US1979761A - Car construction - Google Patents

Description

E. B. NORBOM CAR CONSTRUCTION Nov. E, 1934.

5 Sheets-Sheet l Filed June 17, .1931

BY @70010910774 ATTORN EYS E. B. NORBOM CAR CONSTRUCTION Nov. 6, 1934..

Filed June 17, 1931 5 Sheets-Sheet 2 ATTORN EYS moo oo K Wm @N @N BY CcZ/rnmon/y |||||1 I l l l III I l I l I l E. E. NORBOM l,979,761

CAR CONSTRUCTION Filed June 17, 1931 s sheets-sheet 3 Nov. 6, 1934.

lcw. 6, i934. E. s. NORBOM 1,9793@ CAR CONSTRUCTION 'Filed June 17. 1931 5 sheets-sheet 4' FEW@ @L @GCD OQO@

ATTORNEYS Nov. w34. E. E, NQRBOM .1,979,761

CAR CONSTRUCTION Filed June 17, 1931 5 SheetsSheet 5 QQQQ@ Q Q Q Q Q Q INVENTOR ATTORNEYS Patented Nov. 6, 1934 CAB CONSTRUCTION Einar B. Norbom, Butler, Pa., asslgnor to O. C.

Duryea Corporation, Wllmingto ration of Delaware n, Del.. a corpo- Application June 17, 1931, Serial No.545,098

20 Claims.

This invention relates to car constructions of the typeembodying a continuous draft and buffing column or center member that extends substantially the length of the car structure and is mounted for longitudinal movement relative to the car structure and body bolster.

A moving railway car, whether light or loaded, has stored therein a great amount of energy. In any case where differences of velocity are set up 19 between two adjacent cars as in train service or in coupling one car to another, energy is transferred from one car to another and this energy must be absorbed in some Way as by slowing down one car while setting the other car in motion and by suitable cushioning or energy-dissipating means which are usually embodied in a draft gear at the end of the car. It is desirable to increase the travel of the usual draft gear in order that energy absorbing capacity may be increased without excessively high forces, but at the same time there are rigid limitations on the permissible amount of train slack. Since in the usual draft gear the travel of the gear limits both the train slack and theenergy absorbing travel, it represents a compromise between the desired long travel for cushioning purposes and short travel for train slack purposes. v

It has been proposed heretofore, as for example in the United States patent to Otho C. Duryea,

No. 1,693,194, to provide a car underframe whereby train slack and energy absorption capacity are controlled separately each to' provide the most desirable operating conditions and without the necessity of compromise. The Duryea underframe embodies a center member movable relative to the car structure and body bolsters and adapted for long travel, that is, for travel materially greater-than can be obtained with theusual draft gear because'of train slack limitations, and

40 the car body is cushioned by suitable resilient means or friction means interposed between the center member and the car structure. Train slack is controlled independently of cushioning by means embodying couplers mounted at the ends of the center member for limited movement of any desired extent with respect to the center member whereby the train slack is reduced materially below the train slack provided by the usual draft gear which must have sumcient travel to prevent excessive forces. Preferably the movement of the couplers relative to the center member is also cushioned by resilient means interposed between the coupler and the center member. In the prior application of/Otho C. Duryea, Serial No. 399,311, filed October 12, 1929, there is disclosed a car structure embodying a Duryea underframe and provided with resilient cushioning means interposed between the center member and one bolster and with friction means interposed between the center member and the opposite bolster. The resilient means serves to cushion the car body against draft and bufng blows transmitted to the center member, and the friction means serves to dissipate energy received from draft and bufflng blows and to snub the relative movement betweenthe car body and center member. With an underframe of this type it is desirable to distribute the load approximately equally between the two bolsters, that is, to absorb approximately the same amount of energy in the resilient cushion means at one bolster as is dissipated by the friction means at the opposite bolster. In such a case, however, means must be provided whereby the frictional resistance to relative movement between the center member and car body is less on recoil movement than on shock absorbing movement in order lthat the resilient means may return the car Vbody and center member to their normal relative positions. Moreover, since the center member moves in both directions so. relative tothe car body, it is necessary that the friction means operate in either direction of relative movement between the car body and the center member and it is desirable that the friction elements shall not be released at the intermediate or normal relative position of the car body and center member.

