Patent Application
20170320506
The present invention relates to railcar coupling systems, and more particularly to a yoke for use in draft gear assemblies used in conjunction with draft sills and couplers in locomotives.
Draft gear assemblies form the connection between the couplers at the ends of adjoining railroad freight cars and the draft sills at the ends of the freight cars. The draft sills are commonly cast or fabricated sills that are mounted at the ends of the center sills of the railcar. The draft sills have a pair of front stops and a pair of rear stops, with a draft gear pocket between the stops. The draft gear assembly is received in the draft gear pocket.
Each draft gear assembly is connected to one coupler, and couplers of adjacent rail cars are connected to form the train. The train may be one hundred cars long and drawn or pushed by one or more locomotives. Typically, there is a limited amount of slack or free movement allowed between the cars. This slack permits the rail cars limited movement toward and away from each other in response to train action and yard impact events.
Train action events include, for example: locomotive start up and acceleration; dynamic braking; differences in braking forces of adjacent cars; and gravity-induced movement of the cars as the train moves onto and away from inclines. Yard impact events include “humping” of the individual cars to build the train in the yard; in humping, a car is pushed over a hump in the track in the yard, released and allowed to roll down the incline of the hump toward an awaiting car.
Train action events and yard impact events both subject the couplers of the cars to buff impacts, and train action events also subject the couplers of the cars to draft impacts. These impacts are transmitted from the couplers to the draft gear assemblies to the rail car body. That is, as the couplers are pulled or pushed, the movement is translated to the freight car body through the draft gear assemblies. Typical draft gear assemblies include a yoke element that is connected to the coupler through a pin or key, a coupler follower and a draft gear, as well as other elements. Generally, the coupler follower is positioned against or closely spaced from the butt end of the coupler in the draft gear pocket, within the yoke. The draft gear is positioned between the coupler follower and the rear stops of the draft sill.
In buff events, the butt end of the coupler moves inward against the coupler follower toward the rear stops of the draft sill. As the coupler and coupler follower are moved rearward, the shock of the movement is transferred to the draft gear. The draft gear typically absorbs and dissipates some of the energy from this shock through friction.
In draft events, slack is taken up between adjacent cars beginning at one end of the train and ending at the other end of the train. As a result of the slack being progressively taken up, the speed differences between the railcars increases as the slack at each coupler pair is taken up, with a resultant increase in buff and draft impacts on the couplers. This slack is taken up progressively, coupler pair by coupler pair.
There is an on going review of the weight of freight car and locomotive components in an effort to maintain strength and performance, while lessening the weight of such components. One known yoke for use in a locomotive draft gear assembly is made of Grade B cast steel and weighs about 500 pounds. The yoke of the present invention is usually made of Grade E cast steel and weighs about 288 pounds in a preferred embodiment. The weight reduction of about 42% is significant.
It is an object of the present invention to provide our improved, lighter weight yoke for use in a locomotive draft gear assembly.
In one aspect, the present invention provides a yoke having a front wall, a back wall, a top strap and a bottom strap extending from the back wall toward the front wall. The top strap and bottom strap of the yoke are tapered to a reduced width at the back wall. The top strap and bottom strap also have a reduced thickness by an indentation of the outer surface of each along most of their length.
Referring to the drawings,
Referring now to
Back wall 16 is shown as having an inner concave surface 17 adapted to abut against the complementary convex surface of a rear follower.
Front wall 18 is seen to comprise two side sections 28 that are spaced laterally and extend from top strap 12 to bottom strap 14. Front wall 18 is further seen to comprise a top section 22, center section 26, and bottom section 24. Each of front wall top section 22, front wall center section 26 and front wall bottom section 24 are seen to have a convex edge extending from a center forward most portion back into contact with front wall side sections 28. A draft pin retainer 20 is seen to extend downwardly from front wall bottom section 24. By such a design of front wall top section 22, front wall center section 26 and front wall bottom section 24, significant weight savings are provided with requisite strength.
Bottom strap 14 is seen to include indented section 32 of reduced thickness in a center area of the outer surface of bottom strap 14. The outer surface of top strap 12 contains a similar indented area 34 of lessened thickness in an effort to reduce overall weight of yoke 10. The area of reduced thickness in bottom strap 14 extends from a location inward from back wall 16 to a location inward of the intersection of bottom strap 14 with front wall side sections 28. The area of reduced thickness in top strap 14 extends from a location inward from back wall 16 to a location inward of the intersection of top strap 12 with front wall side sections 28.
Bottom strap 14 is also seen to have reduced lateral extent wherein the width of bottom strap 14 is lessened from front wall 18 intersection with side wall 28 toward back wall 16. A similar reduced lateral extent is present on top strap 12 whereby top strap 12 is reduced in width from front wall 18 intersection with side wall 28 toward back wall 16. The width sections of top strap 12 and bottom strap 14 decreases from about 14.4 inches at the intersection with side wall 28 to about 8.25 inches at back wall 16. Further, back wall 16 has a reduced width of about 5.5 inches. The reduced width of top strap 12 and bottom strap 14 and back wall 16 combine to provide further weight savings in the improved design of yoke 10.
Referring now to
Coupler follower 52 is usually a cast steel, generally rectangular structure. Coupler follower 52 is seen to be inserted between top strap 12 and bottom strap 14 of yoke 10 and adjacent the inner surface 19 of front wall 18. Rear follower 54 is quite similar to front follower 52 but is of a bit larger depth. Rear follower 54 is seen to have a rear face that is positioned adjacent inner surface 17 of back wall 16. Rear follower 54 is also positioned between top strap 12 and bottom strap 14. Both coupler follower 52 and rear follower 54 are usually comprised of cast steel.
Draft gear 56 is seen to be positioned between top strap 12 and bottom strap 14 of yoke 10, and is also positioned between rear wall 72 of coupler follower 52 and rear wall 74 of rear follower 54. Draft gear 56 is seen to comprise a series of plates 58, which are usually circular in cross section and metallic, usually of steel composition. Between each plate 58, elastomer pad 60 is located. As seen from
In a buff situation, when lateral force is applied through coupler shank 64 and pivot end 66 laterally into draft gear assembly 50, sufficient tolerance is provided in the opening for pivot pin 65 such that coupler butt end 66 contacts the front face of coupler follower 52 and imparts a laterally compressive force against draft gear 56. Draft gear 56 accordingly acts as a cushioning device to absorb some of the buff load from the coupler. In draft, when horizontal force is applied through coupler shank 64, such force is applied through pivot pin 65 into front wall 18 of yoke 10.
