TM 9-2350-256-34-2boom, spade, main winch and hoist winch is controlled by the same control valves as used in the main hydraulic system.The operation of the refuel-defuel system is controlled by a manually operated four-way selector valve and an adjustableflow regulator. Description of operation of the basic circuits in the auxiliary hydraulic system will be found inb throughlbelow. Schematic diagrams of the auxiliary hydraulic system idling, the main winch inhaul and payout, the hoist winchraise and lower, the hoisting boom raise and lower, the spade raise and lower, the refuel-defuel pump, and the impactwrench are shown in figures FO-10 through FO-20.NOTERefer to TM 9-2350-256-16 for operating instructions for the boom, winches, spade,refuel-defuel and impact wrench system.b. Auxiliary Hydraulic System-Idling (Fig. FO-10). With the auxiliary power unit operating, the system selector valvein the MAIN position, and the auxiliary power unit (APU) emergency winch control valve in the CLOSED position, oil isdrawn from the hydraulic reservoir (port No. 243) into the pump (port No. 63), and the pump discharges low pressure oil(port No. 64) to the system selector valve (port No. 48) and returns to the reservoir (port No. 236). The above valvelever positions are used when the auxiliary power unit generator is being used to charge the batteries.c. Main Winch-Inhaul (fig. FO-1 1). With the system selector valve in the AUXILIARY position, and the auxiliary powerunit (APU) emergency winch control valve in the OPEN position, hydraulic pressure is directed to the main winchcombination control valve (port Nos. 12 and 13), and returns to the reservoir (port No. 237). With the main winch controlvalve placed in the INHAUL position, the hydraulic pressure at the large area end of the pilot-operated directional controlvalve, in the main winch combination valve, is directed to tank return (port No. 10). The pilot pressure is directed to oneend (port No. 8) of the pilot-operated directional control valve, positioning the valve to direct pump pressure to one sideof the main winch motor (port No. 17) and causing the motor to drive the main winch in the INHAUL direction. Thehydraulic pressure in the brake cylinder is ported to tank return, causing the brake cylinder springs to engage the brake,and the brake ratchet and pawls are available for instant braking. Pump pressure is also being directed to the levelwinder valve (port No. 50) which controls the movement of the cable level winder.d. Main Winch-Payout (fig. FO-12). With the system selector valve in the AUXILIARY position, and the auxiliarypower unit (APU) emergency winch control valve in the OPEN position, hydraulic pressure is directed to the main winchcombination control valve (port Nos. 12 and 13), and returns to the reservoir (port No. 237). With the main winch controlvalve placed in the PAYOUT position, the pilot pressure (port Nos. 15 and 16) tends to equal pump discharge pressureand is directed to both ends of the pilot-operated directional control valve (port Nos. 8 and 10) in the main winchcombination control valve. The ends of the directional control valve differ in size, the larger end at port No. 10 and thehydraulic differential across the valve causes it to move, directing the flow of pump pressure to one side of the mainwinch motor (port No. 18), causing the motor to drive the main winch in the PAYOUT direction. The pilot pressure is alsodirected to the main winch brake cylinder to disengage the winch brake. Pump discharge pressure is also directed to thelevel winder valve (port No. 50) which controls the direction of movement of the cable level winder.e. Hoist Winch-Raise (fig. FO-13). With the system selector valve in the AUXILIARY position, and the auxiliary powerunit (APU) emergency winch control valve in the OPEN position, hydraulic pressure is directed to the hoist winchcombination control valve (port Nos. 22 and 27), and returns through the main combination control valve to the reservoir(port No. 237). With the hoist winch control valve placed in the RAISE position, the hydraulic pressure at the large end(port No. 19) of the pilot-operated directional control valve in the hoist winch combination control valve is directed to tankreturn. The pilot pressure is directed to one end of the pilot-operated directional control valve (port No. 24), positioningthe valve to direct pump pressure to one side of the hoist winch motor (port No. 18) and causing the motor to drive thehoist winch in the RAISE direction. The brake cylinder hydraulic pressure is directed to tank return, allowing the brakecylinder springs to compress the brake band around the winch brake drum, and providing instant braking through thebrake drum ratchet and pawls.f. Hoist Winch-Lower (fig. FO-14). With the system selector valve in the AUXILIARY position, and the auxiliary powerunit (APU) emergency control valve in the OPEN position, hydraulic pressure is directed to the hoist winch combinationcontrol valve (port Nos. 22 and 27), and returns through the main winch combination control valve to the reservoir (portNo. 237). With the hoist winch control valve placed in the LOWER position, pilot pressureChange 12-25
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