JointSpring is used add a spring force to HingeJoint and PhysicMaterial.
using UnityEngine;
public class Example : MonoBehaviour { void Start() { HingeJoint hinge = GetComponent<HingeJoint>();
// Make the spring reach shoot for a 70 degree angle. // This could be used to fire off a catapult.
JointSpring spring = hinge.spring; spring.spring = 10; spring.damper = 3; spring.targetPosition = 70; hinge.spring = spring; } }
| damper | The damper force uses to dampen the spring. | 
| spring | The spring forces used to reach the target position. | 
| targetPosition | The target position the joint attempts to reach. |