US1947812A - Friction draft gear - Google Patents

Description

Feb. 20, 1934. Rl R STEVENS 1,947,812

FRICTION DRAFT GEAR Filed Jan. 29, 1930 'I- sl I /6 /2 /3 /7 /4 T553 Ti .5

ATTO EY Patented Feb. 2G, 1934 PATENT OFFICE` FRICTION DRAFT GEAR Roy R. Stevens, Forest Hills, Pa., assigncr'to The Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Application January 29,

Z Claims.

This invention relates to draft gear mechanism of the type in which the cushioning action is performed by successively acting spring and friction means.

The principal object of the invention is `to provide for the application of pressure to the initial spring resistance directly, and to delay compressive action upon the friction resistance until the spring resistance has been availed of Ito the desired extent.

Another object of my invention is to provide an improved draft gear mechanism of the above type having an improved arrangement of the frictional elements.

Other objects and advantages will appear in the following more detailed description of my invention.

In the accompanying drawing; Figure 1 is a plan view, partly in section, of a draft rigging 'i embodying one form of my invention; Fig. 2

is an end elevation of the draft gear mechanism shown in the draft rigging in Fig. 1; Fig..3 is an end elevation of the draft gear mechanism shown in the draft rigging of Fig. 1 and showing the shell containing the friction elements partly removed from the main gear housing; Fig. 4 is a partial plan view, mainly in section, of a draft rigging showing a modified -form of my invention; Fig. is a transverse sectional view of the draft gear mechanism shown in Fig. 4 and taken on the line 5--5; Fig. 6 is a partial sectional View of the draft gear mechanism shown in Figs. 4 and 5 and taken on line 6-6 of Fig. 5; and Fig. 7 is a partial plan view,

mainly in section, of a draft rigging showing another modied form of my invention.

As shown in the drawing, the draft rigging comprises center or draft sills 1-1 of a railway car underframe, and to the inner sides of said "i sills are secured the usual front stop lugs 2-2 and rear stop lugs 3 The inner end of a draw bar 4 is operatively connected to a yoke 5 of well known form. Disposed within the yoke 5 is a draft gear mechanism embodying my inr jvention, as well as a follower plate 6, the yoke 5 being supported by a detachable saddle plate '7 secured to the draft sills.

The draft gear mechanism shown in Figs. 1, 2 and 3 comprises a chambcred follower 14, constituting a housing for other elements, having side walls 8, tcp and bottom walls 9 and a rear end wall 10 connecting the top and bottom walls 9. The side walls 8 are preferably omitted adjacent the rear end wall 10, and the top and `bottom Walls 9 are omitted at their forward ends.

1930. Serial No. 424,202

A hollow rectangular friction shell 11 is mounted in the forward open end of the mainA gear housing and has sidewalls 16 and top and bottom Walls 17, said shell being open at both ends. A transverse rib or stop lug 12 is provided on the outer face of each side wall 16 of the friction shell 11 and projects into a transverse groove 13 formed in the inner face of each side wall 8 of the main gear casing, the grooves 13 being of greater width than the stop lug 12 for permitting relative movement between the friction shell and main gear housing.

A pair of longitudinal oppositely disposedV wear plates 18 and 19 are fitted against the sidev walls of the friction shell and are anchored in its top and bottom walls 17 by the engagement of lugs 45 on said plates with corresponding grooves 46 in the top and bottom walls. The wear plates 18 and 19 are thus adapted to be maintained in stationary engagement with the inner faces of the side walls 16 and are'provided with wedging friction faces 20 and 21,V respectively, which are adapted to engage outer.; faces of a pair of oppositely disposed movable friction shoes 22 and 23. The friction shoe 22 has a friction face 24 engaging a corresponding friction face of a Wedge block 25, while the fric-V tion shoe 23 has an oppcsitely facing frictionV face 40 engaging a corresponding friction face of a Wedge block 26. Y

The wedge blocks 25 and 26 are disposed on the opposite sides of a thrust-like member 27 and have parallel friction faces 28 and 29, respectively, engaging the opposite parallel sides of said member.

