Wire Parameters in 3dsmax is a powerful feature that makes animating objects simple. In this step by strep 3d tutorial lets see how to use this feature to animate a simple teapot car.
The teapot car is made out of a teapot and four cylinders for tyres as shown below.
Now, when the car moves forward or backward the wheel has to rotate accordingly. Instead of animating the wheels manually we can automate it through parameter wiring. Parameter is nothing but any value that can be modified, eg: Width, height, rotation values etc.
Wiring the wheel:
Select all the wheels and click on the 'Select and link' button, now place your mouse on the wheels, the cursor changes, now click on one of the wheels and you will see four dotted lines from all the four wheels, drag and leave it on the teapot, to link the wheels to the teapot, so that the wheels move along with the teapot.
After Step 1, try moving your teapot, the wheels should also move with the teapot.
Select teapot and click on Animation in the menu bar. From the resulting pull down menu click on Wire Parameters -> Wire Parameters. or just pres Ctrl+5.
From the resulting Popup menu Select Transform -> Position -> X Position (Ref Pic). Our teapot moves forward and backward in X direction. (Z is for up and down, Y for sideways movement.)
After selecting X Position move your mouse pointer, you will see a dotted line following, then click on one of the wheels.
Clicking on the wheel will bring another popup menu, from the menu you select Transform -> Rotation -> Y Rotation. (Ref Pic)
After clicking Y Rotation on the menu you will be presented with Parameter wiring Dialog. On the dialog select Two Way Connection and click 'Connect' button. Then close the dialog.
Repeat Step 2 to Step 6 for all the other wheels. Now you move the teapot and see the wheels Rotating. If the wheel rotates too fast, in the expression editor under Expression for Y Rotation type as below
This makes 1 unit of X Position of teapot to be .5 unit for Y Rotation of the cylinder.
Here is the file for your reference.