This can be caused for a amount of reasons the most coarse of which on new cylinders is incorrect fitting of the seals, however incorrect metalwork clearances may also cause early stage failure. Another physical theorize for this failure once the expedient is in use is corroding, or marking of the seal grooves. The oil itself may also be the cause either because it is contaminated, or else because air has been trapped.
Corrective measures unsurprisingly contain checking and if needful transfer of the seals. Metalwork clearances should be checked in any event and if the oil is found to be contaminated then it should be replaced. There needs to be a clear theorize established for oil contamination as it may be a sign of less unavoidable wear - checking clearances is part of this process.
2 - Piston rod scored
Scoring of the piston rod is often caused by oil contamination, but this may also be contamination of the gland bearing. If not caught in time then the gland bearing may have failed completely.
The gland bearing needs to be checked and replaced if necessary. The entire hydraulic law will need to be flushed and all filters turn before re-assembly and re-pressurising.
3 - Cylinder bore scored
Scoring of the cylinder bore can also be caused by contamination of the oil, which may in turn be a sign of piston head bearing failure.
The piston head bearing will need to be checked and replaced if necessary. For either failure reason, the entire hydraulic law will need to be flushed and all filters turn before re-assembly and re-pressurising.
4 - Barrel internally corroded
The most likely cause of a barrel being internally corroded is water in the oil.
Correction may require disassembly and re-coating, but as a minimum the oil will need be changed. The cylinder will need to be protected from hereafter water ingress and this may also be a sign that it is either wrongly specified or maybe being used in an environment for which it was not designed.
5 - Piston rod pitting
Pretty much the only cause for piston rod pitting is corrosion. This may also be a sign that the cylinder is either wrongly specified or maybe being used in an environment for which it was not designed.
To begin with the rod and even the whole cylinder should be protected from the weather or any other theorize for caress with water. Ideally the rod should also be upgraded to maritime specification.
6 - Leaking from around the gland outer diameter
Leaking from around the gland outer diameter can be caused by o-ring failure, or by having a cracked gland, either which in turn could have been caused by poor clearances.
Clearances will need to be checked and the gland tested for cracks. If the o-ring is faulty then a backup can often be fitted, or the o-ring can be replaced.
7 - Bent piston rod
A bent piston rod may be a sign that the hydraulic cylinder is a being overloaded. This may be because the cylinder and linked piston are working surface of their specification - overloaded in other words. It can also be caused by an surface (sideways) impact of some kind - for example a collision.
The first thing to check is the load and either the cylinder is working within specification, or not, as without this information any repair will not last long. The piston rod can be replaced, but this is also an occasion to describe the specification and upgrade the rod if necessary.
8 - Split weld on base and ports
A split weld on the base and ports may be caused at the original originate (or new repair) by a poor weld failing. It may also be caused by shock loading - or a sudden impact to full pressure (or beyond).
An test of the use of the cylinder is required to make sure it is not being misused, or employed out of its specification. This will ensure the problem does not recur after repair.
Repairing will involve machining off the weld and re-welding correctly.
9 - Eye bearing broken
A broken eye bearing is ordinarily caused by the cylinder working on a load above its specification, or else by a shock loading - or a sudden impact to full pressure (or beyond).
As with other issues above, before a repair is made the operational use of the cylinder should be checked to ensure it is not working out of specification. This investigation can lead to a turn of use, or else an upgrading of specification on repair. For example, the specification of the transfer eye bearing may be upgraded and the clevis pin size may also be increased.
10 - Rod worn on one side
A rod worn on one side is a sign of a sideways movement of some kind either from a lack of bearing support (perhaps from bearing failure), or else too much side load which can be a supervene of misalignment or misuse. The rod itself may literally be under specified for the load and so the use of the cylinder should be checked to make sure it is being used within specification.
A repair will provide an occasion to not just fix the problem, but raise the specification of the assembly by addition the rod size, addition the bearing area or incorporating external guides. A composition of all three is also possible.
The above list is not exhaustive of course, but these are the most coarse failures. Often a hydraulic cylinder repair is an occasion to describe working practices, or raise the specification of the cylinder. This means that not only is the problem fixed but preventive quantum applied to sacrifice the possibility of hereafter recurrence.
