This version of Unity is unsupported.
Removed

Component.hingeJoint

Obsolete Property hingeJoint has been deprecated. Use GetComponent<HingeJoint>() instead. public Component hingeJoint;

Description

The HingeJoint attached to this GameObject. (Null if there is none attached).

using UnityEngine;

public class Example : MonoBehaviour { void Start() { print(GetComponent<HingeJoint>().motor.targetVelocity); } }