One of the objects of the present invention is to provide novel energy-dissipating means which are operable in either direction of movement of the center member relative to the car body and which are not released from frictional engagement when in their normal relative position.

Another object is to provide novel friction means embodying resilient means for maintaining the friction elements in engagement which means provides greater frictional resistance to relative movement of the center member and car body away from their normal relative position than to relative movement toward said normal position.

Another object is to provide novel energy-dissipating means which are simple and efficient in operation, of strong durable construction, and capable of ready adjustment and repair.

A further object is to provide novel slack control means embodying a coupler mounted for limited movement relative to the center member. and resilient means interposed between the coupleit and center member, the coupler being capamitted to the center member.

terfering with the pivot member.

One embodiment of the invention has been il lustrated in the accompanying drawings but it is to be expressly understood that said drawings are for purposes of illustration only and are not to be construed as a definition of the limits of the invention, reference being had to the appended .claims for this purpose.

In the drawings,

Figs. 1 and la are side views, partly in section,

lof the opposite en ds of a car underframe embodying the invention; v v

Figs. 2 and v2av are sectional plan views respectively of Figs. 1 and la;

Fig. 3 is an enlarged plan view of the friction mechanism shown in Figs. 1 and 2`;

Fig. 4 is a sectional view of said friction mechanism taken onthe line4--4 of Fig. 6; a

A Fig. 5 is a sectional view of said friction mechanism-taken on the line 5-5 of Fig. 8;

Fig. 6 is a sectional view of the friction mechanism taken on the line 6-6 of Fig. 3;

Fig. 7 is a sectional view taken on the line 7-7 of Fig. 5; v

Fig. 8 is a sectional view taken on the line 8-8 of Fig. 5;

Fig. 9 is an enlarged plan view of the slack control means shown in Fig. 1; and

Fig. 10 is an enlarged side view of the slack control means shown in- Fig. la.

Referring now to the drawings, the car stmoture embodies at its opposite ends suitable bolster construction including the center brace castings 1 and 2 and cover plates 3 and 4. End sills 5 and 6, flooring 7, and the usual side sills (not shown) all constitute parts of a car body of any suitable type which is supported at its opposite ends on coupler preferably engaging the resilient unit for pivotal movement as described hereinafter. An opening 16 is formed in the shank of the coupler and a'coupier key 17 extends through said opening and through'openings 18 formed in the cheek plates 12. Both the opening 16 and the openings 18 are' slightly longer than the greatest dimension of the coupler key 17. The parts are normally maintained in the position shown in Fig. 9, wherein the outer face of the coupler key is held against the outer edges 'ofopenings 18 and the inner face of the opening 16 is held'against-the inner face of the coupler key 17. The coupler may therefore move inwardly relative to the center member throughla distance equal to the sum of the differenlces between the dimensions of opening 16 and key 17 and the'dimensions of openings 18 `and key 17. 'Ihis movement which may, for

the car bolsters. The" longitudinally movable center member comprises lin the form shown spaced channel members 8 and 9 which extend slidably throughopenings in the bolster construction as shown in Figs. 2 and 2a and which are connected together at suitable points by tie and cover plates-10. In order to limit positively the extent of movement of the center member relative the center member and are adapted to engage the car holsters;

Draft and bumng forces are transmitted to the center member through couplers at the ends thereof, said couplers being preferably mounted for movement `of limited extent relative tothe center member for train slack purposes. As explained above, the extent of movement of the j nism is shown in detail in Figs. 9 and 10. Referring to these figures oppositely disposed cheek plates 12 are secured to the channel members constituting the centervmember'in any suitable manner as by means of rivets 13. These cheek plates are formed with inwardly projecting lugs or shoulders 14 which form supports for a resilient unit through which bufiing forces are trans- 'Ihe coupler 15 extends inwardly between the channels 8 and 9 and between the cheek plates 12, the butt of the example, be of the order of an inch to an inch and a half, provides a small amount of train slack for starting purposes.

Preferably the resilient unit interposed between coupler 15 and the lugs 14 is adapted to provide relatively small cushioning resistance through a limited portion of the coupler movement and to 100 provide a considerably greater resistance to movement of the coupler beyond this limited portion.

