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| Illustration 1 | g00531899 |
Location of the front brake inverter valve | |
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| Illustration 2 | g00496463 |
(1) Signal port (2) Supply port (3) Exhaust port (4) Output port | |
The front brake inverter valve is located above the primary air tanks on the right hand platform next to the cab. When the secondary brake control is applied, the front brake inverter valve allows air to flow to the front brake master cylinder in order to apply the hydraulic caliper service brakes.
Air supply from the secondary air tank flows into supply port (2) of the front brake inverter valve. Air pressure from the secondary brake inverter valve flows into signal port (1). When the pedal for the secondary brake air control valve is fully applied, air pressure to signal port (1) is blocked. This causes the front brake inverter valve to open the passage from supply port (2) to output port (4). Air pressure now flows through a double check valve to the front brake master cylinder. The front brake master cylinder sends oil pressure in order to apply the hydraulic caliper service brakes for the front wheels.
When the secondary brake control is partially depressed, the front brake inverter valve partially allows the air pressure to flow to the front brake master cylinder. The hydraulic caliper service brakes will be partially applied. When the secondary brake control is released, full air pressure flows to signal port (1). Outlet port (4) will be blocked and air will be open to exhaust port (3). The outlet pressure is discharged through exhaust port (3).