Forklift and Fork Control Method

A method for controlling forks of a forklift including forks for holding a load, cylinders for causing the forks to perform an ascending/descending operation at an ascending/descending speed in accordance with a flow rate of hydraulic oil, a first valve for controlling the flow rate of hydraulic oil in accordance with an energizing current, a second valve for regulating the flow rate of hydraulic oil between the cylinders and the first valve in accordance with cylinder pressure on the cylinders, a control portion for supplying the energizing current to the first valve, and an operating portion for starting and stopping the ascending/descending operation, the method comprising:

• a first step for the control portion to calculate a first command value for the energizing current in accordance with an amount of manipulation of the operating portion;
• a second step for the control portion to calculate the flow rate to be regulated by the second valve based on the cylinder pressure, calculate a second command value for the energizing current, with the flow rate to be controlled by the first valve being set equal to the regulated flow rate, and compare the first command value and the second command value;
• and
• a third step for the control portion to change the energizing current in two stages in accordance with the comparison result, with the second command value being set as an upper limit of the energizing current when the first command value is greater than the second command value and the first command value being set as the upper of the energizing current when the first command value is less than the second command value, wherein,
• the forks are accelerated in two stages when starting the ascending/descending is operation and decelerated in two stages when stopping the ascending/descending operation.