Abstract: An hydraulic plunger for cleaning a clogged drain composed of a casing with a piston movable therein and being open at one end. A fitting is provided on the open end that fits against the drain inlet. A water inlet is provided in the casing to permit water to fill the casing on the side of the piston that is open to the drain pipe and the drain pipe to the stoppage therein. An electromagnetic unit is carried within the casing and has a driven member that strikes the piston to create a relatively large impact force against the water and stoppage in the drain.

Abstract: A solenoid operated drive system or actuating unit for driving blood pumps such as intra-arterial "balloon" pumps, implantable pulsatile pumps, external pumps and the like, wherein a shaft attached to the movable end of a bellows is caused to move back and forth by a pair of oppositely disposed solenoids. The extent of the excursion of the shaft and hence the movable end of the bellows is variably controlled by a first stopper fixedly attached to the frame and a second stopper fixedly attached to a carriage which is adjustably carried within the frame. The solenoids are alternately actuated and/or controlled by suitable control signals which are keyed to the heartbeat or R wave. At the beginning of each cycle for each solenoid and for a short time thereafter, depending on the cycle, a voltage is applied to provide maximum drive.

Abstract: A linear motor is operatively connected to operate a pair of axially aligned compressors. A pair of axially spaced and oppositely wound coils are mounted to a cylindrically shaped coil form movably connected to drive the aligned compressors with the coils serially connected to a single phase A.C. power source. A pair of spaced annular magnets provide a pair of annular poles of opposite polarity spaced immediately adjacent to the pair of coils while an outer annular flux conducting member connects the outer radial portions of the annular magnets. One embodiment spaces the pair of compressors at opposite axial extremities of the linear motor construction while a second embodiment centers the compressors within the movable coil form.

Abstract: A compressor of the resonant type driven by an electrodynamic linear motor incorporates means to control the stroke and to improve the power factor. The spring-mass system of the compressor which is forced into vibration by the motor is arranged to have a selectively variable resonant frequency generally centered on the power line frequency. Means responsive to any overstroking are operative to vary the natural frequency of the spring-mass system, for example by varying the stiffness of the spring means, so as to oppose further overstroking and maintain a high power factor.