Chain Drive mechanism on a cylinder with 3m stroke to lift Platform over 6 meters

[JasonM72]

Hi

this is my fist post so please be gentle. I'm currently working on design that has a mechanism that elevates a platform over 6 meters on a hydraulic cylinder (1.6m/minute up and down), which a has a stroke of 3m and is attached to a liftbeam c/w chain and sprocket(mechanism similar to forklift mechanism). Looking for conformation of formula/method to calculate size of sprocket to cover the 6.1 meter distance on the 3m cylinder stroke. The platform lift starts at the bottom of the cylinder.

Many Thanks & kind Regards

J

 

[desertfox]

Please provide sketch or drawings, it’s much easier to help if we have something to visualise

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[JasonM72]

Good Evening

As Requested, see attached, hope this makes more sense

J

 

[JasonM72]

And another

 

[3DDave]

Both pictures were the same. You cannot get more than 6m out of 3m stroke, at least not with one stage. The travel of the sprocket is equal to and added to the stroke of the cylinder.

The function of the sprocket is no different than it would be if a pulley and rope were used. There's no particular contribution of the size beyond being sturdy enough and fitting the volume available to it.

 

[desertfox]

I presume but don’t know is the sprocket just moving along a stationary chain?
Have you any better pictures which are close ups of the chain drive?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[JasonM72]

The link below is similar to mechanism that I'm working with (like a forklift Lifting mechanism). I was told by my team leader that the previous design was based was a 2:1 (speed)ratio between the linear movement of cylinder and rotation of the sprocket. The platform height is at the bottom of the cylinder (0m), when the cylinder is actuated, the cylinder will actuate the sprocket which will begin to pull the platform upwards. So, when the cylinder reaches the end of its stroke, the platform should be at the same height as the extended position of the cylinder (6m total travel for the platform). This was how the theory of this mechanism was sold to me. So I was told that I just need to find a sprocket that will give me this ratio, but 've been scratching my head on this and cant work out the method.

https://www.youtube.com/watch?v=grMBzq0YHH0

Regards

Jason

 

[3DDave]

The algebra is simple. It will turn out the radius of the sprocket cancels out. Also, a linear motion cannot have a unitless ratio with an angular motion. This will also be seen when doing the algebra.

Hint: the length of chain in contact with the sprocket doesn't change.

 

[JasonM72]

Great thanks Dave, can you confirm the formula/method to work this out please?

 

[desertfox]

Hi

This website might help

https://www.real-world-physics-problems.com/rolling-without-slipping.html

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[3DDave]

Sure - show me your work.

 

[desertfox]

Hi

This site might explain it better but scroll down till you see the diagram with the label "rolling without slipping"

https://physics.info/rolling/

Also you will see why 3DDave made the point about the radius cancelling out

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein