Gazebo 4 Wheeled Robot does not move - ros

Question

I made a URDF-File for a 4-wheeled Robot. I would like to test it in Gazebo. I have it working so far. I have 4 wheels, they also turn. I confirmed this by turning on View -> Wireframe. I am using the skid_steer_drive_controller and rosrun teleop_twist_keyboard teleop_twist_keyboard.py. I can see the wheels turning but the Robot does not move.
I am using an offset for my base_footprint, otherwise my robot collapses and starts jiggeling. I also took this offset in the z-Axis in account for the wheels.
I took this urdf as basis, here so i did not declare friction:
This is my URDF:
<?xml version="1.0" ?>
<robot name="explorer">
<link name="world">
</link>
<!-- -->
<link name="base_footprint">
<visual>
<origin xyz="0 0 0.046"/>
<geometry>
<box size="0.235 0.094 0.049"/>
</geometry>
<material name="gray">
<color rgba=".2 .2 .2 1" />
</material>
</visual>
<inertial>
<origin xyz="0 0 0.046"/>
<mass value="0.6174" />
<inertia ixx="2.84523645e-3" ixy="0.0" ixz="0" iyy="3.1763172e-3" iyz="0" izz="5.7814365e-4" />
</inertial>
<collision>
<origin xyz="0 0 0.046"/>
<geometry>
<box size="0.235 0.094 0.049"/>
</geometry>
</collision>
</link>
<joint name="dummy_joint" type="fixed">
<parent link="world"/>
<child link="base_footprint"/>
</joint>
<!-- -->
<link name="wheel_rf">
<inertial>
<mass value="0.036" />
<inertia ixx="9.2562e-5" ixy="0.0" ixz="0" iyy="9.2562e-5" iyz="0" izz="2.9124e-5" />
</inertial>
<visual>
<geometry>
<cylinder radius="0.033" length="0.026"/>
</geometry>
<material name="white">
<color rgba="1 1 1 1"/>
</material>
</visual>
<collision>
<geometry>
<cylinder radius="0.033" length="0.026"/>
</geometry>
</collision>
</link>
<joint name="wheel_rf_joint" type="continuous">
<origin xyz="0.04 0.063 0.033" rpy="1.57 0.0 0.0"/>
<parent link="base_footprint"/>
<child link="wheel_rf"/>
<axis xyz="0.0 0.0 1.0"/>
</joint>
<link name="wheel_lf">
<inertial>
<mass value="0.036" />
<inertia ixx="9.2562e-5" ixy="0.0" ixz="0" iyy="9.2562e-5" iyz="0" izz="2.9124e-5" />
</inertial>
<visual>
<geometry>
<cylinder radius="0.033" length="0.026"/>
</geometry>
<material name="white">
<color rgba="1 1 1 1"/>
</material>
</visual>
<collision>
<geometry>
<cylinder radius="0.033" length="0.026"/>
</geometry>
</collision>
</link>
<joint name="wheel_lf_joint" type="continuous">
<origin xyz="0.04 -0.063 0.033" rpy="1.57 0.0 0.0"/>
<parent link="base_footprint"/>
<child link="wheel_lf"/>
<axis xyz="0.0 0.0 1.0"/>
</joint>
<!-- -->
<link name="wheel_rb">
<inertial>
<mass value="0.036" />
<inertia ixx="9.2562e-5" ixy="0.0" ixz="0" iyy="9.2562e-5" iyz="0" izz="2.9124e-5" />
</inertial>
<visual>
<geometry>
<cylinder radius="0.033" length="0.026"/>
</geometry>
<material name="white">
<color rgba="1 1 1 1"/>
</material>
</visual>
<collision>
<geometry>
<cylinder radius="0.033" length="0.026"/>
</geometry>
</collision>
</link>
<joint name="wheel_rb_joint" type="continuous">
<origin xyz="-0.04 0.063 0.033" rpy="1.57 0.0 0.0"/>
<parent link="base_footprint"/>
<child link="wheel_rb"/>
<axis xyz="0.0 0.0 1.0"/>
</joint>
<!-- -->
<link name="wheel_lb">
<inertial>
<mass value="0.036" />
<inertia ixx="9.2562e-5" ixy="0.0" ixz="0" iyy="9.2562e-5" iyz="0" izz="2.9124e-5" />
</inertial>
<visual>
<geometry>
<cylinder radius="0.033" length="0.026"/>
</geometry>
<material name="white">
<color rgba="1 1 1 1"/>
</material>
</visual>
<collision>
<geometry>
<cylinder radius="0.033" length="0.026"/>
</geometry>
</collision>
</link>
<joint name="wheel_lb_joint" type="continuous">
<origin xyz="-0.04 -0.063 0.033" rpy="1.57 0.0 0.0"/>
<parent link="base_footprint"/>
<child link="wheel_lb"/>
<axis xyz="0.0 0.0 1.0"/>
</joint>
<!-- Gazebo colors to links as upper defined colors are only visible in RVIZ-->
<gazebo reference="base_footprint">
<material>Gazebo/Black</material>
</gazebo>
<gazebo reference="wheel_rf">
<material>Gazebo/Orange</material>
</gazebo>
<gazebo reference="wheel_lf">
<material>Gazebo/Orange</material>
</gazebo>
<gazebo reference="wheel_rb">
<material>Gazebo/Orange</material>
</gazebo>
<gazebo reference="wheel_lb">
<material>Gazebo/Orange</material>
</gazebo>
<!-- DIFFENERNTIAL DRIVEEEEEEEEEEEEE -->
<gazebo>
<plugin name="skid_steer_drive_controller" filename="libgazebo_ros_skid_steer_drive.so">
<updateRate>100.0</updateRate>
<robotNamespace>/</robotNamespace>
<leftFrontJoint>wheel_lf_joint</leftFrontJoint>
<rightFrontJoint>wheel_rf_joint</rightFrontJoint>
<leftRearJoint>wheel_lb_joint</leftRearJoint>
<rightRearJoint>wheel_rb_joint</rightRearJoint>
<wheelSeparation>0.08</wheelSeparation>
<wheelDiameter>0.066</wheelDiameter>
<robotBaseFrame>base_footprint</robotBaseFrame>
<torque>20</torque>
<topicName>cmd_vel</topicName>
<broadcastTF>false</broadcastTF>
</plugin>
</gazebo>
</robot>