How do I know if my hydraulic cylinder is bad?

1. Unusual banging noises

It’s true that hydraulic cylinders produce some level of noise, but this shouldn’t sound like loud thumping, knocking or banging. If your cylinder has started to amp up the noise level and sounds slightly unsteady, then it’s likely that there’s something wrong.

Banging or knocking sounds being produced from a cylinder typically has two main causes: aeration or cavitation.

Aeration is the formation of air bubbles inside the system which appear as a result of too much air entering the pump’s inlet. These air bubbles get compressed and decompressed as they circulate the system, resulting in loud banging sounds.

Cavitation occurs when there isn’t enough fluid getting into a part of the hydraulic circuit. A lack of fluid leads to a huge drop in pressure which causes the fluid to vaporise and prevents the system from running smoothly. The fluid cavity may implode on itself when the pressure returns. This process generates loud knocking noises and can lead to damage of the cylinder.

2. Jerking or juddering movements

Hydraulic cylinders are designed to operate smoothly. If this consistently smooth movement is lost and a cylinder starts jerking or juddering, that’s usually a sign that there’s a problem.

Jerking or juddering movements as the cylinder extends typically signals that the piston and rod can’t move freely. More often than not, this is caused by physical damage to the cylinder from too much friction which can happen when there is insufficient lubrication in the system, or parts have become worn or damaged.

3. High temperatures

Hydraulic cylinders typically operate for long periods of time, and this can naturally result in an increase in temperature. However, they have set temperature ranges and shouldn’t heat beyond this.

As a general guideline, cylinders shouldn’t exceed 80°C during normal operations, but manufacturers will usually set out guideline limits for each specific model. Cylinders may reach temperatures as high as 120°C under high speed/peak load conditions, but this shouldn’t be the norm.

If a cylinder is hotter than it should be, this indicates abnormal conditions and is usually a part of a wider problem such as too much friction or a problem with the hydraulic fluid. It’s a good idea to be aware of your cylinder’s normal operating temperature, and recognise overheating as a warning sign that there may be an issue somewhere in the system.

4. Slow operating speed

If a hydraulic cylinder has a fault, it may start to lose power and start working at a slower pace than normal. This, in turn, affects the operating speed of the entire system.

A loss of speed or power can be a sign of increased friction or internal leakage. In the case of internal leakage, it will take the cylinder longer to build up to the required pressure which slows down the entire circuit.

If your machine is working slower than usual, it’s important to check for the underlying cause and inspect for any damage to the cylinder. Otherwise, the performance of the cylinder will continue to dwindle until it is unfixable.

5. Increased power consumption

A rise in energy bills may also indicate a problem with your hydraulic cylinder. If the component has been subject to internal/external leakage or increased friction, the circuit will need to source more energy to function efficiently.

This means that the hydraulic pump will begin to work overtime in order to deliver more fluid to compensate for the leak, which results in higher power consumption.