Power Steering overview

Description and Operation This vehicle employs electric power steering (EPS). The components of the {Acronym.EPS} ({Acronym.EPS}) are integrated in the steering gear. Layout The {Acronym.EPS} consists of the following main components: {Acronym.EPS} motor, {Acronym.EPS} module, steering torque sensor, toothed belt drive. Functionality overview As soon as the steering wheel is moved, an electric motor assists the steering movement. When a steering movement occurs, it is detected by the steering torque sensor. The signal from the steering torque sensor is used by the module to calculate the power of the steering assistance. The {Acronym.EPS} module drives the {Acronym.EPS} motor with the corresponding current. Advantages of electric power steering {Acronym.EPS} is only active when a steering movement occurs. This decreases the load on the engine and therefore reduces the fuel consumption. The system adjusts the power of the steering assistance specifically for every speed. Not sensitive to disturbances from the running gear which lead to vibrations at the steering wheel. This may include: - imbalance at the wheels or brake discs, - the vehicle drifting to one side. Fewer components compared with hydraulic power steering. The hydraulic pump, hoses and reservoir are dispensed with. Environmentally friendly: - no need to dispose of hydraulic fluid, - escape of hydraulic fluid caused by leaks in the hydraulic system cannot occur. Improved diagnostic facilities via IDS (Integrated Diagnostic System) or FordEtis-IDS. Steering assistance power transfer 1---{Acronym.EPS} motor 2---Drive pinion, toothed belt drive 3---Toothed belt 4---Output pinion, toothed belt drive 5---Steering rack 6---Steering gear rubber boot NOTE: Repairs or adjustments are not permitted at the toothed belt drive! A toothed belt is used to transfer the rotational movement of the motor via a recirculating ball nut to the steering rack of the steering gear. Recirculating ball nut 1--- Inner ring, ball bearing 2--- Outer ring, ball bearing 3--- Balls 4--- Ball return 5--- Steering rack with ball track 6--- Output pinion, toothed belt drive The recirculating ball nut produces a linear movement of the steering rack from the rotational movement of the output pinion. Operation A ball track (thread-like grooves) is machined into the steering rack. The balls of the recirculating ball nut run close together in a row in part of the ball track. The toothed belt causes the toothed belt drive output pinion to rotate. Because of the rotation of the output pinion, the balls build up an axial force and push the steering rack to the right or left. The front and rear ends of the chain of balls are connected via the ball return. The balls therefore run in an infinite loop. The toothed belt drive output pinion runs on a ball bearing. Advantage compared to toothed rack drive: A larger transmission ratio is generated. This is necessary because the {Acronym.EPS} motor is more efficient at higher rotational speeds. In addition, no bending force is generated on the steering rack. WARNING: The ball bearing is sensitive to axial impact load. When working on the front axle or on the front brakes, harsh impacts must be absolutely avoided (such as those caused by hammer blows on the brake disk or wheel hub).