Abstract: Hydraulic tensioning cylinder is a key actuating component in engineering machinery, mining equipment, and industrial production lines, and its sealing performance directly affects the system's work efficiency and reliability. This article analyzes the failure mechanism, replacement process, and maintenance strategy of hydraulic tensioning cylinder seals, and proposes standardized operating procedures and preventive maintenance plans to extend the service life of seals and reduce equipment failure rates.
Keywords: hydraulic cylinder; seal ring; Replacement process; Maintenance strategy; Failure Analysis
I. Introduction
The hydraulic tensioning cylinder of Baishui Palace Cable Car has been in use for 7 years since the sealing ring was replaced after work on March 28, 2018. On April 19, 2025, oil stains were found on the ground at the end of the tensioning hydraulic cylinder. After careful inspection, it was found that hydraulic oil was flowing out from between the end seal and the piston rod. After analysis, it was found that it was caused by aging and wear of the cylinder body seal of the tensioning cylinder. The daily oil leakage of the tensioning cylinder was measured and counted using a measuring cup. The daily oil leakage was around 10-20ml, and there was no increase in oil leakage. Therefore, this article studies the replacement process and maintenance methods of the sealing ring based on this situation (Figure 1).
Figure 1 Oil leakage diagram of hydraulic cylinder
II. Analysis of Failure Mechanism of Sealing Ring
1. The types of failure include wear and tear: lip wear caused by reciprocating motion. Chemical corrosion: Material aging caused by hydraulic oleic acid alkalinity or pollutants. Extrusion failure: The sealing ring is squeezed into the gap under high pressure (such as improper design of the retaining ring). Installation damage: Cutting or deformation caused by improper installation.
2. The influencing factors include work pressure and temperature fluctuations. Cleanliness of hydraulic oil. Compatibility between sealing materials and media.
III. Sealing ring replacement steps
Taking the replacement of the sealing ring of the tensioning oil cylinder of the Baishui Palace cable car as an example below
1. Preparation work
(1) Recheck and confirm the items listed in the tool list and spare parts list before construction;
(2) Before leaving work, complete the sealing component inventory inspection of the hydraulic cylinder replacement parts, and check whether the sealing components are damaged, cracked, or have any impact on use;
(3) Move the tools to the site before leaving work. The gourd, steel wire rope, U-shaped buckle, and burlap bag are moved to the front end of the walking cart (used to fix the walking cart), and other dismantling tools are neatly arranged;
(4) The on-site lighting equipment is installed in place.
2. Disassemble the hydraulic tensioning cylinder
(1) The car is parked in its original position;
(2) The system is powered off, and the carriages of the upper and lower stations are holding onto the tracks;
(3) Slowly open the knob on the stop valve 19.2 that controls the tensioning cylinder, place the heavy hammer slowly at the bottom, and then open the stop valve 19.2. At this point, move the trolley back to the wire rope with the minimum tension of Φ 29;
(4) Place the triangular wood between the walking cart and the frame to prevent the cart from slipping;
(5) Observe the indicated pressure on the tension pressure gauge and record it;
(6) Close the plate ball valve 32.2 (the heavy hammer does not move);
(7) Use a 41 # open-end wrench to loosen the joint between explosion-proof valve 43 and the oil cylinder, and block it with a plug;
(8) Lay the burlap bag under the tensioning oil cylinder and place a square wooden block and cushion it firmly;
(9) Remove the rear opening pin of the tensioning cylinder, use a hammer and copper rod to remove the shaft sleeve, and clean it;
(10) Unscrew the exhaust hole bolt on the sealing device at the end of the tensioning cylinder with an Allen wrench 5 #, drain the hydraulic oil in the cylinder, and tighten the bolt (connect the hydraulic oil in the oil pipe with a basin);
(11) Use manual pushing to press the piston rod into the cylinder body. If manual pushing is not possible, use a jack to slowly press the piston rod into the cylinder body;
(12) Remove device 9 and wrap adhesive tape around the M48 screw at the end to prevent rubbing during disassembly (note: if there are burrs at the end, use fine sandpaper with a grit of 2000 or more for polishing).
