Fig. 4 shows a typical automobile engine equipment. With regard to the very numerous variations in design and details of construction see AUTOMOBILE ENGINE; AEROPLANE; MOTOR BOAT.
The equipment for the starting and control of automobile engines has undergone a continu ous development; the control mostly through the improvement of carburetors, the starting mainly since 1910 and in conjunction with the gradual adoption of electric lighting for auto mobiles, the practicability of electric light ing for vehicles being in turn determined by the perfecting of Tungsten filaments for electric incandescent lamps, as the older filaments were unable to withstand shocks and vibration long enough. The improve ment of carburetors has had three main objects : To obtain the best and most economical mixture at all degrees of throttling, to permit the use of benzol and of the gasoline of higher specific gravity which in the course of the years has become the only kind available in large quantities in the market, and to make it possible to accelerate an engine rapidly. The method adopted has been singularly restricted to modifying the channels through which suc tion from the engine reaches a carburetor and the atmosphere, separate mechanical means for varying the fuel feed rate being rarely tried. Details of this development, by which remark able results have been accomplished by a very difficult route, are given under Atrromosnz ENGINE.
For many years, of the automobile engine was accomplished universally by turning a crank applied to the free end of the crank shaft — nearly always at the front of the motor car, and this is still the method employed in cars of limited pretensions to luxurious equip ment as well as in most motor wagons and trucks. This crank grips only in one direction of rotation and has an automatic spring release. In some cases a special safety clutch is inter posed to protect the operator against reverse rotation of the crank, as may occur if ignition of a fuel charge takes place prematurely in one or more of the engine cyhnders. They are similar to those used for hoists and other ma chinery subject to reverse movements, but are losing importance for automobiles with the gen eral introduction of engine-starter devices.
As the operation of a starting crank involves a physical effort which can become onerous in cold weather or when carburation and ignition are not in perfect order, and is on the whole inelegant and inconvenient, many methods for starting the engine have been tried (see Atrro MOBILE ENGINE). The simplest of these is em ployed in practice in conjunction with a starting crank equipment and consists in turning the timing-lever of the ignition equipment, thereby producing sparks which may ignite explosive charges remaining in one or two of the cyl inders after the last previous operation of the engine. But this method is not dependable. The more radical and reliable methods consist in (1) a mechanical connection enabling the driver to turn the engine shaft without leaving his seat, (2) arrangements for storing com pressed air and by its release turning the crank shaft, and (3) arrangements for turning the crankshaft (often from the rim of the flywheel) by means of a small electric motor receiving current from an electric storage battery which has previously been charged from the engine by means of a generator or from an independ ent source of current. The compressed-air engine-starter arrangement is used mostly in France but is giving way to the electric method. Fig. 5 shows a diagram of one of the many electrical arrangements, which additionally sup ply current for electric lamps.
Power The typical mechan ical power transmission mechanism of a motor car comprises the clutch, the gearset, the drive shaft with universal joints, a bevel gear and a differential gear mounted at the middle of the rear axle and keyed to wheelshafts which are again keyed at their outer ends to the hubs of the road wheels. A transmission set less used for motor cars but more for motor wagons and trucks comprises the clutch, the gearset, the bevel gear and differential on a transverse countershaft near the middle of the vehicle, a The brake type, which is rare, is similar to rear wheel brakes, comprising either two semi circular segments arranged to be expanded against the flywheel rim or a steel band con tractible on a drum secured to the face of the flywheel. It is mostly used in Europe, especially in German cars.