CA1055784A - Vehicle suspension system with rubber springs and friction damping - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A vehicular suspension particularly for railcar trucks. The suspension comprises a carrier with a housing movable vertically relative to the carrier. Elastomeric spring means suspend the housing from the carrier and apply a variable rate spring force to the housing in response to downward movement of the housing produced by application of a downward load on the housing. Damping means are provided simultaneously to apply a variable rate damping force to the housing in response to downward movement of the housing produced by application of a downward load thereto.

Description

~1~557~
RAIL.CAI~ TR~CK
This iovelltion relatt-?~s to :rai]car tru(lss and to susp(?nsion systems ror raiLcar -truclcs and o-ther vehic]es.
Lit-~lt? basi.c c~hange has taken place in ~he pr-in~ipk?s of railcar -~ruck design since -the late 1800 s. The vehicles whic}l rlde C)l~ -these trucks have changed radically, as have t;h(?ir ]oad~carrying requirements and operating speeds. To meet the rapidly increasing demands Lor higher capaci.ty a.nd grt?ater speed, -truçk designers merely scal.ed up. When a problem developed in one component, that eomponent would ~e scal.ed up or some aneillary device woulci be added.
Subsequentl.y, problems were not solved bu-t, rather, were chased ~from one component to another throughout the system.
Sin(e elas-tic de~ormations o~ both rai.l and wheel are `~
relative]y sma].], rai:L joints, track gage, cross-level, and other rail condi-tions all dynamicall.y af~ect the wheels, a.xles and bearings as well as the dependent truck super- :
stru~ture and suspension, car body, and finally -- but most~i.mportantly -- the responsi.ve ladin" in the c.ar. The ~o problems that the railroads ~re curren-tly encountering in operation o~ ireight cars with current track conditions ;and existing equipment a.re: rock-and-roll, a resonant rolli.n~ mode incluced by s-ta~gered rail ,joint.s being eri-countered alternately by the wheels on ei-ther side oE
the -truck a-t k)w speed; high speecl bunting, an oscilla-tion ~ induced by the tendeney Oe a. wheel to re((?nter ~vhich : developes into a resonan-t lat;eral ehatter during high speed operation; and -the inability ol standard truck desi~n to controL random motions which results in multiplieation of 3O rore~?x devel~pt?d during resonllne(?~ ~notll(r desired hut :~ ~ unsolv~?d re~uiremelnt Or s-tandard truck-desi~ll is -t:hat;, ~L~557~34 during static loading, ~% o~ the static load is carried by the unloaded truck wheel or wheels. This requirement, o-~ course, reduces the chance o-~ a wheel liLting o~:~ the track and resulting in a turnover.
A s-tandard railcar truck conslsts o~ two parallel side frames which ride upon two wheeled axles, each mounting two wheels. Each side ~rame is a rigid truss member which spans between the axles and has an opening at its center called a spring pocket. A bolster, a rigid transverse member, /D spans between the side frames and is supported at its ends within the spring pocke-ts by conventional springs. A center bowl, Lormed intermediate the ends o~ the bolster, supports the weight oL the car body by means o r a mating centerplate which is af~ixed to the understructure o~ the car body. The -:
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car body is thereby supported on two points, one at each end.
Consequently, the car body tends to rock to one slde or the other. The tendency o~ the car body to rock is resisted but not eliminated by two spaced apart side bearings, which are loacted on the bolster to either side o~ the center bowl ~o at su~icient clearance with the car body tha-t no contact is e~fected unless the car body rocks to one side or the other.
Such intermittant contact side bearings, however, ~all to eliminate rocking oi the car body.
In addition to the dynamic forces produced in response to rocking o~ the carbody, conventional trucks tend to develop other dynamic ~orces. The axles are press-i`itted at their ends with bearings which are clamped into the end oi`
the side frames by way o~ an adap-ter and keeper. The adapter ~ :
is shaped so that the axle can rotate relative to the side 30 rrame in a hori~,onta.] plane without wracking or eccentrically ~oading the bearing. It is also set with a clearance so .. ' . ~ ,.

~S57~as -that i.-l: is allowed to move la-terally. The keeper i.s not in contac~, with the bearing, bu-t is pLaced xo that the bearing cannot :ra].]. out. The relati.onship be-tween the side I'rame and the bolster is generally simi.lar, The bo'lster is allowed to rotate relati.ve to the side frame and to move latera].ly in the spring pockets until being engaged by a stop at the extreme positions. These relative cJ.earances and motions o:f the axles, aclapters, bolst;er and side fra,me.s a,re allowed with the design purpose oL preventing e~cessive o twis-ting or wracking stresses in the bearings, side frames, and the bolster ends during opera-tion. Unrortunately, to allow excessive or unnecessclry motion between the ca.r body and trlick, or among the truck components, is -to a.].].ow wear and to al]ow motion with the forces of the magnitude encoun- , -i;ered by or developed by a railcar is to allow extremely high-impa.ct and dynami.c forces to develop.
The effects of s~ch high impact and dynamic truck forces upon the responsive lading carried within or upon the car body are highly undesirable; however, the suspension systems ~0 commonly used in standard trucks have been unable to cope wlth modern load-carrying and speed requirements, and hence have failecl to provide adequa-te protection for the responsive lading. In the above-described truck, for example, in addition to the wheel axles, hearings and adapters, the side w' . ' frames (which are -the majori-ty Or the truclc weigh-t) are : : unsprung. The greater the unsprung mass O:e the -t-ruck, the , greate.r the magnitude o:F forces -that are transferred i.nto the ca,r body for a given rail input. Most conventional ' ~: suspensi.on systems have heretofore utili~ed steel sprin~s ~30 of the constant rate type, Such springs a.re designed for .
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~557~4 avelag(? tru(k loading conditions, and hence tend to be overly stii`l' under ligh-l load concli-tions, or Or insu~':fi.ci.ent Stif:r}leSS UlldeY' heavy load condi-tions. IL' overly st;ifL', ~he ~pring.~ cause damaging acce].erati.ons to be imparted ~o the lading. I.r insufficien-tiy s-ti~:L', they all.ow the sprung trucls structure to -~requently engage the spring stops or bumpers, ancl thereby develop damag:ing impact forc(?s whi(h are trallsmitted to the lading. Steel sprin~s cllSO have high vibration and shock transmissibi].i-ty which compound problems /0 or lading damage.
To allevia-te some oL' the shortcomings oL standard steel springs, elastomeric sandwich or sheer compression springs have been designed; ho~vever, sheer compression - springs inherently lack critical damping in the elastomeric material. ancl are o-f nearly constant spring rate. Conse-quently, they must be.designed Eor the average load antici-; pated to be oarried by the vehi.cle. The end result is that tbey presen-t nearly all oI the operational dir-ficulties .
described above with reference to steel springs, or require o additional conventional compression springs -to provide :ru].l load sti:ffness. Fur~hermore, sheer compression springs require bonds between the steel pla-tes and the eiastomeric ,;.. ~ .
: members so that, i.n the event of L`ailure Or a bond, a .failure could result in the entire suspension system. In addition to sheer compression spr:ings, various types oL
non-linear e].as-tomeric springs have been designed heretoIore.
.
Such elas-tome~ric springs usually are in the form oL donuts, square, rectangles, etc. As applied to vehicular suspen-s:ion sy~tems, the donut, square and rectangular conl'igura-ti.ons occupy:too grecl.t a volume i`or t.he t;ight space re~uire-ments of these systems. Square or rectangular shapes also ' :, . ., . .,. ; , . -- --- ..... . .

