US2897014A - Tracks for crawler type machines - Google Patents

Description

July 28, 1959 F. H. DARRAGH, JR 2,897,014

TRACKS FOR CRAWLER TYPE MACHINES I INVENTOR. Frank H.Darragh,Jn

His TTQRNELS July 28,' 1959 x F, H, DARRAGH; JAR l 2,897,014

v TRACkS FOR CRAWLER TYPE MACHINES 5 Sheets-Sheet 2 Filed oct'. 4, 1956 m. m w

Frdnk H.Darragh,J|:

-BY I w His ATTORNEYS July 28, 1.959 F. H. D ARRAGH, JR

TRACKS FOR CRAWLER TYPE MACHINES 5 Smeets-sheet s Filed 001,. 4, 1956 INVENTOR. Frank H.Darragh,J|:

BY A

YHis ATTORNEYS United States Patent@ TRACKS FOR CRAWLER TYPE MACHINES Frank H. Darragh, Jr., Beaver Falls, Pa., assignor to Darragh Mechanisms, Inc., a corporation of Pennsylvania Applicaton October 4, 1956, Serial No. 613,873

11 Claims. (Cl. 30S-10) Crawler types machines are old and Well known in the art and particularly comprise tractors and the like.

There are several objections to tracks presently used for crawler type machines. Such tracks comprise a large number of parts which are small and must therefore be made of exceedingly strong materials to withstand heavy loads. The track mechanism is constantly exposed to dirt and other abrasive material so that lubrication of moving parts is not even attempted, resulting in excessive wear. The jointed tracks, elongated due to stretch and wear, soon get out of mesh with the driving sprockets and are increasingly likely to fly olf, even through greater tension is applied. Thus conventional crawler machines are currently limited in the length of their tracks, and even so they must be operated at slow speeds.

I have heretofore made inventions for tracks for crawler type machines which inventions are disclosed in United States Letters Patent 2,308,327 and 2,581,365. The present invention is an improvement over my prior inventions and obviates dilhculties encountered therein. l provide a track unit comprising machine support means, an endless rail connected to and supporting said support means, said rail having a load bearing portion and a shoe return portion, a plurality of shoes in endless pivotal connection, each of said shoes having a pair of inner rail followers and a pair of outer rail followers, and drive means to cause movement of said shoes along the rail. I preferably provide an endless rail in longitudinally slidable connection with the support member and means urging said rail longitudinally forward. I further pref-A erably provide circular drive means in contact with the inner rail followers and rail transverse stiffening means. Other details, objects and advantages of my invention will become more apparent as the following detailed description of a present preferred embodiment thereof proceeds.

In the accompanying drawings I have illustrated a present preferred embodiment of my invention in which Figure 1 is a side elevational view of a crawler type tractor with a track embodying my invention;

Figure 2 is a sectional view of one track unit taken on line II-II of Figure l;

Figure 3 is a sectional view of a part of one track unit taken on line III-lIl of Figure 1;

Figure 4 is an exploded View illustrating one of the shoes; and

Figure 5 is an exploded view illustrating a modified form of the shoe shown in Figure 4 but with certain parts removed.

Referring to the drawings, a crawler type tractor 1 is illustrated in outline. A crossbar 2 projects from the tractor and serves to support it from the track units on either side. A tractor rear axle 3 projects from the tractor transmission and further supports the tractor. A channel-shaped support member 4 is welded to a raised plate 5 which is in turn fastened to crossbar 2 by bolts 6 and clamps 7. It will be understood that although only one track unit is shown in the drawings, a similar Patented July 28, 1959 track unit is provided on the opposite side of the tractor. A bearing plate 8 is also Welded to the top surface of support member 4 and carries in cradle 9a an outboard axle bearing 9 in which axle 3 is journaled. A continuous track 10 generally encircles support member 4. It is of rectangular cross section throughout, as shown in Figure 2, and may be readily formed from bar stock. It comprises a load bearing portion 10a and a shoe return portion 10b. A load stiffening member 11 comprising a vertical metal plate is welded along the load supporting portion 10a of track 10 adjacent the inner corner which is nearest the tractor. A further stiifening plate 12 Comprises an extensionof plate member 11. A flat plate 13 is welded to the top of stifening member 11 with its axis generally parallel to the axis of load supporting portion 10a. Two spacers 14 are Welded to the upper surface of plate 13 and have bolts 15 threaded into them. Bolts 15 project through slotted holes 16 in support member 4. Front and rear spring castings 17 and 18, respectively, are attached to plate 5 and a pair of springs 19 is fitted in compression between rear spring casting 18 and a saddle 2l) which is slidably mounted in front spring casting 17. A push rod 21 is fitted in saddle 20 and bears against a seat 22 mounted on member 23 which is welded to stiffening plate 12. A projecting guard member 24 may optionally be attached to channel 4. A wheel 25 having a smooth, regular outer circumference is bolted to rear axle 3.

