Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Cylinder Delaying

Cylinder Delaying

Cylinder Delaying

Hello there!

I'm having a problem with two cylinders that are connected to the same valve. Throught the time, one cylinder starts to delay it course, and as they are attached to the same structure, this structure starts to break, causing problems to our process.
My question is: can I detect this delay in a hydraulic way (such as using a manometer), or trough an electrical sensor (such as an linear transducer attached to the cylinder)?



RE: Cylinder Delaying

Yes, you could use two transducers and two control valves to synchronize the cylinders.
It is also possible, simpler, and usually cheaper, to link the cylinders with a sturdy mechanism.

Mike Halloran
Pembroke Pines, FL, USA

RE: Cylinder Delaying

How could the transducer be installed to the cylinder?
The mechanism that you've said is using a metal bar that will connect the two cylinders toguether?
I was thinking in something like the picture attached. A linear transducer connected to cylinder's rod and to the body. This way, as the cylinder extend it's rod, the linear transducer will do it too.
Of course that this is just a concept, it will have to be worked.

RE: Cylinder Delaying

Is it possible to use one larger cylinder?

Aidan McAllister
Metallurgical Engineer

RE: Cylinder Delaying

Are the loads on each cylinder close to equal throughout their strokes? I assume they are, or the design you show would not work at all. The simplest and most common solution is to place speed control valves on each cylinder and adjust them so the cylinders move at the same speed. I am very surprised that your system does not already have this.

RE: Cylinder Delaying

Some cylinder manufacturers offer transducers built into the cylinder, e.g. a magnetostrictive linear sensor extending from the cap end into the hollow center of the rod, or some such. Optional, but usually cheaper and more damage resistant than hanging something alongside the cylinder.

OR, use a linkage, topographically similar to an anti-roll bar on a car, but with a _very_ stiff bar or tube transmitting torsion from one cylinder to the other.

Mike Halloran
Pembroke Pines, FL, USA

RE: Cylinder Delaying

Slave one cylinder to the other. Since there's nothing to go on here it isn't clear how closely the cylinders have to track each other. There are a lot of options that can only be eliminated with detail plans of the installation in order to leave the usable ones.

RE: Cylinder Delaying

Thanks for all replys!

This is the system that I'm talking about. As you can see there are two cylinders that are connected by the transversal red bar.

That problem is when one of them extend faster than the other one. With that, the transversal bar wear up, until it crack or break.
Also with the image you can see that the cylinder do not accept the magnetostrictive linear sensor.

That picture helped?

Some more pictures.

RE: Cylinder Delaying

Have you tried bleeding the air from the cylinders?

Mike Halloran
Pembroke Pines, FL, USA

RE: Cylinder Delaying

What I want to do is something that will notice that the two cylinders are not working in synchronism, is not that they are not working now, is that when one of them don't work properly, it will cause damage to the structure, leading to a wear of the transversal bar, and I want to avoid this.

Researching I notice that there's no flux divider after the valve, so what I want is to install one to certify that the flux is equal to either cylinders.

But when it has an internal leakage caused by wear of the seal, they will still extend at different speed. For that what I want is to install two flux meters right after the tank connection. Thereby I can measure if there's an increase on the fluid returned to the reservoir. And I can electrically stop my machine preventively (like the image below).

RE: Cylinder Delaying

Flow dividers can make things worse. You need to add a connection to allow the cylinders to equalize the cylinders or the flow divider error can accumulate. Right now the pressures are equal so the forces are nearly equal (based on cylinder area)

The differential movement can only due to differential external loads which are resisted by twisting of the cross bar, which looks substantial. Differential movement of the rods will be a symptom of external loads. Note that side loading on the rods is considered external to the pressure inside the cylinders.

The biggest concern I see is that the mechanism is too constrained, so if the rods aren't exactly parallel there is nothing that allows the cylinders to conform and this will apply a side load to the rods. This side load can bind and produce differential movement. I assume the machine is very well aligned, just a suggestion to others building similar devices.

RE: Cylinder Delaying

Ok 3DDave, indeed this is very important, and yesterday the machine was stopped for it monthly preventive maintanace. And one thing that I told then to check is just the alignment of the cylinders. Thanks for the feedback.

But when one of them have an internal leakege, that's when we have the cross bar twisted.
And when this happen, we have a big loss of production.
Isn't there any way to detect that they are moving in different speed?

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


White Paper - PLM and ERP: Their Respective Roles in Modern Manufacturing
Leading manufacturers are aligning their people, processes, and tools from initial product ideation through to field service. They do so by providing access to product and enterprise data in the context of each person’s domain expertise. However, it can be complicated and costly to unite engineering with the factory and supply chain. Download Now
White Paper - Medical Device Design Control
Medical device product development is a highly integrated and regulated process. Implementation of a requirements tracking solution requires attention to a variety of nuanced topics. When presented with the task of tracking the many concept relationships in a project of this type, the initial software solution of choice tends to be a two-dimensional text systems. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close