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provide less ~pring travel, without over-stress o~ -the elastomeric material used, ~or a given height spring.
ThereLore, in limited space requirements, the spring de~lection necessary to produce a varying spring rate has not been practically obtainable. Furthermore, previously usecl elast(>melic springs have nearly always required ancillary shock absorbers.
In addition -to spring rate ancd load carrying capacity, another important element in the consideration o~ Q SUS-/o pension system is the amount and type oL damping in thesyst;em. Prior art damping systems have largely u-tilized constant rorce friction elements or cos-tly hydraulic shock absorbers. Constant ~orce damping, like constant rate springing, is over-damped for light loads and under-dampèd ~or heavy loads, with similar attendant disadvantages. _~
Hydraulic damping is velocity responsive rather than load -responsive and, hence, can allow damage to the lading cluring .
high ~re~uency ~orce and vibration conditions. With respect :
to inherent damping capabili*y, sheer compression or sand-O wlch springs (whether chevron or flat), generally will provide only about 50,~' o-~ the critical damping required for `
~ actual vehicle service without su~ering .rrom harmonic .
~ buildup. The non-linear elastomeri.c springs described above ,~ . .
a~so lack su:E~icient inherent damping ~'or most practical suspension applic~atlons.
Other devices presented as solutions to existing truck prob]ems range ~rom constant-eontact side bearings to other truck-to-car body supportive arrangements. Each of these ;devices ancd the spring and damping devices described above produces some spec~ial si.cle e~fect tha-t results in increased wé;ar, maintenance, s-tress levels, ~'atigue, damage or cost.

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1~557 514 For examp-Le, a recent truck hunting investigation made by the Seaboard ~oas-t Line and the Pullman-Standard Division o~ Pu].lman Incorporated, one a major railroad an~ the other a major railcar building complny, describes standard 3-piece truck frames as oscilla-ting with respect -to the car body in a parallelogram motion with displacement in -the magnitude of one inch as being common throughou-t -the 1;est between the car body and -the truck sideframes. The center plate bowl of the truck bolster oscillated wi-th respect to JO the car body in a -translational as well as a swivel motion. '-Vertical and lateral accel.erations of the two side :frames were cyclical. Longitudina.l accelerations were out o~
phase with respect to each other. Center plate wear resulted in maximum center plate longitudinal movement measured between car body and -truck bolster of 0.8 inches at 50 and 55 mph, The measurements and observations indicated i;~
acceleratecl wear was taking:place during truck hunting.
Presently designed long freight or drop center cars present specialized operational problems. Inasmuch as these lO~ cars~are relatively ligh-tweight, when coupled empty behind a locomotive in a long string of other, heavier cars, the : li.ghweight ].ong cars will tend to ~orm a chord across any substantial tracl~ curvatures when the -train is s-tarti.ng up. ..
The resultant pulling force, directed along a straight R
ne between -the engine and the nearest connected con-ventional~or heavier car, can actually puJ.l a whole string ..
o.f Quch 'ong cars o~ the track on the inside o~ the curve.
A~seoond prob~lem wi.th long cars is -that harmonic vertical ,~. :
acc~lerations can occur in both *he car body and cargo o~bQ~causQ Or the span length between oar -t.rucks. In attempting to~rQduce the problems oaused by~long individual car lengths, G-~: ' :

~s~
various articulated car and truck designs have been proposed. One such proposal is to connect the forward end oF one car and the rearward end of the next adjacent car to a common double-axle truck. A disadvantage with this concept is that the cars do not have four wheels per car when disconnected from the common truck. As a result, a separate, specialized vehicle is necessary to push or pull the car along the track during train make up and car servicing. Other prior art articulated railcars have used a Fixed, single axle truck at each end of ~he car, while others have used telescopically inter-connected but fixed trucks to vary the length of the car itself.
,~ principal object is to provide a wheeled-vehicle suspension which comprises load bearing spring means comprising at least one resilient rod spring associated with each wheel and composed of an elongated body of elastomeric material having opposed elongated longitudinal load bearing surfaces;
damping means; and mounting means for attachment between the body and running gear oF a vehicle, said mounting means carrying said rod spring in a position such that load bearing compressive forces are transmitted to said loadibearing surfaces transversely of the rod spring longi~udinal axis without producing rotation of said rod spring about its longitudinal axis with respect to said mounting means, while simultaneously therewith permitting the unloaded rod spring surFaces to bulge freely, to produce a variable rate spring force; said damping means being operatively associated with said rod spring and said mounting means for producing a damping force simultaneously with said spring force.
The objects, features and advantages of this invention will become apparent in the description and claims to follow taken in conjunction with the accompanying drawings in which:
Fig. 1 is a side elevation of the double axle railcar truck oF this invention;
Fig. 2 i5 a pian of the railcar truck of Fig. l;
F`ig. 3 is a section taken along the line 3-3 in Fig. 2 depicting a car body bolster mounted by the truck of Fig. 1;
Fig. 4 is a section taken along the line 4-4 in Fig. 3;

l~ig. S is a fragmentary longitudinal section of a portion of the suspension system of this invention;

i78~
Fig. 6 is a transverse~ section of the suspension of Fig. 5;
Fig. 7 is a fragmentary section generally similar to Fig. 5 oF a modified form oF the suspension oF Fig. 5;
Fig. 8 is a section taken along the line 8-8 in Fig. 7;

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F:ig. 9 is a sectlon generally similar -to Fig. 8 o-r another mod:ilied -rorm Or th~ suspension t)r l~ . 5;
I~ig. lO is a rragmentary side elevat-ion ol th~ truck oI Fig. l;
Fig. ll is a sec-tion generally similar to Fig. 5 oL
still anoth(~r modified Lorm of the suspension oE Fig. 5 depjc-ted in its loaded conditlon;
Fig. i2 -is a sec-tion taken along the line 12 12 in Fig. 11;
Fig. 13 :is a section taken along the line 13-13 in Fig. 11;
Fig. l~ is a section taken along the line l4-l4 in Fig. ll;
Fig. 15 is a transverse section of one -Eorm of the ~ .
frictional damper piston oE the suspension of Fig. 5;
Fig. 16 is a perspective of a modi:Eied form of the .
rod spring o-E the suspension of Fig. 5;
Fig. l7 is a side elevation partly in section of two single axle railcar trucks according to -this invention ~O:~respectively associated with ad,jacent linked railcars;
~: , Fig. 18 l S a plan of one oE the single axle trucks oL
Pig. 17, Fig. 18A is a plan of a modiEied l`orm o~ one portion ;o~ the truck of Fig. l7;
FIg. ].9 -is a section taken along the line l9-19 in F~g.~L~
Fi.g. 20 i.s an operational schema-tic p:lan oE the two single axle trucks oE Fig. 17 depic-ting operation on a stralght ~ra~k sec~til)n 30~ ~ ~ Fig. 21 is a:n operational schematic generall~ similar to Fig. 20 d~picting the -two single axle trucks of Fig. 17 ~ :
~ ~ . ;:. .

