Common problems with hydraulic cylinders

A complete Hydraulic System consists of four parts: power unit, actuating device, control and adjustment device. It is self-evident that the Hydraulic Cylinder of auxiliary device plays an important role as the main power actuating element. We are going to discuss some minor issues that may arise after a while.

1. Hydraulic cylinder controls oil temperature to prevent seal from deteriorating

An important reason for premature deterioration of seals is the high oil temperature. In most cases, when the oil temperature often exceeds, the oil viscosity will greatly decrease, the expansion and aging of the sealing ring will fail, resulting in leakage of the hydraulic system. According to studies, the life of the seal will be halved whenever the oil temperature rises.

Therefore, the oil temperature should be controlled within the following. For this purpose, the oil outlet pipe inside the tank should be separated from the oil return pipe by a baffle, so as to reduce the distance between the tank and the cylinder or motor of the actuator. The right angle elbow should be used as little as possible in the pipeline. In addition, the compatibility of the oil with the sealing material should be paid attention to.

2. Hydraulic cylinder should assemble sealing ring correctly.

When assembling sealing ring, it should be oiled on its surface. If it has to pass through the opening such as keyway thread on the shaft, guide tool should be used instead of metal tool such as screwdriver.

Otherwise, oil leakage may occur due to scratches on the sealing ring. For directional sealing rings such as the equal-type sealing ring, the lip should be facing the pressure oil chamber when assembling. Pay attention to protecting the lip from scratches such as sharp edges and burrs of parts. Before installing the combined seal, place the seal in hydraulic oil and boil it to a certain temperature, special guide sleeve and collecting tool should be used when installing.

3. Hydraulic cylinder must be reasonably designed to prevent oil leakage from static seal

The dimensions and tolerances of the sealing grooves of the static seals allow the installed static seals to be extruded and deformed to fill the micro-recesses on the mating surfaces and to increase the stress in the seals above the pressure being sealed.

When part rigidity or bolt pretension force is not enough, the mating surface will separate under the action of hydraulic pressure and cause excessive clearance. With the movement of mating surface, static seal becomes dynamic seal.

4. Reasonable Design and Processing of Sealing Grooves for Hydraulic Cylinders

The design or fabrication of the sealing groove in the hydraulic cylinder is a prerequisite for reducing leakage and preventing premature damage of the oil seal if the groove size in the static seal between the piston and piston rod is too small for the sealing ring to move within the groove.

The bottom of the sealing ring will be damaged by reaction force and result in leakage. The design of oil seal groove is mainly based on the structural shape, dimensional tolerance of groove position and roughness of sealing surface.