spool ratio

Forum: Motion Control Motion System Design
1

I would like to ask for some advice regarding if and when getting a ratioed spool is needed.

We plan to use the Bosch Rexroth 4WRLE 25 valve (as we have these on the shelf) with a 150id cylinder and 100od rod. Would it be essential to get the valve adapted with the equivalent spool ratio?
This machine will only operate for a few weeks so it would be nice to keep the valves generic for future projects.

The rig is with the rod pointing up lifting a load.

What would the effect of having a 1:1 ratio spool give me vs a ratio spool on the control and motion?

Thanks in advance for everyones input.

Pete.

2

I would use 1:1 valve you have on the shelf for two reasons.
The rod is pointing up.
the system is moving slow.

The main advantage of using a 2:1 valve is that cavitation can be avoided but that only happens when the rod is facing down or a horizontal load with a heavy mass needs to decelerate quickly.
Your applications meets none of these conditions

3

Thank you Peter for your quick response,

Much appreciated
Pete Britten