A transverse stilfening member 51 is bolted at one end to rear spring casting 18 and has its other end welded to the inner edge of track 10. It adds lateral stiffness to the upper portion of track 10. A cover 52 of light gauge metal protects springs 19.

A plurality of shoes are mounted in endless rolling relation to track 10 in a manner described below in greater detail. Referring now to Figure 4 in which one of the shoes is shown in greater detail, each shoe com.- prises side plates 26 and 27 as well as a bottom member 28. Side plates 26 are `nearest the tractor and side plates 27 are away from the tractor. Bottom member 28 has a cleat 29 welded to it and is adjacent the ground when it is in load supporting position. Curved protective members 3i) cooperate with side plates 26 and 27 and bottom member 28 to further form a box-like shoe structure. A bolt 31 projects through a hole in side plate 27 and is secured by a nut 32 on the opposite side of side plate 26. A bushing 33 having two collars 33a and 33h upon it, is placed over the shank of bolt 31. A spoollike roller 34 having flanges 35 at each end is fitted over bushing 33 and is mounted on tapered roller bearings 36. A spacer 37 is also mounted on the shank of bolt 31 adjacent side plate 26. Spacer 37 and collar 33a serve to maintain roller 34 in proper transverse relationship to the side plates and to maintain proper clearance. Collar 33h maintains a distinct space between roller 34 and side plate 37 as is best illustrated in Figure 2. A second flanged roller is mounted on each shoe in similar fashion with like parts being given like numbers.

ln a similar manner, a pair of inner rail followers 38 is provided for each shoe. Each follower comprises a roller 39 which is journaled upon shaft 40 on a needle bearing. The free end of shaft 40 has a threaded portion which projects through one `of the holes 41 in side plate 27. A link 42 is placed upon each shaft 40 after which `a jam nut 43 is threaded onto the end portion. Shaft 40 is then mounted in hole 41 and a nut 44 is threaded on and drawn tight.

Referring to Figure 4 it will be seen that the link 42 extends between shafts 40 of adjacent shoes. The roller on the adjacent shoe in Figure 4 being designated 39a; It will be observed that vonly the roller and shaft assocated with the -adjacent shoe are shown and that no 3 other portion of the adjacent shoe is illustrated. Studs 45 are welded to side plate 26 in line with holes 40 and receive links 46 which are of the same length as links 42. Links 46 connect to adjacent shoes in like manner jto links 42. VThey `are secured in place by lock nuts 47.

In Figure 5 I have shown a modified form of the shoe illustrated in Figure 4. Like members in Figure 5 have been given like numbers to those shown in Figure 4. It will be noted that in place of round holes 41 elongated and tapered slots 48 are provided to receive tapered blocks 49 of somewhat shorter length. Flat faces 50 have been ground upon the threaded portions of shaft 40. Each stop 49 has corresponding hat sections to receive and engage the at portion of shaft 40. When nuts 44 are drawn tight upon the threaded ends of each shaft 40, the shoulder at the end of ats 50 will be drawn against blocks 49. This will leave proper clearance for full swivel movement of link 42. Nut 44 will span slot 48 and, when properly adjusted will allow movement of block 49 lengthwise of the slot. In some instances the blocks 49 may be omitted land bolts 40 with their associated flat sections can be fitted directly to slots 48.

It will be noted that the distance between the outer rollers 34 in each shoe is greater than the distance between lthe inner rollers 38. The objective is to permit the shoes to roll around the periphery of track with a minimum of slack and clearance. When the shoes are on the at portion of track 10, the ideal positions of the inner and outer rollers is on a perpendicular to the axis of track 10. When the shoes are on the curved portions of track 10, the ideal positions of the inner and outer rollers will again be on a perpendicular to track 10, which will in this instance be a radius of the circle which the curved portion of the track describes. It will be apparent that in this condition -a line through the centers of rotation of the rollers will be at an angle to a perpendicular through the shoe. A minimum variation is obtained by placing the inner and outer rollers in a position midway between the two positions for ideal operation as above described. This condition is obtained when the angle of a line between the rollers and a perpendicular to the shoe is one-fourth of the radial angle formed by the centers of the two inner rollers on one shoe and the center of the circle described by the curved portion of track 10.

