CA1096425A - Tread belt drive system - Google Patents
Tread belt drive systemInfo
- Publication number
- CA1096425A CA1096425A CA308,540A CA308540A CA1096425A CA 1096425 A CA1096425 A CA 1096425A CA 308540 A CA308540 A CA 308540A CA 1096425 A CA1096425 A CA 1096425A
- Authority
- CA
- Canada
- Prior art keywords
- link
- cog
- tumbler
- links
- aft
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D55/00—Endless track vehicles
- B62D55/08—Endless track units; Parts thereof
- B62D55/12—Arrangement, location, or adaptation of driving sprockets
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Transmissions By Endless Flexible Members (AREA)
- Devices For Conveying Motion By Means Of Endless Flexible Members (AREA)
Abstract
ABSTRACT
A tread belt drive system for heavy mobile equip-ment includes an endless thread belt made up of a plurality of identical links joined together by link connecting pins. Each of the links has a ground engaging bottom and a top having a cog, or cog portion, positioned medially of the link ends, which cog has fore and aft driving surfaces. A pair of longi-tudinally extending tumbler rim and roller engaging surfaces which extend above the cog are positioned on the top of the link, one on each side of the cog. The links have fore and aft pin connections with the pin center below the engaging sur-faces in alignment with the driving surfaces. The drive sys-tem also includes rollers which support the weight of the equipment and drive and idler tumblers each having a rim and teeth. The teeth of the driving and idler tumblers are entrap-ped between the fore and aft driving surfaces of the cogs of adjacent links to drive and guide the endless belt; the rollers and the rims of the tumblers bear on and roll along the engag-ing surfaces of the links and the link connection pins follow the tumbler rotation on its pitch circle. In a preferred em-bodiment, the driving surfaces of the cogs have an involute gear rack profile; and the driving teeth of the tumbler have an involute gear profile.
A tread belt drive system for heavy mobile equip-ment includes an endless thread belt made up of a plurality of identical links joined together by link connecting pins. Each of the links has a ground engaging bottom and a top having a cog, or cog portion, positioned medially of the link ends, which cog has fore and aft driving surfaces. A pair of longi-tudinally extending tumbler rim and roller engaging surfaces which extend above the cog are positioned on the top of the link, one on each side of the cog. The links have fore and aft pin connections with the pin center below the engaging sur-faces in alignment with the driving surfaces. The drive sys-tem also includes rollers which support the weight of the equipment and drive and idler tumblers each having a rim and teeth. The teeth of the driving and idler tumblers are entrap-ped between the fore and aft driving surfaces of the cogs of adjacent links to drive and guide the endless belt; the rollers and the rims of the tumblers bear on and roll along the engag-ing surfaces of the links and the link connection pins follow the tumbler rotation on its pitch circle. In a preferred em-bodiment, the driving surfaces of the cogs have an involute gear rack profile; and the driving teeth of the tumbler have an involute gear profile.
Description
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The invention is concerned with a tread belt drive for vehicles and in particular with a construction of a tread belt link.
Tread belt links are so constructed and arranyed in a propelling system to minimize wear in the tread belt ~:`
- system and to improve the interengagement of -the links with ~' the tumblers and rollers.
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Tread belt drives useful for propelling large . :
machinery and other heavy mobile equipment which are fore-runners of the present invention are shown in U. S. Patent 53~ 9 ~9~ Nos. ~ ~ 2,727,794 and 3,680,928. In those patents a drive system is described in which the number of links which are driven by the tumbler teeth at any given momen-t of time in less than the number of links which are wrapped about the ` ~ tumbler. Thls system has the advantage of providing for even ;
wear of the links and is achieved by having the pitch angle between the tumbler teeth larger than the pitch angle of the ;
links.
~ The pitch angle of the tumbler teeth is the angle at the center of the tumbler whlch lS subtended by a line ; drawn from the midpoin-t of one tooth to the midpoint of an adjacen-t tooth, The pitch angle of the links; is the angle at the center of the tumbler that is subtended by a line ; drawn from the center of the pivot pin connection of one link to the pivot pin connection of an adjacent link.
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Tl-e described prior art type of tread belt drive system provides a practical and efEectlve way oE propell.ing large excavating e~uipment. However, the use of 5uch tread belt drive systems is not withou-t problems. One problern which can occur is that of breakage of the links o:r the teeth of the drive systern. This can happen when a li.nk being dri-ven by a tumbler tooth is forced radially outward o:E the tumbler in response to -the driving forces. When this happens there can be a loss of proper driving engagernent be-tween the :10 tumbler tooth and the link and as the link falls back towards the tumbler the link may improperly strike a tumbler tooth and cause a fracture of ei-ther one or bo-th of the members rnaking repairs necessary. ~;
Another problem which can occur is that due to the -;
wear of the bearing surfaces of the tumbler and the links~
Such wear can cause the pltch angle of the links to increase and the pitch angle of the tumbler to decrease. When the pitch angle:of the links exceeds the tumbler pitch angle the ~`
necessary driving relationship of the tumbler to the links is ;~
lost and the links or tumbler must be rebuilt or replaced.
Still another problem which can occur is the jam-ming or breaking of the tread belt when stones or dirt become : :
lodged between the dri~ing surfaces of the tumbler teeth and the link.
Despite the above described problems and the fact .
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that tread belt drive systems are generally noisy and rough operating, tread belt drive systems xemain the most practical way of propelling large excavators and other heavy mobile ma-chinery. Therefore, a need exists for an improved tread belt drive system which provides a smoother, quieter operation and eliminates the problems which accompany the use of prior drive systems. ~;
This invention relates to a tread belt link including a link body having a ground engaging bottom surface and a top having a cog positioned medially of the link ends, said cog ~ :
having fore and aft driving surfaces, a pair of longitudinally :~
extending tumbler rim engaging surfaces on top of the link, one ;:
- on each side of the cog and above the driving surfaces of the ;~-~
cog, one of said tumbler engaging surfaces extending from the cog forward of the main body of the link and the other extending from the cog to the rear of the main body of the link and connection fingers extending fore and aft of the ~.
