Hydraulic System Working Principle - HANGCHA Mini Range CDD12-A2MJ-SZ Operation And Maintenance Manual

2.1 Hydraulic system working principle

Lifting the Loading
Press the lifting button of the control lever and the oil pump motor starts. It passed the torque from
motor to gear pump through the transmission shaft. The gear pump absorbs the hydraulic oil from
the fuel tank and passes the oil to the lifting cylinder through non-return valve. High pressure oil
push the piston rod forward which give rise to the lifting of forks and the loading.
Release the lifting button and the oil pump motor stops. The gear pump stops absorbing the oil.
And the non-return valve is closed which can keep the lifting cylinder and the loading in its original
lifting position. When the lifting cylinder reaches the end or the truck is over loaded, the working
pressure is exceeding the safety pressure defaulted in the system, the overflow valve will be open
and the hydraulic oil returns back to the fuel tank.
Lowering the Loading
Press the lowering button of the control lever and the oil pump motor starts. When the closed
electromagnetic valve is applied with electricity, the hydraulic oil in the lifting cylinder will flow back
to the fuel tank due to gravity. Both the cylinder and the loading start to lower. Governor valve is
used to prevent the trucks and loadings from being damaged due to the rapid lowering speed.
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