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 The Wolfhart Pump Principle

with the first bearing-less, pulling, self aligning piston actuating mechanism



1 - Piston Rotor/Plate ....2 - Cylinder Rotor/Block ....3 - Piston Rod/Screw .....4 - Carbon Control Plate

5 - End Plate .... 6/7 - In/Outlet ....8 - Mechanical Shaft Seal.....9 - Electrical Motor....10 - piston....11 - shaft


This principle is an axial piston type - similar to a Bent Axis Pump, but only at first glance.

In this pump, the cylinder are at a small angle (5) to the drive shaft and Piston Rotor/Plate.

The connecting rods are screwed on the Piston Rotor/Plate.

The drive shaft, piston plate/rotor (with the pistons), and cylinder block/rotor all revolve.

The cylinder block/rotor has no own shaft. It is guided by the pistons.

The pistons (mostly spherical) are swing able in the cylinders.

The in/outlet ports are semi-circular holes in the Valve Plate.

A short stroke motion and large pistons are characteristic for this design.

In this version, the connecting rods only pull the pistons against the high pressure in the housing.

The pistons must be (are) pressure tight only in one direction and only half the revolution.

The aligned rotation of pistons and cylinders at a small angle generates a relative stroke motion between them in the co-rotating reference system. The pistons, passing over the inlet port, suck in and push to the same time backwards against the high working pressure in the housing. Pistons and cylinders only rotate and are counterbalanced. There are no mass forces. Piston rods, piston plate, and drive shaft are one solid piece without any bearings between them. Hydraulic forces are all hydraulically compensated.


The Wolfhart Principle,
a fundamental breakthrough in the design of piston machines with
the simplest but most powerful piston actuating mechanism ever created.

Six screws with sealing elements, function as pistons, are screwed on a plate/shaft being one solid piece without any connecting bearings.