Control Functions; The Automatic Throttle - Husqvarna PP518 Manuel D'utilisation

Control functions

Ignition lock
1 Stop position, no power to any of the electrical devices.
2 Operating position for the hydraulic unit. Note that the
timer records the time regardless of whether the engine is
running or not. If the key is left in the operating position,
the battery also discharges faster.
3 Start position, the engine is started.
Flow regulation (oil)
• Adjust the oil flow by pressing down the flow switch and
pushing it to the left for the required oil flow. Regarding
flow requirements, see the instruction manual for the tool
in question. Never use an oil flow setting higher than the
recommended value.
• Once the work is complete, the flow switch must always be
reset to position 0 before turning off the engine.
• The engine must always be started with the flow switch in
position 0. This ensures that the electric starter motor can
crank the engine.
This hydraulic unit can produce an oil flow of 40 litres (10
gallons) a minute. The factory setting for the pressure relief
valve is an "opening" pressure of 148 bar (2,150 psi).

The automatic throttle

1 Excess flow valve (do not adjust)
2 Adjustable pressure sensor valve for full throttle or idling
The automatic throttle function is triggered by means of an
adjustable pressure sensor for idling and full throttle in the
hydraulic block.
Setting the adjustable pressure sensor for idling and full
throttle for the automatic throttle has no effect on the excess
flow valve setting (= maximum system pressure). It detects
only the system pressure, and signals the engine to run on
idle or at full throttle. The excess flow valve must not be
adjusted.
OPERATING
When the tool is engaged, the oil pressure increases quickly
to over 50 bar (700 psi). This normally makes the automatic
throttle increase the throttle to "full". It is recommended that
the engine reaches full speed when the tool is engaged.
In some applications, the hydraulic system throttle can be set
too low. This allows the engine to continue to idle even after
the tool is connected and full power is required.
The circulation of oil through the hoses creates low pressure,
a so-called counter pressure at the adjustable pressure
sensor valve.
The counter pressure in the system can vary for several
reasons, e.g.:
• Cold hydraulic oil
• The length of the hoses, a longer hose generates a higher
counter pressure.
• The valve in hydraulic tool can restrict flow substantially.
When the flow switch is set to 40 litres (10 gallons), this
volume of oil circulates through the hoses, through the tool
and back to the tank.
Adjustment
In the PP518, the pressure at which the throttle valve reacts,
is adjusted to achieve the required function of a specific tool
and condition.
1 Connect the hoses and the tool to be used.
2 Set the switch for the automatic throttle to position 1.
3 Set the flow switch to a suitable setting for the tool.
CAUTION! If the oil is cold, the counter pressure in the
system triggers full throttle.
4 Allow the hydraulic oil to heat up for 1 to 2 minutes. It is
now ok to begin working. The hydraulic oil reaches a
stable operating temperature in about 5 to 10 minutes.
5 If the machine has been running for 10 minutes and the
automatic throttle function is not working correctly, the
pressure's threshold value between idling and full throttle
can be adjusted.
6 Adjust the pressure in the throttle's pressure sensor with
an 8 mm or 5/16" hex wrench.
If the hydraulic unit's engine is still at full throttle without
engaging the tool and hydraulic oil is hot. Turn the
adjustment screw clockwise 1/8
the correct operation is obtained.
If the hydraulic unit's engine still idles when the tool is
engaged and work well, but the oil is cold. Turn the
adjustment screws counter clockwise 1/8
time until the correct operation is obtained.
th
of a turn at a time until
th
of a turn at a
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English