :intermediate its ends adjacent the upper end of said' upright struoture, an arm xedly attachcd to the upper rendof said upright'stru'ctu're and extending upwardly andi rearwardly 'chere-vV o from, said arm having'` a guidepulleyprovided on the outer end. thereof, said hoist cablefadapted to betrained over 'said'guide pulley'and be;l operasse-,oost

V.portineans 1 a end of said body "fendof, saidlbco arm viixedly at-V said body-having a' hoist cable wound thereon, an upright structure fixedly attached to one end of atively V coinected tothe lend. of ysaid boom for `eile'ctin'g elevation oi' said boom to a substantially vertical f operative position,4` support means mounted on said body below said'iirst mentioned l pivotal support means adaptedtolle pivotally engaged by the lowermost end o! the said boom whenvelevated to the'vertical operative position, and backstays connecting the upper end of said boom tothe forward end of said tractor for limiting pivotal movement of said boomon said sup`l 13.Ay 'tractor comprising` a A ibo-dy, track' type crawler units on the opposite sides of said'body. said body being pivotally supported'at the rear endabout anaxle extendingto saidicrawler units,

yoornpre si'onspring. means supporting the -forward on said crawler units, an operitedly attahedto saidbodyzadiacent the rear f end thereoffa boom,A means including said upright structurel fori supporting said` boom in a generally`-horizontaliy `inoperative`position over- `-lying said-body and ina plane'substantially above "the vhead of an' ;opeator on' said seat.' said boom beingfmountedffor pivotal movement adjacenty f the upper; Vend voi? said upright ystructure between :zsaidinoperative position and an upstanding oper- ;-'ative,. ;fposltinrbsupport means on said body e ,ada tedfto bevpivotally engaged byrthejlowermost "when in the Operativeposition,

'said m'bein'gplvotally movable upon' said support meansto'angular operative positions extendinggrearwardly from said tractor, backstay means 'fconnecting-'thelupperend of said boom to the forwardend-oi` said crawler units,` the height of said support'meansabove said axle being such that the component oi yrotational force about said axle vwith normal capacity load on said boom` when extending angularlyoutwardly from saidtractor is'lessv than'theniaximum `load capacity of said 14. Atractor comprising a body, a winch on saidbodyi` a boom, means includingV said upright structure for. supporting said boomin a generally horizontal inoperative position overlying said body.,y means pivotally supporting `said boom intermediate its' ends adjacent the, upper lend of said'uprightstructure, said holst cable adapted to bego'per'atively connected yto the 'end of said boom Y forfeilectingelevation of vsaidboom.l to a.l substantially' `vertical `operative position',v support `means mounted` on said" body belowsaidfrst mentioned" pivotal support means adapted to be pivotaliy engaged by the lowermost endof theftf said boom when elevated to the vertical operative position, and backstays connecting the upper end ofsaid boom to the forward end of said tractor Vfor` limiting the pivotal movement of said boom

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