Fig. 14-1
14.0 DESCRIPTION OF HYDRAULICS.
AUTO WRAP 1200 EH is driven from the hydraulic system of the tractor. The hydraulics of the
machine can easily be changed from "Open Centre" to "Closed Centre" hydraulic system.
14.1
"OPEN CENTRE" HYDRAULIC.
Most tractors have an oil pump which gives a certain quantity per revolution. Then the crane handle,
(pos. 10, fig.14-2), has to be set in open position. (See chapter 4.7). If no other function is activated,
the oil flows from the tractor, through the main valve block and back to the tank. When one of the
functions on the control unit is operated, the master valve, (pos. 7, fig. 14-1) closes the oil flow
circuit, and simultaneously the valve for the current function is opening.
"CLOSED CENTRE" HYDRAULIC.
For tractors with variable oil pump, like John Deere, the crane handle must be closed.(Pos.10, fig.4-
2)
Then the oil can only come into the main valve block by operating one of the functions.
The "closed centre" valve, (pos. 8, fig. 14-1), opens the oil flow into the block, and simultaneously
the valve for the current function is opening.
THE MASTER VALVE
, (pos. 7), will always close, and the "closed centre" valve, (pos. 8), is
automatically opening regardless of which function that is operated.
14.2
THE CUTTER.
To prevent that the oil pressure to the cutter is falling, so that it not holds the film long enough, there
is a piloted non-return valve, (pos. 9, fig.14-1), underneath the magnet valve on the main block.
(Pos. 1-2, fig. 14-2).
Underneath the above piloted non-return valve, inside the block, there is also a non-return valve that
prevents that sudden pressure impulses in the return system can open the piloted non-return valve.
* Emergency stop: see chapter 2.1
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