Зображення сторінки
PDF
ePub
[graphic][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed]

Fig. 6.-Carburetor Side of Chalmers Unit. Power Plant.

Q. What does the power plant consist of?

A. The usual gasoline automobile power plant consists of a gasoline engine, a carburetion or fuel supply group, an electrical ignition system, a lubrication system, and means for cooling the engine. (Figs. 6 and 7.)

Q. Name functions of carburetion group.

A. The purpose of the carburetion group is to supply the motor cylinders with an explosive gas.

Q. Name parts of carburetion group.

The principal parts of a carburetion group are: a suitable tank or container for the liquid fuel; piping by which this is transfered from the tank to the carburetor or vaporizer which changes the liquid fuel to a gas, and a suitable manifold by which the gas from the carburetor is supplied to the motor cylinder.

Q. Name functions of ignition system.

A. The purpose of the ignition system is to ignite the gas or vapor supplied to the engine cylinder by the carburetion group and to produce power by exploding this gas in the cylinder.

Q. Name parts of ignition system.

A. The parts of the usual electrical system are: some source of electrical current; wires for conveying it from the current producer to a switch or timer which regulates the time the electric spark occurs in the engine; an induction coil or similar apparatus for transforming current of low potential or voltage to current of higher power capable of producing a spark in the cylinder and some form of spark plug which is placed in the combustion chamber and between the points of which the spark that explodes the gas occurs. Some ignition systems consist merely of a magneto or mechanical generator which incorporates in its construction the necessary timing and current intensifying appliances and wires leading from this device to the spark plugs in the motor cylinder.

Q. Why is a lubrication system needed?

A. If the parts of the power plant were not properly oiled, they would wear out very quickly, and in fact it would not be possible to run a gasoline engine for any length of time without supplying oil to

[graphic][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed]

Fig. 7.-Exhaust Side of Chalmers Unit Power Plant.

reduce friction between the piston and cylinder and the other bearings.

Q. What does a lubrication system consist of?

A. A lubrication system, such as commonly used in connection with the gasoline engine, consists of a container or tank in which oil is stored, some form of pump to supply the oil to the bearing points, and piping to convey the oil from the container to the pump, and from the pump to the motor.

Q. What does the cooling system do?

A. As the power of a gasoline engine depends upon exploding gas in its cylinders, it would soon get very hot, due to the high temperature produced by the rapid burning or combustion of gas, and unless it was cooled in some manner and the surplus heat extracted from the metal of which the cylinders are composed, the high temperature existing would soon produce deformation of parts and would put the engine out of commission.

Q. How many types of cooling systems are used?

A. Automobile power plants are cooled by two methods, the simplest of which is to direct a stream of air from a fan or blower on the cylinders, which are provided with flanges to increase the radiating surface, or by passing water thru jackets surrounding the cylinders and afterward cooling this water by passing it thru a radiator exposed to the action of a cooling current of air. Engines are thus cooled either by air directly applied to the heated metal or indirectly utilized when it cools the water which has absorbed the surplus heat of the engine.

Q. What is the purpose of the clutch?

A. The clutch is a simple form of easily operated coupling which makes it possible to run the engine independently of the rear wheels when desired.

Q. Why is change speed gearing needed?

A. Change speed gearing is necessary to provide easily changed ratios of drive between the engine crank shaft and the rear wheels to suit varying road conditions. The gears that give reverse motion to the car are also usually included in the change speed gear set.

Q. How is power usually transmitted to the wheels?

A. The common method of transmitting power from the gear set to the wheels is by means of a shaft and universal joints to a pair of bevel gears or a set of worm gears at the rear axle or by sprockets and chain.

Q. What are the features of chain drive?

A. Power transmission by chains make it possible to obtain varying ratios of drive very easily by merely altering the sizes of the sprockets, and provides for power transmission with minimum loss if the drive is solely by chain.

Q. What are the advantages of enclosed gear drive?

A. Enclosed gearing may be kept free from dirt and grit, and as protected gears may be operated continually in a bath of lubricant, they are not only quiet in operation, but are very enduring and efficient.

Q. Why is the frame needed?

A. The frame is one of the most important parts of an automobile inasmuch as it supports the power plant and power transmission mechanism, forms a connecting link between the axles and the machinery, carries practically all of the controlling elements and power pant auxiliaries, and serves as supporting member for the body which carries the load or passengers.

Q. How is the frame supported?

A. The frame is supported by and attached to the axles thru the medium of resilient members called springs.

Q. How do the front and rear axles differ?

A. The front axle is simpler than the rear and is used only for steering. The wheels are mounted on steering knuckles which are attached to the ends of the axle and which may be moved to the angle necessary to allow the wheels to follow a curve when going around a corner. The rear wheels are attached to the axles in such a way that they cannot move relative to the axle, except to turn around with them, and the general construction of the rear axle on most cars includes the differential and drive gearing.

« НазадПродовжити »