OPERATION OPERATION 2) 2) 1 3 2 6 4 5 7609A4BS31 The pump is a variable displacement piston pump. This pump has a maximum delivery pressure of 250 kgf/cm 2 . The axial piston type pump is used to supply oil flow to the cut off valve. The oil is pressurized by the movement of rotary group in the pump. When the engine is in operation, the drive shaft (1) is driven by the gears in the engine with rotary group. There are nine piston assemblies (2) in rotary group. Each piston inside cylinder (5) is held against swashplate (3) by piston shoe (4). Swashplate can be any angle between the maximum angle and the neutral angle.
The angle of swashplate determines the amount of oil that is pushed out of each cylinder. The neutral angle is perpendicular with drive shaft (1). When swashplate(3) is at the neutral angle, pistons (2) do not move in and out of rotating cylinder. Therefore, no oil is drawn into the pump and no oil is pushed out of the pump. The pump has zero displacement and zero flow. When swashplate (3) is at the maximum angle, pistons (2) move in and out of cylinder. The movement of the pistons allows the maximum amount of oil to be drawn into the cylinder. The pump will produce the maximum displacement. The swashplate (3) angle is controlled by command current signal to control valve solenoid (6).
The pump output pressure level can be set by the solenoid current. When the solenoid current signal drops toward a zero value, the pump output pressure level is the maximum. 侍 FAN SYSTEM OPERATION FAN SYSTEM OPERATION When the brake system pressure is below minimum pressure (125 佳 5 bar), it has the high priority than the fan system. Pump flow to the fan motor is blocked while brake system is charged. However, The fan system has controlled pump when the brake system pressure is charged. The fan speed solenoid valve (6) controls the pressure (fan speed) of pump when the brake system is fully charged. The fan speed solenoid valve (6) is a proportional solenoid.
As current to the fan speed solenoid increases, pump output pressure decreased, therefore, the fan motor rotates slower. When the current of the fan speed solenoid valve (6) is reduced, the output pressure is increased. The pump will be stroked and the pump will send maximum flow to the fan motor, thus, the fan motor is turning faster. 4-11