: main:body of the link, said fingers having:connecting pin j :
1 ~ ~ receiving openings so that a plurality of links can be aligned i 20: and joined together by inserting connecting pins into the : interdigited fingers of adjacent links to form an endless chain in which the tumbler rim engaging surfaces form tracks ln which the~spaces between the tumbler rim surfaces of adjacent links are staggered so that a tumbler rim rolling over said tracks will not pass over a space between adjacent links on both sides of the cog~simultaneously.
This invention also relates to a tread belt link :~:
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having a link body including, a ground engaging bottom surface and a tOpr a cog positioned on the top intermediate the ends of said link, said coy having fore and af`t driving surfaces having an involute gear profilel a pair of :Elat tumbler rim engaging surfaces on top of said link, one of : said tumbler rim engaging su.rfaces being positioned on each side of the cog and rising above the driving surfacPs o-f the cog, one of said tumbler rim engagi.ng surfaces com-mencing adjacent the cog and extending forward past the main body of the link and the other commencing adjacent the cog and extending rearward of the link, and connecting fingers extending forward and aft of the main body of the link, said fingers having connecting pin receiving openings :
` so that when a plurality of links are aligned with the fingers interdigited connecting pins can be inserted into the openings in the fingers to form the links into an endless belt. -A preferred embodiment of the present invention will :.
now be described in reference to the accompanying drawings, wherein:
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- Figure 1 is a plan view of the pre~erred tread belt link of the present invention;
Figure 2 is an end view of the link of Figure l;
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.. ~ --Figure 3 is a view in cross section of tha tread belt l.ink oE Figure 1 talcen on -the plane 3-3;
~; Figure 4 is a view in crosC; section o~ the tread ~; belt link of Figure l taken on the plane 4-4;
.~ Figure 5 is a vlew in crosc: section of the -tread :
- belt link of F.igure 1 taken on the plane 5-5;
Figure 6 is a transverse view of the tread belt . ~ .
` link of Figure 1 with parts broken away and in section so as ; to have a portion thereof viewed through the plane 6-6 indi-cated in Figure l;
. Figure 7 is a plan view of two tread belt links ~
` connected; ~ :
Figure 8 is a partial view of the drive system showing the link belt and the tumbler teeth of the drive .
tumbler in mesh;
Figure 9 is a view of the drive or idler tumbler, Figure 10 is a view in cross section of the drive or idler~tumbler of Flgure 9 taken on the plane 10-10 Flgure 11 is a view in cross section of the tread 20 belt link and roller shown in Figure 8 taken on the plane ~.
Figure 12 is a~view of the link and the idler tumbler with engaging surfaces in contact; and Figure 13 is~a:view of the link cog and a tumbler ,~, .
tooth geometry.
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. ~7 In the drawing, a preferrecl Eorm of a tread belt link 20 i5 sho~l which can be used in a drive system for mobile machinery. A number oE such li.nks 20 may be joined toyether to :Eorm endless ground enCJaging tread belts and a tread belt is disposed on each c:ide of a machine such as an excavator or tractor. The endless belt passes under rollers -that support the machine proper and is in mesh with . a drive tum~ler 21 as seen in Figure 8, which is located at one end of -the belt and an idler tumbler (not shown) at the other end of the belt to provide a drive system for propel-ling the machine along the ground.
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For purposes of description, the direction of travel of the links will be called "longitudinal" and the . directlon across the ]ink from one end to the other end will be called "transverse~ To further acilitate description, the ground engaging surface 22 of the link 20 will be termed .
the "bottom" of -the link and the direction through the link from the ground engagi.ng surface 22 will be termed "upward"
even though some of the links will be oxiented in use so that ~-:,' :
the upward direction will actually point towards the ~round.
. Referring now to Figs. 1-7, it .is seen that -the ~:' - ' . top of the link 20 has a cog or cog portion 23 which is posi-tioned medially of the link ends and a pair of upwardly -~, .
~ facing, flat tumbler rim and roller engaging surfaces 24 : which are located on each side of and directly adjacent to , .
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the cog porti.on 23~ ~rhe sur:Eaces 24 extend longitudinally across the top o:~ the link 20. rIIhe link 20 is Eurther pro-vided with a set of Eour connecting ears 25 which extend forward of the front edge o:E the ].ink. A pair of t.he con-nectlng ears 25 are located on each side of -the cog portion 23 between the tumbler rim and roller engaging surfaces 24 and the ends of the link. There is also a second se-t of connecting ears 26 which extend rearward of the back edye of the link. One oE each of ears 26 is transversely centered between two o:E the opposite ears 25.
The links 20 are connected to one another to form an endless belt by -the connecting ears 26 of one link being interdigited with the connecting ears 25 of the succeeding :
adjacent link and appropriate ~ins 27 inserted in the openings : : ~
' to join the links together as seen in E`ig. 7. As seen best in Fig. 3, the connec-ting ears 25 and 26 are provided with pin ~ openings 28 and the connecting ears 26 are provided w.ith bush-: ings 29. The connecting pins 27 are removabIy secured to the ears 25. The connecting pins 27 are sized to have relative 0movement within the bushing ~29 of the ear 26 and the bushings 29 are designed to be replaced as they wear to re-obtain the correct link pitch angIe~ The connecting plns 27 of the link ~ ~ 20 have no relative motion within the ears 25, and as a re-sult, the pin holes 28 in ears 25 will not wear, thus the ~simple replacement of the pins 27 and/or bushings 29 will cor-'' :
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: ,, . ' ' 6~2~i rect any link pitCIl any1e error that may be due to wear.
