US2364857A - Crawler track - Google Patents

Description

' Dec. 12, 1944.

Filed March 1, 1943 J. A. LAW

CRAWLER. TRACK 2 Sheets-Sheet l gwuwwkw James H. Law

Wag/a Dec. 12, 1944. J LAW 2,364,857

' CRAWLER TRACK Filed March 1, 1943 2 Sheets-Sheet 2 3mm James fLLaw Patented Dec. 12, 1944 UNITED STATES PATENT OFFICE 2,364,857 CRAWLER TRACK- James A. Law, Merced, Calif.

Application March 1, 1943, Serial No. 477,517

11 Claims.

This invention relates to endless or crawler track units, either of the self-powered or idler type.

In units of this character it is desirable that the shoes of the track link shall have a maximum ground engaging length between the end sprockets or the like, and that the shoe shall follow a definite straight path between their limits of ground engagement in order to travel smoothly, lessen vibration and avoid the formation of pockets between the track links or their shoes at the ends.

It is also desirable to use the fewest possible links in order to cut down the number of joints and the accompanying number of parts and wearing elements.

However, even with the relatively short links ordinarily used, their mounting is such that as one link starts to climb about a sprocket, said sprocket imparts a downward blow to the adjacent links not yet engaged and climbing. This causes a pounding or binding of the links against the sprocket, with the resultant bumping action and uneven travel and excessive wear. This is especially evident at the rear end of the track.

With the above facts in mind the objects of my invention are to provide a crawler track unit which has a minimum of links; one in which each link is well supported while in ground engagement, so as to be very rigid and stable and thus making the structure a very effective load carrier; and one in which there is no knocking or pounding action, kinking or oscillation of the links, and the links travel smoothly and through a predetermined fixed path at all times from one end of the unit to the other.

At the same time these advantages are obtained with the use of a short track unit combined with long links, which is favored for certain types of service.

Essentially the invention consists in arranging and supporting the track links in connection with the end sprockets or similar members of the unit in such a manner that the axis of the pivot pins of the links follow a straight line between the sprockets and said line is tangent to the pitch diameter of the sprockets for the full distance between the points of tangency.

A further object of the invention is to produce'a simple and inexpensive device and yet one which will be exceedingly effective for the purpose for which it is designed.

'These objects I accomplish by means of such structure and relative arrangement ofparts' as will fully appear by a perusal of the followlinks symmetrically positioned relative to the I sprockets.

Figure 2 is a sectional plan on line 2--2 of Fig. 1.

Figure 3 is-a transverse section on the line 3-3 of Fig. 1.

Figure 4 is a plan view of a link detached.

Figure 5 is a fragmentary side elevation of the I unit showing a link as initially moving up about the adjacent sprocket wheel.

Referring now more particularly to the characters of reference on the drawings, the crawler track unit in the embodiment here shown, comprises a pair of spaced side frames I connected at ,intervals by cross bars 2 so as to forms.

, rigid structure, and having a central transverse support or hearing member 3 for the mounting axle 4 about which the unit swivels.

Turnably supported by the frames at one end On the outside is a'pair of transversely spaced sprocket or track link engaging wheels 5, while a similar single centrally disposed wheel 6 is sup ported between the frames at the opposite end. The bearing blocks 1 for the wheels are engaged by conventional tightening or take-up devices 8.

If the track structure is driven, the single sprocket wheel would preferably be the drive I sprocket at the rear; the dual sprocket wheels being at the front end. This arrangement main tains the track links against possibl lateral defiection and binding as theycontact the ground,

whilekeeping the wear on the drive sprocket and links to a minimum.

An end1ess track extendsbetween and about the wheels, said track including relatively long A links, each of which comprises transversely spaced rails 9 having'cooperating bosses in at their ends and preferably flush therewith, and ground engaging shoes ll rigid with the rails and bosses. The bosses serve as supports for the connecting hinge pins P of the links and also as wheel engaging members, said wheels, having boss engaging seats or recesses S rather than teeth ofthe normal form. These seats are spaced apart the length of the links, and are of course alldisposed so' as to travel in circular paths concen-;

trio with the axis of rotation of the wheels.

a depressed graduated curvature as at l5.

vided by a guide flange l3 into a pair of transversely separated portions, the rollers for the most part being dual and straddling the guide flanges; l3 so as to engage the rails on opposite sidesof 1 said flange, as shown in Fig. 3, so thateach dual" roller is' always engaged with the flat surface of tangency of the wheels with the pin axis line A, will always be firmly engaged by one or the other of each roller of the dual sets. This feature of course is most necessary on the lower run of the track, since a certain slack along the upper run in relatively immaterial.

It will be noted that the rollers are spaced apart a distance equal to half the length of a link between pins P, so that each link on thestraightaway is engaged by at leastatworollers, and it is therefore impossible for thelinkage": to shift from a straight line position, regardless" of inequalities in the surface engaged.

