Pawl driving ratchet

iain_downs

Hi, all.

I'm trying to model a scenario where a pawl drives a ratchet.

 
as you move the left hand of the lever up and down the pawl pushes the ratchet along one 'tick'.  (you need to imagine a spring holding the pawl to the ratchet and the various axles, of course).

I've seen the posts where the ratchet drives the pawl so it moves in and out, but that's not what I want.  I think I understand how that's meant to work, though I've not managed to replicate it yet.  However, I don't see that it's exactly what I would need to do here.

Any advice (or examples) would be appreciated.

Iain

iain_downs

As an extension to this question is there any way to model a transient connection.  The Pawl here is a good example of that, but there could be others such as a pin in a wheel which tips a lever once per rotation.

Iain

iain_downs

Any thoughts on this - I expect people have been busy over Xmas ...


Iain

MichaelPascoe

What is your end goal? A nice animation, or are you simply after the actual mechanism that will work in the real world?

Onshape animations are limited and require continuous mate connection, so we will have to use work-arounds to get it animated, but it is possible. As far as a working mechanism, that can be simulated in other easier ways.

iain_downs

Thanks Michael.  It's for a working mechanism.  Specifically some clockwork.  There will be a number of pawls involved.  If onshape can't do it at the moment, I get that, but I don't even know where to start with 'other ways'

Iain

MichaelPascoe

@iain_downs in that case, here are two ways I can imagine doing this. Both ways do not involve animations but they do simulate movement of the mechanism to get it working properly. Either way, this course will help you out: Onshape Configurations

1)
- Create several sketches within a part studio to calculate the movement with sketch constraints.
- Optionally use configurations to see the different positions and clearances.

2)
- Place your main parts and in an assembly.
- Create configurations of the important positions.
- Modify the parts using in-context edits with the configurations you need. This will help you modify the parts based on the position of all of the other parts.

iain_downs

That will need a bit of digesting, Michael, but I will work through it!  I have used configurations in a basic way, so I have a little bit of a head start.

Thanks


Iain