The enc1less belt oE links 20 is mounted on a pair of spaced apart tumb:Lers 21 on the machine with the teeth 30 oE the tum~lers 21 entrapped between the cogs 23 of adjacent links 20 as seen in -the partlal view of the drive system in Fig. 8 in which only the drive tumbler is shown. The drive tumbler ls mounted on the machine proper to be driven in a rotational direction to drive the belt and idler tumblers (not shown) mounted in such a manner as to be driven by the belt~ The drive and idler tumblers 21 of the machine are~of similar configuration. Both of the tumblers 21 are provided with a central shaft receiving opening 32 and a rim 33 which extends continuously about the opening 32 and presents a ra- ?
dially outward facing rolling surface 34 (seen best in Fig.
lO)~ Protruding radially outward from the rolling surfaces 34 is a plurality of teeth 30 that are spaced circumferentially from one another to form a gear wheel. As seen in Fig. 8 the machine is supported by rollers 35 which also roll along and -~
bear upon -the surfaces 24.
., 20 Turning to Fig. 11, it is seen that the preferred roller 35 has a rolling surface 36 that rolls along and bears -` upon -the link surfaces 24 and a roller flange 37. The top of the cog 23 is lower than the uppermost surfaces oE the tumbler ; rim and roller engaging surfaces 24 of the link thus allowing ` the roller flange 37 to guide the endless belt. Referring to ~ ' ~
~, , ~, Fig. 12, which is a partia:L view oE the idler twnblQr, it i9 seen that it is -the rolling surface 34 of the tumbler 2:l which rolls along and bears upon the tumbler rim and roller engaglng surfaces 24 oE the linlc 20.
Having completed a general description of the tread belt drive mechanism of the present lnven-tion, the links and tu~blers of the especially preferred embodiment w:ill now be described.
Turning first to Figs. 1 and 5, it can be seen 10 that the cog 23 is an integral part of the link 20 that com-mences at the ground engaging surEace 22 and extends upward.
The cog 23 has its greatest longitudinal leng-th at the bottom of the link and tapers in an upward direction. The taper is comprised of Eore and aft driving surfaces 23a and 23b, which , ., -, are of an involute gear rack type profile which is dependent ~.' .
~ on the involute gear profile of the preferred tumbler teeth.
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The taper of the driving surfaces 23a and 23b of the link 20 is determined ~y the angle E seen only in Eig. 9.
The angle E is measured between the intersection of angles 5 20 and A. S is an angle equal to one-half of the pitch angle Y
o the tumbler which is an angle measured between the midpoint of two adjacent teeth of the tumbler having its apex at the center of the tumbler. A is the angle equal to the pressure ~:, angle of the involute formed tooth 30 (e.g., in a 20% involute, the angle A would be 20~. A is measured off the line created . ' .
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by angle ~?i as shown :in Fig. 9. B is an angle having its apex at the center of the tumbler which i5 measured from the cen-ter of a tooth to the point on the edge of the -tooth on the tum-bler p:itCll circle. Angle B varies with changes in tooth ~ 6thickness. rrhe angle A originates on~tooth pitch circle that angle B was measured -to.
Referring now to Fig. 13, it can be seen t:hat the thickness T of the cog portion 23 of the link 20 is measured longi-tudinally between the driving surfaces 23a, ~3b and from points originating on the tumbler pitch circle with the engag-; lO ing surface 24 of the link in contact with the tumbler rim rolling surface 34. This thickness T and distance P between the center of connecting pins of the link are de-termined to~
gether so as to allow the -tumbler tooth 30 to be in contact with the cog driving surfaces 23a and 23h at the proper time ; and to minimize the travel distanFe of the tumbler tooth 30 from the cog driving surfaces 23a and 23b when the dlrection of tumbler rotation is reversed. A detailed description of the measurement and significance of the link pitch angle and the tumbler pitch angle which are shown in Fig. 13 can be 20 found in U. S. Patent ~o. 2,727,794.
In the preferred embodimen-t of the links 20 the tumbLer rim and roller engaging surfaces 24 extend from a face 24a to an extension face 24b, which extends beyond the link ; edge. This is seen best in Figs. 1, 2, 4, 5 and 7, As seen :
in Figs. 4 and 5, the :Eaces 24a and 24b extend upwardly :Erom the ground engacJing sur:Eace ~2 -the full depth of l.i.nk 20 to the surface 2~1. Thus, when two links 20 are attached to one another as part of an endless tread belt as shown in Fig. 7, the tumbler and roller engaging surfaces 24 of adja-cent links present a nearly continuous surface for engage-ment with the -tumbler rim rolling surfaces 34 and rollers 35 under which the links pass. The nearly continuous path of tumbler and roller engagi.ng surfaces formed by the adjacent links is interrupted on:Ly by the spaces (not seen) between the faces 24a and 24b of adjacent links. The spaces between the faces 24a and 24b of adjacent links are staggered on opposite sides of the cog 23 so that the tumbler rolling surface 34 does not run over the spaces on both sides of the cog 23 at the same time~ As a result, a smoother more efficient operation is obtained.
: Returning to Figs. 1 to 7, it is seen that in the preferred link a reinforcing rib 40 extends from each of the tumbler rim and roller engaging surfaces 24 to end of the link to provide additional strength and durability.
In the especially preferred tread belt drive sys-tem of the invention the tumbler teeth 30 are formed with ; an involute gear profile from the base circle radially out-ward to the tooth tip 31. The tooth 30 is also provided :with a tip relief cut 31a to eliminate tha interference be-~ . ~
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tween the tooth 30 and -the cog driving faces 23a or 23b as the link 20 leaves the tumbler 21 as shown at the top of ?