The member 27 is T-shaped and is provided at its forward end with a cross head 30, the.

rality of nests of springs, comprising outer'.

springs 33 and springs 34 contained within the springs 33. At one end, the springs 33 and 34 engage the rear end wall 10 of the gear housing. The forward ends of the springs 33 engage a spring plate and hold said plate in engagement with the rear end of the member 27. The Y forward ends of the inner springs 34 extend through apertures in the spring plate k35 and sliy engage another spring plate 36 spaced from the spring plate 35 and having a central opening through which the member 27 extends, the front face of the spring plate 36 engaging the rear faces of the two wedge blocks and 26.

A key 37 is fixed in the top and bottom walls 17 of the friction shell 11 and extends through a slot 38 formed in the member 27, thereby limiting outward movement of said member and thus holding the friction elements assembled.

To assemble the draft gear mechanism, the nests of springs 33 and 34 and the spring fcllower are placed in position in the main gear housing through the openings in side walls 3. The spring follower 36 is inserted through the open forward end of the main gear housing. The stop lugs 12 on the friction shell 11 are then started in the 'grooves 13 in the main gear casing, and the friction shell is pushed into the position shown in the drawing, the method of insertion of the friction shell into the main gear casing being most clearly shown in Fig. 3 of the drawing, in which the friction shell is partly removed from the casing.

The wear plates 13 and 19 are then assembled with the lug on each side of said plates inserted into the corresponding groove 46 in the top and bottom walls 17 of the friction The wedge blocks 25 and 26, friction shoes 22 and 23, and member 27 are then assembled in the friction shell in the relation shown in Fig. 1 of the drawing, after which pressure is applied to head 30 of the member 27 which compresses springs 33 and 34 and moves the friction elements to the position shown in the drawing in which the key 37 is inserted through the top and bottom walls 17 of the friction shell l1 and slot 33 in the member 27.

In operation, during compression of the draft gear mechanism, the follower plate 6 and main gear casing are moved relatively toward each other. The pressure applied to the head portion 30 of the member 27 moves it and the friction shell, containing the friction elements,

forward in the main gear housing, thereby compressing springs 33 and 34. During this action the friction elements advance as a unit, that is, without relative movement, and consequently offer no resistance, such advance being opposed only by the springs 34. When the lugs 12 on the friction shell 11 engage the rearward face of the transverse grooves 13 in the side walls 8 of the main gear housing, relative movement of the friction shell and main gear housing is stopped, after which the friction elements contained in the friction shell 11 are operated to build up a greater resistance to compression than is provided by springs 33 and 34.

After the relative movement of the friction shell and main gear housing is stopped, the pressure acting through the head 30 of member 27 forces the friction shoes 22 and 23 inwardly and against the wedge faces of the wear plates -18 and 19 and against the wedge faces of the wedge blocks 25 and 26. Due to the inclination of the wedge surfaces on the wear plates 18 and 19, the friction shoes 22 and 23 are also moved inwardly or transversely of the friction -shell, resistance being effective at the wedging faces 20 and 21 of the wear plates 18 and 19 and faces 31 and 32 of the friction shoes. Such movement of the friction shoes displaces the wedge blocks 25 and 26 rearwardly at a rate exceeding the relative movement of the member 27 and main gear casing, frictional resistance to movement thereby being effective on friction surfaces 28 and 29 which engage the parallel faces of the member 27 and on friction surfaces 24 and 40 of the friction shoes. During this movement, the springs 33 are further compressed by the member 27 and the springs 34 are compressed by the movement of the wedge blocks 25 and 26. This action continues until the follower plate 6 engages the forward face of the side walls 3 of the main gear housing at which time the draft gear mechanism becomes a solid unit.

