Bench Testing of Steering Repairs prior to Reintroduction to Vehicles.
Pressure Output Check
The steering unit under test is connected to a hydraulic circuit and pressurised to the working pressure for the particular test (usually between 100 and 150 bar for most applications). If the pressure achieved is below that specified for the test then there could be a problem with the pump internals and/or the relief valve(s). This would need to be investigated before any further testing could take place.
Flow Rate Measurement
Flow rate is measured in litres per minute. A healthy steering unit will supply constant flow without any surge. Worn vanes or a failing control valve can cause irregular flow.For Power Steering Specialists, see https://westernpowersteering.co.uk/.
Internal Leak-Down Test
The unit is pressurised and held static to check for signs of internal bypassing. If the pressure drops off within a set time frame, this could indicate that the seals have started to wear or that the bores have started to score. This type of test is specifically referred to in mechanical engineering standards for fluid power systems for the validation of hydraulic components.
Torque and Steering Feel
The torque response of the steering unit is tested by applying a certain amount of torque to the steering unit under test and checking for the smoothest possible response.
Noise Under Load
Finally, during load testing for steering noise, any whine, grinding or cavitation noise would indicate air ingress into the bearings (which would cause the same problem when fitted) or other faulty components.