Chapter 9 Steering Systems 181
steering gear because the ball bearings move in a loop, or
circuit, as the worm gear moves the ball nut. The ball bear-
ings can recirculate because of ball guides installed on top
of the ball nut assembly.
The worm and sector gears ride on ball or roller bear-
ings to reduce friction. The steering gear may be lubricated
by 90–140 weight gear oil, or it may require automatic
transmission fluid. Seals at the input shaft and sector shaft
keep lubricant from leaking out of the steering gear. The
worm and sector gears contain thrust washers and spacers
for proper clearance.
Worm-and-Roller Steering Gear
The worm-and-roller steering gear is found on Asian
vehicles, as well as some older Jeep vehicles and European
cars. Figure 9-28 is an illustration of a typical worm-and-
roller steering gear. Unlike the recirculating-ball steering
gear, the worm-and-roller steering gear does not use a ball
nut. Instead, the worm gear turns against a roller installed
in the sector gear. Turning the worm gear causes the sector
gear to move. The rolling action between the worm gear
and the sector roller reduces friction. Note that the worm
gear is tapered, with the end sections being larger than the
center. This worm gear design results in constant full
contact between the worm and roller, no matter what the
sector position. The worm-and-roller steering gear may
have a provision for adjustment.
Worm
Roller
Pitman shaft
Lock washer
Nut
Pitman arm
Bushings
Locknut
Adjusting
screw
Bearing
Shims
Bearing
Roller assembly
Bearing
Case
Worm
Figure 9-28. Exploded view of a worm-and-roller steering gear
assembly. The roller gear engages the worm gear and shaft.
(Toyota)
Adjusting screw stop
Follower peg screw
Follower peg
Gasket
Top cover
Capscrew
Adjusting
screw
Locknut
Washer
Filler plug
Worm gear
Capscrew
Nut
Seal
End cover
Adjusting shims
Gasket
Races
Bearings
Castellated nut
and cotter pin
Washer
Pitman arm
Dust excluder
Oil
seal
Steering box
bracket
Steering
box
Inner
column
Figure 9-29. An exploded view of a worm and tapered pin (peg) steering box assembly. The pin travels in the worm gear.
(British-Leyland)
Worm-and-Follower Steering Gear
The worm-and-follower steering gear is found on
older European cars. Figure 9-29 shows a typical
worm-and-follower steering gear. This design may be