Cup Leather

Backing to prevent leakage around pistons or plungers which have to withstand pre ures of non heated liquids. An annular ring of flexible leather is cut of such a size that when put to work it will lie against the side of the surface which it is to fit, and in the direction from which the liquid pre ure comes. When the pre ure is let on, it forces the flexible leather out against the surface which it is to pack, and the heavier the pre ure the more closely does it fit. Where the pre ures alternate as in a piston, there must be double leathers. The leather will not withstand great heat. and under exce ive pre ures cracks in the bend. It is much used for plungers of cranes and hydraulic pre es, and for pumps.