Hydraulic System; Hydraulic Hygiene - Husqvarna P524 Workshop Manual

Hydraulic system

5.6 Hydraulic system

5.6.1 Hydraulic hygiene

Keep the hydraulic system clean. Remember to:
• Clean thoroughly before opening the filler cap
or disconnecting anything.
• Use clean vessels with topping up oil.
• Use only clean oil that has been stored in
sealed containers.
• Do not reuse drained oil.
• Change the oil and filter according to the
intervals specified in the Service Schedule.
A system that is contamination-free is required to
give a functioning hydraulic system without
shutdowns. Particles are generated during operation
that can cause both wear damage and malfunctions.
The system has filters to separate these particles.
The filter is dimensioned to trap the generated
particles, but if dirt enters the system from outside
the filters will rapidly clog so that they do not work as
intended. If there is dirt in the system, further
contaminants will be generated, creating a vicious
circle. This will result in breakdowns and the need
for large resources to clean the system.
The particles that cause the most damage are the
same size as the play between the moving parts and
the components. Normal play in pumps and valves
is from 3-5 µm and up (1 µm = one thousandth of a
mm). In connection with this, it can be noted that one
particle of size 40 µm can only just be seen with the
human eye.
Each particle of dirt is an abrasive that generates
more contaminants, which will eventually result in
permanent damage. The number of particles will
increase each time the hydraulic system is opened.
After a few hours in operation most of the particles
that have entered are trapped in the filters.
Therefore, avoid opening the hydraulic system
unless really necessary because each intervention
increases the risk of contamination even when the
work is carried out in a professional manner.
Rectify oil leaks
Cavitation is caused by air entering can cause
internal damage to pumps and engines. Air can
enter the system where there is an oil leak. That is
why it is so important that oil leaks are rectified as
soon as possible.
52 – English
Keep hydraulic system fluid clean
You must be completely sure that when opening a
can of oil for the hydraulic system, the area around
the filler cover is absolutely free from dust, dirt,
cotton waste and water. If a vessel, funnel or hose is
required to fill the system, make sure they are clean.
Use only the type of oil specified in the lubrication
schedule. Make sure levels are checked at
established intervals and maintained correctly.
Working methods
Cleanliness also applies to components that are
removed or are going to be fitted. Remember that an
exchanged component will probably be examined
with test equipment at a workshop. It is important
that the component is in the same condition when
examined as it was when it was taken from the
machine. Otherwise the actual fault can not be
established and the test equipment will be
contaminated. It is also possible that submitted
component is not faults and is therefore returned
without action.
The points below should be taken as routine
procedures when working on hydraulic systems:
• Clean roughly as necessary.
• Protect the area where the work is to be done
against dust and other impurities in the air.
Plastic cloth and the like can be used.
• Wash very thoroughly with white spirit or the
like. Only washing the parts that are directly
affected will not suffice. Even areas from where
dirt can fall onto the point of entry while work is
in progress must be cleaned, just as the tools
being used. Use a suitable brush to wash with,
wipe dry and then wash again if necessary.
Finally shower off the area being dismantled,
hose connections and the like with pure white
spirit.
• Apply appropriate protection immediately after
all pipes and hoses have been removed.
Components (also exchanged) as well as hoses
and pipes should be protected.
• All components included in pipe fixtures shall be
replaced or cleaned in pure white spirit and
blown clean with compressed air before being
refitted.
• Maintain cleanliness when measuring pressure.
Shower both parts of quick couplings with white
spirit before connecting. Make sure any
protection is clean before returning it.