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AUTOMOBILE PARTS AND THEIR FUNCTIONS
Automobile Engine Parts—Cooling Systems—Carburetion System-
How Automobile Chassis is Divided into Groups.-In order to deal systematically with the subject of motor-car construction, one may divide the essential mechanism into groups and treat each of these assemblies in detail. In order to understand the functions of the various parts, views of typical pleasure car chassis of latest design with all components clearly indicated are presented. These show conventional arrangements of parts in vehicles which are adapted to a wide range of work. Of the many elements comprising the automobile, the source of power is the most important. Then comes the method of power transmission, and last the various chassis parts which have to do with suspension, control, etc. By referring to illustrations, which show the construction of typical gasoline car chassis clearly, the functions of the various parts and their relation may be easily understood.
The basis of any conveyance, whether animal drawn or power propelled, is a running gear. That of automobiles consists of a frame supported on springs which rest on the axles, which in turn carry the wheels on which the whole assembly can roll over the ground. In a horse drawn carriage, where there is no necessity for a heavy or strong supporting frame, and because of the light weight of the body, it is possible to attach the springs directly to the sills on which the body rests. In a motor vehicle,
however, the frame is usually separate from the carriage work, because it is often necessary to remove the body to gain access to some portion of the mechanism which may need attention. The frame of an automobile must be strong because the engine and some of the parts of the transmission system are installed thereon, and also because the speed possibilities of the automobile make it necessary that the frame be of sufficient strength to resist the stresses due to car movement and frame distortion when driven over uneven road surfaces. These strains are not present in other forms of conveyances. The locomotive, which is capable of high speed and which is very heavy, travels on a smooth track, while ordinary horse drawn carriages are not affected materially by the roughness of the path on which they travel because of their low speed and light weight.
In the frame, or chassis group, one may include the main frame, sub-frame, steering gear, clutch and brake pedals, hanc levers for varying change speed gear ratios and applying emergency brakes; the front axle and its steering connections, the driving axle and brakes, the wheels, the tires, and the springs which form a yielding connection between the axles and the frame.
The power plant of a gasoline automobile is composed of a number of distinct devices of which the engine proper is the most important, though all of them are necessary to insure practical operation. In order to describe power plant construction logically, it may be divided into six distinct parts or groups of which all are composed. The most important assembly is the motor; then the gas supply system, the ignition apparatus, the devices used for lubrication, the system of cooling and the muffler assembly. The power transmission mechanism is the next group of importance. In this assembly one places the clutch, the gearset, the driving means, and, in most instances, the rear axle and traction members.
Parts of Typical Automobiles and Their Functions.--A brief explanation of the function of each important part of the gasoline car chassis depicted at Figs. 1, 2, 3 and 8 will serve to afford a better understanding of the construction of the modern auto
Fig. 2.—Side View of Chalmers Light Six Touring Chassis, Showing Simplicity of Motor Cars of Latest
mobile. The purpose of the front axle is not unlike that of a horse drawn vehicle, but it is much different in construction. The wheels are installed on movable spindles, or steering knuckles, which are supported by yokes permitting one to move the wheels for steering rather than turning the entire axle on a fifth wheel, or jack-bolt arrangement, as in a horse drawn vehicle. This axle is attached to the frame by spring members which allow a certain degree of movement without producing a corresponding motion of the frame. The radiator, which is placed directly over the axle in front of the motor, is employed to hold the water used in keeping the engine cool and is an important part of the heatradiating system. The starting handle is a crank by which the motor crank shaft is given sufficient initial movement by the operator to carry the engine parts through one or more portions of the cycle of operations, this starting the engine. Nearly all cars now have electrical starting means except the Ford. The tiebar joins the arms of the steering spindles on which the wheels revolve, and insures that these will swing together and in the same direction, either to the right or left. The steering link, often called the "drag link," connects one of the steering knuckles of the front axle with the steering gear. The motor may be one of the many forms to be described and one of many distinct types. The dash is a wooden or metal partition placed back of the power plant to separate the engine from the seating compartment. It is often employed to support some of the auxiliary apparatus necessary to motor action or some of the control elements.
The clutch is a device operated by a pedal, which permits the motor power to be coupled to the gearset and from thence to the driving wheels, or interrupted at the will of the operator. It is used in starting and stopping the car and whenever the change speed gears are shifted. The accelerator is a small pedal which actuates a valve on the gas supply device to permit more explosive mixture being fed to the engine when it is desired to increase the motor speed. Its function is comparable to that of the throttle of a steam engine. The pedals are foot-operated levers; one of which releases the clutch, the other applies the service brakes. The motor control levers on the steering column