Chassis, Body And Trailer Units - TM 10-560 War Department Technical Manual

Iii. Springs and shock absorbers VII. Wheels, rims, and tires Appendix. List of references Index 1. Groups. — A motor vehicle is divided into two general groups: the chassis and the body. The chassis group includes all the units necessary for the proper operation of a motor vehicle. The body provides accommodation for the passengers or the load which the vehicle is intended to carry. A motor vehicle can transport loads in addition to those carried in the body by towing a trailer.

2. Classification. — a. Chassis. — (1) A chassis (fig. 1) includes all the units composing the engine and its necessary accessories, the power transmission system, the suspension system, the steering system, the braking system, and the axles and the wheels. These units are all attached to a frame which serves as a structural center for the chassis and as a foundation for the entire vehicle. The engine and its accessories, the power transmission units, the brakes, and the driv- ing (or live) axles are described in other Technical Manuals. All other chassis units are described in this manual.

(2) The frame is supported on the axles and wheels through a suspension system which allows the wheels to move up and down without unduly straining the frame. The steering system turns the wheels (usually the front wheels only) to control the vehicle’s direction.

b. Body. — The body of a motor vehicle is mounted on and directly supported by the frame. Accommodations are provided for the operator and passengers or for the load carried by the vehicle. On trucks, a cab or compartment separate from the pay-load compartment provides accommodation for the operator and contains all the necessary controls and a panel for the vehicle’s operating instruments. Body types and their construction are discussed in section VIII.

c. Trailer. — The function of a trailer is to carry loads. The methods of pulling a trailer and trailer construction are discussed in section IX.

Axis. — A center line; a line about which something rotates or about which it is evenly arranged.

Axle. — A cross support on a vehicle on or with which its wheel or wheels turn. Live axles while carrying the vehicle load also transmit power to the wheels. Dead axles transmit no power to the wheels.

Bending moment. — The tendency of a moment (force at a distance from the supporting point) to bend or distort a beam.

Body. — Structure mounted on a vehicle chassis to provide accommodation for the operator, passengers, and cargo.

Bogie. — A suspension unit consisting of tandem axles joined by a single cross support (trunnion axle) that also acts as a vertical pivot for the entire unit.

Bond. — To bind together.

Cab.— Separate driver’s compartment provided on trucks.

Camber. — To curve or bend; the amount in inches or degrees that the front wheels of an automotive vehicle are tilted in or out from a true vertical at the top. Motorcycles do not have camber.

Caster. — The amount in degrees that the steering knuckle pivots are tilted forward or backward from a true vertical.

Center of gravity. — An imaginary point within the length and width of a vehicle about which all the vehicle weight is balanced.

Chassis. — The framework of a vehicle including. all the parts necessary for its operation.

Cowl.

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