'Thumper' DEMUs are pretty basic; they have 110v starting batteries and separate lighting batteries,Given that the majority of DEMUs don't use the same alternators for traction as they do for auxiliaries anyway, all it is is a different means of power transmission, I don't see how that defines DEMUs as a different super-set to DMUs at all.
If the same alternators where to provide traction and auxiliaries, from my experience of the marine world that would be a different traction type. Where the traction type would be known as IEP, FEP or IFEP (Intergrated Electric Propultion) as apposed to the older systems with shaft, hydraulic, hybrid or electric propulsion systems.
I would agree that as long as the prime mover in a multiple unit is a diesel engine, then it can be called a DMU. Thus any DMU with a mechanical, hydraulic or electric transmission can reasonably be called a DMU. Operationally, as I suggested in post #9, there would be a significant difference between a DMU with an electric transmission and the other two types of transmission, - the torque/speed characteristics would necessitate different driver training, and the inclusion of a large generator, motors and electric traction control gear would require a very different maintenance operation. Thus from an operator's point of view, classifying the DEMUs separately from all other DMUs would be a logical thing to do, which may be why BR did just that from their introduction.Yes, that is indeed the unknown context of the now 1st post.
I was challenging someone's opinion that DEMUs are not DMUs.
This thread was created after another thread went-off topic; yes someone tried to claim that a DEMU was not a DMU, whereas all sources I can find indicate that there are different categories of DMU depending on the transmission type (i.e. hydraulic, mechanical and electric).