FOR PRACTICAL 

 WORKERS 



Dust Proofing the Priming Cup on 

 Automobile Engines 



AS motorists well know, the presence of 

 l small particles of grit and dust in the 

 cylinders of an automobile motor causes 

 much trouble. Unfortunately most prim- 

 ing cups are the source of this trouble. 

 They collect 

 dust which is 

 washed into the 

 cylinder when 

 priming the 

 motor. Here- 

 with is shown a 

 cup designed to 

 prevent such 

 trouble. It 

 consists of a brass body A threaded on the 

 end so that it can be screwed into the cylin- 

 der. Just below the small tapped hole in 

 the body is a conical seat for the needle- 

 valve C, which is made of steel. The upper 

 end of the needle-valve is riveted into the 

 cap B, which is knurled on the outside so as 

 to present a good gripping surface. The 

 needle-valve is seated by screwing down on 

 the knurled cap. — W. Burr Bennett. 



Cap for the cup 

 with needle-valve 



Proper Care of Inner Tubes 

 to Prevent Chafing 



IF tire users better understood the con- 

 struction of inner tubes, and factors 

 which contribute to their wearing out, it 

 would be easy to secure more and better 

 service. Spare tubes should not be carried 

 in the cardboard boxes furnished from the 

 dealers' shelves. There is much danger 

 of their being chafed. Tube bags can be 

 secured for this purpose. 



If the car is equipped with smaller tires 

 on the front wheels than on the rear wheels, 

 an extra tube should be secured for each 

 size. The cross-sections of inner tubes are 

 made a little smaller than the normal air 



space inside of the cases. It is not advis- 

 able to use a 4^-in. tube in a 4-in. case. 

 This usually wrinkles and creases the rub- 

 ber, with bad results. Do not use a 4-in. 

 tube in a 4^-in. case for any length of 

 time. When this is done the rubber is 

 stretched too much and the effect of heat 

 and displacement of air in the tire quickly 

 uses up the life of the tube. 



If put into usage for which it was not 

 designed, the tube will not, as a usual 

 thing, render efficient service. If it were 

 practical to use one size of tube in another 

 size of case, tire manufacturers could effect 

 a big saving in equipment and furnish only 

 a few sizes of tubes. 



Lubrication is most important to con- 

 servation of the tube, but it is a matter 

 that is given the least attention. Practically 

 all tire manufacturers treat the inside of 

 cases with a white solution to prevent 

 tubes from sticking to the adhesive "fric- 

 tion" of the fabric. A good lubricant, 

 however, should also be used. 



Some tire users neglect dusting soap- 

 stone inside of the case when changing a 

 tube. Others use the soapstone so sparingly 

 that it does but little, if any good, or they 

 may use so much that it does more harm 

 than good. If a quantity of it be dumped 

 into the case it will collect at one point, 

 and during the hot weather will heat up to 

 such extent as to burn the rubber of the 

 tube, making it thin, brittle and lifeless. 

 This results in a honeycombed appearance. 

 Soapstone is the lubricant most used for 

 tires and is satisfactory, but not lasting. 

 Therefore, a fresh supply should be put in 

 the tires at least two or three times during 

 the season. Powdered mica has proven a 

 more durable lubricant than soapstone, and 

 quite as effective as graphite, and is much 

 more pleasant to handle. It should be 

 dusted on the fabric all around the case 

 and on the inner tube to cover every par- 

 ticle of the surface. 



455 



