Hydraulic cylinders obviously make up an important part of hydraulic machinery. If you’ve got a lot of machinery, then it’s typical that you’re going to pay out a fair amount on cylinder repair expense.
Researchers have found that failures of design can make up to 25% of mechanical equipment failures. If this is applied to hydraulic cylinders, then it’s possible that as many as 1 in 4 cylinders are not designed adequately for what they are doing.
Even if the cylinder may do the job that it’s been assigned to, it won’t do it with a service life that is acceptable. Here are the main reasons that badly designed cylinders may fail you and what you need to look at to improve matters.
1. Bent Rods
Cylinder rods can bend when the materials they are made of are not strong enough, the rod diameter is insufficient or there is an issue with the cylinder mounting arrangement. Once there is any bend in the rod, it will only get worse when more load pressure is placed on it. This can also result in failure of the seal and increased leakage.
Use the Euler formula to check allowable rod loading.
2. Rod Finish
The life of the rod seal can depend on the cylinder rod’s surface finish. If it’s too smooth, there is not enough lubrication, or if it’s too rough then there will be a lot of leakage at the seal.
In order to extend the service life of the cylinder, treat the rod’s surface with this in mind.
3. Ballooned Tubes
If the cylinder tube wall is not made of strong enough and thick enough material, it could balloon. Once this happens, high pressure fluid could bypass the seal. Couple this with too much heating and the piston seal will come to a premature end.
4. Insufficient Bearing Area
If the side thrust cannot be handled well by the bearing (wear) bands, then the seals could become deformed and therefore have a shortened life span.
With regards to making amends to these issues - you may be able to perform some minor repairs, but if you’re faced with the same issue time and again, it’s advised that you opt for a redesign.