Hydraulic cylinders fail for a wide array of reasons from bad options and misuse to just frequent age. Here are the top 10 reason failure and how to go about the hydraulic cylinder repair.
1 : Regular seal leakage
This can be caused for several reasons the most common of which on new cylinders is incorrect fitting of the seals, however incorrect metalwork clearances may also cause early stage malfunction. Another physical reason for this purpose failure once the device is in use is corroding, or marking with the seal grooves. The oil itself may also be the cause either since it is contaminated, or else because air may be trapped.
Corrective measures unsurprisingly include checking and if necessary replacement of this seals. Metalwork clearances should be checked the point is and if the oil can be found to be contaminated then it ought to be replaced. There needs being a clear reason established for oil contamination as it may be a sign with less obvious wear : checking clearances is part of this process.
2 - Piston rod scored
Scoring of the piston rod is usually caused by oil toxic contamination, but this may also be contamination in the gland bearing. If not caught in time then the gland bearing can have failed completely.
The gland bearing needs to be checked and replaced when necessary. The entire hydraulic system will probably need to be flushed and just about all filters change before re-assembly together with re-pressurising.
3 : Cylinder bore scored
Scoring of the cylinder bore is usually caused by contamination with the oil, which may in turn be a sign with piston head bearing malfunction.
The piston head bearing will probably need to be checked and replaced if necessary. For as well failure reason, the entire hydraulic system will need to be flushed and all filters change before re-assembly together with re-pressurising.
4 - Barrel internally corroded
Probably the most likely cause of a barrel being internally corroded is water in the oil.
Correction may need disassembly and re-coating, but for a minimum the oil need be changed. The cylinder will probably need to be protected from long term water ingress and this will also be a sign that it can be 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 with regard to piston rod pitting is actually corrosion. This may also be a sign that the cylinder is either wrongly specified or perhaps being used in a host for which it hasn't been designed.
To begin with the rod and even the whole cylinder should be protected in the weather or any other reason for contact with water. Ideally the rod should also be upgraded to ocean specification.
6 - Leaking from around the gland outer diameter
Leaking from within the gland outer diameter can be caused by o-ring failure, or by having some sort of cracked gland, either which in turn could have been brought on by poor clearances.
Clearances will probably need to be checked and your gland tested for cracks. If the o-ring is usually faulty then a backup are frequently fitted, or the o-ring may be replaced.
7 : Bent piston rod
A bent piston rod may be a sign that the hydraulic cylinder can be a being overloaded. This may be because the cylinder and associated piston will work outside of their specification - overloaded quite simply. It can also be caused by an outside (sideways) impact of some sort - for example some sort of collision.
The first thing to check is the load and whether or not the cylinder is working inside specification, or not, as without this information any repair will not last long. The piston rod may be replaced, but this is also an opportunity to review the specification together with upgrade the rod when necessary.
8 - Split weld on base and ports
A split weld in the base and ports may be caused at the original manufacture (or recent repair) by a poor weld failing. It might also be caused by shock loading - or maybe a sudden impact to full pressure (or further than).
An examination of the use of the cylinder is required to assure it is not increasingly being misused, or employed using 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 frequently caused by the cylinder focusing on a load above its specification, or else by a shock loading - or a sudden impact to comprehensive pressure (or further than).
As with some other issues above, before a repair is made the operational use in the cylinder should be checked to ensure it is not working out of specification. This investigation can result in a change of make use of, or else an updating of specification on repair. For example, the specification of the replacement eye bearing may be upgraded and the clevis pin size may also be increased.
10 - Rod worn on one side
A rod worn one side is a sign of an sideways movement of some kind either from a lack of bearing support (maybe from bearing failure), or else too much side load which are often a result of misalignment or misuse. The rod itself may actually be under specified for the load and so the use of the cyndrical tube should be checked to check it is being utilized within specification.
A repair will provide possibility to not just fix the challenge, but raise the specification of the assembly by increasing your rod size, increasing that bearing area or incorporating external guides. A mix of all three is also possible.
The above list is not exhaustive of course, but these are the most common failures. Often a hydraulic cylinder repair is an opportunity to review working practices, or improve the specification of the cyndrical tube. This means that but not just is the problem permanent but preventive measure used on reduce the possibility with future recurrence.
REFERENCE:
http://articledome.com/Article/Hydraulic-Supplies---The-Basics/119718
http://articlesdepository.com/Art/146589/50/All-About-Hydraulic-Supplies.html
http://ezmailroom.com/articles/all-about-hydraulic-supplies-2/