During release of the mechanism, upon the actuating force being reduced, the expansive action of the springs 33 and 34 effect restoration of the friction shell 11 to its normal position. Springs 33 force the member 27 outwardly until limited by hey 37 in slot 38, and springs 34 acting on wedge blocks 25 and 26 move said blocks and the friction shoes 22 and 23 outwardly until movement thereof is limited by the head 30 on member 27.

t will be noted that the movement of the member 27 during the latter portion of the compression and release of the draft gear mechanism is resisted by the frictional engagement of the wedge blocks 25 and 26 on opposite parallel faces of said member. Although this is the preferred construction of my improved draft gear mechanism, it may be desirable under certain conditions to have the member 27 movable freely relative to the friction elements, such a modified construction being shown in Figs. 4, 5, and 6 of the drawing. Another modification shown in Figs. 4, 5, and 6 relates to the means for obtaining preliminary spring resistance followed by frictional resistance in a draft gear of the type contained within a single housing.

In the following description of the modified forms of my invention, the parts which are like the parts shown in the preferred form will be indicated by like reference characters.

The draft gear mechanism shown in Figs. 4, 5, and 6 of the drawing, comprises a hollow rectangular housing having side walls 75, top and bottom walls 47 and a rear end wall (not shown), the forward end of said casing being open and the side walls being omitted adjacent the rear end wall.

Within the housing are oppositely disposed a pair of wear plates 13 and 19, engaging the side walls and anchored in the top and bottom walls 47 by the engagement of lugs 45, on each of said plates, in a transverse groove 48 formed in both the top and bottom walls. A spacer 49, having a central rectangular longitudinal opening 51 therethrough and a transverse rib 50 on each end, is disposed within the gear housing, the ribs 50 projecting into transverse grooves 43 in the top and bottom walls thereof. Fricticnally engaging the two opposite sides of 135 the spacer 56 are wedge blocks 25 and 26, and interposed between said wedge blocks and the wear plates 13 and 19 are friction shoes 52 and 53, respectively, each of said friction shoes having a toe 54 extending laterally outwardly overlapping the rearward face of the adjacent wear plate. Engaging the rearward end of the wedge blocks 25 and 26 is a spring plate 36 subject to the pressure of springs 34.

A thrust member 27 is freely movable through the opeining 51 in the spacer 49 and at the rearward end engages a spring plate 35, which is subject to the pressure of springs 33.

To assemble this draft gear mechanism, the springs 33 and 34 and follower plate 35 are in- 15o serted through the open side walls ofthe housing and then positioned as shown inthe drawing. The follower 36 is inserted through the open forward end of the housing. The wear plates 18 and 19 are turned diagonal to the verical transverse axis of the housing, then inserted through the open end of the housing until lugs 45 line up with the transverse grooves 48. The wear plates are then turned parallel to the vertical transverse axis of the housing and positioned as shown in the drawing. in a like manner, the spacer i9 is also assembled in the housing. Next the wedge blocks 25 and 26 are positioned as shown, in engagement with the spring plate 36. The friction shoe 52 is inserted between wear plate 18 and wedge block 25, and the friction shoe 53 is inserted between wear plate 19 and wedge block. 26. The member 27 is inserted through opening 51 in spacer 49 and pressure is then applied to the head 30 of member 27, which acts through spring follower 35 to coinpress springs 33 and at the same time engages and shifts the friction shoes 52 and 53 rearwardly until the toe 54 on each of said shoes passes the rearward end of the wear plates 18 and 19. The key 37 is then inserted through the housing and member 27 after which the pressure is removed from the member 27. Thereupon the spring 33 moves the member 27 to the position shown in the drawing, in which the head 30 is out of engagement with the friction shoes 52 and 53. When pressure is removed from the thrust member, the pressure of springs 34 shifts the wedge blocks and friction shoes to the position shown in the drawing in which the toe 54 on each of said shoes engages the rearward end of the corresponding wear plate.

The operation of this modified form of draft gear mechanism is substantially the same as the operation of the preferred form shown in Figs. 1, 2, and 3 of the drawing and hereinbefore described, except it will be noted'that the member 27 and springs 33 only are in action during the preliminary compression stroke, i. e., before the friction elements are operated, and are entirely free of frictional resistance from the friction elements, since t .e thrust member eX- tends freely through the opening 51 in spacer 49 to engage the spring follower. During compression, when the purely spring action is completed, the head 30 of the thrust member, engages the forward faces of the friction shoes 52 and 53 and operates the friction elements. The friction elements operate in the same manner as those shown and described in Figs. 1, 2, and 3 of the drawing, except that the friction faces 28V and 29 of the wedge blocks 25 and 26, respectively, operate against corresponding faces of the stationary spacer 49 instead of against a relatively movable member 27 as hereinbefore described.

