Full speed one direction, slow the other.

[de_]

We currently have a double ended capable but currently single end powered cylinder that we want to be fast going one direction and slow going the other. Its at the end of our tower so we tried to only use one end (ie one tube for weight and reduced entanglement risks).

We've tried an adjustable flow limiter first on the powered end then on the open end but I am told either slowed the fast direction down too much.

I was wondering if there is such a thing and if it was legal to have a check valve and an adjustable flow limiter in parallel on the unpowered end of the cylinder. In the fast direction, the check valve is open (and the flow limiter has flow). In the slow direction, the check valve is closed and the flow limiter completely controls the rate. Check valves are not normally legal except in this case that circuit is never pressurized by the compressor.

Any other suggestions ?

[Mr V]

There are 3 types of flow metering fittings available. Intake, exhaust, and bi-directional. The first 2 incorporate check valves that allow full flow in one direction and adjustable flow in the other. Using the exhaust valves on the opposite end allows the cylinder to act as a air cushion both slowing the movement and preventing it from slamming at the end of travel. The ones we have are stamped with flow arrows with a large arrow showing which direction the flow is unmetered and a small arrow showing which direction the flow is metered.

[de_]

Thanks, off to my pneumatics supplier!

[de_]

Ouch, we actually already owned the exact item. Didn't know it was full flow in, regulated out. Thought it was regulated both directions. In retrospec we put it on the wrong end of the cylinder no wonder we got bad results.

Lesson: keep the pneumatic stuff away from the electrical guy.