Manual forklifts are lifted by hydraulic cylinders，the reasons they cannot rise are as follows:
Hand truck: 1. No hydraulic oil
2. The purity of the oil is not enough
3. The adjusting bolt is too close or the adjusting screw is too tight, so that the valve is always open.
4. There is air in the hydraulic cylinder
Remedy: 1. Refuel, 2. Change oil, 3. Exhaust air
Manual stacker does not rise
1. Insufficient fuel 2. Impurities in the hydraulic oil make the check valve unable to close
Remedy: 1. Add sufficient hydraulic fluid
2. Remove the oil cylinder, unscrew the bottom plate screws, and remove the impurities on the surface of the bottom plate that contacts the steel balls