The Basics Of Hydraulic Cylinders

The Basics Of Hydraulic Cylinders

A hydraulic cylinder is a hydraulic actuator that converts hydraulic energy
into mechanical energy and does linear reciprocating motion (or swinging motion).
It has a simple structure and works reliably. When used to implement reciprocating motion,
it can eliminate deceleration devices, there is no transmission gap, and the motion is stable,
so it is widely used in hydraulic systems for a variety of machinery.

1.Composition of the hydraulic cylinder

Hydraulic cylinders are usually composed of the main components
such as the rear end cover, cylinder barrel, piston rod, piston assembly, front end cover, etc.;
In order to prevent the oil from leaking to the outside of the hydraulic cylinder
or leaking from the high-pressure cavity to the low-pressure cavity,
a sealing device is provided between the cylinder barrel and the end cover,
the piston and the piston in vain, the piston and the cylinder barrel, the piston rod and the front end cover,
and the dust prevention device is also installed on the outside of the front cover:
in order to prevent the piston from hitting the cylinder head when quickly retreating to the stroke terminal,
the end of the hydraulic cylinder is also provided with a buffer device; Sometimes an exhaust is also required.

2.Hydraulic cylinders are classified by structure

Piston-type hydraulic cylinder

A single piston-rod hydraulic cylinder has a piston rod at only one end.
Its two ends, the inlet and outlet oil ports AB,
can pass pressure oil or return oil for bidirectional motion, hence the name dual-acting cylinder.

Telescopic hydraulic cylinder

With two or more stages of pistons, the sequence of piston extensions
in a telescopic hydraulic cylinder is from largest to smallest,
and the sequence of no-load retraction is generally from smallest to largest.
Telescopic cylinders enable long strokes, while they are shorter in length and more compact when retracted.
Hydraulic cylinders of this type are commonly used in construction machinery and agricultural machinery.

3. Internal design of the hydraulic cylinder

Design purpose: Based on the operating temperature of the site,
the working medium and the processing situation of the plant.
The dimensions of the internal structure are calculated based on the mechanical design manual.

►The seal must be chosen based on the on-site operating temperature,
environmental contamination, and the working medium.

►The cylinder head is sealed as much as possible with a V combination seal,
which compensates for errors in the finish of the grooves.

►The dimensions of the sealing grooves are designed strictly according to the design manual.

►The cylinder piston seals generally use a Glei ring plus a guide band,
which is better for high temperature resistance and pollution resistance.

4. Common problems and maintenance of the hydraulic cylinders

►Oil leakage from the sealing part of the hydraulic cylinder liner and the cylinder head
(or guide sleeve) (solution: replace the new O-ring);

►The piston rod and the guide sleeve are relative to the movement of the oil leakage outward
(solution: if the piston rod is damaged, it can be cleaned with gasoline, and after drying,
it is applied to the damaged place with metal glue, and then the piston rod oil seal
is used to move back and forth on the piston rod to scrape off the excess glue,
and then put into use after the glue is completely cured. If the guide sleeve is worn,
a guide sleeve with a slightly smaller inner diameter can be processed to replace it).

►Oil leakage caused by poor sealing of hydraulic cylinder pipe joints
(solution: in addition to checking the sealing of the sealing ring, it should also be checked whether the joint is properly assembled,
whether it is reliably tightened and whether there are scars on the contact surface, etc. and replace or repair if necessary)