1n Fig. 7 is shown another modified form of my invention which is substantially the same as that shown 1, 2 and 3 and hereinbefore described, except for the wedging system.

The draft gear mechanism shown Yin Fig. 7 comprises a main gear housing 14, a friction shell l1 removably inserted in the forward end of the main gear housing and relatively mov lable thereto. The main gear housing `has top and bottom walls 9, side walls 8 and a rear end wall (not shown), the side walls S being omitted adjacer. the rear wall, and the top and bottom walls are omitted at the forward ends. Contained in the friction shell are removable weer plates i8 and 19 anchored to the top and bottom walls 9 of the main shell by lugs 45 eX- Vtending into corresponding grooves in the shell wall. Frictionally engaging said wear plates are a pair of spaced friction slices 56 and 57 and interposed between said friction shoes and having frictional engagement therewith, is a thrust member 53.

The member 58 extends through the friction shell and a spring follower 36, and engages a spring follower 35 between which and the rear end wall of the main gear casing springs 33 are interposed. The spring follower 36 engages the rearward ends of the friction shoes 56 and 57, and is engaged by one end of springs 34, the opposite ends of which also engage the rear end wall of the main gear housing.

This draft gear mechanism is assembled in the same manner as the draft gear mechanism shown in Figs. 1, 2 and 3 of the drawing and hereinbefore described.

in operation, under compression, the follower plate 6 and main gear housing 14 are moved relatively toward each other. The resistance to movement of the friction elements Within the friction shell is greater than the compressive force of the springs 34, so that under compresion, the friction shell is initially moved as a unit relative to the main gear housing, thereby compressing the springs Se. When the lugs 12 105 on the friction shell engage the rearward faces of grooves 13 in the main gear housing, relative movement between said shell and housing is stopped. Further compression of the gear mechanism then causes the wedge faces 60 and 110 61 on the member 53 to displace the friction shoes 56 and 57 rearwardly along the wedging faces 21 and 2G of the wear plates 19 and 18, which effects a lateral inward movement of said friction shoes.

During release of the mechanism upon a reduction in the actuating force, springs 33 and 34 expand and restore the thrust member and friction shell 11 to their normal positions. Springs 35 acting through spring follower S5 120 shift the member 58 forwardly, which permits springs 34 acting through spring follower 36 to shift and return the friction shoes 56 and 57 to their normal positions.

While illustrative embodiments of the inven- 125 tion have been described in detail, it is not my intention to limit its scope to such embodiments or otherwise than by the terms of the appended claims.

Having now described my invention, what I 130 claim as new and desire to secure by Letters Patent, is:

1. In a draft gear mechanism, the combination with a casing, of a movable compression member extending into said casingY and having friction surfaces at right angles to the longitudinal center line of the casing, a movable wedge bloeit on each side of said compression member, a movable friction shoe on each side of said compression member and adapted to have l wedginCr engagement with each of said wedge blocks and frictional engagement with the friction surfaces on said compression member, a stationary friction plate anchored to each of two opposite sides of said casing and engaging #ai said friction shoes, a spring for opposing the movement of said compression member, and another spring for opposing the movement of said wedge blocks and friction shoes.

2. In a draft gear, in combination, a cham- 55 bered follower, a longitudinally apertured friction block within the open end of the follower and anchored thereto against longitudinal movement and having lateral friction faces, cooperating Wedge elements interposed between and frictionally engaging the side walls of the follower and of the friction block, a, thrust member engageable with the outer end of one of the wedge elements of each pair and having a stem projecting through the friction block, and independent spring means opposing the advance of the Wedge elements and of the thrust member.

ROY R. STEVENS.

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