During the operation of the hydraulic cylinder, there is often a state of jumping, stopping, and walking, and we call this state a crawling phenomenon. This phenomenon is prone to occur especially when moving at low speeds, and it is also one of the most important failures of hydraulic cylinders. Today we will talk about the reasons for the crawling phenomenon of hydraulic cylinders.
Part 1.The reason – the hydraulic cylinder itself
A. There is residual air in the hydraulic cylinder, and the working medium forms an elastic body. Elimination method: Fully exhaust air; check whether the diameter of the suction pipe of the hydraulic pump is too small, and the suction pipe joint should be well sealed to prevent the pump from sucking in air.
B. The sealing friction is too large. Elimination method: The piston rod and the guide sleeve adopt the H8 / f8 fit, and the depth and width of the seal ring groove are strictly made according to the dimensional tolerance; if a V-shaped seal ring is used, adjust the seal friction to a moderate degree.
C. The sliding parts of the hydraulic cylinder are severely worn, strained, and seized.
Poor centering of the load and hydraulic cylinder; Poor installation and adjustment of the mounting bracket. Remedy: Carefully align after reassembly, and the rigidity of the mounting bracket should be good; Large lateral load. Remedy: try to reduce the lateral load, or improve the ability of the hydraulic cylinder to bear the lateral load; The cylinder barrel or piston assembly expands and deforms under force. Remedy: Repair the deformed parts, and replace the relevant components when the deformation is serious; An electrochemical reaction occurs between the cylinder and the piston. Remedy: Replace materials with small electrochemical reactions or replace parts; Poor material, easy to wear, strain and bite. Elimination method: replace the material, carry out appropriate heat treatment or surface treatment; There are many impurities in the oil. Remedy: Change the hydraulic oil and oil filter after cleaning.
D. The full length or partial bending of the piston rod. Remedy: Correct the piston rod; support should be added when the extension length of the piston rod of the horizontally installed hydraulic cylinder is too long.
E. The coaxiality between the inner hole of the cylinder and the guide sleeve is not good, which causes the phenomenon of creeping. Elimination method: ensure the coaxiality of the two.
F. Poor linearity of cylinder bore. Elimination method: boring and repair, and then according to the bore of the cylinder after boring, equipped with a piston or add an O-shaped rubber seal oil ring.
G. The nuts at both ends of the piston rod are assembled too tightly, resulting in poor coaxiality. Remedy: The nuts at both ends of the piston rod should not be tightened too tightly. Generally, they can be tightened by hand to ensure that the piston rod is in a natural state.
For more information about the repair and design of hydraulic cylinder, please just feel free to contact us at sales@fasthydraulic.com
Post time: Oct-19-2022