Abstract: An industrial vehicle having a vehicle body includes a battery, an electric motor, an electrolyte level sensor, a vehicle operating with lowered electrolyte level, a vehicle operating time calculator, a data-storing device storing data of the vehicle operating time, an electric motor limiting condition and a motor controller. The electric motor is driven to generate torque. The electrolyte level sensor detects whether or not electrolyte level of the battery is lower than a predetermined level. The vehicle operating time is a time elapsing while the electrolyte level is lower than the predetermined level. The vehicle operating time calculator counts the vehicle operating time in accordance with the detection of the electrolyte level. The electric motor limiting condition limits operation of the electric motor gradually in accordance with the vehicle operating time. The motor controller controls operation of the electric motor based on the electric motor limiting condition.

Abstract: A load weight measuring device for a multi-stage mast forklift truck has a mast assembly, an oil passage, a flow regulator valve, a pressure sensor, a detecting device, a memory, a selector, and a calculator. The mast assembly has a lift bracket for receiving a load weight, a multi-stage mast unit having masts, and a multi-stage lift cylinder unit having lift cylinders each having an oil chamber for raising the lift bracket along the masts. Hydraulic oil flows in the oil passage. The pressure sensor detects a pressure of hydraulic oil and outputs a pressure signal. The detecting device detects a state which stage of the lift cylinder raises the lift bracket and outputs a detection signal. The memory stores predetermined parameters from which the selector selects the parameter based on the detection signal. The calculator calculates the load weight based on the selected parameter and the pressure signal.

Abstract: An industrial vehicle having a vehicle body includes a battery, an electric motor, an electrolyte level sensor, a vehicle operating with lowered electrolyte level, a vehicle operating time calculator, a data-storing device storing data of the vehicle operating time, an electric motor limiting condition and a motor controller. The electric motor is driven to generate torque. The electrolyte level sensor detects whether or not electrolyte level of the battery is lower than a predetermined level. The vehicle operating time is a time elapsing while the electrolyte level is lower than the predetermined level. The vehicle operating time calculator counts the vehicle operating time in accordance with the detection of the electrolyte level. The electric motor limiting condition limits operation of the electric motor gradually in accordance with the vehicle operating time. The motor controller controls operation of the electric motor based on the electric motor limiting condition.

Abstract: A load weight measuring device for a multi-stage mast forklift truck has a mast assembly, an oil passage, a flow regulator valve, a pressure sensor, a detecting device, a memory, a selector, and a calculator. The mast assembly has a lift bracket for receiving a load weight, a multi-stage mast unit having masts, and a multi-stage lift cylinder unit having lift cylinders each having an oil chamber for raising the lift bracket along the masts. Hydraulic oil flows in the oil passage. The pressure sensor detects a pressure of hydraulic oil and outputs a pressure signal. The detecting device detects a state which stage of the lift cylinder raises the lift bracket and outputs a detection signal. The memory stores predetermined parameters from which the selector selects the parameter based on the detection signal. The calculator calculates the load weight based on the selected parameter and the pressure signal.