Loader operations – Allied Telesis S795 TSL User Manual
Page 21
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General Notes and Instructions to the Operator
Regarding ALLIED
H S L
Loader Operations
1.
The hydraulic self-leveling system (HSL) utilizes two metering cylinders
which displace oil into or out of the bucket cylinders as the loader is raised or
lowered. The cylinder volumes and geometries are carefully matched for
each loader model to provide the correct amount of oil to keep the bucket
level after it is initially leveled.
2.
The HSL system incorporates two relief valves which are only utilized if the
bucket cylinders are at either end of the stroke. If the loader is raised with
the bucket fully dumped, oil will be bypassed at high pressure into the
lower side of the lift cylinder circuit. If the loader is lowered with the
bucket fully rolled back, oil will be bypassed at high pressure into the
raised side of the lift cylinder circuit. Note that these two conditions are likely
to occur only intermittently, and although the pump will be forced to supply
oil at a higher pressure no damage to the loader components will occur. It
is, however, recommended to avoid the above situations and keep the
bucket somewhat level while raising or lowering the loader for smoother
operation.
3.
Note that the large volume (piston side) of the leveling cylinders is connected
to the large volume of the bucket cylinders, and the small volume (rod side)
is
connected
between
the
two
sets
of
cylinders.
The
effect
of
this
configuration is to create a breakout force "boost" If the bucket cylinders are
pressurized towards the rollback position during breakout.
4.
The opposite effect of the above situation is that the loader will have poor lift
capacity
if
lifting
with
the
bucket
cylinders
pressurized
in
the
dumped
position. Jhis is, however, a very unlikely occurrence (lifting a load with
bucket fully dumped).
5.
The cartridge style relief valves are factory set at 2,000 psi cracking pressure
and are capable of bypassing 15-20 GPM. If loader lock-up should occur
due to a low tractor relief setting, higher inlet flows or return line restrictions,
the relief valve setting may be backed off slightly until the lock-up condition
is overcome (as described in note 2 above).
CAUTION; Never utilize the leveling cylinders to raise the loader. This
could occur if the lift cylinders are placed in float while the bucket cylinders
are held pressurized in the retracted position. If the loader should rise,
pressurize the lift cylinders to lower it; otherwise a rapid drop may occur
when the bucket cylinders are extended. Note that this situation is unlikely
to occur during normal loader operation and is possible only with a lightly
loaded bucket.
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