Self-compensating railway hand brake linkage

Claim 2

In a railway car braking mechanism for applying braking force to one or more brake shoes, the combination comprising brake shoe linkage for applying a braking force to a brake shoe, a crank type of lever having an arm which pivots about a fulcrum, a pulley secured at an outward disposed portion of said lever, means for connecting said brake shoe linkage to said lever at a radial location intermediate said fulcrum and said pulley, elongated force transmitting means having at least a portion which is flexible and looped through said pulley and having one end fixedly secured relative to said fulcrum, force applying means connected to the other end of the elongated force transmitting means for applying to said pulley a force acting in a second direction, thereby to rotate said lever about said fulcrum and to apply a greater force to the brake shoe linkage.

Claim 3

The combination claimed in claim 1 wherein said crank type of lever includes a curved surface in the region thereof between the fulcrum and the radial location where the brake shoe linkage is connected, at least a portion of said curved surface having a substantially constant radius of curvature relative to said fulcrum.

Claim 4

The combination claimed in claim 2 wherein said brake shoe linkage is flexible at least in the immediate portion thereof where it is connected to the lever, whereby the flexible portion of said linkage progressively contacts and conforms to the curved surface of the lever as the lever is rotated about said fulcrum.

Claim 5

In a railway car braking mechanism for applying braking force to one or more brake shoes, the combination comprising brake shoe linkage for applying a force acting in a given direction to one or more brake shoes, a bell crank type of lever having an arm which pivots about a fulcrum that is fixed relative to the frame of said car, a pulley secured at an outwardly disposed portion of the lever, means including a first chain for connecting said brake shoe linkage to said lever at a radial location between said fulcrum and said pulley, said lever having a curved surface in the region thereof between the fulcrum and said radial location where the brake shoe is connected, said curved surface being convex in the direction toward said first chain and at least a portion thereof having a substantially constant radius of curvature relative to said fulcrum, force transmitting means including a second chain which is looped through said pulley and has one end fixedly secured relative to the fulcrum, force applying means connected to the other end of the second chain for drawing the second chain around the pulley and thereby rotating said lever about said fulcrum in a direction away from the first chain, said second chain and pulley being arranged to provide a mechanical advantage that multiplies the force that is applied at said other end of the second chain, the connection of said first chain to said lever providing another mechanical advantage which further multiplies the force applied to the other end of the secured chain.

Claim 6

In a railway car braking mechanism for applying braking force to one or more brake shoes, the combination comprising brake shoe linkage for applying a force acting in a given direction to one or more brake shoes, a bell crank type of lever having an arm which pivots about a fulcrum that is fixed relative to the frame of said car, a pulley secured at an outwardly disposed portion of the lever, means including a first chain for connecting said brake shoe linkage to said lever at a radial location between said fulcrum and said pulley, said lever having a curved surface in the region thereof between the fulcrum and said radial location where the brake shoe is connected, said curved surface being convex in the direction toward said first chain and at least a portion thereof having a substantially constant radius of curvature relative to said fulcrum, force transmitting means including a second chain which is looped through said pulley and has one end fixedly secured relative to the fulcrum, force applying means connected to the other end of the second chain for drawing the second chain around the pulley and thereby rotating said lever about said fulcrum in a direction away from the first chain, said second chain and pulley being arranged to provide a mechanical advantage that multiplies the force that is applied at said other end of the second chain, the connection of said first chain to said lever providing another mechanical advantage which further multiplies the force applied to the other end of the secured chain.

Claim 7

The combination claimed in claim 4 wherein the means that includes a first chain for connecting said brake shoe linkage to said lever further includes a floating pulley block connected to the end of the first chain opposite to the end that is connected to said lever, a third chain looped around said floating pulley block and having each end connected to a respective brake shoe linkage.

Claim 8

In a railway car braking mechanism for applying substantially equal braking forces to at least two brake shoes, the combination comprising first and second brake shoe linkages for applying respective forces to said two brake shoes, double bell crank type of lever means having two lever arms rotatable together about a common fulcrum that is fixed relative to the frame of said car, means including respective chain linkage for connecting each brake shoe linkage to a respective lever arm at a location thereon between said fulcrum and an outwardly disposed location, said lever means having two surfaces that are convexly curved in a general direction toward the brake shoe linkages, said curved surfaces being located adjacent the positions where the chain linkages connect to the lever arms and having at least portions thereof of substantially constant radii of curvature relative to the fulcrum, said curved surfaces being located closer to said fulcrum than the locations where the chain linkages are connected to the lever arms, a pulley attached to said lever arms at said outwardly disposed locations, a force transmitting chain secured at one end to the frame of the car and passing through the pulley in such a manner as to provide a force multiplying mechanical advantage when said chain transmits a force to the lever means, force applying means connected to the other end of the force transmitting chain to rotate said lever means and apply a pulling force to the brake shoe linkage.

Claim 9

In a railway car braking mechanism for applying substantially equal braking forces to at least two brake shoes, the combination comprising first and second brake shoe linkages for applying respective forces to said two brake shoes, double bell crank type of lever means having two lever arms rotatable together about a common fulcrum that is fixed relative to the frame of said car, means including respective chain linkage for connecting each brake shoe linkage to a respective lever arm at a location thereon between said fulcrum and an outwardly disposed location, said lever means having two surfaces that are convexly curved in a general direction toward the brake shoe linkages, said curved surfaces being located adjacent the positions where the chain linkages connect to the lever arms and having at least portions thereof of substantially constant radii of curvature relative to the fulcrum, said curved surfaces being located closer to said fulcrum than the locations where the chain linkages are connected to the lever arms, a pulley attached to said lever arms at said outwardly disposed locations, a force transmitting chain secured at one end to the frame of the car and passing through the pulley in such a manner as to provide a force multiplying mechanical advantage when said chain transmits a force to the lever means, force applying means connected to the other end of the force transmitting chain to rotate said lever means and apply a pulling force to the brake shoe linkage.

Claim 10

The combination claimed in claim 6 wherein said chain linkage for connecting each brake shoe linkage to a respective lever arm includes, a floating pulley block having respective linkages connected to the two lever arms, a U-shaped chain looped through said pulley block and having its two ends respectively connected to said first and second brake shoe linkages.