Hydraulic Cylinder Not Working: Troubleshooting Guide

What is hydraulic cylinder?

Hydraulic cylinders are sophisticated actuators that harness hydraulic energy to generate mechanical force, typically producing linear reciprocating motion or controlled rotational movement. These devices serve as the muscle of hydraulic systems, converting fluid pressure into powerful, precise linear force.

Key characteristics of hydraulic cylinders include:

1. Robust simplicity: Their straightforward design belies complex engineering, ensuring reliability and ease of maintenance.
2. Operational consistency: The absence of mechanical transmission gaps results in smooth, jerk-free motion.
3. Force multiplication: Capable of generating immense forces with relatively compact designs.
4. Versatility: Adaptable to various industrial applications, from heavy machinery to precision equipment.

Due to their ubiquity in industrial hydraulics, hydraulic cylinders are integral components in diverse machinery, including construction equipment, manufacturing systems, and aerospace applications.

However, like all mechanical systems, hydraulic cylinders are subject to wear and potential failures. Common issues include:

1. Operational errors: Often stemming from improper use or control system malfunctions.
2. Load pushing inefficiency: Typically related to seal degradation or internal leakage.
3. Piston movement irregularities: Can result from contamination, misalignment, or component wear.

To maintain optimal performance and prevent costly equipment downtime, regular diagnostic checks and preventive maintenance are crucial. This proactive approach ensures early detection of potential issues, maximizing the cylinder’s operational lifespan and system reliability.

Understanding the principles, applications, and maintenance requirements of hydraulic cylinders is essential for engineers and technicians working with hydraulic systems across various industries.

Hydraulic cylinder troubleshooting

From a fundamental perspective, the main components that contribute to hydraulic cylinder failures include the oil cylinder, piston rod, cylinder block, guide sleeve, piston, and cylinder rod sealing. These components can be grouped into four categories:

I. Wear and tear on the mating surfaces of the piston and piston rod II. Wear and tear on the mating surfaces of the piston rod and guide sleeve III. Broken piston seals IV. Damage to other seals, etc.

The hydraulic industry widely recognizes that incorrect operation of the hydraulic cylinder is one of the most common fault conditions. To diagnose and resolve this issue, operators must identify the root cause of the failure.

While the hydraulic cylinder is in operation, check if any pressure oil is entering it. If there is no pressure oil entering the cylinder, the causes and solutions are as follows:

• The reversing valve before the hydraulic cylinder installation is not switching in a timely manner. If no pressure oil is entering the hydraulic cylinder, check the root cause of the reversing valve’s failure to switch and resolve it.
• The system is not receiving oil. Check the cause of the failure of the hydraulic pump and main hydraulic valve and resolve it.

If oil is entering the cylinder, verify that the oil pressure is sufficient. If the system is not functioning properly, it is likely due to an issue with the pump or the relief valve. Check and resolve any problems with the pump or relief valve in a timely manner.

In the case of serious internal leakage, looseness of the piston and piston rod, and serious damage to the seals, tighten the piston and piston rod and replace the seals promptly.

If the pressure regulating valve is faulty, adjust the pressure setting until the required value is reached. If necessary, recalculate the working pressure and replace the pressure regulating component with one that can be adjusted to the desired value.

When the sealing ring on the piston is missing or seriously damaged, or there is a deep groove in the cylinder bore and the nut that locks the piston on the piston rod becomes loose, this will cause severe cavitation in the hydraulic cylinder inlet cavity, resulting in abnormal movement of the components. In this case, replace the sealing ring on the piston and take other necessary repair measures.

If oil is entering the cylinder and the pressure meets the requirements, but the load is too large causing the hydraulic cylinder to be unable to move, several factors should be investigated:

• Check if the load is larger than the predetermined value, particularly if any additional load caused by poor hydraulic cylinder installation is too large. If so, calibrate and reinstall the hydraulic cylinder correctly.
• Verify that the connection between the hydraulic cylinder and the load is correct. Incorrect connections can cause movement and jamming issues. In this case, consider changing the rigid fixed connection to a movable articulated connection or ball head connection, with a spherical surface being preferred.
• Inspect the hydraulic cylinder structure, such as ensuring that the end face of the piston and the end face of the cylinder barrel are properly fitted, and that the piston bearing area is sufficient when the cylinder starts. Also, check if the check valve circuit on the cylinder buffer device is blocked by the piston. Address each issue individually.
• Poor hydraulic cylinder assembly, such as poor concentricity between the piston rod, piston, and cylinder head, poor parallelism between the hydraulic cylinder and the table, and small clearances between the guide sleeve and the piston rod, can cause piston rod jamming.
• Issues in the hydraulic circuit, such as communication of the oil level in the back pressure chamber of the hydraulic cylinder with the fuel tank, non-operation of the reversing valve that communicates with the oil return, failure to open the shut-off valve, and closing of the throttle valve, can result in blocked oil return. Address specific problems as they arise.
• If dirt enters the sliding parts and causes them to become stuck, clean the parts immediately.
• If the hard chromium plating on the piston rod falls off and causes it to become stuck, stop processing immediately to prevent the buildup of tumors, which could make the issue more difficult to resolve later.