[Healeys] Shade tree hydraulics

KENNETH MASON medition at verizon.net
Mon Aug 19 23:02:06 MDT 2013


Hydraulics with no vacuum booster--------------------

Let's say the master cylinder piston is one square inch area and you push on
the brake peddle sufficiently to produce the equivalent of one pound force.

The piston transfers a one pound per square inch pressure (1psi) into the
non-compressible fluid.  That pressure is exerted in all directions throughout
the fluid column.

If the wheel cylinder piston has a two square inch area acted upon by the
fluid pressure (2psi), the piston will deliver two pounds of force to the
brake shoes.

The reason the peddle stroke would be longer than with a smaller diameter
piston is that the volume of fluid to fill the larger area chamber above the
larger wheel cylinder is greater.  Remember the master cylinder piston did not
change.


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