Axial piston motors - for high speeds
Functionality of axial piston motors
Axial piston motors are based on the basic principle of an axial piston pump. The main feature of this motor type is the axis-parallel arrangement of the pistons in a cylinder drum around the axis of rotation. The pistons are supported on a plane lying at an angle to the axis of rotation of the cylinder drum, which creates their stroke. There are two main designs, the swash plate and the bent axis motors.
At the “inlet” of the piston drum, pressurized oil is supplied to the engine. As a result, the pistons make a lifting movement. This is converted into a rotary movement by the piston joint on the drive flange. The cylinder is carried along by the pistons and an output torque is generated at the output shaft. The hydraulic oil that emerges flows back into the hydraulic system.
Since it is an axial piston motor with a constant displacement, the swivel angle is specified and thus fixed. With an adjustable motor, this angle can be adjusted within certain limits. Changing the swivel angle results in a different piston stroke and thus an adjustable displacement. In the case of an axial piston motor in bent-axis design, the output speed is proportional to the inflowing liquid volume.
Swash plate design
In the case of axial piston motors with a swash plate design, the displacement pistons are arranged axially to the output shaft. They support themselves on a sloping disc.
In this design, too, pressurized fluid is fed in at the inlet of the piston drum. The pistons perform a lifting and rotating movement, taking the cylinder with them, which then rotates the output shaft due to the gearing. The hydraulic fluid is “pushed out” on the low-pressure side and fed back into the hydraulic system.
Advantages and disadvantages of axial piston engines
- Axial piston motors are high-speed hydraulic motors . There are high speeds (> 10,000 rpm) can be reached
- High pressure resistance, sometimes up to 450 bar
- High volumetric efficiency
- Lots of adjustment options
- Very well suited for hydrostatic travel drives
- Can be used in open or closed hydraulic circuits
- Relative expensive
- Susceptible to wear (cavitation)