Deploying The Closed-Circuit System; Preparatory Work; Filling And De-Aerating Components; Filling A High-Prssure System With A Special Filling Device - Kramp MPP Manuel D'utilisation

For limit switches, the speed of response of the valve and the stopping speed of the mechanism in question has to be taken
into account because of mass inertia. The temperature monitoring device must be set to the correct maximum temperature.
If the device controls a cooler, take into account the fact that after the first signal and before the temperature of the cooler
has stabilised, the temperature will rise before it drops (time delay). For this reason, the monitoring device must be set at a
temperature below the maximum permitted temperature.
The level control device must be adjusted in such a manner that during normal operation the oil level can fluctuate above the
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critical level without the device being activated.
4.7

Deploying the closed-circuit system

4.7.

Preparatory work

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Air will be forced out of the system during the start-up phase. This may result in the machine becoming temporarily
uncontrollable. In that situation, an external influence such as a small load may cause it to roll away. In order to guarantee
safety, hydrostatically driven vehicles must be placed on blocks, i.e. with their wheels off the ground. In the case of winches
and the like, the drive mechanism must be able to run freely without causing an action such as raising of steel cables. Keep
safety in mind when deploying the system and be prepared for unexpected movements. Never let a closed pump-motor
combination run without oil; this will result in irreparable damage.
4.7.

Filling and de-aerating components

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The system must be filled with clean, filtered oil before it is put into operation (see chapter 5, Hydraulic oil). When assembling
spin-on filters, the filter element must be completely filled to avoid the formation of any air locks during the start-up phase.
The suction pipe connected to the charging pump must be de-aerated or filled as close to the pump as possible. The pump
housing and the motor housing must be filled with clean, filtered oil. The highest point must be used for this. This point is
generally the connection point for a leakage pipe.
4.7. Filling a high-pressure system with a special filling device
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The best method of filling a closed pump-motor combination is by using a filling device, which fills the entire high-pressure
system (internally) under pressure. The filling device consists of a gear pump with a yield of 5 to 6 litres per minute,
a pressure limiting valve (set at 20 bar) and a 10 micron absolute fine filter. The filling device is connected to the manometer
connection of the feed pump. Connect the de aeration pipes to the manometer connections of the high-pressure gate and
connect the latter to the tank. Switch on the filling device and let it run until the oil flowing out of both the manometer
connections of the high-pressure gates is clear and free of air bubbles. Remove the filling device and the de-aeration pipes
and mount measurement nipples or manometers to these gates. Check the oil level in the reservoir and replenish with clean
and filtered oil if necessary.
4.7.

First start-up phase of a closed pump-motor combination

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During the first start-up phase, a closed pump-motor combination must run at as low a load as possible in order to pump out
the air in the filters, pipes, pump housing and motor housing.
If no filling device has been used, proceed as follows:
Phase 1:
The adjustable plunger pump must be in the neutral position. Switch on the drive mechanism at the lowest possible rotational
speed for 10 to 15 seconds. Switch off the drive mechanism for 2 to 3 minutes in order to stabilise the oil flow, enabling any
residual air to escape. Repeat this procedure at least 5 times. Continually check the oil level in the reservoir and also pay
attention to any leakage. During this procedure, the feeding pressure must reach the set value, generally approx. 20 to 30 bar.
If the feeding pressure does not reach this value, the start-up process must be stopped immediately. Check again to ensure
that the suction connection has been properly de aerated, there are no air locks and the suction pipe is sufficiently free. Once
these matters have been checked, the above-mentioned procedure should be repeated until the feeding pressure reaches the
required level.
Phase 2:
Increase the rotational speed of the drive mechanism somewhat and very slowly adjust the pump to one-fourth of the total
stroke volume and leave the pump in this position for at least 30 seconds. Adjust the pump back to the neutral position and
then very slowly adjust it in the other direction to one-fourth of the total stroke volume. Leave the pump in this position for
at least 30 seconds and then adjust it back to the neutral position. The manometer reading for the feeding pressure must
remain at the set value during this procedure. The manometer readings of the high-pressure gates should also indicate a
stable value, depending on the load. The manometer reading for the return pipe of the motor should be virtually the same as
the manometer reading for the feeding pressure. Repeat this procedure until the leak-off oil or rinse oil is clear and free of
air bubbles.
If a special filling device has been used, phase 1 can be carried out over a shorter period of time. However, a 1-minute rest
period should be observed. Phase 2 must be carried out in the same manner.
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