- In the form'shown this is accomplished by employing two banksof spring plates 19 and 20'surrounded by a strap 2l which is preferably inte- 105 gral with a follower plate 22. The bank of spring plates 19 bears against the lugs 14, hardened wear plates 23 being preferably interposed therebetween and wear plates 24 being interposed between the ends of the spring plates and the sides of the cheek plates 12. When the coupler moves inwardly relative to the center member under v a bumng blow, the small bank of spring plates 19 is flrst eifective to resist such inward movement, and the larger bank of plates is inactive until 115 the coupler has travelled inwardly a distance sufficient to deiieotA spring plates 19 untilv they engage the plates 20, whereupon both banksof. plates resist further inward movement of the coupler.

lMeans are provided whereby the coupler butt engages the follower plate 22 so as to be capable of pivotal movement. In the form shown, the oiiter face of the follower plate 22 is cylindrical in shape as shown at 25 and a corresponding cylin- 125 vdrically shaped pivot member 26 is held in ento the car holsters, stop plates 1l are provided on gagement with the cylindrical face 25 by means of curved ribs 27 engaged by similarly curved hook-shaped projections 28 on the follower plate 22. Accordingly the pivot member 26 is capable 130 of rocking movement by virtue of -its cylindrical shape, but it cannot be removed from assembled relation with follower plate 22 without removing the assembly from between the cheek plates l2. The coupler butt is seated on the pivot member 26, the latter being preferablv'provided with an outwardly extending projection 29 which extends into an opening formed in the coupler.

In the form shown, relative movement between the center member and the car body is cushioned at one bolster by suitable resilient means comprising a pair of coil springs 30 (Figs. 1a and 2a) positioned between the channels 8 and 9. 'Ilie springs 30 bear at one end against the inner face of the center brace 2.a follower plate 31 being preferably interposed therebetween. Links 32 extend through the coil springs 30 and through the follower plate 31, said links being pinned yat 93 to the ycenter brace 2. vAt the opposite ends of the springs 30', said links extend through open- 150 ings in a follower plate 34 and are provided with enlarged heads 35. When a bufllng force is'transmitted to the center member by means of the coupler 15, the center member is moved inwardly relative to the bolster and suitable stops 36 secured to the center member engage the follower plate 31 and compress the -springs 30 against the follower plate 34 which is held stationary by virtue of links 32 connected to the center brace. When a draft force is transmitted to the center member through the coupler 15, the `center member is moved outwardly relative to the bolster and suitable stops 3'? secured to the center member engage the follower plate 34 and compress the springs 30 against the follower plate 31 and the center brace 2. Accordingly relative movement between the center member and the bolster is resiliently cushioned in both directions by the springs 30.

At the opposite end of the car, relative movement between the center member and the car body is resisted by a friction unit comprising a wedge member which is engaged by friction elements. The wedge member increases in thickness in both directions away from its central portion and preferably separate shoes are provided to engage the wedge surfaces whereby the frictional engagement is not released when the parts are in their normal position. In Figs. 3 to 8 inclusive, a frictionunit of this type is shown in detail with its parts in the position occupied when the car body and center member occupy their normal relative position, the w'edge member being connected at its right-hand end to the bolster and the friction shoes being carried by av suitable housing secured to the center member. Obviously, however, the friction unit may be reversed and connected with the bolster at its left-hand end, as shown in Fig. 1.

Referring to Fig. 3, the wedge member comprises a substantially U-shaped plate 38 which is connected at 39 to the center brace 1, the outer ends of the legs of the U being secured together by a link 40. Preferably each of the legs of the U is provided with two raised wedge surfaces or tracks which slant in opposite directions. As seen in Fig. 3, the outer wedge surfaces 41 increase in height from right to left. while the inner wedge surfaces 42 increase in height from left to right.

The friction shoes which engage the wedge surfaces 41 and 42 and the resilient means for maintaining such frictional engagement are carried by a suitable housing 43 secured to the channels 8 and 9 in any suitable manner. As shown in Fig. 3, the upper portion of housing 43 extends substantially the entire width of the center member and is held between stops or lugs 44 secured to the channels 8 and 9 in any suitable manner as by rivets 45; The stop members 44 are preferably provided with inwardly extending ribs 46 (Figs. 5 and 8) which serve as upper guides for the wedge member 38. The upper portion of the housing 43 is preferably semi-circular in cross section as lshown at 47 in Fig. 5 and constitutes a housing for pairs of semi-cylindrical friction shoes 48 and 49,4 the outer pair of shoes 48 engaging the wedge surfaces 41 and the inner pair of shoes 49 engaging ,the wedge surfaces 42. The friction shoes are held against lateral movement by means of end walls 50 of the housing 43 and by means of a central rib 51 (Fig. 7).

