Abstract: A first end of a lever pivots about a fixed axis as a second end is raised and lowered by the user. A carriage is disposed on the lever and is designed to travel the length of the lever between the first and second ends. A belt is coupled to a weight and to the carriage through a series of pulleys. The lever is shaped so that the weight neither raises nor lowers as the carriage travels from one end of the lever to the other. The distance that the weight travels in response to movement of the second end is thus proportional to the position of the carriage on the lever. By moving the carriage to numerous positions between the first and second ends of the lever, the torque needed to lift the weight and the distance by which the weight moves may be varied correspondingly in numerous increments over a very large range. A number of different user interfaces may be coupled to the lever for creating an equal number of different weight training machines.

Abstract: Positioning apparatus for vertically moving a scanning assembly includes a vertical support, a first arm pivotally attached to the support and to the scanning assembly, and a second arm pivotally attached to the support and to the scanning assembly with the first and second arms being parallel. A counter-balance is provided and is attached to the support by third and fourth arms which are pivotally attached to the support and to the counter-balance.

Abstract: A sector scanner which compensates for fluid leakage from the sealed transducer cavity includes a bladder in the cavity which is vented to the outside atmosphere whereby the bladder expands to compensate for the loss of fluid and a differential pressure between the cavity and the outside atmosphere is avoided. Alternatively, a fluid filled bladder is provided outside of the cavity and a port in the bladder is in fluid communication with the sealed cavity whereby fluid lost from the cavity is replaced by the fluid filled bladder. The bladder can be expandible with the fluid therein being under pressure.