# JointSpring

> JointSpring is used add a spring force to HingeJoint and PhysicsMaterial.

## Definition

* **Type:** Struct
* **Namespace:** [UnityEngine](/engine/6000.5/script-reference/unityengine.md)
* **Assembly:** UnityEngine.PhysicsModule

```csharp
public struct JointSpring
```

## Examples

```csharp
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;
    }
}
```

## Fields

| Value                                                                                       | Description                                          |
| ------------------------------------------------------------------------------------------- | ---------------------------------------------------- |
| [damper](/engine/6000.5/script-reference/unityengine/jointspring/damper.md)                 | The damper force uses to dampen the spring.          |
| [spring](/engine/6000.5/script-reference/unityengine/jointspring/spring.md)                 | The spring forces used to reach the target position. |
| [targetPosition](/engine/6000.5/script-reference/unityengine/jointspring/targetposition.md) | The target position the joint attempts to reach.     |