McHale Fusion 2 hydraulic systems overview section
12-1
McHale Fusion 2 round baler wrapper technical service manual
Issue 1: 0208
12.1: What is the hydraulic system on the tractor & how
does it affect the
Fusion 2
set-up?
Caution! It is very important to determine the correct hydraulic system on the
tractor, as a wrong set-up will cause serious damage to the tractor hydraulic
system, or at least, excessive heating of the oil. There are 3 systems found on
tractors as outlined below:
1. Open Centre: Is the most common system on tractors. In this system, all the
oil flows through the control valve, when the machine is idle. The tractor will
have a variable displacement pump and the output flow is usually adjustable.
2. Closed Centre: Although not so common on today's tractors, this system is
still found on the older John Deere models (pre 00 & 10 series), but also on
some other makes & particular models. In this system, no oil flows through the
control valve, when the machine is idle, but maintains max. oil pressure in the
feed line. The tractor will have a fixed displacement pump and the output flow
is usually not adjustable.
3. Load-Sensing with Power Beyond fitted: This is, by far, the preferred
system. Most newer tractors have this type system. In this system, no oil flows
through the control valve, when the machine is idle, but it maintains a low oil
pressure in the feed line, (approx. 21 bar). The tractor will have a variable
displacement pump and will always have some means of adjusting the oil flow
on each auxiliary valve.
In it’s most ideal configuration, the tractor will have a ‘Power Beyond’
connection, i.e. oil comes direct from the pump, by-passing the tractor auxiliary
valves, to a ‘Female 1/2” Quick Release’ connection, which becomes the
Fusion 2
feed.
It will also have a 3rd connection to the tractor, called the pilot sensing line,
and this pipe sets the correct oil flow for the tractor to pump for each operation.
This is the most advanced and the most efficient hydraulic system available, as
the
Fusion 2
control valve now controls the amount & pressure of oil required
for each control valve operation, and only the correct amount is pumped. This
will save up to 20 kW pto power on the tractor.
Note:
Although it is possible to operate the
Fusion 2
with an open centre
system via. the tractor auxiliary spools, i.e. continuous oil flow (control valve is
set to open centre set-up and flow is set to 50 lit./min. from the tractor),
McHale do not recommend operating the
Fusion 2
in this set-up, as controlling
the oil flow is too variable from one tractor to another, and there is also a 20
kW pto power loss with it’s associated over-heating of the oil.
Once the correct tractor system is identified, use the map in section 12.2 to
select the best set-up for the
Fusion 2
.
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