The shoes are assembled on track 10 by positioning them with the outer rollers 34 already installed in the shoes. The inner rollers 39 are then put into position and links 42 and 46 are installed. When all of the shoes have 'thus been placed in position they Will be formed in an endless procession around track 10.

In operation power is applied to the rear axle 3 of tractor 1 causing the axle to rotate. Springs 19 urge track 10 in a forwardly direction and cause inner rollers 39 to be pinched between track 10 and wheel 25. The frictional force between inner rollers 39 and wheel 25 will cause rotation of the inner rollers, causing them to VrOll along the inner face of track 10. The shoes will be thus pulled endlessly around track 10 and the inner rollers will be continuously rolled around 4the inner portion of track 10, links 42 and 46 serving to maintain the endless relationship of the shoes. Outer rollers cooperate with inner rollers 39 and track 10 to limit movement of the shoes along track 10. Flanges 35 on rollers 34 overlap the sides of track 10 and prevent the shoes from drifting to either side. The flanges `are deep enough to hold track 10 under all conditions. If the draw bar load upon the tractor is increased, the added load will jam wheel 25 harder against the inside rollers 3S, thus increasing the frictional force for driving.

Experiments have shown that the frictional force, even with moderate pressure by springs 19, is suicient to enable a standard crawler tractor equipped with the tracks as shown to perform Work equal to that of an identical machine equipped with conventional tracks, which can be spun against the ground. The shoes of my machine, being held rigid and motionless while in contact with the ground are capable of carrying larger cleats. They do not slip under the same conditions and hence deliver more thrust. Springs v19 provide adequate pressure to avoid slippage when the tractor is in reverse.

Guard 24 may be optionally installed to prevent pinching objects between the shoes as they roll onto the lower portion of track 10. It may, for example, be desired to install such a guard where the tractor is being used to climb over railroad tracks and the like.

From the foregoing it will be seen that I have invented a new and useful mechanism which is readily constructed, is durable, and has a minimum of parts. It is equally operable in either direction. Springs 19 provide adequate force to permit reverse operation. The track and rollers are self-cleaning to ythe greatest possible degree and are constructed of the simplest possible components; they will not foul when the tractor is operated in reverse. It will be seen that the invention makes possible crawler vehicles of sizes, speeds and capacities heretofore thought impossible.

Although I have illustrated a present preferred embodiment of mycinvention, it is tobe understood that I do not limit myself thereto and that my invention may be otherwise variously practiced within the scope of the following claims.

I claim:

l. A track unit for a crawler type machine comprising machine support means, a single endless rail `connected to and supporting said support member, Said rail having a load-bearing portion and a shoe return portion, a plurality of spaced apart shoes mounted on said rail, each of said shoes having inner rail followers on a pair of axes and outer rail followers, on a pair of axes link means pivotally connecting adjacent shoes, and drive means t0 cause movement of said shoes along said rail.

2. A track unit for a crawler type machine comprising a single endless rail having a load-bearing portion and a shoe return portion, a plurality of spaced apart shoes mounted on said rail in rolling contact with the rail, link means pivotally connecting adjacent shoes to form an endless track, a pair of longitudinally spaced inner rail rollers on each shoe, a pair of longitudinally spaced outer rail rollers on each shoe, and shoe drive means in driving connection with the shoes.

3. A track unit for a crawler type machine comprising a machine support member, an endless rail in longitudinally slidable connection with said support member and having a load-bearing portion and a shoe return portion, means urging said rail longitudinally forward, a plurality of spaced apart shoes and intermediate link means in endless, pivotal connection, each of said shoes having inner rotary rail followers on a pair of axes and outer rotary rail followers on a pair of axes positioned for rolling contact with said rail, and drive means in frictional contact with said inner rotary rail followers adjacent a part of said rail.

4. A track unit for a crawler type machine comprising a machine support member, an endless rail in longitudinally slidable connection with said support member and having a load-bearing portion and a shoe return portion, means urging movement of said rail longitudinally, a plurality of spaced apart shoes and intermediate link means in endless, pivotal connection, each of Said shOeS having inner rotary rail followers on a pair of axes and outer rotary rail followers on a pair of axes positioned for rolling contact with said rail, rotatable drive means abutting the inner rotary rail followers adjacent a portion of the rail and opposing urging of longitudinal move ment of the rail.