~S57~

on a curved -tra,ck section.
The do-lble axle truck ol` I~'igs, l-~ compr-i.se~ tw(>
para1lel sicle frames 50 which are interconnected in~er-mediate -their lengi,hs by a torsionall.y cornp'Liant bolster 54. rl`he ends of -the side frames are suspendc3d by sprung ;' and damped suspensi.on means, presently -to be descrl.bed, from axle hearings 5 whiell are ri.xed to the out1)oard ends Or axles 2, a.nd ouLboard oL wheels ~.. Consequently, by suspending the si.de frames I'rom l.oeations ck~sc?-to the rail, 0 the unsprung mass of the truek is redueed -to a minimum, and ,-~henc(-3 damaging aecelerations a,nd :rorees -to the responsive lading are mi'nimized, The railcar body (not shown) is mounted by a car body bolster .16. Continuous eontact sicle bearings 53 support and transmit vertieal ]oad from the ends ofFbolster 16 direetl,y to the side frames 50. Thus, lateral _.
ro~kin~ of the car body is eliminated. A sprung allcd clamped .~ . .
e~nter pin mechanism 52 pivotally interconneets and transmits horizontal as~ well as longltudinal loads between the mid- ' p~ints.of the car and truc,k bolsters l6 and 5~. The cen.ter ... .... ..
~p~in meehanism also defines a verticcll pivot axis about which ~: the truc:k and car body can swing relatively. ~s depie-tecl n broken ]ines in Fig. 2, a conven-tional brake aetuating meehanism 36 is or may be moun-ted between the side :1'rames : 50 adjaeent eaeh axle 2 for operating bra,ke shoes 37.
The truck bolxter 5~ is r i.xed at ecleh end to a side -rrame,50. Thus, unlike the eonventi.oncll three piec,e trucks - with. sprung bolsters deseribed previous]y, the truek of ; ~ this inventi.on uti].izes an unsprung bolster to oh-tain im~rov~cl operationa'1 eilara.et:eris-tics. The truck bolster . 3~ 5~is m.lde ul- Or a torsi.onally (ompl.iant beam 55 which, .
:
~ wh(-3n twisted about its 10ngitudina]. a~is, a~Llows -the :t'orward ~ ''" , . .

~S~7~3~
and a:rt ~vheels associated wi.th one side of -the truck to "walk" or rotate in a ver-ti,cal plane re'l.~tiv~ to -the fore and a~`t wheels o:f -the opposite side in order to main-tai,n relatively constant loading on eac,h ol' the l'our truck wheels. This beam in combination with side frames 50 forms an elastically rigid H frame which is torsi.onally yieldable ,to enable the side -frames -to rock lengthwise of -the truck or to swing in respective pl.a.nes perpendicular to the length oE beam 55, while restraining any other relative motion of the side erames. The beam 55 is preferably 11 or I shaped in transverse cross section and includes side flanges 55a (Fig.
3) and strengthening side bars 54b. The beam is, in ef~ect, a narrow flanged flat bea.m which.is still in the longitudinal or para.l.lelogramming direction. In addition, this beam is very s-tiff in the tramming direction, that is, with respect . ~
to ].eaning in and out of the side l`rames 50. Consequently, : the beam 55 resists relative leaning of the side frames more . st~rongly than it resists relatlve movement thereof in a plane pe~rpendi.cular to its l.ength (or movement of the side 0 rrame~S which tends to twist the beam 55 about its 10n6i-; tudinal axis). Thus, the beam 55 reduces both trammingand parallelogrammlng. The end result is a significant decreàse in bearing wear as well as in moment or racking Eorces on the bearings 5. , ~:
~ :.
The ends Oe the ca.r body bo1ster 16 are di.rectly and continuous].y suppl)rted a.t two spaced apart vertical load support polnts by side bearings 53 upon the upper surfaces Oe~ the side frames 50 intermediate their lengths. The side , .' bearings 53 provide point suspension between the ends of : ' 30 the~bolster 16 and tbe truck along :L~ines SP which are out-board Oe vertical centerlines CL through the longitudinal ,, ~, , ,. . ,,: , , ,.,, . ; . .. . . . , , , . : : : , . , , ", ., , , :,.

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center ol` the tracks TR, shown in phantom. Such placement of the .side bearings 53 reduces bendlng movements in -the bols-L;er l6 and provi~es high ro'Ll-over s-tabil:ity ror the railcar.
, Relerring to Fig. 3, the side bearings 53 each comprises a lower bearing member 53a which is fixed to the top o~ the side frame 50, a Eloating cen-tral bearing member 53c, and an upper bearing member or p:late 53d which is Lixed to the underside of the bolster 16 adjacent one end thereof.
/0 The cen-tral and lower bearing members may be maintained in ~' continuous load bearing~contact with each other by spring clip means (not shown) and by the weight Or the railcar body upon the truck. The lower bearing member 53a includes an upstanding peripheral flange whicb surrounds a domed mldsection of` generally hemispherical cross sectional con- _ ~iguration. The domed mid~ection includes a recess in which is secured a polished or smooth metal plate 53b, also o-f ~' generally hemispherical cross sectiona] configuration. The [ ~ .
:~loating central bearing member 53c has a concave lower 1 surface. This concave surface is O-e a generally hemispherical : .
cross seotional configuration projected at substantia]ly the~same radius from a common centroid C as the curved surface of the lower bearing member domed midsection. A
; concave antl-frlction composite disk is or may be secured to the lower surEace of the cen-tral bearing member and ,: . . .
bears aga]nst~or ma.tes with the domed midsection of the lower bearing member 53a, as shown. The an-ti-:Eriction disk is La~ricated O:e low friction material, which preferably ~, :
' has~a coer-ficient o~ -~riction from .02-.10 and most prererably 30 ~-04. The central bearln~ member 53c~ bas a Llat up~er surrace in or on which is bonded a second anti-friction'composite .
~ disk. This second disk is flat and bears against the under .
,, ~ . -: . ~, - . _ . .

