Fig. 314. How Electric Current is Applied to Advantage for Lighting, Operating Warning Signals and
Other Uses on the Packard Automobile.

the generator might produce sufficient current to burn out the lamp filaments. If the current is taken from a storage battery alone, this becomes exhausted in a short time and needs frequent recharging. By combining the two systems of current production, the dynamo is employed to keep the battery properly charged, and as the storage cells are always at full capacity it delivers a steady current of the proper voltage for the lamps.

Q. What are the principal types of automobile warning signals?

A. Automobile warning signals are usually in the form of a horn or whistle, though sirens, electric buzzers and mechanical horns

have received wide application of late. The bulb horn shown at A, Fig. 315, is a cheap and satisfactory signal for city use, but it is not powerful enough to carry the sound any distance, which is necessary when touring. The operation of a horn of this character is simple, a pressure of the hand on the rubber bulb serving to send a draft of air past a reed located in the horn member.

The exhaust whistle shown at B is attached to the exhaust pipe by some form of valve which will cause the gas to pass through this horn instead of through the muffler when desired. As four whistles of varying size and length are provided the device will emit a pleasing musical tone which varies in intensity according

to the velocity of the exhaust gas which in turn depends upon the speed of the engine.

The form of electrical horn generally used is shown at C. This is operated from the ignition or lighting battery current which rotates a small motor that acts on a diaphragm by means of a cam provided with a large number of points so the diaphragm is caused to vibrate very fast, and produces a discordant shrieking note that can be heard a long distance away.

The bulb horn shown at D has four independent reeds which are brought into action progressively by a simple pneumatic shutter so the series of impulses of air produced by squeezing the bulb will cause the device to give a musical warning sound like a bugle call. The electrically operated horn will throw the warning note farther ahead than any of the others, but the exhaust whistle is superior to the bulb horn. The types of warning signals that have been evolved are legion, but those shown are representative and practical and show the principal forms.

Q. Why are speed indicators valuable?

A. Speedometers, which indicate the velocity of the car in miles per hour, are valuable in enabling the motorist to regulate his speed according to the law. As most of these devices are provided with trip and season odometers which indicate the distance actually traveled the device provides a useful check on the life of tires, gasoline and oil consumption and general service the car is capable of giving A speedometer is also useful in following routes given in various road guide books. A typical speed indicator and clock combination is shown at Fig. 316-A.

Q. What value have tire chains?

A. When plain tread tires are used it is necessary to provide some means by which greater traction or adhesion on wet or slippery roads may be obtained than would be the case if only the smooth rubber and road surface came in contact. The simplest and cheapest method of obtaining this end is by means of antiskid chains, as shown at B, Fig. 316. These not only insure proper traction on unfavorable highways but also provide positive control when the brakes are applied because they prevent skidding.

Q. What is the wind shield?

A. The wind shield is a frame of metal tubing in which are placed lights of plate glass, so the operator and passengers may be shielded from the dust or cold wind without interfering with the vision. A typical wind shield is shown at C, Fig. 316. The frame may also be made of wood or a light metal frame covered with leather and having celluloid pieces instead of glass may be used. Q. What is the Stepney emergency rim?

A. The Stepney spare wheel is a rim adapted to carry a fully inflated tire and having lugs and anchorage members by which it

may be quickly attached to the rim of a wheel having a flat tire without removing the defective tire. This device is not widely used at the present time because quick detachable and demountable rims have been developed that permit one to make a tire change in but very few minutes. A spare rim of this form with tire in place showing the attaching lugs is depicted at D, Fig. 316.

Q. What are shock absorbers, and how do they work?

A. Shock absorbers are devices intended to prevent harsh action of chassis supporting springs, either by providing some retarding means to keep the spring from working too fast, deflecting too much or act as a check to prevent too rapid rebound after deflection. The principal forms of shock absorbers are outlined at Fig. 322. The Ames device is a supplementary laminated leaf spring fitted on top of a regular semi-elliptic form to prevent rapid rebound. The J. M. shock absorber is a type designed to replace the usual spring shackle and operates by providing sensitive springs to take the shocks produced by minor road irregularities. Devices of this nature are not true shock absorbers but are more in the nature of auxiliary springs. The Sager device is a simple coil spring attached to frame and axle. These are supplementary members which act to retard rapid movements of the main spring. The Gabriel device is a rebound check that prevents a rapid return of the spring after deflection. The Connecticut shock absorber has a series of leaf springs in a housing attached to one arm to retard the motion of a cam piece attached to the other arm joined to the spring. The Truffault-Hartford comprises friction pads at the joint of levers attached to the spring and frame respectively. These friction pads prevent rapid axle movement, either on deflection or rebound. The Flentje shock absorber is a hydraulic form in which too rapid spring movement is prevented by the dash pot action of a piston provided with small passages working in a cylinder filled with glycerin. The auxiliary springs such as the Sager are very useful if rough riding is caused by the main springs being weak. The J. M. type provides easy riding when the main supporting springs are too stiff. The