constant transmision values for Gazebo

Hi all, I have a simulated PTU which is not controlled, so that it constantly swings around in Gazebo. I don't want to spend time writing a controller for it, I would just be happy if the PTU could just stay at a fixed angles but I don't know how to do it without writing a controller. Is there a way to tell Gazebo that the PTU should always stay at a fixed set of angles? I suppose it must be something inside the transmission file, which currently contains the following: transmission_interface/SimpleTransmissionEffortJointInterfaceEffortJointInterface1transmission_interface/SimpleTransmissionEffortJointInterfaceEffortJointInterface1