1al 5571!34 surfa(e or the upper be~rin~ member 53d, which pre:eerably is po.l;sllecl or an~ rriction coatecl. Thus, the central hearing member 53c can move omni-direct.i.onally and arcuately about the centroid C re].ative -to the lower bearing member 53a, while simultaneously therewith -the upper bearing member 53d can move omni-direc-tionally in a plane relative to the centra] bearing member 53c. Any or all or -the i.nterengaged surLaces oL the upper, central and lower bearing members are or may be coatecl or impregnated with teflon or 0 other known low friction materials to provicle low :rriction movement. The en-tire bearing assembly is covered by a neoprene coated nylon boot 53e having a breather vent (not shown). The boot is secured between the upper edge oL the lower bearing member peripheral f].ange and the upper bearing member, as shown (Fig. 3). The boot restricts entry of foreign material into the vicinity oL the friction sur-f.aces.
Because.there are frequent lateral as well as l.ongi-: tudinal motions between the truck and the bolster 16, the mating or engaging anti-Iriction sur-faces of the side 20 bearings 53 must be permitted to move in any rotational directi.on in order to continuously main-tain compliance of the upper surf:aces o:f their central bearing members 53c with the undersurface of the upper bearing members 53d. Conse-quently, vertical loa.ds transmitted Lrom the bolster 16 to N
the truck are transm:i-tted direc-tly to the truck sid~ .rrames 50 without any cushioning arrangement -to weaken the structura].
viability o-~ the entire system. ~urtherLore~ it is possible, by selec;ting a coeL-ficien-t of ~riction of the bearing contact :
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:material used, to provide fric-tiona]. clamping :ror the car ~body system. Such damping is of great value in decreclsing or~6liminatlng~trllck shimmy, high speed hunting, and other . -12-:, ~ :
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1~557~

undesirable -truck or car bocly'reac-tions and motions.
Rel'erri.ng now -to ~`igs. 3 and 4 the bolster '16 is provi~c-cl with a rigid pi.vot pin P whi~l depends :from its ctepressecl m1dsection. This pill is mounted on t:he -truck by the c-enter pin mechanism 52 whi.ch is integrally :rormecl on the truck bo'lster 54 intermediate~ the length thereo~
The pivot pi.n P is mounted compllantly l)y the cente~r pin mechllnism 52. A ring 52a is rormed at the center o.l' the truck bols-ter 5~. The pivot pin P which :eits axially wi-thin the ring 52a is surrounded by a metaliic sleeve 52b. An elast.omel 52c which Fits wi-thin -the space be-twec?n the ring 52a and sleeve 52h concentrical.ly surrounds and is bonded to ~he outer surFace oF the mid-section Or the sleeve 52b.
The elastomer is oi' generally parabolic cross sectional con~igura-tion when relaxed and is precompressed when install.ed a.n amount sligh-tly great:er than the ma.ximum deLlection in use. Such precompression Or the elastomer 52c during initial instal.:lation changes the cross sectional conLiguration of the elastomer to that shown in Figs. 3 and 4. The parabolic ~ dO relaxed coni'iguration and precompression o~ the elastomer : dur~ng initial installation al.low the use o~' a lower spring rate elas-tomer while assurlng fu11 e.lastomer contact with the ri.ng 52a under all deflections. Consequently wall -.
: contact by the rubber on -the trailing sido o.l' the elastorner : will be maintained evc3n under maximum de-rlec-tion. Diametri- -cally opposed pairs oi' shock pads 52d are r i.xed to the rront ~ :
and rear open ends o~ the ring 52a (see also Fig. 2) such tha-t the pads 52d engage and termina-te movemen-t o~' pin P
nder 'longi.l~ldinal i~mpact~conditions alld thus prevent over-o stressing Or the ela.stom~r 52c. Sin(~ he di~ti.l en(:l Or : *he el.astomer is held by precompression against the ring 52a ~ .

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1C1 5~7~

relative rolation between -the car body and truck bolsters 16 and 5~ is resi~ient ancl will be selF c(-~ntering so as to return th(? 1-)olster l6 to i-ts original ~lignment above -the truck arl:er the rotation-causing l'orces arc-~ rernoved.
Thus, the combination OL` frictioncll damping of the side bearings 53 and the damped and sprung movement at the -center pin P provides both sprung and damped rotationa'l movelllent or the truck, with to-tal resistence -to rotation ~eing about tile same as or less than is encoun-tered with 0 conventiona1, dry center plate car--truck cons-truction. The friction~lly damped compliance oI the center pin P a]so helps to reduce rock and roll motion of the truck by al]owing cushioned motion be-tween the car body and truck which reduces dynamlc lateral -forces -therebetween. Additionally, this cushioned motion tends to maintain the center of rotation of the car body on a theoretical longitudinal axis through the transverse cien-ter of the truck axles. Consequently, dynamic lateral forces between the car body and the truck are reduced. This result is achieved due to the compliant naturc-? of the elastomer 52c, which al]ows the cen-ter point of pivot pin P to shif't laterally rather than merely rock in response to lateral ~orces. In ee~'ec-t, -the elastomer reduces the lateral :Eorces which tend to over-turn -the rail-car.' Furthermore, since -the side bearings 53 hold -the pivot pin P in perpendicu:1ar alignmen-t with the lengthwise axis o:L`-the -truck bolster 5~, only hor:i~ontal moments are absorbed by the elastomer. Consequently, extraneous torsional forces on the bols-ter 5~ are reduced. This results in longer li~e ~' for the -truck bolster 54.
The suspension system o:l` this invelltion is described herein with particular reference to the doubLe a~le truck oF

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~igs. 1-~; however, the single axle truck of Figs. 1.7-21, is or may be e(~ ippecl with -the identical suspensioll system.
(The parts oL the suspension system as applied to the single axle truck are not described in detail wi-th reference numerals; however, some parts are generally designated for rereren(e purposes.) The suspension sys-tem o~ the double axle truck i.s macle up o:~ Eour suspension uni-ts respectively located bet:ween bearings 5 and the ends Or side Lrclmes 50.
In~Fig. 1, one such suspension unit is indicated in broken lines at the left end oi the illustrated side -Lrame. (The single axle truck, of course, includes l;wo suspension units.) Referri.ng now in particular to Figs. 5 and 6 oL the drawings, one suspension unit of.the truck suspension system o~ this invention is shown in additional detail. (The ,~ . .
remaining suspension units are~ or may be, identical.) A _ ~ :
suspt?nsion housing 82 is secured to the side ~rame 50 and is movable vertically therewi-th relative to a bearing adapter or.carrier 93. Adapter 93 ls supported upon the axle bearing 5 which cent.rally positions the wheel axle 2 in the housing ao 82. Inasmuch as each suspension uni-t is mounted by -the ~:
adapter 93 adjacent the truck axle, the suspension system of this invention i~s extreme1.y stable and the unsprung mass of the truck is minlmiæed.
A three -tier stack of elastorneric rod springs designated 8~, 85 a.nd 86 are supported upon adapter 93 within the housing 82 sucll that -their longitudi.nal axles are gen~.?rally horizon-tal. The upper tier is comprised oL a single rod spring 84 which is orientated with its center axis paral].el to the ~ ~ .
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longi.tlldina~ axis oL the truck. The upper and lower sur:faces : 30 Or the upper rocl spri.ng 84 are provi.ded with rla.ts 84a (see Fig. 6) which respectively engage the lower sur:Eace oE the , ~ , ~OSS~8~

upper wall c):L housing S~ and the upper surrace oI a h~ri~,on-tal ~pacer r)late 87. The in~erm~?di.ate l.ier is ~ade up of -three transverse ro~l springs 85, one centered over the axle

