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| Illustration 1 | g00505673 |
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Location of the secondary brake inverter valve | |
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| Illustration 2 | g00496463 |
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(1) Signal port
(2) Supply port (3) Exhaust port (4) Output port | |
The secondary brake inverter valve is located in the compartment behind the cab. When the secondary brake control is applied, the secondary brake inverter valve restricts the air pressure that is sent to the parking and secondary brake valve.
Air supply from the secondary air tank flows into supply port (2) of the secondary brake inverter valve. When the pedal for the secondary brake air control valve is fully applied, full air pressure flows to signal port (1) of the secondary brake inverter valve. This air pressure causes the secondary brake inverter valve to block the passage from supply port (2) to output port (4). The air pressure that is flowing to the parking and secondary brake valve is now blocked. The parking and secondary brake valve then blocks the oil pressure that releases the parking brakes. When the secondary brake control is partially depressed, the secondary brake inverter valve partially blocks the air pressure that flows to the parking and secondary brake valve. The parking brakes will be partially applied. When the secondary brake control is released, outlet port (4) will be blocked and air will be open to exhaust port (3). The outlet pressure is discharged through exhaust port (3).