Electric power steering has specific advantages over hydraulic power steering. The weight and massiveness of a hydraulic power steering system is due to the power steering pump. This power steering pump uses excessive power (expressed in terms of horsepower), which becomes uneconomical in the face of newer electric power steering systems. Electric power steering systems are built without the power steering pump. In the process, weight is reduced and fuel is saved. When hydraulics are removed from the power steering system, the power steering fluid hoses become obsolete. By removing the hoses, the car no longer requires maintenance for power steering fluid leaks. Electric power steering is executed by software, which makes power steering tunable with an electric power steering scanner. This means that electric power steering is tuned to the driving style or the driver's needs by making slight adjustments to the software module (modules contain executable programs for the amount of power steering applied). Electric power steering is available even when the engine is turned off.
Hydraulic Power Steering Operation
The steering rack houses the steering pinion, which is connected to the driver's steering wheel via an assembly of joints and shafts. The pinion directs the steering rack left or right depending on the direction the driver turns the wheel. At the termination points of the steering rack are the connectors to the wheels on the front of the car. An assembly of hoses and rings house the fluids and act as conduits for the fluid when pressure is supplied by the hydraulic pump. The hydraulic pump is activated by the power of the car's engine. The pressure created by the hydraulic fluid makes it possible for the driver to turn the wheel (steering rack) with less effort.
Electric Power Steering Operation
The electric power steering system is entirely electronic (unlike electro-hydraulics which uses the electric motor to run a hydraulic pump). An electric motor is connected to a steering column or a manual rack. A sensor reads the X-Y coordinates and degree of rotation as the steering wheel is turned by the driver. The data from the sensor and an additional torque detector on the steering shaft are computed by the electric power steering control module. The amount of power from the steering assistance provided by the electric power steering system is computed from these and other variables (including speed of travel and traction [stability control system]). A control module directs the rotation degree of the motor at the same time the motor sensor communicates with the control module. These components work together to sustain a monitoring system for the electric power steering operation.