2 ancl the other -two spaced ecluldistantly on either side of the axle. The intermediate L`Od sprlngs 85 each include uPper and lower f].ats 85a (Fig. 5) which respectivel.y engage ~;he undersurface oi! spacer pla-te 87 ancl the -top sur.face Or a second, intermedia-te spacer plate 88. The lowermost (;ier is comprised of two tra.nsverse rod springs 86 which are /D equidistantl.y spaced on either side ol the ax~Le 2. The springs 86 also are provided with upper and lower fla.ts 86a which respectively engage the undcrsur:race Oe spacer plate 88 and the top sur~ace oL a third, lower spacer p]ate 90. The spacer plate 90 is bonded -to an elastomer pad 9l which is carried by the adapter 93. The pad 91 provides latera.l spring return motion for the truck and railcar ..
between the ~vheels and the side frames. Consequently, as the si.de frame 50 is loaded, the housing 82 i.s driven down-wardly relative to the adapter 93. Thus~ a.s wi.ll be described ~o in more detail herein, the rod springs 84, 85 and 86 are : : compressed therebetween in a ver-tical dire(tion which is .
generally perpendi.cular to their lon~ltudinal axes. A l~nmper or stop 9~ limi.ts clownward movement Or the housing 82 relat.ive to thc~ adapter 93 to preven-t over-compression o-~
the springs 86.
In most pr~lctica1 railcar truck app:l.ications, -the rod springs 86 (].owest tier) preferably are the stiLfes-t springs.
: : :
In use,~ the suspension system is precompressed to the initial upper limit ot -three inch travel all.owed :For conventional ?rs and thus prov:ides good spring efre(-t even in the unloaded condi.tion o-E the velll.cle~ Each Or -the center tier i5~7~

rod springs 85 is sor-ter, as are each or -the upper tier o~
ro~ sprin~s 84. The relative stiffnesses o~' the rod springs ~, 85 and 86, of col,lrse, may va-ry clepending on the spring a.nd damping curves desired, as wi.ll be~ described presently.
In a mod:iLied and pre:rerred f'orm of' the trllck suspension, shown in Figs. 7 a.nd 8, the upper and i.n~ermediate spring tiers are comprised o:f' parallel rod springs 8~ and 100 which are orien-ted with -their axes i.n the longitudinal direction. The bottom tier is comprised of transverse rod /D springs 86. These lower springs, although sti~L'er than the springs of the upper two tiers, provide, to a large exten-t, the so-f't portion of the spring rate in the suspension system.
Compression with ligh-t loading on the car will al],ow the lower rod springs 86 -to absorh some o-~ the loads; but -~or ,'~
most loads and all. heavy lading, the wpper rod springs 84 and 100 come into play. It should be understood that the size, number and arrangements o-r the rod springs are dependent upon the load capacity and type of application required; there:Eore, -the examples are to be considered as illustrative only, In some instances, i.t is desira.b].e to provide a.ddi.tional `stahility to -the rod springs, particularly whe~ll the rod springs shown in Figs. 5 and 6 are not s-tacked directly in alignment w;,th one another. For th;.s purpose~ the modifi-ca-tions shown i.n I~'igs. 7 and 8 are provlded w;.th several axia.lly spaced apart bosses l.OOa which projec-t ou-twardly from their upper and lower diametrically opposed Llats.
The bosses locate in recesses lOOb and thereby locate and s-tabi'Lize as well as allow ease Or assembly and movement 30 of' the stack~.?d springs to and :~rom housing 82. The bosse~
.

are spaced in Lrom the ends o~ the rod xprings to minimize . :

. ~

1C1 55~7~
s1;ress con(~(?nt-ration al; I;he encls o-f the springs.
~ lthough -there is a certclin amount of inheren-t in-ternal cl~mp:in~ in the rod springs, clependent upon the modulus Or elast;icity Or the rubber used, i-t is insu.Eficient to provide the total dal7~ping necessar,y for most loacl conditions experlenced by the ra.ilcar. As an example, a rubber having approximately 15 per cent lnt(?rllcll d~mping may amount, in the illustraled suspension system, to less than 8 per cent of,thc-? critica.l (effective) damping needed fo-r -the total system. In many practical cases, as much as 20 per cen-t of cri.tical damping is required. The additiona], rc-~quired damping is obtained from unique variable ra.te damping means a.gain best i.ll~stra,ted in Fig. 5 of the drawings.
*he variable rate damping means oL this invention prefera.bly comprises two frictional clampers spa.ced equidista.ntly on either side of the axle rotational axis.
~ach frictiona]. damper comprises an ela.stomeric rod ~pr~ing 96 (although volute or other ~ari.able rate springs may be used) mounted in an inclined cyllnder 95. The rod springs 96 are or may be generally similar to the rod springs a.].r,eady described herein. Each da.mper :rurther ine~ludes a ,Eri,ccti.on shoe 98, o-f a conventional brake shoe-type material having a c~oel'.f'icit?nt o:E friction ol' approximat,ely .~. The '.
friction shoe of each damper is reciprocally suppc>r-tc?d by a ~.ectangu].a.r piston 99 (Fi.g. 15) the inner end O:r which a.buts agains-t the curved side o-E the respective rocl spring 96. The fa.ces of shoes 98 oppose inclined rri.ction surraces 46 whlc,h are -formed on the in-terior.oL' the downwa.rdly divergent fron-t and rear wal].s oL housing 82. Consequently, lo~ve~ g the housin~ 82 in response to increa.sed vertical : .
; :loads or dynumic forc,es a.cting or3 1:he ca.r, causes thc-~:Eriction ` sllrfaces 46 t-~ move downwardly into sliding en~a~emc?nt with ' :

