MAINTENANCE
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8.7 THE HYDRAULIC SYSTEM
* In order to function, the crane needs the hydraulic system, which includes a prime mover, a
pump, an oil tank, filters and other necessary hydraulic equipment.
* When replacing the hydraulic system components such as hoses, couplings, gaskets, etc., the
smooth and safe operation is ensured best when using original KESLA spare parts.
* For the crane's hydraulic system should be chosen a suitable oil, which must be handled
and maintained properly.
* In the hydraulic system the oil operates as a force transducer and as a lubricant.
* The use of high quality oil is the first prerequisite for the proper functioning of the crane.
* The hydraulic system, to which the crane is connected to, has to definitely be clean. The system
is to be equipped with a pressure filter and a return filter.
* The system must also have a breather filter. This is to prevent large dirt particles from entering
the hydraulic oil. Despite the breather filter dirt particles access the oil tank along with the air ab-
sorbed into it.
* Foreign particles are dangerous because the pump and valves operate with minimal clearances.
*Due to the temperature fluctuations hydraulic system condenses water. Water can cause operat-
ing problems, especially in the winter. As a result, the oil is changed often enough, according to
maintenance recommendations, or at least two times per year; in spring and in autumn.
* Change the filters often enough, according to the maintenance recommendations as well as al-
ways when changing the oil.
* The oil tank can be cleaned with petrol or white spirit (not with fuel oil).
8.7.1 Requirements set for a good hydraulic oil
*The solidification temperature must be less than -50°C.
* The recommended hydraulic oil viscosity is 20-30 mm2/s
* Note the effect of temperature to the oil viscosity.
* The viscosity must not sink below 10 mm2/s.
* Hydraulic oil must contain the necessary additives for lubricating ability, anti-corrosion and foam-
ing prevention purposes.
* The oil must be suitable for the crane sealing materials. (Do not use engine oil in the hydraulic
system).
* Even the new hydraulic oil contains dirt particles, which due to their size can cause interference.
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