Fig. 8. The tip relief 31a of -the tooth reduces wear, as the tooth 30 does not slide appreciab:Ly along the link 20 as it leaves its tumbler. The use of an involute ge~r profile allows the tooth 30 to contact the link at a point below the surface 24 and to drive the link 20 o~
the pitch circle as shown in Fig. 8.
Referring still to Fig. 8, it can be seen that 10 distance between the trailing edge of one link and the leading edge of the successive link is increased as the ;~
links 20 pass around the tumbler 21 as compared to the distance between the link edges when the links 20 are on the ground. As the link distance is increased as the links 20 are guided onto the tumbler 21 and the tumbler tooth 30 enters the space 39 (seen in Fig. 7) between ; ~
the links, foreign material, such as stones and the sort, `
are ejected from between the links. This removal of foreign material is not as easily accomplished with con-20 ventional chain driven links as the material is forced -into the chain and is retained by the bolted link to ;.
the chain. The same problem of foreign material removal ~
is present in systems using conventional excavator links ;~-where the driving tang is located at the top of the link.
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When the proper pitch angles are employecl with components of the proper dimensions, the link connecting pins 27 are located on the tumbler pitch circle when the tumbler rim engaging surfaces 24 and t:he tumbler rolling surEaces 34 are in contact (best seen in Fig. 12). As a given link 20 moves about -the driving tumbler to the top ; of the tumbler 21 and to the point of driving action (the arrow seen in Fig. 8), the link 20 tends to follow the pitch cirle. Since the polnt of driving action and the pin centers are below the tumbler rolling surface 24 and the links 20 are urged to briefly follow the tumbler ro-tation as the lînk breaks contact with associated tumbler teeth 30 and starts its run to the opposite end of the endless link belt. As a result, the link belt and teeth remain in proper mesh, and the problems of breakage that can occur when they are out of mesh are eliminated.
In the preferred embodiment, the driving surfaces - of the link cog portion have an involute gear rack profile ' and are positioned below the roller and tumbler rim engag-ing surfaces of the link close to the link bottom and the level of the link connecting pln centers. The teeth of the -preferred drive and idler tumblers have an involute gear pro~ile and points of driving engagement with the driving ;~ surfaces of the link cog portions remaining on the pitch cir-cle or migrate towards the link bottom. As a result, as the , .: ~
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link turns with the tumbler driving force upon the link doesnot create excessive torque about the link pins which might otherwise tend to liEt the link out of mesh with the -tumbler and cause the tee-th or the links to be damaged.
In order for the inevitable wear of the bearing surfaces of the links which can cause the pitch angle of the links to increase and exceed the tumb:Ler pitch angle~ the link pin connections in the preferred form of the link are ; bushed for link connecting pins and the pins and bushings are hardened with the pin being slightly softer. Then as wear of the pins and bushings occurs and the link pitch angle increases,excessive link tumbler engagement error can be avoided by replacing the link pin and/or the bushings to once again obtain the correct link pitch angle.
The possibility of a tread belt of the preferred links being jammed or broken is reduced because an endless belt of the preferred links is self-cleaning. As the belt of preferred links travels about the tumblers the teeth o~ -the tumblers enter between the links and the distance between the link bottoms is increased due to the angle between the links and the tu~bler teeth so that anystones or dirt lodged between the driving surfaces of the tumbler teeth and the llnks are removed.
In addition, an endless belt of the preferred links provides a smoother operating tread belt drive system . :
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because the ro:Ller and tumbler ri.m engaging surfaces are constructed so that when the links are joined together a nearly continuous roller and tumbler ri.m engagi.ng surface is provided~ The engag;ng surfaces extend longitudinally fore and aft o:E the link edges so tha-t when -the links are joined together the openings between the tumbler and roller will not run over openings on both sides of the cog at the same time. The use of teeth of an involute gear rack pro-file results in a gear and :rack type action which results in a smoo-ther more efficient operating drive system.
It will be readily apparent to those skilled in the art that the novel tread belt drive system described pro-vides a smoother more efficient operation than that obtained with conventional tread belts and tumbler arrangements.
Although an especi.ally preferred embodiment has been described in which the driving surfaces of the link have an involute gear rack profile and the driving teeth of the tumbler have an involute gear profile the invention is not so limited. For example, there may be some applications in ,: .
which it may be desirable to dispense with the use of invol-` ute gear profiles and retain the other desirable features of `, : the link and drive systems or to make other changes. There-:~! fore, the invention is not to be limited by -the illustrative - description, but only by the claims which follow.
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The invention is concerned with a tread belt drive for vehicles and in particular with a construction of a tread belt link.
Tread belt links are so constructed and arranyed in a propelling system to minimize wear in the tread belt ~:`
- system and to improve the interengagement of -the links with ~' the tumblers and rollers.
~ .
Tread belt drives useful for propelling large . :
machinery and other heavy mobile equipment which are fore-runners of the present invention are shown in U. S. Patent 53~ 9 ~9~ Nos. ~ ~ 2,727,794 and 3,680,928. In those patents a drive system is described in which the number of links which are driven by the tumbler teeth at any given momen-t of time in less than the number of links which are wrapped about the ` ~ tumbler. Thls system has the advantage of providing for even ;
wear of the links and is achieved by having the pitch angle between the tumbler teeth larger than the pitch angle of the ;
links.
~ The pitch angle of the tumbler teeth is the angle at the center of the tumbler whlch lS subtended by a line ; drawn from the midpoin-t of one tooth to the midpoint of an adjacen-t tooth, The pitch angle of the links; is the angle at the center of the tumbler that is subtended by a line ; drawn from the center of the pivot pin connection of one link to the pivot pin connection of an adjacent link.
