Abstract: A brake includes a rotor rotatably coupled to a rotating body for rotation about a rotational axis. A brake plate and an armature are disposed on opposite sides of the rotor. A spring and an electromagnet urge the armature in opposite directions into and out of engagement with the rotor to move the rotor into and out of engagement with the brake plate and engage and disengage the brake. The brake plate and electromagnet each define a central bore configured to receive the rotating body. The brake is characterized by a target supported on a radially extending face of the rotating body or the rotor and a sensor aligned with the target through the central bore of the brake plate or the electromagnet. The sensor generates, responsive to the target, position signals indicative of a rotational position of the rotor and rotating body.

Abstract: A wheelchair or a vehicle for sand or loose soil comprises one or more skids, each equipped with a spring-loaded roller or roller plate. Examples of the vehicle include a wheelchair and a planetary rover. Preferably, a beach, shower or pool wheelchair comprises two front skids in place of front wheels. The skids provide a resistance-free, broad footprint in the sand and a low-resistance narrow footprint when used on hard, e.g. boardwalk, surfaces. A wheelchair may further comprise a lightweight, easy to fold frame, which closes like a pair of eyeglasses. Still further, a wheelchair may provide a removable and reclining lounge chair seat to allow the user to exit the wheelchair to enter the water or sit and recline on the sand. In addition, dog bone or dumbbell shaped wheels provide the wheelchair strong, lightweight support and a wide footprint and can be equipped with grip notches for user self-propulsion.

Abstract: A wheelchair or a vehicle for sand or loose soil comprises one or more skids, each equipped with a spring-loaded roller or roller plate. Examples of the vehicle include a wheelchair and a planetary rover. Preferably, a beach, shower or pool wheelchair comprises two front skids in place of front wheels. The skids provide a resistance-free, broad footprint in the sand and a low-resistance narrow footprint when used on hard, e.g. boardwalk, surfaces. A wheelchair may further comprise a lightweight, easy to fold frame, which closes like a pair of eyeglasses. Still further, a wheelchair may provide a removable and reclining lounge chair seat to allow the user to exit the wheelchair to enter the water or sit and recline on the sand. In addition, dog bone or dumbbell shaped wheels provide the wheelchair strong, lightweight support and a wide footprint and can be equipped with grip notches for user self-propulsion.