Front end of a diesel?

Which end is actually considered the front end of a diesel locomotive?
On a shunter, and similar one cab locos, is it nose or cab?
On loco's which are cabbed at both ends, single engined, is it the engine end?
On loco's which are cabbed at both ends, twin engined, which end would it be?

I've heard of A-end and B-end on diesel locos before, but which is which?


I've always tended to assume its the end with the fan vent on the roof, but then some locos like Deltics have fan vents at both ends. What's actually the case?

 

Not my area of expertise, but i remember that on an EE Type 4 (class 40) No.1 end was the end where the large radiator grill was just behind the cab door ? I'm sure the info for each class would be availble in a simple search.

 

On a conventional diesel loco No1 end is the cooler group end. {the end with the rad fan] HST power cars however No1 end is the driving end.
If you can get close enough to see there are normally identification marks to assist maintenance staff. On coaches No1 wheel is identified by a small arrow above it.
On twin engined locos I understand A end is more to do with the internal equipment layout. I was once told A end on a western is where the cooker is

 

In my experience (08, 37, 122 and assorted industrials), if there's a single cab "forward" is nose first, while if there are two cabs "forward" is cab you're driving from first (so there isn't a single defined front end: forward from one cab is reverse from the other).

 

For the GM diesels ie the Class 59 & 66 the number 1 end is the cab furthest from the radiators - on the 59's they have a bell at the No1 end.
UK standard definition is the number 1 cab is the one nearest to the cooler group/radiators for locos with 2 cabs.
Single cab locos the nose end is number 1
Not sure about the Class 14-17 Type 1s though.

 

Class 50s have an A end and B end. The A end is that which has the large-bladed radiator shutters (one set fixed and the other two moveable) i.e:

A end: http://englishelectric.zenfolio.com/50042/e17440658

B end: http://englishelectric.zenfolio.com/50044/e3a81cfee

Some diesel locos (e.g. a Deltic - see below) it is far more difficult to distinguish between the two ends.

Deltic: http://englishelectric.zenfolio.com/55009/e20c8a943