Landships II

The photo PDA posted of J12 Jericho in this current thread made me think: why did some tanks have regular spacing of grousers and others have groups of them, interspersed with stretches of normal track. A post by Gwyn Evans in the linked thread states that the tanks of that particular battalion had grouped grousers, so obviously at least some of the difference is explained by the practices of differing units.

So, does anyone know more about which units followed which method, if there was any variation over time that might suggest one method provided better traction than the other? Information and theories both welcomed.

For my own part, the thought occurred that the grouped arrangement may work better, using a principle similar to that employed by motorcycle manufacturers and by the late sports car firm TVR (on their AJP V8 engine) to minimise tyre slip: a principle of engine design which has been called "big-bang", because it groups combustion cycles rather than having them evenly spaced. In engines, this is done by having unusual cylinder-bank angles; the aforementioned TVR V8 used a 75 degree angle instead of the normal 90 degrees, resulting in combustion cycles alternating between 75 degrees and 105 degrees of crankshaft rotation for successive pistons instead of a regular 90 degree spacing.

The effect of this is to briefly interrupt the torque flow to the driven wheel(s), allowing them/it to regain lost traction - particularly useful on bikes. My theory is that a similar effect might take place if grousers are grouped rather than spaced evenly - that even spacing might tend to make a track gouge a hole in the ground where the group might bite into the ground suddenly after the preceding section of un-grousered track has slipped.

Discuss!