; ~ the sùoes 98. Thus~, the pi.stons 99 a.re progressively driv~n ' -'18-~ 5 5~ ~34 towarcl-their con-trac-ted positions while simultaneously -therewi.th progressi.vely compressing the rod springs 96 in a d:irectlen -transverse -to thei:r longitudinal axes. The greater the resultant ou-tward,.spring force applled by the rod springs 96 against -the further contrac:tive movemen-t of pistons 99, and on the shoes 98, the grea-ter the sliding engagement of the shoes 98 with l'ric-tion su1:faces ~6, and hence 1;he greater the ~ric:tional efi'ort applied to surEaces 46. It is this progressively increasing :Erictional e~'fort that provides the variable damping force applied. In the unloaded colldition, the shoes 98 are spaced at close clearance :rrom -the surfaces 46> or the suspension system may be preloaded sufficien-tly to.bring shoes 98 in-to contact with surfaces 46. It will be recognized tha-t thermal insu-lation means (not shown) may be provided to insula.te the springs 96 from :Erictional heat produced by the shc~es 98. .
The symmetric spacing oi` the friction shoes 98 and rod springs 84, 85 and 86 about the axle 5 balances da.mping and springing movements and tends to centc-3r the housing 82 at all. times rel.ative to the rota.-tional axis of' the axle.
Bec,ause the spring and damping elemen-ts are positioned to l~ala.nce the Iorces around the actual cen-ter o:f thc-3 rotation axis within t.he housing 82 (i.e., the wheel. axle 2), all.
forces are resolved through the center horizontal transverse axis o~ the truck suspension, thus reduci.ng undesirable moments that could increase wear or change the system spring loading or frict:ion damping characteristics. TC? further .
reduGe:wear, -the adapter 93 may be restrained against longi~

tudlnal movement to preve.nt ~ore and aft movement o:f each , :
o wheel l re]a.tive to the side t'rame. Such restrainl, is ,.
provicled by the l'riction shoe~ 98, and, under more severe .-:

~35S78~
:loading, by replaceable s-tee:L wear p~ates97' and replaceable plate~i and mountings 97 (~i~s. 7 and lO) sec~lrecl to fore and a.rt surl'ace~s Or the ad(lpter 93 l'or enga.gement in an axial slot 99 in the side frame 50.
The da.mping force providecl by the vari.able rate Lric- , tional damper oL this invention varie~ with ver-tical distance Or travel of the housing 82 on a varying exponent-ia.l f'orce curve whi{h :is designecl to closely match tha-t O-r the main suspension rod springs 84, 85 and 86 and to add cumulatively /o to their inherent damping. The varying exponential damping force curve provides a slowly changing rate under low loads a.nd a. rapi,dly increasing rate in the upper load range.
Pret'erahly, the damping f~rce applied is directly related to l;he spring force provided by the preferred rod springs 84, 86 and IOO (Figs. 7 and 8). I-t is, of course, under- - :
stood that the a.ngle of the sloped ~urfaceb ~6 may be varied to a.chieve optimum da.mping, or to control the rate a,t which damplng forc~,e is applied. One of the a,dvan-tages ot' the suspension system o~ this invention is that spri.nging and ~o dampine -f'orces are applied suo~h that both increase at approxi-mately the same rate under loading, dynam:ic or static. Thus, ~where ].oads are high,.the spring Lorcc? is-high and the : damping ~orce is high; however, when the loads are light, ,;~
the spring t'orce is low and the damping force is low, thus ushioning the shock to ~ragile lading. The t'riction clampers ';
.
o~:this invention al,so provide load responsive, lateral ;damping and may be employed with lateral pacl springs.
Another modified ~orm of -the su~spensiorl unit o~' this ~.
nvention is i.llus-trated in Flgs. 11.-l~. This unit is or .30~mly be carried by a fixed a~le. The rocl springs 1.~0 a.nd 'l5l, whic~ù are generally simi~.ar to rod ~springs 8~ and 10~ of ~, ~
~ -20-1~i57~
Fi~s. 7 and ~ a.re sepa.rated ly a spa~er p'La-te :1.18. Like- -wise. rod springrs 1.~9 are generally similar to rod sprinKs 96 of I~'ig. 5. The hous-ing l53 andalrri.er 155 are general].y simila.r -to the housing 82 and adapter 93 descri.hed pre~vi(~ s'ly.
The rod springs (both the main spring ek--ments 150-15'1 as wel]. as dampi.ng spring elemen-ts 1~9) are shown compre~s(?d radially with their r~spec-tive opposi.ng rla-t~ c].early distinguisha.ble. Th~? :t`riction shoe element;s 1.75 are sh-)wll a.s just engaging -the respective :rriction surfac:es 171 such that essentially no friction damping occurs until application of the light weight O-r the vehicle causes damping rod springs 149 to be compressed and thereby urge the l'riction shoe el.ements 175 into -Erictional eng?gement with 1;he respective -Eriction surfaces 171.
Figs. ].1.-14 also depict modified variable rate damping means made up o~ two frictionaL dampers disposed symmetri-cally relative to a rotational axis (not shown). One such damper is described in detail. herei.n and is depicted in cross section in Fig. 11. The other damper shown in side dO eleva.tion is ident.ical. Rather tl~an provi.ding a recipro-cable guide cyli.nder as at 99 in F-ig. 9 -Eor each .Eriction sh~e a pair oL guide pla-tes 157-159 are mounted by carrier 155. Each guide pla-te is provided with a guideway 161 into which the respective Irict1Orl pis-ton 163 is pivotally and ~:
sli.dably moun-ted.. This pivoted moun-ting may be provided by a pivot pi.n l65 or by cylindrical bosses extending outwardly :~rom;the side walls o:E the -~riction pis-ton 1.63 to pivo-ta11y and slidably enga.ge the guideways 161. The guideways 161 may be provi.ded~in a replacelb1e ch.anllel 167 Ia.bricated 3o ~rrom wear r~sistant ma-terial. The~ 1Ower rearwa.rd por-tion o:F each .rriction piStOII 163 is provided with a I1anged .
' 557~
por-tion 169 to insure rotention of the rod spring 149.
The spri.ng l49 and baclc wa]l Or the Lriction piston 163 are a.]so l)rovided wl-th a mati.ng boss and recess to s-tabilize the positlon o~ spring 149.
The abili.ty o~ -the friction piston ].63 to pivot as well as slide enables -the rricl;ion damping sys-tem to accommodate unbalanced loa.d or shock :rorces which ~end to rock housi.ng 153 or carrier 155 relative to one another. The Fig. 11 embodiment :i.s partiGu].arl.y suited to mounting a moveable portion o-~ a vehicle suspension which will shift position in an arcuate manner (and not slmply ver-tically) in response to load and shock :Corces, particularly the latter.
In this and simllar applications, the housing 153 would be rigidly secured to the vehicle body or frame and, as a result, any ~orce -tending to brlng the housing 153 and carrier together, ~or example, would tend to ca.use the opposing -i~riction surface 171 and spring bearing sur~ace 173 .:
to become mis-aligned. The combined ability oi the ~riction pi6ton 163 to pivot and slide, however, will enable the ricti.on shoe element 175 to remain in L`ull .~rictional conta.ct with the eriction suriace 17l.
:`
In most instances, the guicleway.s 161 are aligned normal to fric:Lion sur~ace 171. I e the guideways 161 are aligned such that an acute angle is ~ormed be-tween the axis ol the guidewa.ys and friction surface .171, the l`ric-tion pist.on 163 ~i :
:: :
will have an inereased component o~ vertical travel relative to verLiçal travel o~ the carrier 155 a.s carrier 155 travels upward. I e the guideways 161 are aligned such that an obtuse angle is Eormed be~tween:the axis oE the guideways and -friction :::: ~ : :
30 surla.ce 171, -Irictlon piston 16~ wi]:L ha.ve a. decrea.sed com-~ ponent O-r vt?rtical travel rela.tive to vertieal -travel o~` ~

