Steering (Operation): Description and operation

OPERATION

1. Spring
2. Worm gear
3. Worm wheel
4. Output shaft
5. Ball bearing
6. Pin
7. Lever pin

EPAS Mechanical operation

The motor, clutch and motor worm gear are mounted on the cast gear housing on the column. The worm wheel is attached to the output shaft. The input shaft and the output shaft are joined by a torsion bar.

When the steering wheel is rotated, torque is applied to the torsion bar which twists causing an angular deflection between the input and output shafts.

8. Rotary potentiometer
9. Slider/ball bearing (inset)
10. Ball
11. Slider
12. Torsion bar
13. Input shaft

The deflection causes the slider to rotate via the balls in the ball groove which causes linear movement of the slider along the axis of the output shaft.

The rotary potentiometer in the torque sensor has a pin, which is fitted with a ball bearing. The bearing locates in a groove in the slider. The linear movement of the slider is converted back to rotational movement of the potentiometer, via the bearing and pin. The torque sensor converts the torque applied into an electrical signal which is proportional to the steering torque.