5. A track unit for a crawler type machine comprising a machine support member, an endless rail in longitudinally slidable relation thereto, said rail comprising a pair of substantially parallel horizontal portions and semicircular portions therebetween, means urging longitudinal movement of said rail, a plurality of spaced apart shoes each having inner rail rollers on a pair of axes and outer rail rollers on a pair of axes in rolling contact with the rail, means linking said shoes endlessly and pivotally, and circular drive means in frictional contact with the inside rollers in contact with one of said semi-circular portions, said drive means opposing said urging means.

6. A track unit for a crawler type machine comprising a machine support member, an endless rail in longitudinally slidable relation thereto, said rail comprising a pair of substantially parallel horizontal portions and semi-circular portions therebetween, means urging longitudinal movement of said rail, a plurality of shoes each having inner rail rollers on a pair of axes and outer rail rollers on a pair of axes in rolling contact with the rail, means linking said shoes endlessly and pivotally, circular drive means in frictional contact with the inside rollers in contact with one of said semi-circular portions, and said drive means opposing said urging means, and rail transverse stiifening means.

7. A track unit for a crawler type machine comprising a machine support member, an endless rail in longitudinally slidable relation thereto, said rail comprising a pair of substantially parallel horizontal portions and semicircular portions therebetween, means urging longitudinal movement of said rail, a plurality of shoes in rolling contact with the rail, a pair of longitudinally spaced inner rail rollers on each said shoe, a pair of outer rail rollers having a greater longitudinal spacing than the inner rail rollers, means linking said shoes endlessly and pivotally, circular drive means in frictional contact with said inner rollers in contact with one of said semi-circular portions and opposing longitudinal urging by said urging means.

8. A track unit for a crawler type machine comprising a support member, an endless rail in longitudinally slidable relation thereto and having a load-bearing portion and a shoe return portion, means urging movement of said rail longitudinally, a plurality of discrete spaced apart shoes in rolling contact with said rail, said shoes having inner rail rollers on a pair of axes and outer rail rollers on a pair of axes and contiguous end, side and load-carrying portions, link means endlessly connecting the shoes by pivotal connection at the inner axes, and circular drive means in frictional contact with only a portion of the inner rollers at any given time and opposing said means urging longitudinal movement of the rail.

9. A track unit for a crawler type machine comprising a single endless rail of uniform rectilinear cross section having a shoe load-bearing portion and a shoe return portion, a plurality of spaced apart shoes in rolling contact with the rail, longitudinally spaced inner rail rollers on each shoe on a pair of axes, outer rail rollers on each shoe on a pair of axes, the rollers of one of said pairs being anged, and shoe drive means in driving connection with the shoes, and link means extending between the inner pivotal axes of adjacent shoes.

10. A track unit for a crawler type machine comprising a machine support member, a single endless rail of uniform rectilinear cross section having a load-bearing portion and a shoe return portion, a plurality of spaced apart shoes in rolling Contact with the rail, said shoes being endlessly and pivotally connected, inner rail rollers 0n a pair of longitudinally spaced axes on each shoe, flanged outer rail rollers on a pair of longitudinally spaced axes on each shoe, shoe drive means in driving connection with the shoes, and means urging the rail and some of said shoes longitudinally against the drive means.

l1. A track unit for a crawler type machine comprising a machine support member, a single endless rail of rectilinear cross section in longitudinal movable connection therewith, said rail having a load-bearing portion and a shoe return portion, a plurality of shoes in rolling contact with the rail, said shoes being endlessly and pivotally connected, inner rail rollers on a pair of longitudinally spaced axes on each shoe, anged outer rail rollers on a pair of axes spaced a greater distance apart than the inner roller axes, circular drive means in frictional contact with some of the inner rollers, and means urging said rollers against said drive means.

References Cited in the le of this patent UNITED STATES PATENTS 1,839,766 Tourneau Jan. 5, 1932 2,581,365 Darragh Ian. 8, 1952 FOREIGN PATENTS 10,404 Great Britain May 27, 1895 648,008 Great Britain Dec. 28, 1950 UNITED STATES PATENT OFFICE CERTIFICATE 0E CORRECTION Patent No. .2,897,014 July 28, 1959 Frank H.. Darragh, .In

/N It is hereb certified that error appears in the -printed specification of the above numbered patent requiring correction and thatl the said Letters Patent should read as corrected below.

Column l, line4 l5, for "types" read type column 4, line 36,

for "followers, on a pair of axes" read followers on a pair of axes, column 6, line 42, list o' references cited, under UNITED STATES PATENTS, for "Dari-sgh" read Darragh, Jr, --0

Signed and sealed this 22nd day of December 1959.,

(SEAL) Attest:

KAEL H. AXLTNE ROBERT C. WATSON Attesting Ofcer Commissioner Of Patents

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