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US 4,926,973 AGranted
Mobile wheelchair lift and brakes therefore
OwnerDave W. Smithinventor
Life of this patent
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OwnerDave W. Smithinventor
Estimating the term…
A lightweight frame supports a wheelchair platform for up and down movement between four vertical standards, one at each corner. A lifting mechanism includes a winch supported between two of the standards and connected to the platform by cables which pass over pulleys mounted in an upper cross bar pivotally secured and extending between the two posts with the pivot being offset from the longitudinal axis of the crossbar thereby giving a camming or offset partial rotational movement. The winch includes a one way clutch which is disengaged when the platform is elevated but engages automatically as soon as the platform starts to descend thus locking a brake drum to the winch. A brake band extends around the drum and is operatively connected to an offset pin on the upper crossbar by rigid links so that as soon as the platform starts to descend, the brake is automatically applied thus preventing inadvertent downward movement of the platform unless the friction or resistance between the drum and band is overcome by actuation of the winch for controlled lowering of the platform. Wear is automatically compensated for by the linkage between the brake pad and the pin on the upper cross bar which acts in a camming fashion with the offset pivot mounting thereof.
A mobile wheelchair lift comprising in combination a base frame, a vertically situated support structure extending upwardly from adjacent each end of said base frame, a substantially horizontal wheelchair platform, a winch assembly including a cable drum and a cable system operatively connected thereto, and supporting said platform between said support structure for elevating and lowering action within said support structure, said cable system including at least one upper pulley and at least one lower pulley, upper and lower pulley support means and a cable operatively extending between said cable drum and said upper and lower pulleys, and an automatic braking system cooperating between said winch assembly and said platform to prevent inadvertent descent of said platform, said braking system including at least one brake drum means operatively connected to said cable drum, brake means operatively connected to said brake drum means, and operating link means operatively extending between said upper pulley support means and said brake means to actuate said brake means, said upper pulley support means including a cam action therein for pivotally supporting same to said vertical support structure whereby the initiation of descent of said platform moves said link means to actuate said brake means.
An automatic braking system for mobile wheelchair lifts in which said wheelchair lift includes a base frame, vertically situated support structure extending upwardly from at least each end of said base frame and substantially horizontal wheelchair platform mounted within said support structure, a winch assembly including a cable drum, and a cable system within said support structure and operatively connected to said platform for selective elevating and lowering said platform within said support structure, said cable drum rotating in one direction when said platform is elevating and in the opposite direction when said platform is descending;
Dependencies are inferred from the claim text.