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1949 Delco Brakes Service Manual (Courtesy of Pat Gizz) |
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DELCO BRAKE SERVICE MANUAL |
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spongy pedal, and slow and
inefficient brake operation.
A secondary cup is fitted over
the piston in this type of master cylinder and a primary cup rides ahead
of the piston. (See Figures 2 and 3.) The construction of the piston is such that reserve
fluid from the reservoir passes through vent "B" Figure 2 into the recessed area of the piston.
Thus, we have fluid on both sides of the primary cup. The secondary
cup is merely a seal to prevent loss of reserve fluid into the rubber
boot. |
The Delco Master Cylinder is
known as a compensating type. Its primary compensating function is to
maintain a constant volume of fluid in the system at all times, regardless of expansion
due to heat, or contraction due to cold. The secondary compensating
function is the replacement of fluid into the system to counterbalance any
loss due to gravitational seepage.
The return of the piston and
piston cups to "off" position is much faster, in displaced volume, than
the return of the fluid through the
outlet fitting, past the check valve, and into the master cylinder.
A momentary vacuum is created in the cylinder barrel and additional fluid
is drawn into the pressure system through the drilled holes in the
piston |
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Fig, 4A—Delco Hydraulic Brake
Master Cylinder (Exploded View) |
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4 |
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