The Sherman tank was a staple of the Allied effort in WWII, with a total of about 50,000 vehicles produced, among which were a host of different variants such as the M4 Sherman 105mm Howitzer, a variant used in fire support. The M4 hull featured rolled steel plates, and it employed a 9-cylinder air-cooled radial engine in the rear which powered the front sprockets via a 5-speed transmission with reverse; the 105mm gun fired howitzer rounds, smoke rounds and incendiary ammunition. The late production vehicle had horizontal vertical spring suspension (HVSS) of which 840 units were produced. It was used for infantry support as well as taking part in assaults on enemy strongpoints from Europe to the Pacific Theater. Controlled Differential Steering System In WWII, the average tracked vehicle used a clutch brake system, whereby the sprocket on the turning side was braked to create a difference in speed between the tracks and let the vehicle turn. While it did enable pivot turns on the spot by completely stopping one track, it required considerable skill to operate, not to mention the fact that it experienced mechanical power loss and a tendency to overheat the brakes. On the other hand, the M4 Sherman used a controlled differential system that braked a sprocket wheel via a differential gear: as the turning side track slowed, the other track sped up, leading to smooth turns and in one fell swoop both minimizing mechanical loss and negating brake overheating issues. This system was also employed on the M24, the M8, and the M2 high speed tractor, vehicles which all contributed to the eventual success of the Allied WWII campaign. Mechanical Steering System A differential gear transfers power from the Type 540 motor. When the tracks rotate at the same speed the model moves in a straight line, turning as the track speeds differ. Transmitter commands cause servo movement, which in turn slows the turning side, track via one of the brake discs in the differential. A planetary gearbox in the differential unit speeds up the unbraked track. Special Features: Just like the actual tank, the model uses a controlled differential steering system. Metal components are used for drive sprockets, suspension arms and idler wheelbase. The horizontal-vertical suspension spring (HVSS) uses metal coil springs. Pre-assembled plastic tracks use metal pins and connectors. Updated gearbox recreates the Cletrac steering system just like the actual tank. When turning right and left, servo works for braking and differential gears generate rotation differences of right and left sprockets. Independence of steering and throttle handling allows the ease of operation of wheel-type transmitter. DMD CONTROL UNIT & DMD Multi-Function Unit not included or used with this product. What's In The Box: 1/16 scale R/C model assembly kit. Type 540 motor Full ball bearings ESC (electronic speed control) What you'll need: 2-channel radio Steering servo 7.2 volt battery with compatible charger. Tamiya paints