The friction shoes 48, 49 and the wedge member 38 are maintained in frictional engagement by a suitable resilient means which is adapted to ,set up a greater frictional resistance to relative movement of the` friction shoes and wedge member away from the position shown in the drawings than toward said position. In the form shown, housing 43 is provided with a depending strap'constituted by arms 52, within which is a followerV plate 53 resiliently held in engagement with the lower face of the wedge member 38. The follower plate 53 extends transversely of the centermember and is provided at its ends with depending end walls 54 adjacent the inner faces of the channel members 8 and 9, these end walls being 'held longitudinally between stops or lugs 55 formed on the stop members 44. Preferably the end walls 54 are provided with lugs 56 (Fig. 6) which engage under the stops 55 to hold the follower plate against upward movement.

' Follower plate 53 is likewise provided with downwardly extending projections 57 which form between them a pocket 58 in which is positioned a bank of spring plates 59. The initial tension of spring plates 59 is regulated by the thickness of a spacing member 60 interposed between said plates and the bight of the strap formed by arms 52. Spacing member 60 is held in place by a downwardly extending lug 61 on ,one end and by a similar lug 62 which is secured to the opposite end in any suitable manner as by welding after the spacer has been inserted in position.

Operation- Draft and buiiing forces are transmitted to the center member through the coupler 15. In train service, coupler 15 is permitted a. limited amount of longitudinal movement relative to the center member which longitudinal movement is cushioned by the light spring unit 19 and is preferably only suiiicient to provide a small amount of train slack for train starting is preferably considerably less than that provided by the travel of the usual draft gear, being The train slack provided in this Way` of the order of one inch or less if desired. The

coupler 15 may also pivot with respect to the center member by virtue of the pivot member 26.

A draft force applied to the coupler 15 at the right-hand end of the car as seen in Figs. 1 and 1a is transmitted to the center member through the key 17 and cheek plates 12 so that the center member is moved from left to right relative to the bolsters. The car body is cushionedresiliently at the bolster at the right-hand end of the car and frictionally at the left-hand end of the car, and preferably the resilient resistance to relative movement between the car body and center member is equal to the frictional resistance so that the load is distributed between the bolsters. Referring to Fig. la, the stops 37 secured to the center memberengage the follower plate 34 and compress the springs 30 against the follower plate 31 and against the center` brace 2. Referringto Fig. 1, the housing 43 moves with the center member and carries with it the friction shoes 48, 49. The outer shoes 48 are held by the resilient means 59 in frictional engagement with the outer wedge surfaces The wedge member 38 is held stationj' portion of the energy. The inner shoes 49 are ineffective because the inner wedge surfaces 42 decrease in thickness from left to right as clearly shown ln Fig'. 1.

The resilient energy stored in springs by their compression as above described is effective to return the car body to normal position relative to the center` member since in this return movement the friction between shoes 48 and wedge surfaces 41 is less than it was on the shock absorbing movement. This result is due to the use of a resilient unit comprising the plate springs 59. During the shock absorbing movement the tension on the springs 59 increases and the spring plates tend to flatten out but this tendency is resisted to a large extent by virtue of the friction between the spring plates themselves. During the return movement of the shoes 48, the tension on the spring plates 59 is decreasing and the plates tend to return to their normal deflected condition so that the friction between the plates themselves is released.. Owing to this dierence in action of the resilient unit 59, the frictional resistance due to movement of the friction shoes relative to the wedge member in either direction away from their normal relative position shown in the drawings is greater than the resistance on return movement of the shoes and accordingly the load on the car bolsters may be divided evenly while at the same time the resilient force effective to return the car body and center memberA to normal relative position is greater than the frictional resistance to such return movement. The greater resilient force accordingly returns the center member and car body to normal relative position whileethls movement is snubbed by l the friction unit.

