D860MGB rev04
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Close the main line shut-off, unscrew screw no. 3 (rod counterpressure) and press the manual
emergency button in order to lower the pressure to zero.
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Unscrew the fixing screws of the block to inspect the ball seats.
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Remove the seeger which blocks the spring and the ball.
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Inspect the seats and if they appear grooved or faulty, attempt to repair them by repositioning the
balls in their proper place and clinching them by using a proper punch.
Warning: do not hammer strongly because the seat is in aluminum, and may damage or break
through. If possible, replace the balls used to clinch the seats.
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Reassemble all the components properly, reassemble the block and check the sealing.
Figure 20 - Check of emergency valve working
c) Down travel electro-valve EVD.
The sealing ball of the down travel valve (see Figure 21), can remain slightly open and loose oil.
The following checks must be carried out without pressure inside the valve. It shall be therefore
necessary to close the main line shut-off, unscrew screw no. 3 (rod counterpressure) and press the
manual emergency button in order to lower the pressure to zero.
The reasons why the downward travel valve may not work properly are the following:
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Small metal particles or dirt have got inside the coil between the tube and the cursor delaying or
preventing the return movement of the coil cursor.
It is necessary to remove the coil, unscrew the mechanical part of the EVD and shake it backwards
and forwards with the hand to insure that the inside piston is free. If not, replace it.
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The EVD coil button has got caught after having been manually activated with a screwdriver and the
coil cursor cannot return to its resting position. In this case it is necessary to remove the coil,
unscrew the mechanical part of the EVD and push its piston completely back.
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Some metal particles lay between the ball and the sealing seat preventing the closing or damaging
the sealing seat of the EVD valve. To check the EVD electro-valve sealing it is necessary to remove
the coil, unscrew the mechanical part of the coil, remove the pin and the EVD aluminum valve.
At this point it is necessary to inspect the EVD valve and then proceed in the following way:
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Remove the seeger which blocks the spring and the ball in the lower part of the EVD valve.
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Inspect the ball seat and if it appears grooved or faulty, attempt to repair it by repositioning the ball in
its proper place and clinching it by using a proper punch.