Maybe they “pulled” when on the level and “rowed” downhill, relying on the track-friction to act as a brake?

I can certainly see that using a combination of both methods you could get fantastic control – you could tilt the front upwards, just as you reached a small hillock, and you could steer it left and right by tilting one side but not the other, whilst pulling.

Also, when you came to a bigger hill, by tilting the front, adding a packing log, tilting the back, adding a larger packing log, then pulling, you could get up the whole hill in a series of small horizontal pulls. By the time you’d got to the top, you’d have travelled by means of a combination of 2 vectors: horizontal, entirely by bullocks pulling horizontally, and vertical, entirely by levers. Both vectors would have been achieved by the most appropriate and energy-efficient means.

I expect I mean oxen, not bullocks. But then, someone may tell me that bullocks is derived from bullox, so it might be right....