Figure 2: Disassembling the Tensioning Cylinder
3. Replace the sealing ring
(1) Loosen the bolts on the sealing device at the end of the tensioning cylinder using Allen wrench 4 #;
(2) Symmetrically loosen the bolts on the sealing device at the end of the tensioning cylinder using an Allen wrench 10 #;
(3) Symmetrically remove the bolts on the sealing device at the end of the tensioning cylinder using an Allen wrench 14 # (bolts are numbered);
(4) Slowly remove device number 1 and transfer it to an open area;
(5) Remove the bolts from the sealing device at the end of the tension cylinder using an Allen wrench 4 # (number the bolts);
(6) Symmetrically remove the bolts on the sealing device at the end of the tensioning cylinder using an Allen wrench 10 # (the bolts are numbered);
(7) Slowly push out two M8 bolts, remove the components slowly, and clean all components;
(8) Remove the oil seal and dust ring, and clean and inspect them;
(9) Prepare and replace the oil seal with a new one;
(10) Slowly install to, installation number 11, tighten bolt 21 after it is in place;
(11) Slowly install the assemblies numbered 5, 1, and 11 onto the piston rod, and tighten bolt 20 after they are in place (note: apply hydraulic oil to the sliding contact area of the sealing ring);
(12) Install dust rings numbered 14 and 10, and tighten bolt 19 after they are in place;
(13) Install serial number 9 and tighten it;
(14) Use the method of moving the car forward to move to the rear end of the piston rod, install it on the frame, and complete the installation of the shaft and split pin.
Attention: Apply hydraulic oil lubrication to the sealing ring, avoid excessive stretching, and confirm the sealing direction.
Figure 3 Replacing the sealing ring
4. Oil pipe installation, exhaust and testing
(1) Use a 41 # open-end wrench to tighten the joint between explosion-proof valve 43 and the oil cylinder;
(2) Close plate ball valves 31 and 32.2, and use the principle of hydraulic system to move the trolley;
(3) Supply oil to the tensioning cylinder through a manual pump and observe the extension of the tensioning cylinder piston rod (whether the operation is smooth, whether there is any jamming, and ensure that there is no obstruction when the piston rod extends);
(4) Use exhaust bolt 40 for exhaust;
(5) Finally, slowly open the plate ball valve 32.2 and raise the heavy hammer to the required state through a manual pump;
(6) Observe the condition of the hydraulic oil in the fuel tank and replenish it as needed;
(7) Complete installation work and clean up the work site;
(8) Preparation work before the test drive.
IV. Subsequent maintenance plan for the sealing ring
1. In terms of preventive maintenance: (1) It is recommended to establish a regular inspection system for seals (such as comprehensive disassembly and replacement every 2 years); (2) Consider using more durable sealing materials to extend the service life while ensuring the normal operation of the equipment; (3) Increase oil contamination testing and oil replacement time, and make testing a regular monitoring item.
2. Technical optimization: It can evaluate the use of intelligent seals with wear indicators; Research on surface treatment processes for hydraulic cylinders (such as hard chromium plating) to reduce seal wear; Consider adding a cylinder stroke sensor to monitor the sealing status
3. Execution level: It is recommended to increase the measurement records of oil cylinder stroke before and after construction; Can supplement the pressure holding test steps after the installation of the sealing ring; Consider adding an infrared thermal imager to check the temperature distribution of the oil cylinder.
4. Maintenance suggestions:
(1) Daily inspection: Check the leakage of the oil cylinder every week and record it; Check the cleanliness of hydraulic oil every month; Measure the variation of oil cylinder action time every quarter.
(2) Professional maintenance: Professional inspection of sealing status every 2 years; Consider preventive replacement of seals every 5 years; Replace the oil every 3 years or according to the pollution level test results
(3) Fault warning: Establish an oil leakage change alarm threshold (such as>30ml/day)
V. Summary
The performance of the sealing ring of the hydraulic tensioning cylinder, as an important actuator of the hydraulic system, directly affects the sealing performance and energy conversion efficiency of the system. The sealing ring prevents hydraulic oil leakage, ensures stable pressure, and avoids energy waste and equipment failure caused by seal failure. If the sealing ring is worn or aged, it may cause oil leakage, pressure drop, and even hinder the operation of the oil cylinder. In severe cases, it can shorten the service life of the equipment and increase maintenance costs. Therefore, regular maintenance and timely replacement of sealing rings are the core measures to ensure the long-term stable operation of hydraulic tensioning cylinders. This article provides a brief analysis of the replacement and maintenance of the sealing ring based on the recent oil leakage situation of the tensioning oil cylinder in the Baisui Palace cable car. We hope that colleagues can point out any shortcomings.
2026 August 3rd Week VAFEM Product Recommendation
VAFEM Hub units are designed to allow rear wheels, especially in passenger cars, to turn on an axle even under heavy loads.
Features:
magnetic, electric, and mechanic ABS
with and without ABS
flange only
Steel Material: GCr15/52100/100Cr6
Steel Type: Forged
Ball Grade: G10
Grease: Shell
2026-08-21