Worm And Level Steering Gear: The worm and rotter steering gear (fig. 8-21) is quite similar to the worm and sector, except a roller is supported by ball or roller bearings within the sector mounted on the pitman arm shaft. These bearings assist in reducing sliding friction between the worm and sector. As the steering wheel turns the worm, the roller turns with it, forcing the sector and pitman arm shaft to rotate.
 
The hourglass shape of the worm, which tapers from both ends to the center, affords better contact between the worm and roller in all positions. This design provides a variable steering ratio to permit faster and more efficient steering.

Figure 8-21.- Worm and roller steering gear
\"Variable steering ratio\" means that the ratio is larger at one position than another. Therefore the wheels are turned faster at certain positions than at others. At the center or straight-ahead position, the steering gear ratio is high, giving more steering control. However, as the wheels are turned, the ratio decreases so that the steering action is much more rapid. This design is very helpful for parking and maneuvering the vehicle.

Cam and Lever
The cam and lever steering gear. in which the worm is known as a cam and the sector as the lever, is shown in figure 8-22. The lever carries two studs that are mounted in bearings and engage the cam. As the steering wheel is turned, the studs move up and down on the cam. This action causes the lever and pitman arm shaft to rotate. The lever moves more rapidly as it nears either end of the cam. This action is caused by the increased angle of the lever in relation to the cam. Like the worm and roller, this design allows for variable steering ratio

It is a worm for the active parts, crank pin for the steering gear follower. Worm has a trapezoidal thread, referring to a finger-shaped pin with tapered bearings in the crank bearings, the crank shaft and the shift into one arm. Shifted through steering wheel rotating worm, helical worm embedded in the cone-shaped slot means the marketing side of the rotation, the side rocker shaft to do around the shifted arc movement, thereby stimulating and steering crank arm swing down and then turning to make shift transmission wheel deflection. This steering is usually used to turn power on a larger truck.
 
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