Popular Science Monthly 



The weight of the car will determine 

 the size wire to be used in the coil 

 springs; 3/16" for the front springs and 

 34" for the rear ones is about right for 

 a car in the 2,000 pound class. This is 

 figured for a touring car where five pas- 

 sengers are to be carried. In the case of 

 the roadster the rear springs could be of 

 one size smaller wire. In the case of 

 cars materially heavier the size of the 

 wire should be increased. In order that 

 the springs may carry the load properly 

 they must be made 1" longer than the 

 place they are expected to fill. This 

 means that when they are assembled in 

 the finished shock absorber, they are 

 already under compression. According- 

 ly those for the front absorbers should 

 be 6" and those for the rear springs 7" 

 long. The inside diameter of the springs 

 should be not less than 1^4" in any case. 



Those fortunate enough to have ac- 

 cess to a machine shop can wind their 

 own springs if desired, although there 

 will be no great saving as the springs 

 will be made up as ordered by any good 

 spring manufacturer for about twenty- 

 five cents each. 



When placing the absorbers on the car 

 they should first have their springs com- 

 pressed and tied down with wire in order 

 that they will not interfere with placing 

 the bolts through. To compress them, 

 use a cabinet clamp or vise. 



The entire cost of the absorbers de- 

 scribed was just $3.34 outside of the 

 work. 



Key Controls Battery Current 



WHERE batteries are placed on 

 bicycles or motorcycles for light- 

 ing purposes, it is a great temptation to 

 mischievous boys to turn the current on, 

 a circumstance which, of course, means 

 a loss of money to the owner of the 

 vehicle. Such happenings can be averted 

 if a lock switch is employed for con- 

 trolling the battery current. 



281 



The batteries should be placed in a 

 metal cylinder, the ends of which are 

 plugged with wooden discs. On one of 

 these discs a small drawer lock is fasten- 

 ed. At one side of the lock — the side 

 from which the bolt emerges when the 

 key is turned — a brass or phosphor- 

 bronze contact spring should be fas- 

 tened.. When the key is turned, the bolt 

 pushes this spring against a brass con- 

 tact, and current flows from the bat- 

 teries to the lamps. 



Eliminates Pants' Guards for 

 Bicycle Riders 



ACHAT N guard can be made for 

 bicycles which will dispense with 

 the need of pants guards. 



A circular piece of stiff metal, having 

 a diameter i'' greater than that of the 



C 



D 



When the key is withdrawn, the auto-thief or 

 mischievous boy is foiled 



A circular piece of metal protects the trousers 

 from the sprocket gear 



large sprocket, should be cut and 

 crimped along the edge. Clamps should 

 be fashioned from heavy steel or iron 

 for the purpose of grasping the spokes 

 of the sprocket. The clamps should be 

 soldered to one face of the protecting 

 disc and holes bored through the two. 

 Machine screws pass throug'. the holes, 

 terminating in tapped holes in similar 

 clamps on the opposite side. 



A Try- Square Aid 



WHEN using a try-square to deter- 

 mine if stock is true, one cannot 

 remember all the high and low spots. If 

 the edge of the try-square is dipped in 

 lamp black before using, and is then run 

 on the piece, all the high spots will be 

 black while the low places will remain 

 untouched. 



