The angular velocity of the joint in degrees per second.

	print(hingeJoint.velocity);

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Example() {
        print(hingeJoint.velocity);
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Example() as void:
		print(hingeJoint.velocity)