How to distinguish between different "Peak" class 44/45/46 locomotives

[DB]

They did. Their electrical equipment was used by Brush to build D1500-D1519, which is why this batch were different to the rest. The ETH was tapped from the generator rather than an alternator, and the braking system was also different.

Not quite correct - they had an ETS generator in addition to the main traction generator. Later ETS 47s had a similar setup of separate machines for traction power and ETS, but in this case the ETS one was an alternator.

This setup of two separate machines was the norm, with alternators succeeding generators for both over time (last as-built BR loco to use generators was the Class 50). Very recent locos use a DC-link setup with just one alternator and the output from that split to provide traction power and ETS - Class 68 and the Brush-rebuilt 73s have this arrangement.

The only BR-era class I know of where the ETS power was taken off the traction generators was the Class 55, where there wasn't room for additional electrical machines. This led to issues with some stock as the ETS output fluctuated considerably depending on traction power demand. More sophisticated modern locos such as the Class 68 have control systems which avoid issues like this.

 

[MrEd]

They did. Their electrical equipment was used by Brush to build D1500-D1519, which is why this batch were different to the rest. The ETH was tapped from the generator rather than an alternator, and the braking system was also different.

That’s right. I seem to recall that the first 20 Class 47s, unlike the Peaks and unlike the rest of the Class 47 fleet, were fitted with Westinghouse brakes rather than Davies and Metcalfe. Why was this I wonder?

Did Brush have some Westinghouse equipment spare from the 31s (which use this braking system) which they had just finished constructing?

 

[D1537]

Not quite correct - they had an ETS generator in addition to the main traction generator. Later ETS 47s had a similar setup of separate machines for traction power and ETS, but in this case the ETS one was an alternator.

Quite right - I meant to say "a generator" rather than "the generator".

That’s right. I seem to recall that the first 20 Class 47s, unlike the Peaks and unlike the rest of the Class 47 fleet, were fitted with Westinghouse brakes rather than Davies and Metcalfe. Why was this I wonder?

Did Brush have some Westinghouse equipment spare from the 31s (which use this braking system) which they had just finished constructing?

Good question. The 46s were D&M so it wasn't for that reason, and all the other 47s were too. Given that there was barely a month between the delivery of D1519 and D1520, it does suggest that they did have some spare equipment knocking about.

 

[Cowley]

They did. Their electrical equipment was used by Brush to build D1500-D1519, which is why this batch were different to the rest. The ETH was tapped from the generator rather than an alternator, and the braking system was also different.

I seem to remember that the reason they made a bit of a roaring/hoover type sound at times was because they had a different cooling system too (maybe different radiator fans and vents in the cooler group or something similar)?

 

[Richard Scott]

I seem to remember that the reason they made a bit of a roaring/hoover type sound at times was because they had a different cooling system too (maybe different radiator fans and vents in the cooler group or something similar)?

They had electric fans like 45s and 50s as opposed to hydrostatic fans in 46s and rest of the 47 fleet.

 

[Cowley]

They had electric fans like 45s and 50s as opposed to hydrostatic fans in 46s and rest of the 47 fleet.

That’ll be it then. Thanks.

 

[Helvellyn]

Never realised the Generators had so many differences. Surprised they weren't classed as their own sub-class at the very least given the Class 48 designation was used for the five machines that had a different power plant!

 

[xotGD]

Never realised the Generators had so many differences. Surprised they weren't classed as their own sub-class at the very least given the Class 48 designation was used for the five machines that had a different power plant!

Class 46/1?