Abstract: A piston pump for conveying a fluid includes a cylinder which is not flanged to the pump casing, but rather is inserted in the pump casing and is retained in the longitudinal direction by a pretensioned spring. A seal is arranged between the cylinder jacket and the pump casing in order to seal the pressure side with respect to the suction side of the piston pump. An extremely compact piston pump results therefrom, suitable, in particular, for use in the low-temperature range due to very low cold losses.

Abstract: A piston pump having an intake valve whose valve member is approached by the pump piston. The piston magnetically attracts the valve member during the intake stroke to overcome the force of the spring biasing the valve member into its closed position.

Abstract: A valve for controlling the admission of gas to a cylinder of a piston-type machine, or for the discharge of gas therefrom, comprises a magnetic armature shiftable between a pair of magnetic poles formed to receive the armature with minimal radial play and with a predetermined air gap from the attracting pole in the energized condition of the coil. The energizing circuit includes an inductive proximity switch which is triggered without engagement by a metal formation on the crankshaft and applies its signal to a pulse former generating a steep-flank pulse triggering a timer to produce two rectangular voltage pulses of different durations. These pulses are applied to a gating circuit which produces a stepped signal with a high initial amplitude which is amplified and applied to a power converter energizing the coil with a corresponding current waveform. A monitoring circuit responds to deenergizing the coil to drain residual magnetism from the pole piece to enable a spring to rapidly close the valve.