« НазадПродовжити »
Mechanical Starters.—While different makes of cars have been marketed using air starting systems, there has been no car offered with a mechanical starter, so wherever these are used they have
been applied by the owner of the vehicle and not the manufacturer. Owing to the wide distribution of the Ford automobile, and the fact that the makers make no provision for a self-starting motor, various forms of simple starters by which the motor may be cranked from the seat have been offered. Two of these are shown at the top of Fig. 281. That at A consists of a ratchet clutch
which is attached to the starting end of the crankshaft and which is operated by means of chain connection with the smaller pulley of a two diameter pulley wheel. The larger wheel carries a wire cable which is attached to a straight rod running through the dashboard and terminating in a handle convenient to the drivers hand. A pull on the spade type handle provided at the end of the rod will move the pulley wheel and produce a corresponding movement of the starting ratchet which turns the engine crankshaft over in the same way as the hand crank does. A modification of the device shown at A is outlined at B. This works on the same principle, except that an odd-shaped member is used to turn over the engine crankshaft. These devices are in no sense of the word "self-starters,” but on light motor cars they provide an effective substitute in that the engine may be turned over without undue exertion and without leaving the seat. This is an advantage of some moment when the engine stalls in traffic, or under conditions where it would be inconvenient to get out of the car.
Two types of mechanical starters known as the Wilkinson are shown at the bottom of the illustration, Fig. 281. The one at D is operated by pulling a handle on the dash, the one at C by a pedal designed for foot actuation. The mechanism is such that the flywheel is pushed around by a lever which will engage with either a stud or a shoulder on the flywheel. The type at the left uses the studded flywheel, there being four of these marked “S.” When the arm C is moved by depressing a pedal, the finger A contacts with one of the studs and turns the flywheel. Return engagement is produced by the large spring shown. In order to minimize liability of injury from backfire, the Wilkinson device is constructed so that the pawl D rises on the cam which bears against the collar E, and thus throws the finger out of engagement with the stud. One thrust of the pedal will turn the fly. wheel of a four-cylinder engine sufficiently to cause one cylinder to fire should ignition and carburetion and carburetion systems be functioning properly. The type at D is just as simple, but is modified somewhat in its construction. In this a hand lever is used to rotate the flywheel, and instead of using studs on the flywheel rim, four shoulders in the interior periphery do the work.
These shoulders may be cast with the wheel, or in some cars it is possible to have them cut in the flywheel. The operation is the same as that of the type previously described as the movement of the cable causes the finger to engage with one of the shoulders, and thus turn the flywheel.
The results obtained with any of these mechanical starters are not to be compared with that obtained from an electrical device which spins the motor much faster than normal hand-cranking speed, whereas the mechanical starter produces a movement of not more than half a revolution of the flywheel. Various forms of spring-operated starters have been devised and placed on the market, but these have not been very popular on account of their bulk and lack of reliability. The amount of power that can be stored in a spring is not great, and at the most the motor could only be turned over three or four revolutions. If the ignition or carburetion systems were not functioning just as they should be, it will be apparent that the spring would be unwound and incapable of starting the motor. In order to turn the motor over it is necessary with most of these starters to rewind the spring with a hand crank provided for the purpose. If the engine starts promptly the spring is rewound automatically by the engine, and as long as the engine starts without delay the starter is available for use. Practically all of these devices require special fittings, with the exception of those described for the Ford car, and as full instructions are furnished by their makers for application the repairman who is called upon to fit a mechanical starter may do so without trouble by following the instructions provided.
Pneumatic Starters.—Three prominent makes of automobiles which have been marketed in fairly large numbers, namely the Winton, Pierce-Arrow and Chalmers, have used pneumatic or air starters all of which have operated on exactly the same system. At the present time these cars are furnished with electrical starters of the conventional pattern. In case the repairman is called upon to repair one of the models equipped with an air starter, the writer believes it necessary to consider the arrangement of the parts and the method of operation briefly before considering the subject of electrical starters. All the components of typical sys
Fig. 282.-Diagram Showing Parts of Air Starting Systems Used on Some Early Models of Pierce-Arrow
tems, one of which was used on Pierce-Arrow cars, is shown at Fig. 282. It will be observed that an air pump of the four-cylinder type was attached to the gear box and driven from the counter shaft of that member. This supplied air to an air reservoir or container attached to the chassis. This container communicated with the top of an air distributor when a suitable control valve was open. An air pressure gauge is provided to enable one to ascertain the air pressure available. The top of each cylinder is provided with a check valve, through which air can flow only in one direction, i.e., from the tank to the interior of the cylinder. Under explosive pressure these check valves close. The function of
BALATHER Pire (Oil Funsa)
SILENT CHAIN OHIVE
Fig. 283.-Some Important Components of Early Chalmers Air Starting