The steering gear used in the Master models passenger cars with knee action is of the ball bearing roller sector type with an hour glass worm and with a gear ratio of 16 to 1.
Fig. 214— Steering Gear Assembly — Knee Action Cars
In this type of steering gear, the worm is rotated as usual, by movement of the steering wheel at the upper end of the worm or main shaft.
The sector has the tooth contours turned annularly around its entire circumference, like a roller. In addition to acting as sector teeth, this roller forms the outer race for a two-row ball bearing.
The inner race of this double-row bearing is made in two halves, one assembly forming each end and held together by a snap ring at the middle. This bearing is pre-loaded to prolong its useful life.
The combined ball bearing and roller sector is pivoted on a hardened and ground bolt in jaws at the inner end of the pitman arm shaft. This jaw is forged integral at an angle normal to the worm centerline.
A slightly tight fit is provided through the central range of the worm movement, where most wear occurs, to increase the life of the gears. The pitman arm shaft bears in two long babbit bearings having oil grooves. The upper roller bearing on the worm, is mounted in the adjusting sleeve insuring accurate alignment.
Bolts passing through the frame side rail and sub-frame secure the steering gear housing rigidly to the frame.
The steering gear used in the Master Conventional, 1/2 ton and 1 1/2-ton trucks and the Standard passenger cars is of the worm and sector type with a gear ratio of 14 to 1.
The worm and inner cones for the roller bearings are machined in one piece from solid stock, properly heat treated to give long life. This design insures the worm being always true with its bearings assuring a free steering gear without binding or tight spots.
Fig. 215— Steering Gear Assembly — Master Conventional,
1- Ton and 1½-Ton Trucks and Standard Models
The sector and shaft is a one-piece forging accurately machined, heat treated for strength and finely ground. A feature of this design of the sector teeth, is that in the straight ahead position all back lash between the gears is automatically reduced, but on curves a few thousands of play is allowed for ease of handling.