Finally after almost forty years a question has been answered!
Why are buses fitted with Voith DIWA Transmissions so fucking noisy?
Screaming and humming:
Aha! This is probably why… only encountered these as a driver a couple of times:
I prefer the Semi- Automatic Leyland Pneumocyclic or Hydracyclic family- Wilson types related to WW1 Tanks…
Or the ZF Ecolife. 
Niche
Oh dear Pt 1:
Oh dear Pt 2:
I know this route very well. Used to drive it. fucking tight especially when encountering a Tourist Coach or Delivery Lorry…
London’s Least Frequent Bus - The R5/R10
Source: YouTube
https://search.app/NqoBz
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Bloke needs to have a wash 
Reminds me I’ve still got to try the day out on Britain’s rarest bus service. The 112 from Tavistock to Dawlish and back. Miss the September one & you’ll wait 6 months for the next.
