Hydrulic cylinders failure

[Alnadabi]

Gents

This is my first post and I need your help. My english is not my mother tong so please forgive me

We had a hydulic clinder failure which resulted into an incident. The full load disconnected from the cylinders and fell to the ground while the cylinders were still extended . But not fully. The cylinders are a Parker hydrulic double acting telescopic cylinder..

The whole load of about 8 tons fell down causing some injuries . The first thinking is that it was a hydrulic failure ( some air got to the pump) but now the contractor blames the pad eyes to which the cylinders are attached.. we can not prove that there was a hydraulics issue because the cylinders were still extended after the incident. Is there a chance for the cylinder to fail and then to expand if any air gets into them.

 

[zeusfaber]

Can you post a sketch of how this whole thing was meant to work? I'm having trouble picturing the system, let alone what might have gone wrong with it.

Could also be useful to clarify what you mean by "load disconnected from the cylinder". Do you mean that the load fell off the cylinder, or that the hydraulics yielded under load (so the direction of travel reversed), or that the load ran away from the hydraulics (so the load moved in the direction it was being pushed, but out of control) - or something else?

A.

 

[desertfox]

Hi aindabi

Without some information on the system we cannot help you but from your post its sounds like the cylinders were mounted above the load and the pad eyes on the load failed and the 8 tons fell to the floor I am correct?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[HPost]

Your contractor is correct, the pad eyes have failed under tensile strain.

The cylinders cannot and will not expand as a result of air in the oil. Even if they did, it would only cause the cylinders to fully extend, but not fail.

It is possible that a high air content in the oil could cause the system to become unstable, thus putting excess strain on the pad eyes.

Adrian Wright CEng MIMechE
Engineering Specialist
Hydraulic Systems
Caterpillar (UK) Ltd

 

[chicopee]

Pictures of failed equipment or manufacturer'cataloq on web site would help for those of us trying to come up with satisfactory answers.