Most WWII tanks used braked or controlled differential steering systems that could not neutral turn.
The Tiger was the first production tank with the Maybach double differential steering system, allowing it to neutral turn. It was designed by Henschel based on the Merritt-Brown gearbox used on the Churchill tank.
http://www.youtube.com/watch?v=FWSYa7b3Vjo"STEERING UNIT
Steering is effected by imposing different speeds on to the sun wheel of an epicyclic, whose annulus is positively driven by a bevel meshing with the main gearbox output bevel, and whose planet carrier carries the output flange to the final drive. There is one of these epicyclics at each end of the bevel shaft meshing with the gearbox output bevel.
The direction and speed rotation of the sun wheel and the choice of left or right hand sides are governed by the engagement of two or four hydraulically operated multi-disc clutches. These clutches connect the sun wheels through a lay shaft meshing with the small bevel on the extension of the gearbox input shaft. In this way a choice of two speeds both proportional to engine speed, is imposed at will upon the sun wheel of the epicyclic whose annulus is already rotating at a multiple of engine speed according to the gear engaged. In addition, in neutral with no output from the main gearbox bevel, a drive is still obtained from the bevel on the extension of the gearbox input shaft, and this produces with the engagement of the appropriate steering clutch opposing rotations of left and right sun wheels. As the annuli are unable to rotate in opposite directions owing to their being secured to the same shaft this opposite rotation of the sun wheel, of necessity, produces opposite rotation of the output flanges, resulting in a neutral turn. For one full revolution of both output flanges the gearbox input flange performs 117 revs.
Oil pressure from a pump driven by an extension of the fore and aft gearbox shaft is admitted to the required steering clutches through ports in the steering assembly casing, the opening of which is controlled by a piston valve. Movement of piston valve is governed by the driver's steering wheel. In this way two distinct radii of turn are available for each gear engaged, and identical for left and right turns. A mushroom shaped knob on the gearbox casing operates hydraulically a brake on one section of the main shaft, thereby eliminating clutch drag and making the neutral turn more positive.
The tank can also be steered when required by steering levers on each side of the driver which operate the right and left brake assemblies."