. , :

-the carrier :155 as carrier 155 travels u~ward. Wi-th respect to vert:ical upwartl travel or calrier 155, an i.ncreased vertica~ ra.vel componen-t f`or the i'riction piston 16'3 will callse the sprinK element l49 -to exer-t a greater rrictional damping ~orce agai.ns-t the friction surLace 171 and a decreased verti,cal, travel component wil]. result in -the exerti.on or a lesxer Lrictional damping Eorce. ~i-th respect to verti.cal downward 1:ravel of carr:ier 155, the obverse will be true.
The same resu].ts may be obtained by shimming the member provi,ding fric-tion sureace 171 as to position -eriction surfact? 171 a-t a non-perpendicular angle to -the axis o~
guideways 161, or by providing a member having a :~riction surrace 171 that is not perpendi,cular to the axis o~ guidt~iways 161.
Addi,tionally, Fig. 11 depicts the member provi,ding .rriction surfa.ce 171 as replaceable. An upper stop 179 is secured to housing 153, and inclined at an appropriate angle to hold the ~riction surEace member when -the latter is buttecl agai.nst the stop. The lower end oL the :Eri.ction sur:eace member is secured to housing 153 by a recessed screw 18]. which is threaded into hous1ng 153 a-t an angle parallel to the a.ngle of stop 179. As the eric-tion surIace member wears, a substitute friction surface member may be inserted between the worn member and housing 153. Upon -the inser-tion of the subs-ti-tute member, the worn rnember will bt? shiI'ted downward].y such that the aperture~ in the worn member, for screw 181 will remain aligned with thrt?adt?d hole in housing ~53. Thus, the screw 181 may be reinser-ted to secure both members. ~s a resul-t, the worn member can continlle to wear un-til it disinteglates and slliLrs away t.o expost? tht~ rresh ~'riction Sur~act? o~ the subs-titute mt-?mber. ~lternatively, the , ,-.- .,.._. _ .. . ., . . ; . :

lC~SS7~4 worn memher (ould be rem~)ved a~er in~(?rtioll or ~he sub-Sl,itUt(? member. In ei-ther caseJ replacemt?nt of 1,he worn member can be accompl.ishecl without; dismantlement ol the suspension s-ince re:lease or damping for((? urging friction shoe e~lement 175 against -fric~ion surfacc? ].71 is not required.
Alterna-tely, rriction surface 171 may be l)rovided by a wedge shaped elemen-~ (not shown) to p:rovide multiple angul.arity :ror the rri.c-tion shoes -to ac-t upon.
The rod spring of this inventi.on whicll constitutes the o preferred mai.n spring and damping spring elements oe the sus-pension comprises an elongated solid body of elastomeri.c ma.-terial, preferabl.y natural rubber o:r i-ts equivalent, having a curvi:linear cross-sectiona] outline. Its cross-sectional configuration is selected to provide a variable shape fac-tor in response to radial compression produced hy a compressive load applied along a ]oad application axis substantially ~perpendicular to the longitudinal axis of the body. Shape eactor is defirled as the ratio o~-e the area of the spring load bearing surIaces to the area of its non-load bearing surfaces :.:
~o wl~ich are :free to bulge in response to an appl.ied compressive . load. The higher the shape eactor, the grea-ter the a.mount oe ~load required -to produce a certain spring de-~lection, and hence the steeper the spring curve obtained. Consequen-tly, with respect to the ful.l range Or load conditions, including both light and heavy loads, the spring curve obtained is non-linear or variable rate. :
The suspension system oL this invention employs parallel ].oad application surface to squeese each rod spring there-:~between, wi-thout rotat;i.onal movement t.hereof. The load . 30 a.pplication surraces between whicll each rod spr~ing is posit:ioned .and squeezed are provi.ded by the spacer plcl-tes, suspension ; .: . -2~-. . .

. ; . : . . , : , ~ ; , , . . ,: .:: , : ~ , . .:: . . . . .

~ss~

honsirlg ancl bo~LIring adap-ter i.n the case of -the ma:in spring elements, and by the rriction p:iston ancl ey'linder or carrier in the ea.se c,r the damping spring elemc-?nts. The mannc?r in whi.ch these l.oad app].ication sur~`acés operate wi.th l,he rod spring o:r -thi.s invention to obtain variable rate or non-linear spring and damping curves may be under~tood by comparing Figs. 7 a.nd 8 wi.th Figs, Il and 1.2 in whi.c,h -two typical rod spril)gs a.re depic,ted in their loaded and un~Loade(l c,ond-iti.ons, respectively, In the unl.oaded eondi-tion (Figs, i and 8) ~;, to the upper and lower ~].a-ts cons-ti-tute -the spring load bearing ,`
sur~aces, and hence the spring shape factor is smal.l. I~hen loaded (Figs. Il and 12), the sides and end sur-~aces o.f the rod spring adjacent -the load appl.ication surfaces roll. down ':~
into ~lush engagement therewith, to t;hereby increase the area of the spring load bearing surfaces. Consequently, the spring _ shape :~ae-tor is correspondingly increased. As the shape factor increases, increasing compressive loads are recluired to obtain a given de:~lection.
Thus, it is possible, by forming -the rod spring of a ~ cross-secti{)nal con~iguration wtlich provides a load vari.able - sha.pe fac`tor, to control the sprlng curve ohtained and hence the spri.ng and damping curves o~' the suspens:ion spring and damping elements. The pref'erred sprin~ cross-secltional eon-:figurat;i.on ib symmetri.ea]. relative to the l.oad applieàtion a~is w a.nd most pre-ferab].y is.generally cylindri.eal. It wi:ll be recogni.zed -that'other spring configurations may be used and that the con~i.gurations i'llustrated and described herein are : nc>t eonsLclered as limiting. For example, the ends Or the rod -.
sprirlg may be general.ly h~mi.spherical, us depi--ted in Fi.g. l5.
::. 30 It:i.s possib].e, o~` course, to control the spri.ng curve obtai.necl ~: by other.meansJ~such as by modi~ying the a.rea and/or ::

