Figure 33-9. Cam and Lever Steering Gear
because of its added strength and steering stability.
Figure 33-10. Worm and Nut Steering Gear
33-7. Worm and Nut Type. Another form of steering
33-8. Rack and Pinion Type. In the rack and pinion
gear is the worm and nut, which is made in several
steering system (fig. 33-11) the steering gear shaft
different combinations, A nut is meshed with the worm
utilizes a pinion gear on the end, to mesh with a long
and screws up and down on it. The nut may operate the
rack. The rack is connected to the steering arms by tie
pitman arm directly through a lever, or through a sector
rods, which are adjustable, to maintain proper toe angle.
on the pitman arm shaft. An example of the recirculating
As the steering wheel is rotated, the pinion gear on the
ball type of the worm and nut steering gear is shown in
end of the steering shaft rotates. The pinion moves the
figure 33-10. In this steering gear, the nut, which is in the
rack left and right to operate the steering linkage (para
form of a sleeve block, is mounted on a continuous row
33-3c). Rack and pinion gears are used on small
of balls on the worm to reduce friction. This ball nut is
passenger vehicles where a high degree of precision
fitted with tubular ball guides to return the balls diagonally
steering is required. Their use on larger vehicles is
across the nut to recirculate them as the nut moves up
limited because of the conflicting space requirements of
and down on the worm. With this design, the nut is
rack and engine.
moved on the worm by rolling instead of by sliding
contact. Turning the worm moves the nut and forces the
sector and the pitman arm shaft to turn.