Releasing winch system without shifters

[Yerdan]

Hi guys,are there any ways of releasing winch system without using shifters(any optional systems)?

[Mike Schreiber]

If you want a fixed shot it's very easy to use a cam to wind and release. The easiest example I can think of is 217 and 148 in 2010. I'll look for links in a bit.

[Yerdan]

I would be really grateful if you could give me a little information about cam release mechanism.

[androb4]

He's referring to the cam they used to power their kicker.

I've heard it called a da vici cam.. Like this.

http://img.rlt.com/x/12131.jpg

[jijiglobe]

Our team has talked about using a gear with some missing teeth which would be on a ratchet so that it can wind up and when its ready to shoot we can rotate the gear to the part with missing teeth and it'll slip. We haven't prototyped it yet though...

[roystur44]

Yerdan,

Take a look at a ratchet and pawl. Mcmaster Carr sells them

http://www.mcmaster.com/#gear-ratchets/=q8grgr

[discobrisco]

I believe team JVN used a non shifting system which was powered by a bag motor, it had a double jointed arm on a gear which would release by simply turning it past it's point of being fully loaded. It didn't even have a gearbox, and seemed like a very good setup to me. The have their schematics on their website, much easier to see how it works using that.

[Ether]

Originally Posted by androb4

He's referring to the cam they used to power their kicker.

I've heard it called a da vici cam.. Like this.

http://img.rlt.com/x/12131.jpg

One nice feature of a cam is that, with a little math, you can derive the equation for the spiral so that the torque required to drive it remains constant as it is pulling back the arm. Then you can use that equation to cut out the cam.

[Ether]

Originally Posted by discobrisco

It didn't even have a gearbox,

Yes it had a gearbox. A BAG motor would fry trying to do that without one. 100:1 speed reduction gearbox followed by 84:18 speed reduction external gearing.

[androb4]

Originally Posted by Ether

One nice feature of a cam is that, with a little math, you can derive the equation for the spiral so that the torque required to drive it remains constant as it is pulling back the arm. Then you can use that equation to cut out the cam.

That's sweet!

I've made this (https://www.dropbox.com/s/vmkm7jq1km...%2012%20AM.png) the other day using Inventor's Create Spiral tool. What do you think?

[TD78]

Originally Posted by discobrisco

I believe team JVN used a non shifting system which was powered by a bag motor, it had a double jointed arm on a gear which would release by simply turning it past it's point of being fully loaded. It didn't even have a gearbox, and seemed like a very good setup to me. The have their schematics on their website, much easier to see how it works using that.

Would you be able to post a web link to this schematic? I have not been able to find one so far.

[androb4]

Originally Posted by TD78

Would you be able to post a web link to this schematic? I have not been able to find one so far.

Here's the CAD for Team JVN's robot.
http://www.buildblitz.com/final-cad-files/

[TD78]

Originally Posted by androb4

Here's the CAD for Team JVN's robot.
http://www.buildblitz.com/final-cad-files/

Ahh...yes I have the CAD. When you said schematic, I took it literally to mean you were suggesting there was a dimensioned drawing on their website of this subsystem.

[androb4]

Originally Posted by TD78

Ahh...yes I have the CAD. When you said schematic, I took it literally to mean you were suggesting there was a dimensioned drawing on their website of this subsystem.

Well, discobrisco said schematic..

No they have not released a schematic with dimensions.

Have you checked out that mechanism? It's pretty cool, I was pretty impressed by that. It pretty much winds up the 2 linkages then it winds up the first linkage using an obstruction on the gear, then it releases both linkages once the second linkage passes over the obstruction, freewheeling the gear 180 degrees to allow the extension on both linkages. Kinda hard to visualize but you'll get it if you mess around with the CAD.

[Jon Stratis]

Originally Posted by jijiglobe

Our team has talked about using a gear with some missing teeth which would be on a ratchet so that it can wind up and when its ready to shoot we can rotate the gear to the part with missing teeth and it'll slip. We haven't prototyped it yet though...

I'm intrigued by this idea... I hope I see it somewhere to know if it works!