When a sumciently great bumng force is applied to the coupler l5, the center member is moved relative to the car body from right to left as seen in Figs. 1 and la. This movement is resiliently resisted at the right-hand end of the car since the stops 36 on the center member engage the follower plate 31 and compress the springs 30 against the follower plate 34 which is connected to the center brace 2. The operation of the friction unit at the left-hand end of the car is substantially the same as above described under a draft force, except that the housing 43 now moves from right to left relative to the bolsters and car body and the inner shoes 49 engage the inner wedge surfaces 42 while the outer friction shoes 48 are ineffective.

It will be understood that the coupler mechanism. the resilient cushion means and the friction unit may be substantially entirely enclosed in housings constituted by the channel members 8 and 9 and top and bottom cover plates 10. Should the coupler be broken or damaged and require replacement, it is only necessary to remove the key l'I whereupon the coupler 15 may be withdrawn and a new coupler inserted. This replacement interferes in no way with the pivot member 26 which is held in position by the interlocking ribs 28 land projections 29. In order to remove the resilient unit or pivot member, the bottom cover plate 10 is taken off and the entire unit dropped down. Until this is done it is impossible to withdraw the pivot member 26.

It will be seen that the frictional resistance afforded by the friction unit is the same whether the center member moves from left to right or from right to left with respect to the car body since the inner cam surfaces 42 and outer wedge surfaces 4l are similar. By the use of separate wedge surfaces and separate shoes, one or the 1,97avs1 other pair of shoes is always in frictional engagement with its wedge surfaces. Accordingly when the parts are in normal position shown in thedrawings, the shoes are not released from frictional engagement.

Advantage is taken of the characteristics of a bank of plate springs such as the spring unit 59 in order' that `the frictional resistance due to movement of the shoes away from their normal position on the wedge member shall be greater than on return movement of the shoes toward their normal position. This enables draft and bufilng blows to be distributed evenly between the two bolsters at the opposite ends of the car while at the same time the energystored in the resilient cushioning unit is in excess of the frictional resistance to return movement. Hence the car body and center member are normally maintained in their proper relative position and in the event of relative displacement under draft or bufllng blows are returned gradually to this position, the return movement being snubbed by the friction unit.

The tension ofthe plate springs 59 and hence the frictional resistance of the friction mechanism can be adjusted by varying the thickness of the spacing member 60. For example, if it is desired to increase the frictional resistance for any reason, the llug 62 is cut away from the spacing vmember '60 which is then withdrawn and replaced by a thicker spacing member. These spacing members can be made available in standard sizes and numbered so that adjustments may be .made by relatively unskilled workmen by merely replacing one sp'acer with the next spacer in the series.

`It will be understood that the invention is not limited to the embodiment described and illustrated in the drawings and that changes may be made in the form, details of construction and arrangement of the parts without departing from the spirit of the invention. Moreover, the coupler mechanism and the friction unit may be used in' other combinations. For instance,` it may be4 desirable to employ the particular coupler mechanism with two resilient'cushioning means or the friction unit may be used with other types of resilient cushion gears and coupler mechanism. Reference is therefore to be had to the appended claims for a definition of the limits 'or the ivention. e f

What is claimed is:

1. In a car structure of the type embodying a l continuous center member extending substantially the length of the car structure and mounted for longitudinal movementl relative thereto and resilient means operatively interposed between the center member and the car body and normally maintaining the same in a predetermined relative position, cooperating friction means secured to 13 the center member and car body for resisting relative movement therebetween, one of said means comprising a wedge'member which increases in thickness towards both of its ends, the other' of said means comprising a plurality of friction elements one engaging said wedge member to resist relative movement vof the center member and car body in one direction only and another engaging said wedge member to resist such relative movement in the other direction only, and means for maintaining said cooperating friction means in frictional engagement.

` 2. In a car structure of the type embodying a continuous center member extending substantially the length of the car structure', and mounted for longitudinal movement relative thereto and resilient means operatively interposed between the centermember and car body and normally maintaining the same in a predeterminedrelative position, the combination of a wedge member and cooperating friction elements, one secured to the center member and the .other to the car body, said wedge member having*4 separate wedgesurfaces effective in opposite directions of relative movement of the center member and car body, one of said friction elements engaging one of said surfaces and a separate friction element engaging the other surface, and means for maintaining said friction elements in frictional engagement with said surfaces. l

