Wagoneer L6-242 4.0L VIN M FI (1988)
Brake Fluid Accumulator: Description and Operation
ACCUMULATORS
There are two accumulators used in this brake system. One accumulator is located inside the booster pump and motor assembly and the other
accumulator and low pressure switch is located under the hood next to the master cylinder/power booster assembly. Both accumulators store fluid
under pressure (approximately 1700 - 2000 PSI) for power brake operation. Both accumulators are gas (nitrogen) charged. The accumulator
located inside the booster pump and motor is a piston type accumulator and has a 3.0 cubic inch displacement and 450 PSI nitrogen pre-charge
. The accumulator located next to the master cylinder/power booster is a diaphragm type accumulator and has a 19.5 cubic inch displacement and
1000 PSI nitrogen pre-charge.
OPERATION
Although there are two types of accumulators used (one piston type and one diaphragm type), they both have a gas (nitrogen) pre-charge and
operate basically the same.
Fig. 29 - Pre-charged Accumulator - Brake System Pressure 1000 PSI
With no brake fluid in the system, the nitrogen gas pre-charge applies approximately 1000 psi pressure to one side of the diaphragm (fig. 29).
Fig. 30 - Brake System Pressure Approximately 1700 PSI
