Operation and Care

The steering mechanism used in automobile construction is arranged to operate independent of the axle, or in other words the wheels turn on a pivot, or knuckle, held between the yoked ends of the axle. A spindle or axle extends outward from each steering knuckle to accommodate the wheels. A set of short arms extend to rear of the steering knuckles; an adjustable spacer bar, commonly called a tie or spread rod, serves as the connection between the arms. The arms incline slightly toward each other; which causes the inside wheel to turn on a shorter angle than the outside wheel when turning a corner. Another steering arm carrying a ball at the outer end, describes a half circle over the axle, and is attached to either the spread rod arm or the steering knuckle. An adjustable rod, or drag-link, carrying a ball socket at each end serves as the connection between the steering arm extending from steering gear and the half circle arm of the knuckle. To adjust wheels see chapter on “Wheels and Axle Alignment.”

Steering Gear Types.—Three types of steering gears are commonly used by automobile manufacturers. They are namely, the worm and sector, worm and nut, and rack and pinion types.

Fig. 135 shows the construction and operation of the worm and sector type. The lower end of the steering shaft carries a worm gear which meshes with the sector gear supported by a separate shaft. The sector has a ball arm extending downward, which moves in a forward and backward direction when the steering shaft is turned.

Adjusting the Worm and Sector Type of Steering Gear.—An eccentric bushing is provided to take up play between the worm and sector. This adjustment is made by driving the notched cone to the right to take out play, and to the left to slack up or take out stiffness.

Fig. 136 shows the worm and nut type of steering gear. This type of steering gear as well as the worm and sector, is called the irreversible steering gear, which means that no reverse action takes place, or is present at the steering wheel, should one of the front wheels encounter a stone in the road, or drop into a deep rut. The worm and nut type consists of a double armed and pivoted steering arm. Each arm carries a ball. The drag link socket is attached to the ball on the lower arm while the ball on the upper and shorter arm fits in a socket in the nut through which the worm on the steering shaft passes. This nut is threaded to fit the worm which passes through it and moves up and down on the worm according to the direction which the steering wheel is turned. The housing of this type of steering must be well packed with a light cup or graphic grease to prevent the screw or worm from binding, which will make steering difficult and tiresome.

Fig. 137 shows the rack and pinion type of steering gear. This type of steering gear is used on a few of the lighter weight cars and is not as dependable owing to a reverse action through the steering mechanism when an obstruction is encountered by one of the front wheels. This type of steering device consists of a solid shaft with the steering wheel keyed to the upper end.

A small spur gear is keyed and locked to the lower end, and meshes with a horizontal toothed shaft which slides inside of a housing. The connection between the steering gear and the steering knuckles is made by a short rod or drag link carrying a split ball seat on each end. One end of the drag link socket is fitted to a ball on the end of the horizontal toothed shaft, while the socket on the other end is fitted to a ball on the upper end of the bolt which connects the tie rod and knuckle.

Steering Gear Care.—Steering gears should be closely adjusted. The housing should be packed with a medium hard oil or graphite grease at least once in every thousand miles that the car is driven. All bolts and nuts connecting the different parts of the steering gear should be regularly inspected and kept in a perfectly tight condition.

Fig. 138 shows the location of the spark and gas control levers which usually operate on a quadrant on the upper side of the steering wheel. The short lever always controls the spark, which may be advanced or retarded by moving it. The long lever is attached to the carburetor, and controls the speed of the motor by regulating the volume of gas vapor supplied to the motor.