How to determine Hydraulic cylinder The quality of a product, whether good or bad

　　As everyone knows, hydraulic cylinders are among the terminal control components of a hydraulic system, making them highly important. Their quality directly affects the overall performance and operational characteristics of the hydraulic system. Below, we will analyze how to assess the quality of cylinder products.

　　Hydraulic cylinder cushioning

　　Installing a cushioning mechanism at the end of the hydraulic cylinder’s stroke enables the piston rod assembly to decelerate to nearly zero upon reaching the stroke limit, thereby mitigating mechanical impacts between the piston rod and the cylinder liner caused by the piston rod’s inertial forces and hydraulic pressure. This reduces noise and prevents damage to the hydraulic cylinder.

　　General basic requirements for buffer mechanisms:

　　(1) The buffering mechanism should be capable of dissipating and absorbing substantial mechanical energy within a relatively short buffering stroke.

　　(2) In the buffering stage, the pressure variation within the buffer chamber is relatively mild, and the peak operating pressure remains below 1.5 times the standard pressure rating of the hydraulic cylinder.

　　(3) When mechanical energy is converted into heat, causing the hydraulic oil temperature to rise, the oil’s operating temperature must not exceed the maximum allowable limit for the hydraulic seals.

　　How can fault diagnosis be performed when a hydraulic cylinder malfunctions?

　　1. Causes of incorrect operation or operational failure

　　(1) Valve body seizure or valve port blockage: When the spool of a flow control valve or directional control valve seizes, or when a valve port becomes blocked, the hydraulic cylinder is prone to malfunction or failure. In such cases, inspect the condition of the hydraulic fluid; check whether contaminants or gelatinous fiber deposits have caused the spool to seize or the valve port to become obstructed; examine the oil circuit board for damage; clean or replace the filtration elements; flush the reservoir; and replace the hydraulic fluid.

　　(2) If the hydraulic cylinder is seized to the cylinder liner or becomes blocked, it will remain immobile or exhibit only minimal movement regardless of control inputs. In this situation, check whether the piston rod and its seal are excessively tight, whether contaminants or collagen fiber deposits have entered, whether the axis of the hydraulic cylinder aligns with that of the cylinder block, whether any components or sealing materials are defective, and whether the required load is excessively high.

　　(3) If the hydraulic control system operates at too low a working pressure, the throttling valve in the control line may have excessive frictional resistance, the flow valve may be improperly adjusted, the pressure‑control settings may be unsuitable, or other adverse factors may be at play. In such cases, the control system should be inspected to ensure that the pressure is adjusted to the specified nominal value.

　　(4) Gas ingress into the hydraulic system is primarily caused by leaks within the system. In such cases, check the hydraulic oil tank’s level gauge, the suction-side seals of the hydraulic pump, and the T‑connectors; also verify whether the return‑line coarse filter is excessively clogged. If so, replenish the hydraulic fluid, repair or replace the seals and T‑connectors, and clean or replace the coarse filter element.

　　(5) The hydraulic cylinder initially moves slowly. Under relatively low ambient temperatures, the hydraulic oil has high viscosity and poor flowability, resulting in sluggish cylinder operation. To address this, replace the hydraulic oil with one that exhibits better viscosity‑temperature characteristics. In cold environments, use an electric heater or the equipment’s built-in heating system to raise the operating temperature; maintain the system’s normal operating temperature at around 40°C.