Understanding Pressure vs. Flow

There are a lot of myths surrounding power steering and its functions. Most of these myths are concerning pressure and flow rate settings within the power steering system. In this article, we discuss power steering pressure and flow rate and their respective functions.

There are two distinct functions that the power steering pump is designed to perform. The first function is to deliver a constant flow rate to the power steering rack or box control valve. The flow rate will determine the sensitivity of the control valve when input is applied through the steering wheel. In conjunction with the control valve design, a given flow rate will result in a given steering feel and performance. Adjusting the flow rate is a fine tuning adjustment of the steering system and is not considered an all-inclusive adjustment.

The second function of the power steering pump is to provide enough pressure to assist the driver in overcoming steering load. The pump only builds pressure when it is required to by the steering rack or box control valve. The power steering pump’s maximum pressure should be set at a minimum of 200 psi above the system operating pressures. For example, if the system’s requirements are a 1000 psi, then the pump’s maximum pressure should be set at 1200 psi or above. Vehicles that regularly see track situations will likely require pump pressures between 1500-1800 psi.

Each system is unique and its requirements may be different. This is a generalization of the dynamics of the power steering system to help our customers further understand how the steering system operates. Tuning of your steering system is a delicate matter and should be done only under the guidance of a qualified technician. If you have any questions or need assistance, please feel free to contact our technical service department.