D860MGB rev04
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10 MAINTENANCE
10.1
GENERAL INFORMATION
Generally, the hydraulic components are not subject to a frequent wear, they are safe and need few
maintenance operations. These results are reached when the components are chosen and dimensioned
correctly on the basis of the installation characteristics. Moreover the hydraulic oil has to suit with the room
temperature and the installation traffic conditions.
It is however necessary to make, according to the established times, the test and maintenance
operations reported in the periodical recommended maintenance sheet and get rid of the detected
faults immediately.
In case irregularities or faults, which can jeopardize the safety of people and installations, are met on
the components, the installation has to be put out of service until the defective parts are repaired or
replaced.
10.2
OIL LOSSES AND CAR LOWERING
Oil losses in the hydraulic circuit cause the car lowering with respect to the floor level even when controls,
which make the electrical re-leveling intervene, are absent.
Please remember that the car lowering can also be caused by the oil cooling.
This phenomenon is evident when the installation stops, oil is very hot and the room temperature is
much lower than the oil one.
At these conditions the electrical anti-creep system has no to be deactivated, since the car lowering
could be very important.
Oil losses in the hydraulic circuit can be due to the following causes:
LOSSES ALONG THE PIPES
Losses are usually localized in the joints of the rigid pipes or along the flexible hoses. These losses can be
visually detected. They can be eliminated tightening the fitting nuts, joining the pipes correctly or replacing
the flexible hoses.
CYLINDER LOSSES
Big cylinder losses are due to wear or to damaged seals, which are located in the head of the cylinder itself.
The oil coming out from the cylinder is collected in a proper room and, through a PVC pipe, conveyed to a
transparent tank. It is necessary that the room inside the cylinder head and the hole leading to the PVC pipe
are not obstructed by dirt. The cylinder losses depend on the traffic intensity and seal wear.
When losses are more than one or two liters per month, it is better to replace the cylinder seals.
In underground direct acting cylinders, oil losses can be due to chemical or electrical corrosion of the
cylinder. This phenomenon provokes the continuous decreasing of the oil level in the tank.
Underground cylinder have to be put inside a protection wrapping to avoid ground and groundwater
pollution.
In case oil soaks into the ground, the underground cylinder has to be disassembled and replaced.
LOSSES INSIDE THE VALVE GROUP
When the installation is motionless at floor and the electro-valves are disconnected, the load pressure
involves the part of the valve shown in Figure 19 with black colour.
The valve sealing is proved as follows:
-
When the valve temperature is the same as the room temperature, close the main line shut-off valve
and increase the pressure, using the hand pump, until twice the static pressure;
-
If there are no losses in the valve, pressure keeps constant or decreases slowly, not more than 5/6
bar during the first 3/4 minutes and tends to settle;