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Tl-e described prior art type of tread belt drive system provides a practical and efEectlve way oE propell.ing large excavating e~uipment. However, the use of 5uch tread belt drive systems is not withou-t problems. One problern which can occur is that of breakage of the links o:r the teeth of the drive systern. This can happen when a li.nk being dri-ven by a tumbler tooth is forced radially outward o:E the tumbler in response to -the driving forces. When this happens there can be a loss of proper driving engagernent be-tween the :10 tumbler tooth and the link and as the link falls back towards the tumbler the link may improperly strike a tumbler tooth and cause a fracture of ei-ther one or bo-th of the members rnaking repairs necessary. ~;
Another problem which can occur is that due to the -;
wear of the bearing surfaces of the tumbler and the links~
Such wear can cause the pltch angle of the links to increase and the pitch angle of the tumbler to decrease. When the pitch angle:of the links exceeds the tumbler pitch angle the ~`
necessary driving relationship of the tumbler to the links is ;~
lost and the links or tumbler must be rebuilt or replaced.
Still another problem which can occur is the jam-ming or breaking of the tread belt when stones or dirt become : :
lodged between the dri~ing surfaces of the tumbler teeth and the link.
Despite the above described problems and the fact .
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that tread belt drive systems are generally noisy and rough operating, tread belt drive systems xemain the most practical way of propelling large excavators and other heavy mobile ma-chinery. Therefore, a need exists for an improved tread belt drive system which provides a smoother, quieter operation and eliminates the problems which accompany the use of prior drive systems. ~;
This invention relates to a tread belt link including a link body having a ground engaging bottom surface and a top having a cog positioned medially of the link ends, said cog ~ :
having fore and aft driving surfaces, a pair of longitudinally :~
extending tumbler rim engaging surfaces on top of the link, one ;:
- on each side of the cog and above the driving surfaces of the ;~-~
cog, one of said tumbler engaging surfaces extending from the cog forward of the main body of the link and the other extending from the cog to the rear of the main body of the link and connection fingers extending fore and aft of the ~.
: main:body of the link, said fingers having:connecting pin j :
1 ~ ~ receiving openings so that a plurality of links can be aligned i 20: and joined together by inserting connecting pins into the : interdigited fingers of adjacent links to form an endless chain in which the tumbler rim engaging surfaces form tracks ln which the~spaces between the tumbler rim surfaces of adjacent links are staggered so that a tumbler rim rolling over said tracks will not pass over a space between adjacent links on both sides of the cog~simultaneously.
This invention also relates to a tread belt link :~:
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having a link body including, a ground engaging bottom surface and a tOpr a cog positioned on the top intermediate the ends of said link, said coy having fore and af`t driving surfaces having an involute gear profilel a pair of :Elat tumbler rim engaging surfaces on top of said link, one of : said tumbler rim engaging su.rfaces being positioned on each side of the cog and rising above the driving surfacPs o-f the cog, one of said tumbler rim engagi.ng surfaces com-mencing adjacent the cog and extending forward past the main body of the link and the other commencing adjacent the cog and extending rearward of the link, and connecting fingers extending forward and aft of the main body of the link, said fingers having connecting pin receiving openings :
` so that when a plurality of links are aligned with the fingers interdigited connecting pins can be inserted into the openings in the fingers to form the links into an endless belt. -A preferred embodiment of the present invention will :.
now be described in reference to the accompanying drawings, wherein:
:.~
- Figure 1 is a plan view of the pre~erred tread belt link of the present invention;
Figure 2 is an end view of the link of Figure l;
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.. ~ --Figure 3 is a view in cross section of tha tread belt l.ink oE Figure 1 talcen on -the plane 3-3;
~; Figure 4 is a view in crosC; section o~ the tread ~; belt link of Figure l taken on the plane 4-4;
.~ Figure 5 is a vlew in crosc: section of the -tread :
- belt link of F.igure 1 taken on the plane 5-5;
Figure 6 is a transverse view of the tread belt . ~ .
` link of Figure 1 with parts broken away and in section so as ; to have a portion thereof viewed through the plane 6-6 indi-cated in Figure l;
. Figure 7 is a plan view of two tread belt links ~
` connected; ~ :
Figure 8 is a partial view of the drive system showing the link belt and the tumbler teeth of the drive .
tumbler in mesh;
Figure 9 is a view of the drive or idler tumbler, Figure 10 is a view in cross section of the drive or idler~tumbler of Flgure 9 taken on the plane 10-10 Flgure 11 is a view in cross section of the tread 20 belt link and roller shown in Figure 8 taken on the plane ~.
Figure 12 is a~view of the link and the idler tumbler with engaging surfaces in contact; and Figure 13 is~a:view of the link cog and a tumbler ,~, .
tooth geometry.
' : ::: -: ~: - : , :: : : ~ ;:.
64,'~ :
. ~7 In the drawing, a preferrecl Eorm of a tread belt link 20 i5 sho~l which can be used in a drive system for mobile machinery. A number oE such li.nks 20 may be joined toyether to :Eorm endless ground enCJaging tread belts and a tread belt is disposed on each c:ide of a machine such as an excavator or tractor. The endless belt passes under rollers -that support the machine proper and is in mesh with . a drive tum~ler 21 as seen in Figure 8, which is located at one end of -the belt and an idler tumbler (not shown) at the other end of the belt to provide a drive system for propel-ling the machine along the ground.
; ,. .
