Internal leakage in a hydraulic cylinder

Hydraulics is the transmission of power through fluids. The forces and pressures acting in hydraulic systems are very high. This has the advantage that enormous loads can be moved, but it also leads to significant challenges. One of these challenges is the unavoidable internal leakage in hydraulic cylinders.

Internal leakage in linear motors with sealing problems

Hydraulic cylinders are linear-acting motors. They consist of a cylinder housing, a piston rod, and one (in the case of plunger cylinders), but usually two valves. Although the piston rods are generally sealed at least three times, leakage can never be completely ruled out. However, the design ensures that the leakage flows inwards rather than outwards.

Filters for case drain oil

Dirt particles in the oil are the greatest enemy of hydraulic systems. Although the drain oil has no contact with the outside air, it can still become contaminated over time. To prevent these contaminants from causing internal damage to the hydraulic system, drain line filters are used. They filter even the finest particles out of the oil before it flows back into the oil tank. Regular maintenance of the drain line filters can significantly extend the service life of the hydraulic system.

Design of a drain line filter

A drain line filter consists of a cylindrical housing. It is equipped with two connections through which the drain oil flows in and back out towards the tank. The filter cartridge is installed inside the housing. It is screwed in from the top and sealed airtight. Ideally, there is an additional sampling point on the housing for oil analysis.

Oil analyses provide information on internal leakage

Even with regular changes of filters and hydraulic oil, gradual damage can occur within the hydraulic system. It is therefore advisable to have the oil analyzed at regular intervals. Specialized laboratories can use a sample to determine exactly which particles are present in the oil. Characteristic wear from piston rods, valves, seals, radial motors, or pumps can thus be identified easily and very precisely.

This allows the operator to be precisely informed about weak points in their hydraulic system and to initiate targeted measures.

Application of drain line filters

Drain line filters are used in heavy-duty hydraulic systems. It is primarily construction vehicles such as excavators, loaders, large forklifts, or handling machines that are equipped with drain line filters. The high dynamics, significant temperature changes, and vibrations of the diesel engine place heavy demands on these hydraulic systems. At the same time, particularly high pressures are used in heavy construction machinery to develop the required forces. These factors contribute to increased internal leakage, making the use of drain line filters necessary.

Maintenance intervals for drain line filters to prevent internal leakage

High-quality oils, modern components, and high-performance standard filters protect the fine filters for drain line systems particularly well. Therefore, the maintenance and replacement intervals for drain line filters are usually twice as long as those for standard hydraulic oil filters. A currently achievable value is approximately 1,000 operating hours, at which point the drain line filter should be inspected. Furthermore, the drain line filter does not necessarily have to be replaced in every case. Many models can be cleaned and then reused without any problems.