Brakes – Vehicle
Reexamination Certificate
2000-06-12
2002-01-29
Butler, Douglas C. (Department: 3613)
Brakes
Vehicle
C188S031000
Reexamination Certificate
active
06341671
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally concerns parking brakes, wheel locks, hill holders and like devices fitted to wheeled trolleys and conveyances, particularly to wheelchairs.
The invention particularly concerns a parking brake for a wheelchair.
2. Description of the Prior Art
2.1 General Background
Existing wheel chair wheel locks based on friction between a moveable portion of a brake, or lock, and the tire or wheel of the wheelchair suffer in effectiveness in that a limited area of contact between the brake and the wheel permit the wheel to slip and rotate under high lateral loads, such as during the egress of the wheelchair occupant from the wheelchair. It is desirable that wheelchair parking brake, or lock, should substantially preclude any further wheel rotation whatsoever, once engaged, nonetheless to being easy and reliable to engage and dis-engage.
2.2 Specific Background
U.S. Pat. No. 4,462,605 to Morgan, et. al. for a WHEELCHAIR HAVING ANTI-ROLLBACK MECHANISM shows propulsion wheels of a manually propelled wheelchair equipped with one-way engaging and one-way freewheeling clutch devices which cooperate with races fixed to the wheelchair frame, whereby unwanted backward movement of the wheelchair is prevented and forward movement at all times is enabled. An override mechanism including a spider attached to each hand propulsion ring disables the one-way engaging clutch devices when the wheelchair occupant intentionally moves the propulsion wheels in a backward mode. No controls separate from the manual propulsion wheels are present, assuring the chair occupant constant control of the chair through the hand propulsion rings at all times.
U.S. Pat. No. 4,538,825 to Delahoussaye, et. al., for a WHEELCHAIR ANTI-ROLLBACK MECHANISM shows the customary side hand propulsion ring adjacent to each main wheel of a manual wheelchair mounted through a lost motion connection between the propulsion ring and main wheel so that the propulsion ring can have limited rotational movement relative to the main wheel. A friction brake drum or partial drum fixed to the wheelchair frame inside of the main wheel is engaged by at least one of a plurality of circumferentially spaced over center friction locking devices pivotally held on the main wheel. Each over center friction locking device is moved by a release element to a non-locking position relative to the drum or partial drum in response to reverse movement of the propulsion ring by a chair occupant. Economy and ease of operation are provided for. The wheelchair occupant need not remove his or her hand from the propulsion ring when operating the anti-rollback mechanism.
U.S. Pat. No. 4,570,756 to Minnebraker, et. al., for a BRAKE DEVICE FOR WHEELCHAIRS shows a brake device for use with wheelchairs of the type having a main frame and a pair of spaced apart large diameter driving wheels, such as rear wheels. The brake device comprises a bracket or other mounting element for mounting to the wheelchair frame and a lever arm which is shiftable to a wheel locking position to move a brake tab into engagement with the rear wheel of a wheelchair to lock the wheel against further rotation. The lever arm is also capable of being shifted to a reverse or non-locking position so that it moves the tab out of engagement with the wheelchair driving wheel and to a position where it cannot be engaged with the driving wheel to permit free-wheeling movement thereof. The brake device is constructed so that the tab is moveable to a non-interfering position where it is generally parallel to the plane of rotation of the wheel and is not likely to be contacted by the hand of a user. In one embodiment, the tab is manually moveable to the non-interfering position. In another embodiment, the tab is automatically moved to the non-interfering position when the lever arm is shifted away from the locking position.
U.S. Pat. No. 4,691,933 to Strauss for a WHEELCHAIR PARKING BRAKE shows a wheel locking device for use on a wheelchair, including a locking bar connected to a shaft that is movably axially and rotationally within a fixed tube, by a single operating handle. As the operating handle is moved from a release position to a locking position, the shaft is first axially translated by means of a cam on the handle, and simultaneously rotated by means of a guide pin extending radially from the shaft and engaging a slot in the tube, to move the locking bar from a retracted position well clear of a wheel of the chair to an operative position located transversely with respect to the wheel circumference. Further movement of the operating handle translates the locking bar transversely into locking engagement with the wheel.
U.S. Pat. No. 4,749,064 to Jinno, et. al., for a BRAKE SYSTEM FOR A WHEELCHAIR shows a brake system for a wheelchair comprises a base plate fixed to a frame of the wheelchair and a swing lever pivotally mounted to the base plate and provided with a brake member engagable with a circumferential surface of a wheel of the wheelchair. A toggle joint mechanism composed of two pivotally interconnected links is pivotally mounted to the base plate and connected to the swing lever to move the swing lever between an extended braking position and a retracted inoperative position. An operating lever is pivotally mounted to the pivot which interconnects the two links of the toggle joint mechanism. The operating lever has cam surfaces engageable with the two links to depress the latter when the operating lever is moved in either of two directions by pushing it or pulling it. Such action drives the swing lever into braking engagement with the wheel. A biasing spring is provided to urge the links of the toggle mechanism towards retracted position.
U.S. Pat. No. 4,805,711 to Lautzenhiser for a MECHANICAL CONTROL MECHANISM FOR CONVEYANCE shows an electric wheelchair, or other conveyance, provided with a function control which includes a unitary control, and which is effective to control applying and releasing of power transmitted from an electric motor to a wheel, or to another type of propulsion element, and to control applying and releasing of a parking brake, in response to positioning of the unitary control.
U.S. Pat. No. 4,749,064 to Jinno, et. al., for a BRAKE SYSTEM FOR A WHEELCHAIR shows a brake system for a wheelchair comprises a base plate fixed to a frame of the wheelchair and a swing lever pivotally mounted to the base plate and provided with a brake member engagable with a circumferential surface of a wheel of the wheelchair. A toggle joint mechanism composed of two pivotally interconnected links is pivotally mounted to the base plate and connected to the swing lever to move the swing lever between an extended braking position and a retracted inoperative position. An operating lever is pivotally mounted to the pivot which interconnects the two links of the toggle joint mechanism. The operating lever has cam surfaces engageable with the two links to depress the latter when the operating lever is moved in either of two directions by pushing it or pulling it. Such action drives the swing lever into braking engagement with the wheel. A biasing spring is provided to urge the links of the toggle mechanism towards retracted position.
U.S. Pat. No. 5,174,418 for a WHEEL LOCK MECHANISM FOR A WHEELCHAIR shows a wheelchair wheel lock system is provided that can be adapted for either pull-to-lock or push-to-lock operation. The wheel lock system includes a function plate with first and second pivot holes. An operating lever is attached to the function plate, and rotation of the lever causes rotation of the function plate and thereby moves a contact arm into engagement with the wheel of the wheelchair to lock the wheel against movement. The operation of the wheel lock system is changed between push-to-lock and pull-to-lock by adapting the function plate to rotate about either the first pivot hole or the second pivot hole. The operating lever can be attached to the function plate in a variety of orientations, providing added f
Butler Douglas C.
Fuess & Davidenas
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