3. In a car structure of the type embodying a continuous center member extending substantaining the same in a predetermined relative position, the combination of a wedge member operatively secured to the car body and having separate wedge surfaces one increasing in height in one direction and the other increasing in height in the opposite direction, a plurality of friction shoes operatively connected to the center member, one of said friction shoes engaging one of said surfaces and a separate friction shoe engaging the other of said surfaces, and means for maintaining said shoes in frictional engagement with said surfaces. v

4. In a car structure of the type embodying a crntmuous center member extending substantial.;r4 the length of the car structure and mounted for longitudinal movement relative thereto and resilient means operatively interposed between the center member and the car body and normally maintaining the same in a predetermined relative position, cooperating friction means secured to the center member and car body for resisting relative movement therebetween, one of said means comprising a wedge member which increases in thickness towards both of its ends, the other of said means comprising a plurality of friction elements one engaging said wedge member to resist relative movement of the center member and car body in one direction and another engaging said wedge member to resist such relative movement in the other direction, and resilient means maintaining said cooperating friction means in frictional engagement, the frictional resistance caused by said resilient means on'relative movement of said center member and car body away from said predetermined position being greater than the resistance on relative movement of the center member and car body in returning to said predetermined position.

5. In a car structure of the type embodying a continuous center member extending substantially the length of the car structure and mounted for longitudinal movement relative thereto and resilient means operatively interposed between the center member and car body and normally maintaining the same in a predetermined relative position, the combination of a wedge member and cooperating friction elements, one secured to the center member and the other to the car body, said wedge member having separate wedge surfaces eifective in opposite directions of relative movement of the center member and car body, one

-and resilient means operatively interposed .be-

taining said wedge member and friction elements in frictional engagement, the frictional resistance caused by saidv resilient means on relative movement of said friction elements and wedge member away from their normal position being greater than the resistance on relative movement of said friction elements and wedge member towards said normal position. y

6. In a car structure of the type embodying a continuous center member extending substantially'the length of the car structure and mounted for longitudinal movement relative thereto tween the center member and car body and normally, maintaining the same in a predetermined relative position, the combination of a wedge member operatively secured to the car body and Having separate wedge surfaces one increasing in height in one direction and the other increasing in height in the opposite direction, a plurality of friction shoes operatively connected to the center member, one of said shoesengaging one of said wedge surfaces and a separate shoe engaging the other wedge surface,:and resilient means maintaining said friction shoes in frictional engagement with said wedge surfaces, the frictional resistance on movement of said shoes relative to said wedge surfaces away from normal position being greater than the frictional resistance on movement of said shoes toward normal position.

7. A friction unit comprising a housing, wedge means extending through said housing and increasing in thickness in both directions from its central portion, a plurality of individually mounted friction shoes carried by said housing, a separate shoe engaging each portion of increasing thickness, and means for maintaining said friction shoesin vfrictional engagement with said wedge means. a' 8. A friction unit comprising a housing carrying friction shoes, a wedge member having separate cam surfaces increasing in height in opposite directions, a strap depending from said housing, a follower plate extending through said strap and slidably engaging said wedge member, and resilient means interposed between said follower plate and the bight ,of the 'strap for. maintaining said shoes in frictional engagement with said wedge surfaces. y

9. A friction unit comprising a housing carrying friction shoes, a strap depending from said housing, a wedge member having portions slidably embracing said strap, said we dge member having surfaces increasing in heightv in opposite directions, a follower plate slidably engaging the lower surface of said wedge member, and resilient means interposed between said follower plate and the bight of the strap for maintaining said friction shoes in engagement 'with said wedge surfaces.

10. A friction unit comprising a housing having a substantially cylindrical portion and carrying therein a plurality of friction shoes, a strap depending from said housing, a wedge member having portions slidably embracing said strap, each portion having wedge surfaces increasing in height in opposite directions and said housing carrying a separate shoe for each surface, a follower plate extending throughthe loop of the strap and slidably engaging the lower surface of said wedge member, and resilient meas interposed between said follower plate and the bigh of the strap.

11. A friction unit comprising a housing,

x friction shoes wedge member increasing in thickness in-both directions from its central portion, friction shoes carried by said housing, a separate shoe engaging each portion of increasing thickness on opposite sides of sa'id housing, and resilient means comprising a plurality of plate springs for maintaining said shoes in-frictional engagement with y said wedge member.

