797F Off-Highway Truck: Gear Pump (Brake Cooling, Hoist) Hoist Control

Location of the gear pump for hoist and brake cooling for the shallow brake arrangement (1) Pump drive (2) Gear pump for the hoist and for brake cooling(3) Hoist control valve

Location of the gear pump for hoist and brake cooling for the steep brake arrangement (1) Pump drive (2) Gear pump for the hoist and for brake cooling(3) Hoist control valve

Note: The 797F XQ Off-Highway Truck uses the steep brake cooling system and not the shallow brake cooling system.

Gear pump (1) for the hoist and for the brake cooling is located between the transmission and the frame on the right side of the truck. Gear pump (1) has four sections. All four sections of gear pump (1) send oil to the hoist control valve for the hoist and for the brake cooling.

(1) Pump drive (2) Gear pump for the hoist and for brake cooling (4) Inlets from the hydraulic tank(5) Outlets to the hoist screen

Oil from the hydraulic tank flows into inlets (4) of gear pump (1). Gear pump (1) pumps oil through outlets (5) and into a screen. The oil continues flowing to hoist control valve (3). Hoist control valve (3) sends the oil to the hoist cylinders, or to the front brake cooling system and the rear brake cooling system.

Relief Valve (Brake Oil Cooler)

(1) Relief valve (2) Valve (3) Shims (4) Spring (5) Plug (6) Shims (7) Opening to hydraulic tank(8) Opening for brake cooling oil

There are two brake oil cooler relief valves that are located inside the hydraulic oil tank. One brake oil cooler relief valve is located in-line on the front brake oil cooler pump. The other relief valve is located in-line of the rear brake oil cooler pump. Pressure oil is sensed at the end of valve (2) through opening (8). When the oil pressure exceeds the relief pressure, valve (2) moves to the right. Spring (4) is under compression. Oil is allowed to flow past valve (2) and out opening (7) into the hydraulic tank. Shims are added or removed from shim (6) in order to adjust the pressure setting of relief valve (1).

Hoist Control

(1) LOWER position (2) FLOAT position (3) HOLD position(4) RAISE position

The hoist control is located to the right of the operator's seat. The hoist control has four positions: RAISE, HOLD, FLOAT and LOWER. The machine should normally be operated with the hoist control in the FLOAT position.

The hoist control is connected to the hoist control position sensor. The hoist control position sensor sends electrical signals to the Chassis Electronic Control Module. See the hydraulic system System Operation, "Position Sensor (Hoist Control)" for additional information.

When the hoist control is released a spring will move the hoist control from the RAISE position to the HOLD position or from the LOWER position to the FLOAT position.

MARYGAR

797F Off-Highway Truck: Gear Pump (Brake Cooling, Hoist) Hoist Control 2012-11-30T19:23:00-08:00 Rating: 4.5 Diposkan Oleh: Unknown