Manufacturers Of Mechanical Locking Hydraulic Rams

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You can find whatever you need there.

If blowing out and or chewing up piston seals and having hoses collapse internally sending bits of rubber everywhere that plug up critical interlock components says to me that there is a total lack of proper maintenance given it's critical fail to safe mode requirements.

When was the last time the filters were changed and inspected?

When was the last time fluids were changed and inspected?

When was the last time hoses were replaced?

When was the last time hydraulic cylinders were overhauled?

Maintenance? MAINTENANCE?

We don't do no stinking maintenance!

Yup

I expected those kind of replies.

A very important part of engineering is to understand the question and find answers for it rather than creating your own F.tainment

And asking an anonymous forum to solve your ill defined symptom is not engineering.

Ask the cylinder supplier to help you. Admit to them that you are not an engineer.

The telephone is the correct tool for the job.

Email? Pah!

There is now a person doing all of the above in response to the failures identified.

The same person also wants to find a replacement cylinder that has a secondary safety mechanism to overcome the risk that any of the incidents you have mentioned could occur suddenly.

Even if you replaced the 97 hoses on a yearly rotation ( when 5 yearly when be adequate ) there is still the risk that a tiny bit of hose could be stuck to a fitting since manufacture and shed itself 4 months after the hoses were replaced , hence we want a secondary layer of protection........

So thank you for adding the criticisms and assumptions , however they are already on the table.

So who manufactures cylinders with mechanical locks ?

The list that Lyn very kindly linked to gives me only one so far ( DME )

I don't know that anything in your primary system can be completely foolproof. You may need some kind of secondary system that actively clamps the primary actuator.

We consider the existing system is inadequate as there is no secondary lock.

As mentioned the primary system has failed twice , once with a check valve that blocked open and once with a split piston seal , both of those scenarios cause a failure in function in a system where zero risk is required.

I am hoping to find a cylinder that has a "deadman type" of shaft lock where loss of hydraulic pressure will lock the cylinder rod in whatever part of its stroke it was in at the moment of failure , on top of having a Counterbalance valve or check valve at the primary level.

I agree,nothing can be 100% failure proof...Even NASA with 5 redundant systems has failures.

All you can do is reduce the probability to an acceptable level using redundant backup systems,separate and independent of the primary system.

I agree completely about AP's.

Especially AP's with attitudes!

thanks for the serious consideration that you have given in your reply.

people sometimes dont disclose all the information about an application due to commercial or contractual sensitivity , however i can say it is ground based but associated with avionics and marine.

It has been in operation for nearly 40 years , albeit with complete rebuilds and also spot maintenance over that time as required , it is not run daily but has prestart tests and routine diagnostic tests before being operated under load , the 2 failures occurred during operation some hours after prestarts were carried out.

You might argue that 2 documented failures in 40 years in negligible however the current operator of the equipment has a strict safety philosophy and has tagged off the equipment until an appropriate upgrade is implemented.

Modern equipment in this role will have no less than 2 levels of redundancy with electronic indicators and automatic isolators to cut operation in fault mode , and that is why i am looking for products to fullfil that need.

Yes , i have searched self locking , shaft locking , auto locking , mechanical locking cylinders but nothing suitable was found yet.

optimism is still maintained .

thanks for your reply

Depending on how much force you need, some other type of actuator such a ball screw might be easier to lock in a fixed position.

It is impossible to make anything foolproof...because fools are very ingenious.

Stepper motor.

high torque low speed linear stepper motors have been looked at but they would require a massive modification to incorporate a slip ring into a rotating assembly.

We would prefer a drop in hydraulic cylinder replacement if we can find one but the steppers are still on the table for consideration.

thanks for the thoughts.

:) thankyou

that is the closest product range so far to achieving what we want , a little bit more compact in length would be good but we have contacted them.

( and they didnt come up in the searches i did btw )

thankyou kindly