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Page:Popular Science Monthly Volume 90.djvu/602

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��Popular Science Monthly

��At Last! An Automatic Motor- Driven Tire Pump





��C5 to the com- pression-cock of an automobile- motor, the novel airpump for pneu- matic tires shown in the accompany- ing drawing is dis- tinguished by the use of a differen- tial piston and a spring - operated diaphragm in which the tension of the spring con- trols the pressure of the air pumped into the tires by means of an exter- nal notched dial.

The pumping of the air is effected through the use of two cylinders, one large and one small. The larger is open to the gases of the engine, while the smaller is open to the atmosphere at one end.

The differential piston, working in the two cylinders, is carried on a hollow piston- rod. As the piston is moved in one direc- tion by the suction of the engine, air is sucked into the small cylinder through a check-valve.

On the compression or explo- sion stroke of the engine, the large piston is forced in the opposite direction, and the air is forced into the small cylinder be- cause the check-valve is closed, then through the hollow piston-rod to the chamber controlled by the diaphragm under spring tension and thence to the tire in a tube.

Both large and small cylinders are water cooled from the engine system. The use of the differential piston on the hollow rod permits the air to reach the tire without becoming im- pregnated with any oil from the engine-cylinder. The pump is operated through a valve in the compression-




���GAS fNSINE CYLINDER Diagram of the automatic motor-driven tire pump. The tension of the spring controls the pressure of the air by means of an external dial

��cock nipple, which valve can be turned on or off from the driver's seat by means of rod

connections. Air pumped by the device after the pressure at which the diaphragm has been set js reached, is passed off into the at- mosphere, as indi- cated in the accompanying il- lustration.

In this way all the strenuous la- bor accompany- ing the pumping up of the automo- bile tire is done away with.



���The pocket is attached to the rear face of the garter and extends down into the sock

��A New Safety Pocket- Book Is Combined witli the Garter

PICKPOCKET would have no chance of getting possession of the contents of pocket-book illustrated, without a strenuous tussle with the wearer. The best of it is that no thief would be likely to sus- pect the 'existence of such a pocket.

Made as part of the garter, it is fastened under the front pad and made to extend down into the sock, as shown. There is a flap which fastens with a glove button arrangement to the outer part of the garter. The pressure of the elastic band serves to make the closing still more secure. The pocket-book is thus con- cealed inside the sock and is made to lie flat against the leg so that there is no discomfort. If through

careless fastening or other negligence, the clasp should come open while the garter is in use, the purse would slip down into the sock and would be immediately felt, so that there would be no possible chance for it to be lost without the owner's being aware of it.

It is the invention of Ed- ward V. Crouse, of Chi- cago, 111.

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