Steering (Steering Rack): Description and operation (page 2 of 2)

The outer sleeve is located in the main bore of the valve unit. Three annular grooves are machined on its outer diameter. PTFE rings are located between the grooves and seal against the bore of the valve unit. Holes are drilled radially in each annular groove through the wall of the sleeve. The bore of the outer sleeve is machined to accept the input shaft. Six equally spaced slots are machined in the bore of the sleeve. The ends of the slots are closed and do not continue to the ends of the outer sleeve. The radial holes in the outer sleeve are drilled into each slot.

The input shaft is splined at its outer end and has a cross hole for location of the torsion bar. The inner end has splines which are a loose fit in corresponding splines in the pinion shaft. The width of the splines allows the torsion bar to twist several degrees before the splines contact one another. The splined coupling between the input shaft and the pinion shaft ensures that if the power steering fails, the steering can be operated manually without overstressing the torsion bar. The central portion of the input shaft has equally spaced longitudinal slots machined in its circumference. The slots are arranged alternately around the input shaft.