3 wheeled vehicle. Wheel keeps slipping/spinning

Unity Engine
1

Hi everyone.

I’m trying to make a simulator with some forklift trucks, but I’m really struggling with getting the wheel colliders to make them behave properly.

Some of the forklifts have 3 wheels; 1 in the front which drives and steers the truck and 2 under the forks of the truck.
(the forks of the truck point backwards)

I’ve gotten the wheels to work in some situations, especially short trucks work fine driving forward, but a lot of times I notice that the wheel I’m setting the MotorTorque of (the singular one in the front) just spins a lot without moving the truck much.
I’ve noticed this the most when driving backwards or with longer model trucks.

I’ve tried many things. I’ve read the Unity3D manual on wheel colliders over and over. Tried adjusting the friction values but whatever combination of frictions I use I didn’t get the desired effect.
(I have a bit of trouble understanding the friction curves and how the Slip and Value parameters interact with each other)
I tried upping the Extremum values super high, assuming that it would make the wheel “never slip,” but instead it made the movement super jittery and makes the truck fly off some times.

I really hope someone can point me in the right direction on how I can get this to work properly.

2

Hi,

A few things you can check:

  1. Your vehicle’s scale. Wrong scale can cause WheelColliders to not work as they should i.e when applying torque. For reference, a normal car would have a wheel collider radius of about 0.3

  2. Your vehicle and wheel collider mass. Try playing around with these values. Maybe 50 on the wheel colliders and 2000 on your forklift rigidbody.