5 possible causes of hydraulic rod seal failure

5 possible causes of hydraulic rod seal failure


Hydraulic and piston seal repair guide 2020

hydraulic rod seal manufacturers in china

Hydraulic rod seal are amazing devices that we use in many industries. They operate the excavators of construction machinery. Moreover, they are used in agricultural machinery, and discreetly in factories and furniture. So how does hydraulic rod seal work?

The hydraulic cylinder is a device made up of 3 main elements.

 These are:
  1. the cylinder which contains a movable piston attached to a rod
  2. a fluid which circulates inside the tube
  3. and joints in flexible materials which ensure the tightness of the system

The job of the hydraulic rod seal is to transform energy into mechanical force. By putting the liquid under pressure by injecting it from one side. Furthermore, in this way the piston is pushed. It is a movement that can be used to lift a load.

There are two categories of hydraulic rod seal

  1. Single-acting hydraulic cylinders

This model only works in one direction. Under pressure, the oil is sent to one of the 2 chambers to cause displacement of the piston and the rod.  In addition, the return can be by spring or by an external force.


2- Double-acting hydraulic cylinders

Generally, this model is controlled by 2 ports. To move the rod in or out, hydraulic pressure must be sent to one of the chambers.

This model gives you the possibility to feed the 2 rooms at the same time. Just use different pressures to limit the force and speed of movement.

Function of hydraulic rod seal

We find the seals in several places across the hydraulic cylinder.

The hydraulic rod seal is placed between the piston and the cylinder wall. It is designed to allow the oil pressure to push it against the wall and cause a great sealing force.

The role of the O-ring is to prevent oil from escaping between the rod stuffing box and the cylinder wall.

For the stem seal, it takes the shape of a “U”. Its job is to prevent oil from escaping between the stem and the stuffing box and to scrape the oil off the stem.

As for the wiper seal, it prevents dirt from entering the cylinder.

Usually the gaskets are made of:

  • polyurethane
  • viton or
  • nitriles

Hydraulic cylinder repair: hydraulic rod seal

The hydraulic cylinder can be subject to many types of failure.

The twist of the rod

Under intense resistance, hydraulic rod seal can twist. In this case, you simply have to order the part from a supplier to replace it. If the twist is slight, it is possible to correct the positioning of the rod.

The cylinder leak

This is the most common failure. This can be external or internal. In the second case, the leak is very difficult to identify.


To correct this problem, either replace the affected part or go through lapping or chrome plating.

Subsequently, a hydraulic cylinder can be damaged over time. This cylinder can then remain fragile if it is not repaired. Similarly, it requires good maintenance to ensure proper functioning of the machines that use it. Because it allows mechanical movement to be generated via hydraulic energy.

The hydraulic rod seal are mainly used in:

  • Agriculture
  • the construction sector
  • industrial handling or
  • in the transport sector

In the event of a failure, the entire system can malfunction. And in some cases this can cause significant damage or even be dangerous.

 What to do then as soon as hydraulic rod seal failure occurs?

We offer you an overview of the various possible breakdowns and the different repairs that must be carried out in the event of a breakdown.

  1. The various possible failures of hydraulic cylinders
  2. The most common failures that cause the actuator to malfunction are:
  3. Twisting of hydraulic rod seal

The rod may twist if there is too much resistance when deploying the cylinder. Moreover, this failure causes immediate malfunction and is quite easy to notice. We can then opt for a replacement of the rod or rectify its position if the torsion is slight.

Even with slight torsion calling in hydraulic rod seal specialist to make sure correct position correction is necessary.

Hydraulic fluid leaking from the cylinder

This is the most common failure. Simultaneously, the leak can be external. And we then see the fluid escaping from the jack, or are internal. In this case the fluid escapes outside the chamber.

This failure is sometimes difficult to spot in the event of an internal leak. Moreover, the leak can be due to two causes:

  1. wear of the rod causing a micro-scratch but large enough for the fluid to escape
  2. or wear of the seals no longer being tight enough to contain the fluid

Hydraulic rod seal Mechanical failure

It sometimes happens that the hydraulic rod seal suffers damage due to an external impact. This happens in particular on delicate sites in which the machines are exposed to projections or debris. This is a fairly uncommon cause but the cylinder can be much damaged in some cases.

We speak more of external material damage than a failure due to a malfunction of the cylinder itself. In these cases, the damaged part or the entire cylinder must be repaired if the damage is too severe.

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Hydraulic rod seal Age and deterioration

Sometimes the cylinder components are old and malfunction due to wear. This happens more often with hydraulic rod seals which then need to be replaced or repaired.

Call in hydraulic rod seal repair specialists

We note that most failures are natural in the sense that a jack that is used frequently must be checked regularly. It is to ensure that it is functioning correctly over time. Maintenance is important and it is therefore necessary to call on a specialist hydraulic rod seal manufacturer.

The repair of hydraulic cylinders can be broken down in several ways depending on the failure encountered and the type of cylinder. Therefore, a complete check of the cylinder is often preferred and consists of

  • a disassembly in order to check each component of the cylinder
  • the condition of the joints, and
  • the quality of the welds