HELI G Series Operation & Service Manual page 113

5.1.4 Cut-off valve
The cutoff valve is mounted at the bottom of the hoist cylinder (See Fig. 5-17) to
prevent the goods from falling suddenly when the high pressure pipe is broken. The oil
from hoist cylinder passes through the hole A on the outer circumference of the spool
when returning to oil tank, if flow rate of oil through the hole is less than the setting value
of the valve and the pressure difference before and after spool smaller than spring force,
the spool will not move at this time and slide valve does not work. If the flow rate
through the spool hole exceeds the setting value due to high pressure pipe cracking or
other reasons, the pressure difference before and after spool will be larger than the spring
force and move the spool to the left. In this way, hole A is closed, only small amount of
oil flows out from the small clearance of spool and valve bush and the goods descends
slowly.
Fig. 5-17 Working principle of the cut-off valve
5.1.5 Flow regulator valve
The flow regulator valve, located in the lift cylinder circuit to limit the descending
speed of loaded forks, has the construction as shown in Fig. 5-18.
Flow less than the setting valve
Flow more than the setting valve
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