It may also be noted that while I have'illustrated' and described a certain definite arrangement of wheels, link rails, and rail'engaging rollers; such arrangement may obviously be altered considerablyas.individual installations may justia rail portion. The endmost rollers [4, however,

are single and engage only one rail portion, and as here shown" each endmost roller is disposed, at

straight line until the relatively trailing end of such link (or the leading end of the following link) isengaged by a sprocket seat, or so that the axial line A of the link pins remains tangent to the pitch diameter line D of the wheel; theroller engaging face of each rail portion is formed with This curvature extends from one end fora certain distance along'the rail and is plotted by atemplate to such a length'and depth relative to the position of the corresponding end roller l4 and thewheel, as to cause the roller, to ride the bottom ofthe curved rail portion and support the. corresponding 'link as it is being lifted by the wheel until said relatively trailing end of such link passes under the roller and the latter supports the rail ,of the linkrbeyond to-maintain the link pins in such, straight path.

By reason of this feature, which is the heart of the invention, the descending boss-engaging elemerits of. a wheel does not contact with a link already. tending to lift, as is otherwise the case, and hencev a pounding. and other objectionable action is eliminated.

A. similar link engaging action takes place atj It will be noted that the roller engaging curva-,

ture [5 of. the rails extends along the leading or front half ofv one rail portion, and along the trailingor backhalf of the other remaining portion; the remaining roller engaging faces of the rails being flator straight.

. The endmost rollers l4 are disposed in proper transverse planes so as to engage corresponding concavities, such rollers at one end being on the. inside and at the, other end. on. the outside. Also, the rollers l4 at the top are disposed in the re-,

verse relation to thoseat the bottom.

Provision is thusmade for properly guiding thev links onto or off of the wheels irrespective of'the direction of travel of thetrack, and also supporting the links so that binding strains are taken.

off'the. boss engaging elements of the wheels.

At the same. time the straight track linkage, be-:

tween the turning points or between thepoints of fy without departing from the spirit of the invention, which, as stated, is the provision of a means to maintain thelink p insin. a. straightli e the full distancebetweeni and. tangent tothe pitch diameter line of the end wheels about which thev linkage travels.

While I have here shown dual-purposerails.

having a combination. ofiflat and curved roller en-.

gaging faces, it. is obvious thatarail arrangement.

could be provided whereinone rail is utilized sole,- ly for engagement by the endmost. rollers, and

another railv is engaged. solely by. the intermediate rollers.

It ,is also possible to use a single dual purpose. rail instead. of, the two shown.

As previously stated; the sprocket wheels ene recesses S1 of wheels 5 engage the outer or trailing end bossses ill of the links ahead or which are already lifted and passing, about thewheels. If,',.

on-the other hand, the track is traveling. toward the left, then the central'wheel 61 engages the central bosses IU of the links, which are then at the trailing' end of the links. In either c'ase' th'e result is that once a link boss becomesso engaged, there isandcan-be no turning'oi" the boss'in its wheel-recess, as thesprocket rotates and drives porting frame, rotary members turnably mounted on the frame'at its-ends, an endless track unit extendingabout and between the members and comprising a plurality of individual links and pivot pinsconnecting thelinks: at adjacent ends for relative fiexingin a vertical plane, the members including elements. engaging the links passing about saidi'membersi adjacent the link, pins and moving. in circular paths concentricjwith the. axes. of: rotation. of the members, the linksbeing relatively long and. each including a longitudinalrail unit projecting, radially inward, and means engaging. the. rails; of. the

links of the lowerirun of the. track tohold the same against upward deflection from a prede' termined' path; said means, and the rails being arranged to cause the link pins tortravei along a straight line tangent to the circulari-paths oii the members for the full distance between the points of tangency'and supporting a link dur-' ing a predetermined portion of its upward movement about one of the members after the relatively leading end of such link has been engaged by an element of saidone member at the lowest pointv of its movement along its circular path. l I 2. An endless track structure including a supporting frame, wheels turnably mounted on the frame at its ends, an endless track unit extending about and between the wheels and comprising a plurality of links, cooperating bosses at the ends of the links and pivot pins connecting the bosses and a longitudinal full-length rail unit on each link projecting radially inward, the wheels including boss engaging elements movable through circular paths concentric with the axes of rotation of the wheels, and rollers mounted on the frame and engaging the rails of the lower run of the track; the rollers and rails being arranged relative to the wheels to cause the pins of the links of said lower run to travel in a straight line tangent to the circular paths of the wheel elements for the full distance between the points of tangency. 4