For purposes of description, the direction of travel of the links will be called "longitudinal" and the . directlon across the ]ink from one end to the other end will be called "transverse~ To further acilitate description, the ground engaging surface 22 of the link 20 will be termed .
the "bottom" of -the link and the direction through the link from the ground engagi.ng surface 22 will be termed "upward"
even though some of the links will be oxiented in use so that ~-:,' :
the upward direction will actually point towards the ~round.
. Referring now to Figs. 1-7, it .is seen that -the ~:' - ' . top of the link 20 has a cog or cog portion 23 which is posi-tioned medially of the link ends and a pair of upwardly -~, .
~ facing, flat tumbler rim and roller engaging surfaces 24 : which are located on each side of and directly adjacent to , .
.
, :
~. .
.. . . . .
:. , : ~ . ; . : :
~-- ?8 ~ 2S
the cog porti.on 23~ ~rhe sur:Eaces 24 extend longitudinally across the top o:~ the link 20. rIIhe link 20 is Eurther pro-vided with a set of Eour connecting ears 25 which extend forward of the front edge o:E the ].ink. A pair of t.he con-nectlng ears 25 are located on each side of -the cog portion 23 between the tumbler rim and roller engaging surfaces 24 and the ends of the link. There is also a second se-t of connecting ears 26 which extend rearward of the back edye of the link. One oE each of ears 26 is transversely centered between two o:E the opposite ears 25.
The links 20 are connected to one another to form an endless belt by -the connecting ears 26 of one link being interdigited with the connecting ears 25 of the succeeding :
adjacent link and appropriate ~ins 27 inserted in the openings : : ~
' to join the links together as seen in E`ig. 7. As seen best in Fig. 3, the connec-ting ears 25 and 26 are provided with pin ~ openings 28 and the connecting ears 26 are provided w.ith bush-: ings 29. The connecting pins 27 are removabIy secured to the ears 25. The connecting pins 27 are sized to have relative 0movement within the bushing ~29 of the ear 26 and the bushings 29 are designed to be replaced as they wear to re-obtain the correct link pitch angIe~ The connecting plns 27 of the link ~ ~ 20 have no relative motion within the ears 25, and as a re-sult, the pin holes 28 in ears 25 will not wear, thus the ~simple replacement of the pins 27 and/or bushings 29 will cor-'' :
~,' .
.
:~.
. .
: ,, . ' ' 6~2~i rect any link pitCIl any1e error that may be due to wear.
The enc1less belt oE links 20 is mounted on a pair of spaced apart tumb:Lers 21 on the machine with the teeth 30 oE the tum~lers 21 entrapped between the cogs 23 of adjacent links 20 as seen in -the partlal view of the drive system in Fig. 8 in which only the drive tumbler is shown. The drive tumbler ls mounted on the machine proper to be driven in a rotational direction to drive the belt and idler tumblers (not shown) mounted in such a manner as to be driven by the belt~ The drive and idler tumblers 21 of the machine are~of similar configuration. Both of the tumblers 21 are provided with a central shaft receiving opening 32 and a rim 33 which extends continuously about the opening 32 and presents a ra- ?
dially outward facing rolling surface 34 (seen best in Fig.
lO)~ Protruding radially outward from the rolling surfaces 34 is a plurality of teeth 30 that are spaced circumferentially from one another to form a gear wheel. As seen in Fig. 8 the machine is supported by rollers 35 which also roll along and -~
bear upon -the surfaces 24.
., 20 Turning to Fig. 11, it is seen that the preferred roller 35 has a rolling surface 36 that rolls along and bears -` upon -the link surfaces 24 and a roller flange 37. The top of the cog 23 is lower than the uppermost surfaces oE the tumbler ; rim and roller engaging surfaces 24 of the link thus allowing ` the roller flange 37 to guide the endless belt. Referring to ~ ' ~
~, , ~, Fig. 12, which is a partia:L view oE the idler twnblQr, it i9 seen that it is -the rolling surface 34 of the tumbler 2:l which rolls along and bears upon the tumbler rim and roller engaglng surfaces 24 oE the linlc 20.
Having completed a general description of the tread belt drive mechanism of the present lnven-tion, the links and tu~blers of the especially preferred embodiment w:ill now be described.
Turning first to Figs. 1 and 5, it can be seen 10 that the cog 23 is an integral part of the link 20 that com-mences at the ground engaging surEace 22 and extends upward.
The cog 23 has its greatest longitudinal leng-th at the bottom of the link and tapers in an upward direction. The taper is comprised of Eore and aft driving surfaces 23a and 23b, which , ., -, are of an involute gear rack type profile which is dependent ~.' .
~ on the involute gear profile of the preferred tumbler teeth.
. -~;
The taper of the driving surfaces 23a and 23b of the link 20 is determined ~y the angle E seen only in Eig. 9.
The angle E is measured between the intersection of angles 5 20 and A. S is an angle equal to one-half of the pitch angle Y
o the tumbler which is an angle measured between the midpoint of two adjacent teeth of the tumbler having its apex at the center of the tumbler. A is the angle equal to the pressure ~:, angle of the involute formed tooth 30 (e.g., in a 20% involute, the angle A would be 20~. A is measured off the line created . ' .
~' - ~ :
by angle ~?i as shown :in Fig. 9. B is an angle having its apex at the center of the tumbler which i5 measured from the cen-ter of a tooth to the point on the edge of the -tooth on the tum-bler p:itCll circle. Angle B varies with changes in tooth ~ 6thickness. rrhe angle A originates on~tooth pitch circle that angle B was measured -to.
