# Calculation: Time for a spring index plunger to release

1. Dec 4, 2013

### rustie2013

Hi,

I need to calculate the time for an index plunger to fully release. Can anyone help.

The basic setup is simple. It pretty much identical to a collapsible loft ladder. Within a sliding mechanism, we have a fixed plate and a sliding plate. A plunger is housed within the fixed plate. This plunger is compressed as it is pressed against the sliding plate. The sliding plate has a through hole in it. As this sliding plate slides across the fixed plate the through hole will at some point align with the spring plunger. At which the plunger will be free to release.

The challenge is the moving plate moves very quickly. I need to ensure that the spring plunger can release quickly enough to guarantee the plunger engages into the sliding plate. Can anybody suggest how I can calculate the time for the plunger to release.

Thanks.

2. Dec 4, 2013

### Staff: Mentor

Welcome to the PF.

Do you have any drawings and/or pictures that you can upload or link to? It's hard to understand the setup just from your word description.

We would also need to know things like weights, friction coefficients, etc., to be able to help you set up the calculations...

3. Dec 4, 2013

### rustie2013

Hi, I think for now I can keep things very simple. Friction can be ignored.

All I need to do is determine the time it would take for this index plunger to release. A sketch of the index plunger can be found here:

https://www.dropbox.com/s/vdunol8hvco3q24/Index Plunger.jpg

I need to determine the time for the plunger to travel from F2 to F1.

I know the following:

force @ F2 = 24N
force @ F1 = 9N
Distance plunger can travel Aka distance between F2 to F1 = S = 0.003m

I don't think anything else is needed? I just cannot piece it all together!