What is a hydraulic cylinder?
Hydraulic cylinders are hydraulic actuators that convert hydraulic energy into mechanical energy and produce reciprocating or oscillating linear motion.
The hydraulic cylinder has several notable features, including its simple structure, reliable operation, no transmission backlash and smooth movement. Due to its versatility, it is widely used in hydraulic systems of various machines.
However, as it is general-purpose industrial equipment, failures are likely to occur during its use. In extreme cases, these failures can result in equipment shutdown, making daily diagnosis and maintenance of failures essential.
In general, hydraulic cylinder failures can be categorized as incorrect operation, inability to push loads, and difficulty moving or sliding the piston.
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 seal. These components can be grouped into four categories:
I. Wear on the contact surfaces of the piston and rod II. Wear on the contact 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 hydraulic cylinder operation is one of the most common failure conditions. To diagnose and resolve this problem, operators must identify the root cause of the failure.
While the hydraulic cylinder is in operation, check for pressure oil entry. If there is no pressurized oil entering the cylinder, the causes and solutions are as follows:
- The reversing valve before installing the hydraulic cylinder does not change in a timely manner. If there is no pressurized oil entering the hydraulic cylinder, check the root cause of the reversing valve replacement failure and resolve it.
- The system is not receiving oil. Check the cause of failure of the hydraulic pump and main hydraulic valve and resolve.
If oil enters the cylinder, check whether the oil pressure is sufficient. If the system is not working properly, it is probably due to a problem with the pump or relief valve. Check and resolve any problems with the pump or relief valve in a timely manner.
In the event of severe internal leakage, piston and piston rod play, and severe damage to the seals, tighten the piston and piston rod and replace the seals immediately.
If the pressure regulating valve is defective, 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 piston sealing ring is missing or seriously damaged, or there is a deep groove in the cylinder bore and the nut securing the piston to the piston rod becomes loose, it will cause severe cavitation in the hydraulic cylinder inlet cavity, resulting abnormal movement of components. In this case, replace the piston seal ring 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 not to move, several factors must be investigated:
- Check whether the load is greater than the predetermined value, especially if any additional load caused by poor installation of the hydraulic cylinder is very large. In this case, calibrate and reinstall the hydraulic cylinder correctly.
- Check whether the connection between the hydraulic cylinder and the load is correct. Incorrect connections can cause movement and locking problems. In this case, consider changing the rigid fixed connection to a movable hinged connection or ball head connection, with a spherical surface being preferred.
- Inspect the structure of the hydraulic cylinder, ensuring that the piston end face and cylinder end face are properly fitted and that the piston bearing area is sufficient when the cylinder is started. Also, check whether the check valve circuit in the cylinder damper device is blocked by the piston. Address each problem individually.
- Poor assembly of the hydraulic cylinder, such as low concentricity between the piston rod, piston and cylinder head, poor parallelism between the hydraulic cylinder and the table and small gaps between the guide sleeve and the piston rod, can cause it to jam. of the piston rod.
- Problems in the hydraulic circuit, such as communication of the oil level in the hydraulic cylinder's counterpressure chamber with the fuel tank, non-functioning of the reversing valve that communicates with the oil return, failure to open the shut-off valve, and closing of the butterfly valve, may result in blockage of oil return. Address specific issues as they arise.
- If dirt gets into the sliding parts and causes them to stick, clean the parts immediately.
- If the hard chrome coating on the piston rod falls off and causes it to become stuck, stop processing immediately to prevent tumor build-up, which can make the problem more difficult to solve later.
