Axial piston pumps

How an axial piston pump works

In an axial piston pump several pistons are arranged in a ring inside a rotating cylinder block, parallel to the drive shaft. In the swashplate design, used by all the series on this page, the pistons slide on an inclined plate through their shoes: as the block rotates, each piston moves back and forth, drawing in oil in one half of the revolution and pushing it out in the other half, through the kidney-shaped ports of the valve plate.

The stroke of the pistons, and therefore the displacement, depends on the angle of the swashplate. With a fixed plate the pump has a fixed displacement; if the angle can be changed by a regulator, the pump becomes a variable displacement pump that delivers only the flow the circuit needs. In the bent-axis design, used for example in many hydraulic motors, it is the whole cylinder block that is inclined with respect to the shaft.

Main parts of an axial piston pump

• Drive shaft, connected to the electric motor or the engine
• Cylinder block (barrel) with the bores of the pistons, rotating with the shaft
• Pistons with slipper shoes, which slide on the swashplate
• Swashplate, whose inclination sets the displacement
• Valve plate, with the suction and delivery ports
• Regulator (compensator), which moves the swashplate according to pressure, flow or power

Variable displacement and regulators

The regulator is what makes an axial piston pump efficient: instead of discharging excess flow through a relief valve, the pump reduces its displacement. The most common controls are:

• Pressure compensator: keeps the set pressure, reducing the flow to almost zero when the circuit is stationary
• Load sensing: adapts pressure and flow to what the actuators actually require
• Constant power (torque limiter): limits the absorbed power so that a smaller motor can be used
• Electro-hydraulic and digital P/Q controls: pressure and flow set by an electronic signal, as on the Atos PVPC LQZ and PERS versions

Piston pumps vs gear pumps

Axial piston pump series available from Interfluid

Replacing a piston pump from another brand

Many customers come to us to replace a pump that is no longer available or has long delivery times. These are the equivalences we offer:

Send us the code on the nameplate and we will check displacement, flange, shaft and regulator of the equivalent pump.

How to choose an axial piston pump

• Flow and displacement: required flow at the motor speed.
• Pressure: up to 280 bar continuous HSP and PVPC, up to 320 bar Kawasaki K3VL.
• Regulator: pressure compensator, load sensing, constant power or electronic P/Q control.
• Mounting: ISO or SAE flange and shaft, through-drive for multiple pumps.
• Fluid and environment: ATEX versions available for Kawasaki K3VL and Atos PVPC.

Axial piston pump FAQ

How does an axial piston pump work?

Pistons arranged in a rotating cylinder block slide on an inclined swashplate: each piston draws in and delivers oil once per revolution, and the angle of the plate determines the displacement.

What is a variable displacement piston pump?

A pump in which a regulator changes the angle of the swashplate, so that the flow adapts to the needs of the circuit and energy is not wasted.

What is the maximum pressure of an axial piston pump?

Up to 320 bar continuous and 400 bar peak with Kawasaki K3VL; up to 280 bar continuous and 350 bar peak with Atos PVPC and Hydraut HSP.

Is there an alternative to the Rexroth A10VSO pump?

Yes: Hydraut HSP and Atos PVPC pumps are alternatives to the Rexroth A10V(S)O series, and Hydraut also supplies compatible spare parts.

Why choose Interfluid

• Official Kawasaki partner for Italy, official Atos distributor and Service Center, Hydraut brand owner
• Kawasaki K3VL, Atos PVPC, Hydraut HSP and PQ usually in stock
• Technical support in choosing displacement and regulator
• Online ordering on Fluid-Hub.net

Tell us the pump code you use today or flow, pressure and regulator of your application – request a free consultation.

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