Systems Overview Toyota Pallet Truck Service Manual Theory of Operation emergency reverse sensor is disabled until the horn button is released. Lift-limit switch (SW8) transmits a lift-limit signal to the TPA that removes power to the lift motor when the forks reach a preset lift-limit Lift/Lower System The lift/lower system consists of an electrically operated hydraulic pump and related components. When the lift button is released: The pump contactor coil (M2) is de-energized. This stops the lift motor and pump.
The forks are held in position by hydraulic fluid trapped in the cylinder by the check valve, the static position of the relief valve, and the closed lowering solenoid valve The hydraulic pump assembly has a positive displacement rotary gear pump with reservoir mounted to an adapter. A DC electric motor is mounted to the opposite side of the pump adapter. An adjustable relief valve, check valve, and a solenoid-operated release valve are installed within the adapter. The relief valve opens if the hydraulic pressure exceeds the preset limit With the forks elevated, the normally-closed solenoid valve and the check valve prevent hydraulic fluid from returning to the reservoir.
Lower When the battery is connected, the truck is ON, and the lower button is pressed: Lift Lower signal instruction is transmitted thru the CAN bus from the VM JP3-2 and JP3-3 to TPA JP1-23 and JP1-35 When the battery is connected and the key switch is ON: When the grab rail lower button (SW14) is pressed (if supplied), a 12V lower request signal is transmitted thru JP4-2 to TPA JP1-11 When the control handle lift button is pressed, the lift switch closes and a lift request signal is transmitted thru the CAN bus thru VM JP3-2 & 3 to TPA JP1-23 & 35 A ground is supplied to SOL 1-Y from TPA JP1-3.
The TPA then opens lowering solenoid valve (SOL 1) When the grab rail lift button (SW15) is pressed (if supplied), a 12V lift request signal is transmitted thru JP4-1 to TPA JP1-12 Hydraulic fluid in the lift cylinder returns to the hydraulic reservoir thru the lowering valve and the flow control valve. The lowering speed is regulated by the flow control valve A ground is supplied to contactor M2 from TPA JP1-5 The lift pump contactor (M2) closes, applying B+ to the lift pump motor (MP) causing the lift pump to operate.
Hydraulic fluid is drawn thru a filter, lift pump, and check valve The forks lower Jog Pick Mode Jog Pick mode is an operating mode where the brake is released at all times and speed is restricted to Walking Speed. Jog Pick mode is intended for order picking while walking beside the pallet truck. There are two possible Jog Pick modes: As the pump rotates, oil is forced out the pressure port thru the lift hose to the lift cylinder. Oil can not return to the reservoir because of the closed pressure relief valve and the closed lowering solenoid valve Hydraulic pressure in the lift cylinder lifts the forks (optional on Model 8HBE30/40 only) 3-10 00700-CL398-07, Issued: 9 August 2007