Abstract: A saw blade balancing tool which comprises a balancing gauge adapted to be mounted to a saw blade hub, and a balancing stand. The balancing gauge comprises a frame, a balancing mechanism mounted to the frame, and a level indicator mounted to the frame. The balancing mechanism includes adjustable elements for balancing a saw blade and for indicating a locus for removing material from the saw blade to balance the saw blade about its hub. The said balancing stand has a saw blade mounting cap for mounting a saw blade at its hub and for positioning the balancing gauge on the saw blade. The balancing mechanism comprises a pair of sliders carried by the frame and mounted for movement in synchronism with one another, one of the sliders being adapted to receive a balancing weight and the other of the sliders being adapted to indicate the locus for removing material from the saw blade.

Abstract: The cross-piece portion of a tubular T-joint has a cross-section of constant inside diameter from one end of the cross-piece to the other and increasing outside diameter from one end towards it center, then decreasing from its center towards it opposite end to define a double tapered tube wall for the cross-piece of maximum thickness at its center. A stem portion for the T-joint is in the form of a hollow tube extending normally away from the center portion of the cross-piece to terminate in a free end. The cross-section of the stem has a constant inside diameter from its free end to its point of interception with the cross-piece and an outside diameter increasing from its free end to its point-of-interception with the cross-piece so that the maximum thickness of the T-joint is at the interception between the cross-piece and the stem and yet the inside diameters are all uniform so that other tubes can be readily telescoped through the cross-piece.

Abstract: The gear reduction system is of the differential type utilizing two ring gears with teeth on their inner circumference and first and second eccentric wheels having external teeth engaging the teeth on the ring gears as they roll about the inner circumference. The first and second wheels have their eccentricities mounted in an offest relationship so as to provide dynamic balancing during operation. By making the number of teeth on one of the eccentric wheels different from the number of teeth on the other, adding the second ring gear and providing appropriate pin carrier means coupled in a given arrangement, a very high gear reduction can be achieved in a single packaging. This gear reduction is equivalent to that heretofore only obtainable by ganging together separate reduction gear systems of this type.

Abstract: The gear reduction system is of the differential type utilizing two ring gears with teeth on their inner circumference and first and second eccentric wheels having external teeth engaging the teeth on the ring gears as they roll about the inner circumference. The first and second wheels have their eccentricities mounted in an offset relationship so as to provide dynamic balancing during operation. By making the number of teeth on one of the eccentric wheels different from the number of teeth on the other, adding the second ring gear and providing appropriate pin carrier means coupled in a given arrangement, a very high gear reduction can be achieved in a single packaging. This gear reduction is equivalent to that heretofore only obtainable by ganging together separate reduction gear systems of this type.

Abstract: The forward castor wheels for wheelchairs are each provided with shock absorbing leaf springs concealed within the fork frame structure rotatably mounting the wheels. The normal swivel shaft rather than connecting directly to the fork frame passes through an enlarged opening in the upper portion of the frame and terminates in a cross member pivoted to the upper portions of the fork arms so that the fork frame and wheel can execute slight rocking movements relative to the swivel shaft. The leaf springs pass down inside the fork arms, the upper ends of the leaf springs being secured to the cross member and the lower ends bearing against inwardly directed projections on the inside of the fork arms to bias the fork relative to the swivel shaft. The leaf springs will absorb shocks experienced by the castor wheels such as occur when passing over cracks in sidewalks and the like to thereby greatly increase the riding comfort of the wheelchair.

Abstract: The latch is used to raise a downwardly biased plunger on the frame of a wheelchair normally received in an opening on a swingable foot rest supporting tube to thereby release the tube and permit swinging of the wheelchair foot rest to an out-of-the-way position. The latch includes a plate member cooperating with a lever such that either pressing downwardly on the lever or lifting up on the lever will release the foot rest support. With this arrangement, even a severely handicapped patient can more easily operate the release than otherwise.

Abstract: A wheelchair frame is uniquely designed to permit folding of the chair in such a manner that the left and right wheels of the wheelchair lie in the same vertical planes as the left and right wheelchair frame portions supporting the seats and arm rests so that in effect a narrower folded configuration results for a given width wheelchair seat when in unfolded position as compared to conventional wheelchairs.

Abstract: The normally provided manually operable switch lever on an electrically drive wheelchair incorporates pairs of switch arms so that additional circuitry can be provided for interconnection with the normally provided left and right wheel drive motors. This additional circuitry comprises electrical resistances arranged to be connected across the motor leads by the manually operable switch when in an unactuated position for the particular motor in question. The provision of these resistances across the motor leads when the motors are unenergized results in absorption of back voltage spikes to thereby avoid burning out the switch means, dynamic braking when the motors acts as generators as a result of the wheelchair coasting, easier steering control when only one of the motors is energized to effect a turn, and permits the use of permanent magnet type d.c. motors for the left and right wheel drive motors.

Abstract: Telescoping tubes are added to the left and right front posts of a wheelchair for cooperation with the front post slides normally received in the front posts to permit greater telescopic extension of the slides from the front posts when the wheelchair is folded. With such arrangement, a wider seat may be applied to a conventional wheelchair, the addition of the telescoping arrangement not requiring any major alteration of the basic components making up the wheelchair. Each telescoping arrangement includes an extremely inexpensive and unique interior coupling preventing telescopic extension beyond a certain distance so that the front posts and front post slides will not become separated.