Traction motor sounds

[contrex]

As a small kid in the 1950s I used to hear older and newer EMU stock pass the end of our back garden, and on rail trips. I noticed that most older stock's motors sounded different from the 'newer' stock - I mean that (say) 1920s type SUBs, and the later BILs, LAVs etc had a kind of rich 'warbling' sound when starting and running, whereas most Queen Mary SUBs, EPBs, etc made more of a plain whining sound. I found it hard to put my finger on it or find an example of the difference but recently I found a video on Youtube "LT Review Vol 1" and you can clearly hear Sarah Siddons at around 13:37 making the 'older' sound.

https://www.youtube.com/watch?v=09mdVYLHgJU

For comparison here is an EPB from Cannon Street to Ladywell in 1995 (plenty of sounds here!) but typical is around 0:52.

https://www.youtube.com/watch?v=-Y8m6AyJQYI

Does anybody know what sort of things would make such a difference? Motor design? Age of motor? Reduction gearing? I remember some Queen Mary SUBs sounded 'older' and I think they had BTH motors as against the EE type fitted to the majority.

 

[JohnElliott]

Up to the late 1940s, the standard motor for suburban stock was the MV 339, or later (once English Electric had become the preferred supplier) the EE 339. After that the lighter EE 507 was used, for both suburban and mainline stock.

 

[AM9]

The difference between the older Sarah Siddons motors and the more recent EE507 types is mainly of size & speed. The typical DC motor sound is mainly the drive pinion, magnetostrictive forces of commutation and case resonance. Bearing and pinion wear determines just how loud the total noise is.
Historically, DC motors were kept in service for very long periods, just getting commutator skims, bearing changes and rewinds giving the case and shaft another life every few years. The class 442s were probably the last of the 'stretched life' resistively controlled DC motors used in the UK. Their EE546 motors (400hp versions of the EE507s) started life on the 4-REPs in the mid-'60s, were then switched to the MKIII 442 bodies and look like being finally withdrawn in the next 5 years. A working life exceeding 55 years.

 

[contrex]

Bearing and pinion wear determines just how loud the total noise is.

This is what I was thinking too...

 

[JohnElliott]

The class 442s were probably the last of the 'stretched life' resistively controlled DC motors used in the UK. Their EE546 motors (400hp versions of the EE507s) started life on the 4-REPs in the mid-'60s, were then switched to the MKIII 442 bodies and look like being finally withdrawn in the next 5 years. A working life exceeding 55 years.

There are the EE507Js in the 455s, which were rebuilt from EE507s recovered from 4-SUBs. They must be 10 or more years older than the motors in the 442s.

 

[gimmea50anyday]

Most motors on new traction these days are AC powered, even if the shore supply is DC. This makes them smaller, lighter and more powerful while needing less energy and maintenance.

The last use of DC motors as traction is the behemoths that can be found in the cl91's and the 321/456 fleets, After which AC motors were used, first application of them in the 323's and in the networker fleet.

 

[thenorthern]

AC motors on trains I would say is the biggest thing as I think all trains use AC three phase motors now regardless of if its supplied by DC or AC.

Also trains have better sound proofing to make them quieter in response to customer feedback.

You have also got to remember the sound you hear from a motor is technically energy being wasted when its converted from electrical energy into kinetic energy so as motors become more efficient the quieter they will become.

 

[ilkestonian]

If you want to hear some interesting traction motor sounds, try listening to this...

https://m.youtube.com/watch?v=3ucWrBNkJ7o

 

[100andthirty]

Often the loudest noises are the gearboxes, certainly at low speed. The gear teeth were not always designed to be quiet. Modern oil lubricated gearboxes are usually commendably quiet.

 

[gimmea50anyday]

Almost as tuneful as the formula one sounding 323's
--- old post above --- --- new post below ---

There are the EE507Js in the 455s, which were rebuilt from EE507s recovered from 4-SUBs. They must be 10 or more years older than the motors in the 442s.

Think the brake compressers may also be recovered from the SUBs which may well be even older if they were recovered from earlier SR builds as opposed to the BR builds.