12. A friction" unit comprising a housingcarrying a plurality'of friction shoes, a wedge member having separate wedge surfaces increasing in height in opposite directions, a strap depending4 from said housing, a follower plate slidably en-.'

gaging the lower surface ofA -said wedge member, and a plurality of plate springs interposed between said follower plate and the bight ofthe strap for maintaining the friction shoes in engagement with said wedge surfaces.

13. A friction unit comprising a housing carrying a plurality of friction shoes, a strap depending from said housing, a wedge member having portions slidably embracing said strap, said wedge member having friction surfaces which increase in height in opposite directions, a follower plate extending through the loop of the strap and slidably engaging the lower surface of said wedge member, and a plurality of plate springs interposed between the follower plate and the'bight of the strap for maintaining the in engagement with said friction surfaces.

14. A friction unit comprising a housing carrying a plurality of friction shoes, a wedge member having cam surfaces increasing in height in opposite directions, a strap depending from said housing, a follower plate slidably m8381118 the lower surface of said wedge member, and resilient means interposed between the bight of the strap and said follower plate for maintaining the friction shoes in engagement with ,said

wedge surfaces, the frictional resistance on movement of said housing in either direction away from its normal position relative to said wedge member being greater than the resistance on movement of said housing toward normal position.

15. A friction unitcomprising a housing carrying a plurality of friction shoes, a wedgemember having friction surfaces increasing in height in opposite directions, a strap depending from said housing, a follower plate slidably engaging the lower surface of said wedge member,r resilient means interposed between/said follower plate'and the bight of the strap for maintaining the friction shoes in engagement with said friction surfaces, and means for varying the initial tension of said resilient means. 1 y

16. A friction unit comprising a housing carrying a plurality of friction shoes, a wedge member having friction surfaces increasing in height in opposite directions, a strap depending from said housing. a follower .plate slidably engaging the lower surface of said wedge member, resilient means interposed between said follower plate and the bight of the strap for maintaining the fricftion shoes 'in engagement with said friction of the strap for fixing the initial tension of. said,

resilient means.

vmember interposed between said plate springs ing, a follower plate slidably .engaging the lower `surface of said wedge member, a plurality of plate springs operatively engaging said follower plate for maintaining said friction shoes in engagement with said wedge surfaces, and a spacing and the bight of the strap for fixing the initial tension of said springs.

18. A friction unit comprising a housing having a pocket and carrying therein a plurality of friction shoes, a strap depending from said housing, a wedge member having side portions slidably embracing said strap, said side portions having wedge surfaces which increase in height in opposite directions and said housing carrying a separate shoe for each surface, a follower plato extendlngthrough the loop of the strap and slidably engaging the lower' surface of said wedge member, a plurality of plate springs operatively engaging said follower plate, and a spacing member interposed between said plate springs and the bight of the strap.

19. In a car structure of the type embodying a continuous center member .comprising spaced members mounted for ,longitudinal movement relative to the car body and holsters, a housing 105 positioned betweenlsaid spaced members, means for securing said housing to said spaced members for longitudinal movement therewith, a plurality of friction shoes carried by said housing, a wedge member operatively connected toone `of said bolsters and having wedge surfaces increasing in height in opposite directions, said housing carrying a separate shoe for each surface, a strap depending from said housing, a follower plate extending through the loop of said strap and slidably engaging the lower surface of said wedge member, means for securing said follower plate to said spaced members for longitudinal movement therewith, and resilient means interposed 'between saidfollower plate and the bight of4 the s rap.

20. In a carstructure of the type embodyingl a draft and bufilng column comprising spaced members mounted for longitudinal movement relative to the car body and bolsters, a housing 121i positioned between said members, means operatively connecting said housing with said members v for longitudinal movement therewith', said housing being capable of vertical movement with respect to said members, a plurality of friction 130 shoes carried by said housing, a wedge member i operatively connected to one of said holsters and 'having wedge surfaces increasing in height in opposite directions, a follower plate slidably engaging the lower surface of said wedgemember, means operatively connecting said follower plate to' said spaced lmembers for longitudinal movement therewith and holding said follower plate against vertical movement, a strap depending from said housing, and resilient means interposed between said follower plate and the bight of the strap for maintaining said friction shoes in engagement with said wedge surfaces.

EINAR B. NORBOM.

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