Referring now to Fig. 13, it can be seen t:hat the thickness T of the cog portion 23 of the link 20 is measured longi-tudinally between the driving surfaces 23a, ~3b and from points originating on the tumbler pitch circle with the engag-; lO ing surface 24 of the link in contact with the tumbler rim rolling surface 34. This thickness T and distance P between the center of connecting pins of the link are de-termined to~
gether so as to allow the -tumbler tooth 30 to be in contact with the cog driving surfaces 23a and 23h at the proper time ; and to minimize the travel distanFe of the tumbler tooth 30 from the cog driving surfaces 23a and 23b when the dlrection of tumbler rotation is reversed. A detailed description of the measurement and significance of the link pitch angle and the tumbler pitch angle which are shown in Fig. 13 can be 20 found in U. S. Patent ~o. 2,727,794.
In the preferred embodimen-t of the links 20 the tumbLer rim and roller engaging surfaces 24 extend from a face 24a to an extension face 24b, which extends beyond the link ; edge. This is seen best in Figs. 1, 2, 4, 5 and 7, As seen :
in Figs. 4 and 5, the :Eaces 24a and 24b extend upwardly :Erom the ground engacJing sur:Eace ~2 -the full depth of l.i.nk 20 to the surface 2~1. Thus, when two links 20 are attached to one another as part of an endless tread belt as shown in Fig. 7, the tumbler and roller engaging surfaces 24 of adja-cent links present a nearly continuous surface for engage-ment with the -tumbler rim rolling surfaces 34 and rollers 35 under which the links pass. The nearly continuous path of tumbler and roller engagi.ng surfaces formed by the adjacent links is interrupted on:Ly by the spaces (not seen) between the faces 24a and 24b of adjacent links. The spaces between the faces 24a and 24b of adjacent links are staggered on opposite sides of the cog 23 so that the tumbler rolling surface 34 does not run over the spaces on both sides of the cog 23 at the same time~ As a result, a smoother more efficient operation is obtained.
: Returning to Figs. 1 to 7, it is seen that in the preferred link a reinforcing rib 40 extends from each of the tumbler rim and roller engaging surfaces 24 to end of the link to provide additional strength and durability.
In the especially preferred tread belt drive sys-tem of the invention the tumbler teeth 30 are formed with ; an involute gear profile from the base circle radially out-ward to the tooth tip 31. The tooth 30 is also provided :with a tip relief cut 31a to eliminate tha interference be-~ . ~
~ , , . :,.
: ,, , -6~
tween the tooth 30 and -the cog driving faces 23a or 23b as the link 20 leaves the tumbler 21 as shown at the top of ?
Fig. 8. The tip relief 31a of -the tooth reduces wear, as the tooth 30 does not slide appreciab:Ly along the link 20 as it leaves its tumbler. The use of an involute ge~r profile allows the tooth 30 to contact the link at a point below the surface 24 and to drive the link 20 o~
the pitch circle as shown in Fig. 8.
Referring still to Fig. 8, it can be seen that 10 distance between the trailing edge of one link and the leading edge of the successive link is increased as the ;~
links 20 pass around the tumbler 21 as compared to the distance between the link edges when the links 20 are on the ground. As the link distance is increased as the links 20 are guided onto the tumbler 21 and the tumbler tooth 30 enters the space 39 (seen in Fig. 7) between ; ~
the links, foreign material, such as stones and the sort, `
are ejected from between the links. This removal of foreign material is not as easily accomplished with con-20 ventional chain driven links as the material is forced -into the chain and is retained by the bolted link to ;.
the chain. The same problem of foreign material removal ~
is present in systems using conventional excavator links ;~-where the driving tang is located at the top of the link.
,~ :
.
:
-13-~
When the proper pitch angles are employecl with components of the proper dimensions, the link connecting pins 27 are located on the tumbler pitch circle when the tumbler rim engaging surfaces 24 and t:he tumbler rolling surEaces 34 are in contact (best seen in Fig. 12). As a given link 20 moves about -the driving tumbler to the top ; of the tumbler 21 and to the point of driving action (the arrow seen in Fig. 8), the link 20 tends to follow the pitch cirle. Since the polnt of driving action and the pin centers are below the tumbler rolling surface 24 and the links 20 are urged to briefly follow the tumbler ro-tation as the lînk breaks contact with associated tumbler teeth 30 and starts its run to the opposite end of the endless link belt. As a result, the link belt and teeth remain in proper mesh, and the problems of breakage that can occur when they are out of mesh are eliminated.
In the preferred embodiment, the driving surfaces - of the link cog portion have an involute gear rack profile ' and are positioned below the roller and tumbler rim engag-ing surfaces of the link close to the link bottom and the level of the link connecting pln centers. The teeth of the -preferred drive and idler tumblers have an involute gear pro~ile and points of driving engagement with the driving ;~ surfaces of the link cog portions remaining on the pitch cir-cle or migrate towards the link bottom. As a result, as the , .: ~
--~ .
4;~:~
link turns with the tumbler driving force upon the link doesnot create excessive torque about the link pins which might otherwise tend to liEt the link out of mesh with the -tumbler and cause the tee-th or the links to be damaged.
In order for the inevitable wear of the bearing surfaces of the links which can cause the pitch angle of the links to increase and exceed the tumb:Ler pitch angle~ the link pin connections in the preferred form of the link are ; bushed for link connecting pins and the pins and bushings are hardened with the pin being slightly softer. Then as wear of the pins and bushings occurs and the link pitch angle increases,excessive link tumbler engagement error can be avoided by replacing the link pin and/or the bushings to once again obtain the correct link pitch angle.
The possibility of a tread belt of the preferred links being jammed or broken is reduced because an endless belt of the preferred links is self-cleaning. As the belt of preferred links travels about the tumblers the teeth o~ -the tumblers enter between the links and the distance between the link bottoms is increased due to the angle between the links and the tu~bler teeth so that anystones or dirt lodged between the driving surfaces of the tumbler teeth and the llnks are removed.
