reese drum mowers and tedding

I had a look at their website ( not familiar with that mower in England) What made me smile was the way they sing the praises of their belt driven mowers,the fact that they are a lot less complicated than those horrible nasty gear driven disc mowers, a lot less to go wrong etc etc.
You then scroll down to the bottom of the page and lo and behold they market gear driven disc mowers which are uncannily like the Lely! The power requirement for them is less too. I would love to see a belt driven drum mower in action, because if the drums are belt driven the knives on adjacent drums won't overlap will they?(Overlapping blades prevent striping ) Otherwise, if the belt became slack and slipped timing the blades would collide, or is it driven by a toothed belt. on a gear drive cutterbed they are 'timed' (as in the above illustration) so this can't happen.

Thanks,
John