Application Note: Quality Control

TRW Automotive in Gelsenkirchen wants to ensure that the pumps on hydraulic steering gears do not make any unwanted noises while driving. All motor pump assemblies (MPA) are subjected to numerous test steps as soon as they have been assembled and before being installed in the steering system. The vibration characteristics are measured by PDV-100 vibrometers and are used as an indicator of the actual noise under normal operating conditions. Based on the vibration spectrum the process controller either approves the assembly for subsequent processing or rejects it as being faulty.

TRW manufactures modern steering gears with electro-hydraulic control at their facility in Gelsenkirchen, Germany. These electrically powered hydraulic steering (EPHS) systems are shipped to automotive assembly lines, preassembled, filled with hydraulic oil and completely completely tested. Separate motor pump assemblies (MPA) are also supplied to auto manufacturers who prefer to install, attach hoses and fill with hydraulic fluid. Hydraulic pressure is generated by a motorized pump and is electronically regulated consistent with the vehicle speed, the steering force and the steering angle rate. The MPA is first assembled and then thoroughly checked for noise and performance values while passing through several automatic test stations. Production is approximately 1500 units per day per plant.

SOURCE: Polytec