Gazebo model messed up with ros_control & JointVelocityController

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Using ros_control controller manager, I'm trying to actuate wheels of a differential drive 'car-like' robot in Gazebo. I would like to publish velocity commands on JointVelocityController (of both wheels).

MYBOT_CONTROL.yaml:

*// Publish all joint states
joint_state_controller:
  type: joint_state_controller/JointStateController
  publish_rate: 50  

// Velocity Controllers
left_wheel_velocity_controller:
  type: effort_controllers/JointVelocityController
  joint: left_wheel_joint 
  pid: {p: 100.0, i: 0.01, d: 10.0}
right_wheel_velocity_controller:
  type: effort_controllers/JointVelocityController
  joint: right_wheel_joint
  pid: {p: 100.0, i: 0.01, d: 10.0}*

In my launch file, the controller_manager is invoked :

<node name="controller_spawner" pkg="controller_manager" type="spawner" respawn="false" output="screen" args="left_wheel_velocity_controller right_wheel_velocity_controller joint_state_controller"/>

With above setup, the robot model in Gazebo is deformed. Left wheel, right wheel & caster all appear at the center of the robot base.

However, when I replace JointVelocityController with JointPositionController, the robot model appears fine.

With that background, a few questions-

• Is JointVelocityController supported by ros_control + Gazebo?
• Is it the right way to control a diff drive robot?

Thanks