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Improved Wheelchair Brake Shoe

IP.com Disclosure Number: IPCOM000004560D
Publication Date: 2001-Jan-31
Document File: 5 page(s) / 145K

Publishing Venue

The IP.com Prior Art Database

Abstract

A conventional wheelchair brake consists of a single rod or bar that is pressed against the tire of a wheelchair. Typically one brake is provided for each large wheel. In one common design, a system of links and levers provides a locking action that holds the braking element against the tire. The user of the wheelchair may use such brakes to control speed on an incline as well as to hold the wheelchair in a stationary position. The rod or bar braking element must be adjusted correctly to balance the braking force necessary to hold the wheelchair in place against the force required on the handle in order to engage the brake. Often, the force necessary to hold the chair in place on an incline necessitates adjusting the assembly such that considerable force is needed to engage the brake. What is needed is a brake mechanism that will provide added braking force without increasing the effort needed to engage the brake. FIG. 1 shows a typical wheelchair brake assembly, including a handle 110, a stationary link 120, a floating link 130, a brake link 140, and a brake shoe 160, connected as shown. Stationary link 120 is firmly connected to the wheelchair frame 105 by mounting bolts 125 and 128, which engage threaded holes in frame 105. Handle 110 is connected to stationary link 120 by mounting bolt 128 and to floating link 130 by link bolt 136 with enough looseness to allow pivoting action. Brake link 140 is connected to stationary link 120 by link bolt 135, to floating link 130 by link bolt 135, and to brake shoe 160 by brake shoe bolt 165, also with enough looseness to provide pivoting action. Brake shoe 160 is attached to one end of brake link 140 by brake shoe bolt 165 with enough looseness to provide pivoting action. Brake spring 170 is attached to brake shoe bolt 165 and held firmly in place as shown in FIG. 2. FIG. 2 shows a front view of the assembly of FIG. 1, indicating the additional elements of link nuts 250, which are self-locking nuts that include a plastic ring or other insert to provide locking to the threads of a bolt, and lock nut 260, of similar design. Link nuts 250 are adjusted to allow pivoting action of the links connected to corresponding bolts 136, 165, and 135 (not shown). Brake spring 170 is shaped to fit around brake shoe bolt 165 and is held firmly against link nut 250 on brake shoe bolt 165. Brake spring 170 is also shaped and attached to provide a rough alignment of brake shoe 160 and wheel 175 when the brake is disengaged as shown in FIG. 1. FIG. 3 shows the brake mechanism in an engaged state with brake shoe 160 in firm contact with tire 175. In operation, the user pushes handle 110 in a forward direction (to the right in FIG. 1) in order to engage the brake. This causes floating link 130 to push brake link 140 in a rearward direction (to the left in FIG. 3), pivoting at the brake link 140 point of attachment to stationary link 120. As brake link 140 pivots on link bolt 135, brake shoe 160 is forced into firm contact with wheel 175. When the angle between handle 110 and floating link 130 passes 180 degrees, the mechanism locks as shown in FIG. 3. FIG. 4 shows front, side, and bottom views of brake shoe 160. As seen in FIG. 4., the surface of brake shoe 160 that contacts tire 175 has a texture 450 which consists of raised bumps, dimples, ridges, or other pattern that substantially increases friction between brake shoe 160 and wheel 175, thus improving the holding force of the brake.

This text was extracted from a RTF document.
This is the abbreviated version, containing approximately 84% of the total text.

Improved Wheelchair Brake Shoe

A conventional wheelchair brake consists of a single rod or bar that is pressed against the tire of a wheelchair. Typically one brake is provided for each large wheel. In one common design, a system of links and levers provides a locking action that holds the braking element against the tire. The user of the wheelchair may use such brakes to control speed on an incline as well as to hold the wheelchair in a stationary position. The rod or bar braking element must be adjusted correctly to balance the braking force necessary to hold the wheelchair in place against the force required on the handle in order to engage the brake. Often, the force necessary to hold the chair in place on an incline necessitates adjusting the assembly such that considerable force is needed to engage the brake. What is needed is a brake mechanism that will provide added braking force without increasing the effort needed to engage the brake.

FIG. 1 shows a typical wheelchair brake assembly, including a handle 110, a stationary link 120, a floating link 130, a brake link 140, and a brake shoe 160, connected as shown. Stationary link 120 is firmly connected to the wheelchair frame 105 by mounting bolts 125 and 128, which engage threaded holes in frame 105. Handle 110 is connected to stationary link 120 by mounting bolt 128 and to floating link 130 by link bolt 136 with enough looseness to allow pivoting action. Brake link 140 is connected to stationary link 120 by link bolt 135, to floating link 130 by link bolt 135, and to brake shoe 160 by brake shoe bolt 165, also with enough looseness to provide pivoting action. Brake shoe 160 is attached to one end of brake link 140 by brake shoe bolt 165 with enough looseness to provide pivoting action. Brake spring 170 is attached to brake shoe bolt 165 and held firmly in place as shown in FIG. 2.

FIG. 2 shows a front view of the assembly of FIG. 1, indicating the additional elements of link nuts 250, which are self-locking nuts that include a plastic ring or other insert to provide locking to the threads of a bolt, and lock nut 260, of similar design. Link nuts 250 are adjusted to allow pivoting action of the links connected to corresponding bolts 136, 165, and 135 (not shown). Brake spring 170 is shaped to fit around brake shoe bolt 165 and is held firmly against link nut 250 on brake shoe bolt 165. Brake spring 170 is also shaped and attached to provide a rough alignment of brake shoe 160 and wheel 175 when the brake is disengaged as shown in FIG. 1.

FIG. 3 shows the brake mechanism in an engaged state with brake shoe 160 in firm contact with tire 175. In operation, the user pushes handle 110 in a forward direction (to the right in FIG. 1) in order to engage the brake. This causes floating link 130 to push brake link 140 in a rearward direction (to the left in FIG. 3), pivoting at the brake link 140 point of attachment to stationary link 1...