FlexibleTorqueJoint is HingeJoint:
    with FlexibleJointTrait
    actuator becomes DriveTrain.TorqueMotor:
        connectors: [drive_train.motor_shaft.input]

    drive_train becomes FlexibleJointDriveTrain:
        hinge_actuator.mate_3d: mate

    # actuator_input is Physics.Signals.Input: actuator.torque_input
