Problem with joints---ratchet mechanism not working

[AlbaDeGr8]

I'm new to fusion 360 and I have a problem with my ratchet mechanism. The ratchet wont spin when the handle is rotated counterclockwise. I don't know where the problem is, but I think that its the pawls not working properly, or I just didn't do the joint limits correctly. Please help me with this problem.

[TrippyLighting]

I've not fully analyzed the design, but I can already tell you that with the normal tools, simulating a ratchet mechanism is not possible. 

Also, you used a number of techniques I would not recommend. For example in a simple mechanical design like this I would not expect to see  a position capture or move feature.

[AlbaDeGr8]

There are "not" normal tools? I didn't know that. And regarding the position capture and move feature, can you tell me why you don't recommend them? Sorry for asking too much, I just downloaded fusion 360 about 2-3 days ago

[TrippyLighting]

Much of Fusion 360's functionality is available through an API. that is what I call "not normal" tools as it is not accessible through the usual menus. 

[jhackney1972]

When you start using Contact Sets in Fusion 360 motion, you are asking a lot.  I changed a few things and left some pins out to demonstrate.  Contact Sets are very undependable especially when you want them to work in combination with other joints.  In the attached model, right mouse click on the indicated Joint and select Animate Joint Relationships and you will see the motion.  I added a hole, indicated by the arrow, in the gear to let you follow the motion.  You will see it is not dependable.  I also tried to fix the ratio between the gear and the rack.  I changed the model units to Millimeters as I cannot think in Centimeters.  Model attached.

Edit: If you manually drag the gear component in a way to step through the ratcheting process, it works pretty good.  The driving of the lever joint leaves something to be desired due to the Contact Sets.

[jhackney1972 · Accepted solution]

I added a Motion Study and it works a lot better.  Open the Motion Study and run it one cycle at a time for best results.  If you select the Play Loop button and then run it the rack will displace.  Model is attached.

[AlbaDeGr8]

Thank you for that and sorry for the late reply. I'll check the model you attached later as I'm currently on lunch break and I still have classes (SHS student) this afternoon. I don't know what "Motion Study" is as I am still new, but since you said that it improved the mechanism, I'll have a go at figuring it out. This whole mechanism is actually for my capstone proposal, and it's for a manual ratchet-operated trash compactor, hence the rack and pinion as I'll use it for the downwards motion of the pressing plate. I don't know enough physics/mechanics, so I don't know if this mechanism is applicable to my objective, I'd like to hear your opinion.

[AlbaDeGr8]

I'll look into it later, thanks.

[jhackney1972]

I have been wondering if you have taken a look at my solution?  If my Forum post solved your question, please select the "Accept Solution" icon to do three things. First it allows others to find a solution to a similar question, two, it closes the Forum post and last, it acknowledges that you accept the solution given. If you need further help, please ask.

[AlbaDeGr8]

Sorry for not replying. Yes, I've seen your solution and how it works, I've been so busy for the past few days, I'm sorry for not replying quickly.