3. An endless track structure including a supporting frame, Wheels turnably mounted on the frame at its ends, an endless track unit extending about and between the wheels and comprising a plurality of relatively long links, cooperating bosses at the ends of the links and pivot pins connecting the bosses and a longitudinal full-length rail unit on each link projecting radially inward, the wheels including boss engaging elements movable through circular paths concentric with the axes of rotation of the wheels, and rollers mounted on the frame and frame ,at-lts ends, an endless track unit extend,-

lng about and between the wheels and comprising a plurality of relatively long llnks, cooper, ating bosses at the ends of the links and plvot, pins connecting the bossesl and 'longltudmal, full-length rails projecting radially inward, the

wheels lnCluGlng b0SS engaging elementsmovable through circular paths concentric with the axes OI rotation oI' the wheels, and means to cause the link-pins along the lower run or the track'to -'follow and remain ina straight :lme

cent the opposite end and in the transverse plane of the other endmost roller is formed with a similar concave curvature.

6. A structure as in claim 5 in which the rollers l intermediate the endmost rollers are disposed to engage the rails for, substantially their full math.

I. A structure as in cla1m b, with a longitudinal guide nange projecting radially inward or the track from each rail and laterally separating the curved portions thereof; the intermediate rollers of the row being dual and straddling said flange.

engaging the rails of the lower run of the track and extending in a row for the major distance between the vertical central plane of thewheels; the endmost rollers being disposed a distance from said planes less than the length of a link and the adjacent rollers being located from said planes a distance substantially equal to the length of a link; each rail being formed on the surface engageable by an endmost roller so as to hold the corresponding link, when initially engaged at its relatively leading end and raised at said end by a wheel element upon rotation of the corresponding wheel, in such position that the relatively trailing end of said link remains in a plane on a line tangent to said circular paths until said trailing end reaches the vertical central plane of said wheel.

4. An endless track structure including a supporting frame, wheels turnably mounted on the frame at its ends, an endless track unit extending about and between the wheels and comprising a plurality of relatively long links, cooperating'bosses at the ends of the links and pivot pins connecting the bosses and a longitudinal full-length rail on each link projecting radially inward, the wheels including boss engaging elements movable through circular paths concentric with the axes of rotation of the wheels, and means to cause the link-pins along the lower run of the track to follow and remain in a straight line tangent to said circular paths for the full distance between the points of tangency; said means comprising a, row of rollers mounted on the frame and engaging the rails, the roller engaging face of each rail for a portion of its length being formed with a concave curvature of predetermined contour.

8, In an endless track structure WIllClIl includes a supporting frame, rotary members turnably mounted on the frame at its ends and an endless track unit extending between and about the members and including a'plurality of links pivoterl together; a plurality of rollers mounted on the frame and engaging, the links of thelower run of the unit, said rollers being so spaced and arranged that each link not engaged by a member is engaged by at least two rollers while a link as initially engaged with a member is also engaged by at least one roller.

9. An endless track structure including a supporting frame, rotary members turnably mounted on the frame at its ends, an endless track unit extending about and between the members and comprising a plurality of individual links and pivot pins connecting the links at adjacent ends for relative flexing in a vertical plane, the members including elements engaging the links passing aboutsaid members adjacent the link pins and moving in circular paths concentric with the axes of rotation of the members, the links being relatively long and including a pair of longitudinal full-length rails projecting radially inward from each link and forming continuous rows lengthwise of the track and means to cause the link-pins along the lower run of the track to follow and remain in a straight line tangent to the circular paths of the members for the 'full distance between the points of tangency; said means comprising a row of roller units engaging the rails of one row, said rails having flat rail, engaging faces, and endmost rollers engaging the rails of the other row; each last named rail, for each endmost roller, being formed for a portion of its length from adjacent one end with a concave curvature of predetermined contour for engagement with the corresponding roller.

10. In an endless track structure, a supporting frame, a single endless track unit comprising a I 5. An endless trackstructureincIuding a 5111),, porting frame, wheels turnably mounted on the.

pluralitya-ofi individuazl links, transversexbosses -0n the -links at their ends and pivot connectionsme-h tweenthe: bosses; a, pair of transverselyq: spaced; sprocketwheels mountediongthe framefl'at tone rendh aboutw-hichimhe;unitapassesland engaging; the. 5;; bosses adjacenmthe side edges of thalink's, and,

end: bosses; on each: link: ae one end, as-qc.entrally;;- disposeck'b'oss on: each; linliva'fo the: other endz;.an;i

pivot; pins ;.through:. corresponding-bosses: of; ache jacentlin'ks:and1connecting the same; ahpaifiofi transverselyspaced wheel'samountedionwtheframea andi having; recesses to; receive; the: transversely? spacedxbosses:ofiithexlinksrandeaboutzzwhichaxthee j trackunit passes, and a, single wheel mounted:

theefirst named; wheels.and: aboutiwhichgthertracle;

unit,;passes;:. and,;having: recesses-1:0 receive:;.the;;

v cenfinally::disposedbossesmf the*links.;.

JAMESQJAQLAW.

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