Land vehicles – Wheeled – Occupant propelled type
Reexamination Certificate
1999-03-12
2001-03-06
Hurley, Kevin (Department: 3619)
Land vehicles
Wheeled
Occupant propelled type
C074S527000, C403S083000, C403S095000, C403S107000
Reexamination Certificate
active
06196568
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to wheelchairs and to a rotary adjustment mechanism for wheelchair components. More particularly, the invention relates to a mechanism for releasably locking two relatively rotatable members for adjusting the positioning of a wheelchair footrest or other components.
Wheelchairs generally include a frame that supports a pair of drive wheels and a pair of front casters. The drive wheels make contact with the ground and are driven to propel the wheelchair. The drive wheels may be driven manually or powered by an electrical motor. The wheelchair frame also supports a seat assembly comprising a seat and a backrest. The seat assembly is oriented above and between the drive wheels and the front casters to provide stability. Generally, a pair of rigid frame extensions extend off the frame relatively forward from the front casters. Paired foot supports, is consisting of a foot support arm and a foot support plate, are connected to the rigid frame extensions.
Typically, each foot support is joined to its corresponding frame extension using an adjustable mechanism to permit the angle of each foot support to be easily adjusted to meet the specific needs of the user. For example, if the wheelchair user has a leg or foot fracture or other injury in one leg, the foot support can be adjusted to position the affected limb parallel to the ground.
An adjustable locking mechanism is described in U.S. Pat. No. 5,689,999, titled
Adjustable Rotary Locking and Unlocking Apparatus.
This locking mechanism consists of two members rotatably connected by a bolt through a central bore. A first member has a plurality of arcuately spaced locking pins that are movable between a projected and a retracted position. A second member has a plurality of arcuately spaced sockets configured so that each socket can accommodate any of the locking pins. To reposition the foot support, the user pushes an actuator to retract all the locking pins into the second member thereby permitting the first member and the second member to rotate freely relative to each other.
Any mechanism for adjusting the angle of the foot support must be solidly constructed because the foot support arm acts as a lever arm to concentrate pressure placed on the foot support plate. In the rotary locking apparatus described in the '999 patent, pressure on the footplate is focused on the bolt. The '999 patent describes careful fabrication to provide a snug fit between the locking pins and the sockets and the supporting bolt and the central bore. Unfortunately, this increases cost without a proportional increase in the overall strength of the mechanism.
Thus, it would be desirable to have an improved adjustable rotary positioning mechanism of increased strength that can be inexpensively fabricated.
SUMMARY OF THE INVENTION
The present invention provides an improved adjustable rotary positioning mechanism that is more robust and less expensive to manufacture than previous -designs. This adjustable rotary mechanism consists of a rotatable rod end in combination with a clevis, where relative rotation between the clevis and the rod end is prevented by spring loaded locking pins, at least one of which engages a series of uniformly distributed bores in one arm of the clevis. More particularly, the mechanism comprises a clevis having a central axis, a first arm, a second arm, and a plurality of bores arcuately spaced around the central axis through the first arm of the clevis. A rod end having a central axis and a plurality of sockets is rotatably connected to the clevis through the central axis. The plurality of sockets are arcuately spaced around the central axis and positioned colinearly with the plurality of bores. A plurality of locking pins are carried in the sockets and configured to project into the plurality of bores to lock the clevis and the rod end together and to retract from the plurality of bores to permit relative movement of the clevis and the rod end.
Another embodiment of the invention is a wheelchair comprising: a frame, drive wheels and steerable wheels supporting the frame, and paired foot supports each of which is adjustably connected to the frame using an adjustable rotary positioning mechanism as described above.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.
REFERENCES:
patent: 4407045 (1983-10-01), Boothe
patent: 5056805 (1991-10-01), Wang
patent: 5347883 (1994-09-01), Thony
patent: 5689999 (1997-11-01), Wiley et al.
Hurley Kevin
MacMillan Sobanski & Todd LLC
Sunrise Medical HHG Inc.
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