In addition, an endless belt of the preferred links provides a smoother operating tread belt drive system . :
>
'~'' i . -.: ~ . : .
.: ~ : . , .. . .
: ' ' ' , ~ ' ' ' ~@~9G~25 ~,f .; ,~ S
because the ro:Ller and tumbler ri.m engaging surfaces are constructed so that when the links are joined together a nearly continuous roller and tumbler ri.m engagi.ng surface is provided~ The engag;ng surfaces extend longitudinally fore and aft o:E the link edges so tha-t when -the links are joined together the openings between the tumbler and roller will not run over openings on both sides of the cog at the same time. The use of teeth of an involute gear rack pro-file results in a gear and :rack type action which results in a smoo-ther more efficient operating drive system.
It will be readily apparent to those skilled in the art that the novel tread belt drive system described pro-vides a smoother more efficient operation than that obtained with conventional tread belts and tumbler arrangements.
Although an especi.ally preferred embodiment has been described in which the driving surfaces of the link have an involute gear rack profile and the driving teeth of the tumbler have an involute gear profile the invention is not so limited. For example, there may be some applications in ,: .
which it may be desirable to dispense with the use of invol-` ute gear profiles and retain the other desirable features of `, : the link and drive systems or to make other changes. There-:~! fore, the invention is not to be limited by -the illustrative - description, but only by the claims which follow.
~' , ~ .. ~,, :...................................... : :
. . . .
Claims (6)
1. A tread belt link includes a link body having a ground engaging bottom surface and a top having a cog positioned medially of the link ends, said cog having fore and aft driving surfaces, a pair of longitudinally extending tumbler rim engaging surfaces on top of the link, one on each side of the cog and above the driving surfaces of the cog, one of said tumbler engaging surfaces extending from the cog forward of the main body of the link and the other extending from the cog to the rear of the main body of the link and connection fingers extending fore and aft of the main body of the link, said fingers having connecting pin receiving openings so that a plurality of links can be aligned and joined together by inserting connecting pins into the interdigited fingers of adjacent links to form an endless chain in which the tumbler rim engaging surfaces form tracks in which the spaces between the tumbler rim surfaces of adjacent links are staggered so that a tumbler rim rolling over said tracks will not pass over a space between adjacent links on both sides of the cog simultaneously.
2. A tread belt link of claim 1 in which the driving surfaces of the cog have an involute gear profile.
3. The tread belt link of claim 2 in which there are two pair of fingers extending forward of the main body of the link and one pair extending aft.
4. The link of claim 3 in which the tumbler rim engaging surface is flat.
5. A tread belt link having a link body including:
(a) a ground engaging bottom surface and a top, (b) a cog positioned on the top inter-mediate the ends of said link, said cog having fore and aft driving surfaces having an involute gear profile, (c) a pair of flat tumber rim engaging surfaces on top of said link, one of said tumbler rim engaging surfaces being positioned on each side of the cog and rising above the driving surfaces of the cog, one of said tumbler rim engaging surfaces com-mencing adjacent the cog and extending forward past the main body of the link and the other commencing adjacent the cog and extending rearward of the link, and :
(d) connecting fingers extending forward and aft of the main body of the link, said fingers having connecting pin receiving openings so that when a plurality of links are aligned with the fingers interdigited connecting pins can be inserted into the openings in the fingers to form the links into an endless belt.
(a) a ground engaging bottom surface and a top, (b) a cog positioned on the top inter-mediate the ends of said link, said cog having fore and aft driving surfaces having an involute gear profile, (c) a pair of flat tumber rim engaging surfaces on top of said link, one of said tumbler rim engaging surfaces being positioned on each side of the cog and rising above the driving surfaces of the cog, one of said tumbler rim engaging surfaces com-mencing adjacent the cog and extending forward past the main body of the link and the other commencing adjacent the cog and extending rearward of the link, and :
(d) connecting fingers extending forward and aft of the main body of the link, said fingers having connecting pin receiving openings so that when a plurality of links are aligned with the fingers interdigited connecting pins can be inserted into the openings in the fingers to form the links into an endless belt.
6. The tread belt link of claim 5 in which the link has two pairs of fingers extending forward of the main body of the link and one pair extending aft.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US86388077A | 1977-12-23 | 1977-12-23 | |
| US863,880 | 1977-12-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1096425A true CA1096425A (en) | 1981-02-24 |
Family
ID=25342000
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA308,540A Expired CA1096425A (en) | 1977-12-23 | 1978-08-01 | Tread belt drive system |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5490728A (en) |
| CA (1) | CA1096425A (en) |
| GB (1) | GB1602143A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19920025C2 (en) * | 1999-04-27 | 2001-03-08 | Mannesmann Ag | Crawler track |
| DE10022080C2 (en) | 2000-05-03 | 2002-07-18 | Demag Mobile Cranes Gmbh & Co | Turas |
| DE10026084C1 (en) | 2000-05-24 | 2001-08-09 | Atecs Mannesmann Ag | Drive turas |
| DE10113412A1 (en) * | 2001-03-20 | 2002-10-31 | Ekm Gmbh | Chain track running gear has chain wheel in disc form with cylindrical roll surface with radially protruding teeth located along center line and in contact with support surface of chain links extending in chain's running direction |
| GB0113127D0 (en) * | 2001-05-30 | 2001-07-25 | Heard Stephen J | Drive wheel for rubber track system |
-
1978
- 1978-05-26 GB GB2353578A patent/GB1602143A/en not_active Expired
- 1978-08-01 CA CA308,540A patent/CA1096425A/en not_active Expired
- 1978-08-31 JP JP10697878A patent/JPS5490728A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5490728A (en) | 1979-07-18 |
| GB1602143A (en) | 1981-11-04 |
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| MKEX | Expiry |