Kawasaki Pumps

The Japanese heavy-industry company Kawasaki Heavy Industries has been developing and producing high-performance axial piston motors for more than 40 years. The product range provided is optimized for the industrial and mobile sectors and offers a wide variety of operating pressures, displacements, and diverse power control options. The large, internationally active group also has development and production sites in shipbuilding, vehicle manufacturing (including construction vehicles, railways, and especially motorcycles), building and civil engineering, aerospace engineering, as well as energy systems and mechanical engineering (for example gas turbines, wind turbines, baggage handling systems, or robots).

In the United States and Europe, the Japanese group is best known for manufacturing motorcycles. The company is already more than 100 years old and currently employs around 35,000 people in a wide range of divisions (as of March 2016).

Axial piston motors for Kawasaki pumps

Kawasaki’s very extensive motor product range includes, in particular, axial piston motors with variable displacement for open circuits as well as axial piston motors with very high pressures for various industrial vehicles.

In addition, the motor manufacturer offers gear pumps and vane cell pumps. A distinction is made here between constant-speed and speed-controlled pumps. These are available in tandem versions with an open or closed circuit. Between the axial piston units with axial piston pump and motor, a further distinction must be made between pumps with constant or variable displacement. For axial piston pumps, there are variants with an inclined axis (so-called bent-axis pumps) and variants with an inclined swash plate (so-called swash-plate pumps).

Kawasaki axial piston motors and pumps

Kawasaki pumps are primarily used in hydrostatic transmissions in various vehicles. Power is transmitted to the shaft via an oil pressure of around 400–500 bar. The oil pressure can be regulated continuously, resulting in a continuously variable transmission with a very high power density.

Typical applications for this type of pump include, for example, wheel loaders, snow groomers, combine harvesters, increasingly tractors, excavators, and many different low-speed vehicles. In contrast to a hydrodynamic torque converter, in which torque at the output is generated by the oil flow, in a hydrostatic transmission the oil pressure generates the torque at the output. During operation, in an axial piston pump the pistons are supported axially in spherical socket bearings and at the same time drive the cylinder drum radially. This function results in the following characteristic properties of the axial piston pump:

• Suitable for fluctuating pressures
• Insensitive to dirt
• Easy to start and self-priming
• Can only be adjusted with considerable time and effort
• Very sensitive to vibrations when accelerating and decelerating the vehicle
• Flexible to use, as the flow rate can be adjusted

Data on axial piston units

Axial piston pumps and motors are very similar in design. Only axial piston motors convert hydraulic energy (with the physical quantities flow rate and pressure) into mechanical energy (speed and torque).

Both designs are characterized by high stability and very good internal sealing. This enables very high pressures, power outputs of up to 1,000 kW, and speeds of up to 12,000 rpm. Axial piston units normally have only an odd number of cylinders; seven or nine cylinders per unit are common. This is because six cylinders produce only 6 pressure peaks per revolution, whereas seven cylinders already generate 14 pressure peaks per revolution. The distinction between a bent-axis unit, a swash-plate unit, and a wobble-plate unit is based on the pistons’ principle of motion.