With its low profile design, strong torque and precision movement the HS-75BB is a great choice to move your retract gear in the realistic manner that you want it to.
Specifications
Bearing Type: Ball Raced
Dimensions: 44x23x25mm
Gear Type: Nylon Gears
Speed @ 4.8v: 0.45S/60dg
Speed @ 6.0v: 0.34S/60dg
Torque @ 4.8v: 6.6Kg/Cm
Torque @ 6.0v: 8.2Kg/Cm
Weight: 35g