<mujoco model="spring">
    <compiler coordinate="local" angle="radian"/>
    <option gravity="0 0 -9.8"/>
    <size njmax="795" nconmax="250" nstack="631875" />
 	
 	<worldbody>
 		<geom name="ground" type="plane" pos="0 0 -0.925" size="4 4 .05" rgba="0.7 0.6 0.5 1"/>
 		<body name="bot" pos="0.0 0.0 0">
            <geom name="bot" rgba="0.2 0.2 0.2 1" type="box" size="0.2 0.5 0.02" contype="1" conaffinity="1" />
        	<body name="rod" pos="0.0 0.0 0.22">
                <!-- for cylinder it seems to take radius and full randius -->
        		<geom name="rod" rgba="1.0 0.0 0.0 1" type="cylinder" size="0.05 0.2" contype="1" conaffinity="1" />	
        		<body name="top" pos="0.0 0.0 0.22">
        			<geom name="top" rgba="0.2 0.2 0.2 1" type="box" size="0.2 0.5 0.02" contype="1" conaffinity="1" group="0"/>
                    <joint name="axle" type="slide" pos="0 0 0.42" axis="0 0 1" range="0.0 1.0"/>
                </body>

        	</body>
        </body>

        <body name="box" pos="0.0 0.1 2.0">
            <geom name="box" rgba="0.2 1.0 0.2 1" type="box" size="0.1 0.1 0.02" contype="1" conaffinity="1" />
            <inertial pos="0 0 0" mass="10000" diaginertia="166.667 166.667 166.667"/>
            <joint name="box" type="free" limited="false"/>
        </body>
    </worldbody>
 </mujoco>