1~5S~

con~i.gura-tion Or the spring :r].ats. ~ddi-tionally, -the spring curve obtained may ~e controllcd by usin~ elas-tomeric materia1 o~ varying hardness.
The rod spring o~ this invention has the advanta~re o~
being highly compact and thus readily adaptable to the coniined .
space of a raiIcar -truck. To achieve still greater space savings, -the rod .,pring may include latera1. r~-?l.ief cuts (not s11own) whi.ch may serve to re~uce the -thickness of each pre:eerred suspension unit. Thus, it is possi.ble, using such reduced /0 thickness spring elements, to position opposite suspension uni-ts at grea-ter transverse spacing to provi~le added roll.-over stabi.lity :I`or the truck.
. In addition to the double axle truck of Figs. l-~, the ;.
prineip]es Or this invention also apply to the single axle truc1c of I~'i.g~. 17-21 whieh may be used with long freight or drop oenter railcars to -.form a.n articul.ated railcar train of severa1 such cars. In such a train, the intermediate cars : are supportecl at each end by single axle trueks; however, the forwardmost and rearwardmost ca.rs in the chain have the double axle trucks of Figs. l-~ at their respective forward and rear ends. The adjacent single axle trucks 20 and 120 : .
(Flg. 17) respective].y a.ssociatecl with adjacent ends of the intermediate linked cars are i.nterconnected by -te].escopic ..
nk means, presently to be described, which al:low rotational and l()ngitudinal relative movement be-tween the adjacen-t trucks , : while maintaining -them in longitudina1 ali.gnment. Consecluent1y, : adjacent ].inked trucks are steerable rela-ti.ve l;o their respec-ti.ve cars and are separable along a longitudinal axis there-? `, . ' . .
; ; be1;ween. Inac;much as the two single nxl(3 trucks 20 and 120 0~can rotate re1.at:ive1.y at varying longitudi.nal spacin~, they are ab:le to ti.lt or "wa].k" relatlve ~o eacll other. Thus, they :

~557~34 behave, wh~-?n intelconnec-l;ed, in much the same manner as the double axle ~ruck of Figs. 1-~. That is, each o~ their load-carrying wheels canries a subs-tantially constant load regard-less Or track irregulari-ties. Draw bar coupling means, also presently t.o be described, couple and maintain cons-l;an-t spacing between adjacent ends of the car bodies 10 and 1].0 independen-tly of the relative posi.tions of their respective trucks 20 a.nd 120.
Tc) enab].e the adjacent trucks 20 a.nd 120 to move toward and aw.ly from each other without swinging rela-tively, a tele-o scopi.c connect.i.on between -the trucks is provided through members 114 and 1]5 which can freely rotate relative to one another.
This connection is sealed by a flexible boot 116 to prevent dirt from ge-tting i.nto -the space between the -telescopic parts and to contain conventional lubricants. As the two linked cars move l`rom a straight to a curved track section, as depicted in Figs. 20 and 21, the telescopic ~onnection will enable the spa.cing between the trucks 20 and 120 to decrease while -.
simultaneously allowing the car bodies 10 and 110 to swing relative to their respe~tive -trucks. Additional].y, simul-: ~o taneous relative rotational and longitudinal coaxial movement :e the members 11~ and 115 enables the trucks t:o ti]-t rela-tively about a longitudinal axis therebetween or "wa]k" so as to e-Ei`ect equa:l load distribution on their right and le~t wh~els.
~..
The spacing between the adjacent ends o~f ca.r bodies 10 and 1:l0 is maintained constant by a conven-t:iona.l draw bar ll2 which ls connected therebetween by pivots 113 (Figs. 20 and 21) in a well known manner. The draw bar 112 wi.ll transmit pushi.ng ;~ a.nd pulling rorces between the car bodies 10 a.nd 110 and will .
~o;enabie 1;hem to swing rela-tively, as depictecl in Figs. 20 and 21.

Holding -the -trucks 20 ancl 120 against relative swi.nging does .

:

~S5,~
no-t deter relative swing,ing of the car bodies 10 a.nd 110 while negc)tiating curves in the track, however, because each car body is gu:idecl for both tilting and swinging relative to i-ts : respe(ti.ve -trucks by -the center pin and si.~e 'bear.ing means described previously.
The remain,ing parts o-E -the single axle truck depi.cted in Figs. 17-21 a.:re iden-tical to those pa.rts a]ready il].ustrated and described with re:~erence to the double axle t;ru(k of Figs.
]-4 and the suspension system of Figs. 5-10, except -that the lo side ~ra.mes 50 are in-terconnected at each end by transverse ..
members 130 and -the pivot mechanism 52 is mounted by longi-tudina], memb(-3~ 132, which is secured at its ends to the mid-points oL members 130 as shown ~ig. 18).
When two adjacent railcars are connected ~or normal :
, running a.s shown in Figs. 20 and 21, they have two distinct characteris-tics which distinguish them from any other railcar s~stem o-~ a,rticulation. One is that the telescopic inter-connec-tion between the adjacent single axle truc~s has no lon~:itudinal tension or compressioo strength Or it:self. Con-sequently, i-t allows longitudina,l and rotational movement while .
resisting bending, laterally or ver-tically. Second1y, a1J.
forc:es ta~en by pulling, pushing or i.mpacting -the combined , ,, railca,r bodies and -trucks are applied through -the car body ,.
s-tructure and its ~truetural in'terconnectin~ means, .such as the draw bar l12.
One advantage oi' using -two single ax'Le trucks to combine two separa-te railcars is that, when the railcars are separated, .~' they always have at least two single axl.e trucks, one at each ,,`
endi to al]ow them to be pulled c-r pushed along the ~rack to make up new int~reonnec-ted railcars or ~or shop servicing pur pose s .

1~55~

Although the pre~erred embodim(?nt Or the te:les(opi.c members ll~ and -11.5 are sllown rigidl.y c01lne(:ted t;o th(?ir respec-ti.ve trucks, they may also be hinged ror pivota:l movement a.bou-t verti(.:al a.Yes as sho~vn in ~ig. :18~ to prov:ide ~urther comp:lia.nce to track irregulariti.es.
While the preferred embocdiments of the -invention have been :i.llustrated and descr:ibed herein, i.t should be understood that variati.ons wilL be apparent to one ski.lLed in the art.
~ccordi.ngly, -the embodiments ill.ustrated and described herein /0 are not to be ]imitlng and the true scope and spirit of the inven-tion is to be determined by reference to the a.ppend(?d claims.

, ,:
'.

. .

~ , ,. ~

: ^ :
' :~ 9

Claims (2)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A wheeled-vehicle suspension which comprises load bearing spring means comprising at least one resilient rod spring associated with each wheel and composed of an elongated body of elastomeric material having opposed elongated longitudinal load bearing surfaces; damping means; and mounting means for attachment between the body and running gear of a vehicle, said mounting means carrying said rod spring in a position such that load bearing compressive forces are transmitted to said load bearing surfaces trans-versely of the rod spring longitudinal axis without producing rotation of said rod spring about its longitudinal axis with respect to said mounting means, while simultaneously therewith permitting the unloaded rod spring surfaces to bulge freely, to produce a variable rate spring force; said damping means being operatively associated with said rod spring and said mounting means for producing a damping force simultaneously with said spring force.

2. The suspension of claim 1 wherein said damping means includes a pair of friction surfaces, and a friction damping member slidably engaging said friction surfaces and operatively associated with said rod spring such that it will engage said friction surfaces with increasing force as a result of an increasing load bearing force being transmitted to said rod spring.