View Full Version : Steam Train Wheels and Piston

06 June 2006, 06:29 PM
Does anyone know of any tutorials converned with the rigging of the wheels of a steam strain (or tutorials that might be helpful). My model is only a small tank engine with only two wheels but I feel somewhat in the dark with regards to rigging the motion - having only done a few tutorials on character rigging.

Any tips or help would be greatly appreciated.

Here's the model so far:

06 June 2006, 09:40 AM
Hi there, I hope I've understood you correctly :)

here is a quick sample of what might do, I hope you'll get the basic principle, the rest is just setting up the right constraints

06 June 2006, 01:44 PM
That really isn't the way that a train piston works. The piston is fixed along a defined path. The problem with this is that the distance the piston travels with any given rotation of the wheel is best calculated with trig. Here is an example diagram I have of that working. There are two other methods that are not accurate but easier to set up but I don't have those graphed out for you.

The advantage of the trig method that I have working in this image is that you can change the radius of the wheen or the length of the conRod and the piston automaticaly updates and works correctly.

I should also mention that I'm doing two master classes at Siggraph 2006 on vehicle rigging in 3DS Max. This might include this very example.

06 June 2006, 08:37 PM
Thanks for the replies.

I'm actually using Maya but I'll try and apply what you've given me here.

I was hoping to make my first visit to SIGGRAPH this year but alas, it fell through. Have a good one and thanks again.

11 November 2006, 06:14 PM
I'm trying to animate a steam locomotive using expressions to control the whole system. Ideally I'd like to have a set-up where everything relates back to the translation of the main body of the train (ie-moving the body moves the piston, which rotates the wheels and rod). The equation and variables from the above look good but I don't know how to translate them into maya's syntax. Can anyone help?

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11 November 2006, 06:14 PM
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