Zhenhua Machinery Co.,Ltd.
Add.: No. 7, Tianshun Road, Dongqing Industrial Park, Zhenlu District, Yangshan Town, Wuxi City, Jiangsu Province, China
Tel.: +86-510-83690000
Fax.: +86-510-83691767
Contact person (General Manager): Yang Haiyan

Make the right choice
Speaking of choosing a hydraulic cylinder, we usually make the decision according to the inner diameter, stroke, working pressure, and mounting type. Actually, there are a few more tips we should keep in mind. Firstly, when the movement speed of a loaded cylinder reaches a certain point, a buffering device is needed in the hydraulic cylinder. A deceleration valve is needed if the speed is even higher. Secondly, proper hydraulic oil and oil seal are important. The type of oil seal should be chosen according to the hydraulic oil, so that cylinder's service life can be extended.

Correct usage
1. When choosing the cylinder diameter, rod diameter and pressure, we should take the hydraulic system pressure and pressure loss into consideration. The pressure is controlled by a pressure regulating valve.

2. Before the cylinder starts to work, it should operate back and forth driven by a low pressure that is higher than the start-up pressure, and then open the one way vent valves at both ends of the cylinder in turn to expel all the air in the cylinder.

3. The joints at the inlet and outlet oil ports should come with obturating ring assembly to avoid the oil leakage.

4. The working medium should not contain any impurities, avoiding inner wall scratches or seal damages, which can cause inside and outside oil leakage.

Proper maintenance
1. Change the hydraulic oil and clean the filter screen regularly during the usage to lengthen the service life.

2. Five full strokes should be conducted before the hydraulic cylinder gets loaded. The strokes can expel the all the air and water in the system, and warm up different parts. Thus air explosion (or burning), which could lead to seal damages and inside oil leakage, will be avoided in the barrel.

3. Control the temperature of system well, because high temperature can shorten the service life of the seal parts. Long-term high temperature can cause permanent deformation, or even completely failure.

4. Protect the surface of the piston rod from being hit or scratched, because these damages can cause the failure of sealing elements. Remove the impurities around the scraper seal at the moving parts and bare piston rod to avoid them from entering the cylinder and hurting the piston, barrel and seal.

5. Check the components such as screw and bolt regularly. If they are loose, tighten them immediately.

6. Lubricant the connecting parts regularly to avoid unnecessary rust and abrasion.

General faults and solutions
Phenomenon Reason Solution
Unstable movement and uneven speed 1. Air intrusion
2. The obturating rings at both ends are too loose or tight.
3. Obturating ring leakage
4. Piston rod and piston are not coaxial
5. The total (or part of) piston rod is curved.
6. Installation position shift of the hydraulic cylinder
7. Poor straightness of the inner bore of the cylinder tube
8. Rust and cracks appear in the inner bore.
1. Expel all the air, run several more strokes or add counterbalance valve to the oil return line, or open the vent valves
2. Replace the seal components with quality ones, ensuring the piston rod can move and no leakage exists.
3. Improve the concentricity between the piston rod and the piston, and make sure the error is less than 0.04 mm.
4. Calibrate the straightness of the whole piston rod, make sure it is less than 0. 2/100 mm
5. Change the piston rod
6. Make sure the installed hydraulic cylinder is parallel with its moving direction of the machine.
7. Hone or polish the inner bore, and then replace the piston rod according to the real inner bore diameter. Change the cylinder tube if necessary.
8. Remove the rust and bumps. Change the cylinder tube if necessary.
Slow movement and insufficient strength 1. The bottom of the sealing slot in the piston is not small enough in diameter, leading to too much space around the sealing components.
2. Serious leakage makes the pressure difficult to ascend.
3. The resistance is increased due to the poor straightness of the piston rod.
4. The obturating rings arewore out
5. The back-up ring has deformed and become too tight, resulting in more resistance.
6. Parts of the barrel have a poor roundness that significantly exceeds the tolerance, resulting in the hydraulic oil circulation between the two sides of the piston.
1. Replace the piston rod according to the real inner bore diameter.
2. Change the sealing components.
3. Calibrate the parallelism and straightness of the piston rod. Change the piston rod if needed.
4. Adjust he piston rod for a great coaxiality with the piston. Change the piston rod if needed.
5. Hone or polish the back-up ring, reaching a clearance fit of H9/f9
6. Boring the inner bore,replace the piston rod accordingly. Change the cylinder tube if necessary.