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| Illustration 1 | g00604216 |
(1) Knob (2) Valve body (3) Spring (4) Orifice (5) Outlet port to the housing assemblies (6) Inlet port from the air tanks (7) Exhaust port to the atmosphere (8) Valve assemblies | |
The secondary brake control valve has control over the supply of air to the secondary brake pilot valve. When knob (1) is pulled to the OUT position, the lines to the pilot valve have no pressure. There is no pressure air at the control passage of the secondary brake pilot valve so pressure flows to the air/hydraulic cylinders for the wheel brakes. The wheel brakes become activated.
When knob (1) is pushed in, the air pressure flows to the control passage of the valve (brake). This stops the flow of pressure air to the air cylinders. The wheel brakes are released.
When all of the air reservoirs on the tractor are full of pressure air, the secondary brakes at all four wheels will now be activated by the secondary brake control valve. Now, when the knob is pulled to the OUT position, the flow of pressure air from the control valve is stopped. The wheel brakes are activated.