In response to market needs, the QR range has been developed to combine very high efficiencies with very low noise levels while retaining the rugged simplicity of well-proven hydraulic gear pumps. These are cast iron construction and high quality steel gears, supported by hydrodynamic plain (bush) bearings which are lubricated by a system which draws cool fluid from the inlet port. QR spur gear pumps are designed for minimum pressure ripple. The pumps will work at continuous pressures up to 250 bar (3625 psi), with peak pressures up to 280 bar (4060 psi). Careful attention to inlet porting enables most pumps to run at up to 3000 rev/min.