Steering (Valve unit): Description and operation

VALVE UNIT

1. Input shaft
2. Torsion bar
3. Circlip
4. Oil seal
5. Valve housing
6. PTFE ring - 4 off
7. Outer sleeve

The torsion bar is fitted inside the rotor and is connected to the input shaft and the pinion shaft with pins. The central diameter of the torsion bar is machined to a smaller diameter than at each end. The smaller diameter allows the torsion bar to twist in response to torque applied from the steering wheel in relation to grip of the tyres on the road surface.

8. Pinion shaft
9. Bearing
10. Oil seal
11. Nut
12. Bearing
13. Pin - Pinion shaft to torsion bar
14. Pin - Rotor to torsion bar

The pinion shaft has machined teeth on its central diameter which mate with the teeth on the steering rack. A bore in the upper end is machined with loose splines which mate with similar splines on the rotor. The pinion shaft locates in a cast housing which is part of the steering rack and rotates on ball and roller bearings.