# B2.RevoluteJoint

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Supported platforms:
Available since: Gideros 2011.6
Inherits from: b2.Joint

### Description

A revolute joint constrains two bodies to share a common point while they are free to rotate about the point. The relative rotation about the shared point is the joint angle. You can limit the relative rotation with a joint limit that specifies a lower and upper angle. You can use a motor to drive the relative rotation about the shared point. A maximum motor torque is provided so that infinite forces are not generated.

### Examples

Revolute joint

```--create empty box2d body for joint
local ground = world:createBody({})
ground:setPosition(300, 480)

local jointDef = b2.createRevoluteJointDef(body, ground, 300, 300)
local revoluteJoint = world:createJoint(jointDef)
--will not let ball spin for ever
revoluteJoint:setMaxMotorTorque(1)
revoluteJoint:enableMotor(true)
```

### Methods

b2.RevoluteJoint:enableLimit enables or disables the joint limit
b2.RevoluteJoint:enableMotor enables or disables the joint motor
b2.RevoluteJoint:getJointAngle returns the current joint angle in radians
b2.RevoluteJoint:getJointSpeed returns the current joint angle speed in radians per second
b2.RevoluteJoint:getLimits returns the lower and upper joint limit in radians
b2.RevoluteJoint:getMotorSpeed returns the motor speed in radians per second
b2.RevoluteJoint:getMotorTorque returns the current motor torque given the inverse time step
b2.RevoluteJoint:isLimitEnabled is the joint limit enabled?
b2.RevoluteJoint:isMotorEnabled is the joint motor enabled?
b2.RevoluteJoint:setLimits sets the joint limits in radians
b2.RevoluteJoint:setMaxMotorTorque sets the maximum motor torque in N*m
b2.RevoluteJoint:setMotorSpeed sets the motor speed in radians per second