THEORY OF OPERATION - CONTINUED
BRAKE AND HYDRAULIC FAN SYSTEM - CONTINUED
Brake Operation at Cut-Out Pressure. When brake system pressure reaches cut-out pressure, cut-out
valve opens. Cut-out valve drains spring side of cut-in valve to tank return port. System pressure over-
comes spring pressure on cut-in valve, shifting cut-in valve right. When cut-in valve shifts right, pressur-
ized oil from right side of shuttle valve and spring side of priority valve is metered to tank return port.
System pressure overcomes spring pressure on priority valve, opening priority valve and allowing pump
flow to fan system. Simultaneously, shuttle valve shifts right, allowing pump to sense fan system pressure
requirements. Check valve closes and check valve maintains brake system pressure.
Hydraulic Fan System Operation.