EMU motors

[73001]

Do modern EMU motors always spin in the same direction (and use a gearbox to reverse direction) or are they reversed to go in the opposite direction.

 

[323 Class]

http://www.railway-technical.com/tr...in-equipment/electric-traction-control-d.html
A good read.

 

[73001]

http://www.railway-technical.com/tr...in-equipment/electric-traction-control-d.html
A good read.

Thanks.

 

[37057]

On 350s there's sometimes a thud when taking power after changing ends which is caused by the motors reversing and taking up the slack in the gearboxes.

By the way, these come under the asynchronous category of that site and are powered by IGBTs. Direction of travel is ultimately done by the sequencing of these IGBTs. The motor itself is mounted on the bogie frame and drives an axle-mounted double reduction gearbox with a flexible coupling.

https://live.staticflickr.com/65535/49223894596_93f2d65ed8_c.jpg

 

[156420]

Can anyone explain what a motor “paxolin” is that is found on EMU’s?

 

[323 Class]

Can anyone explain what a motor “paxolin” is that is found on EMU’s?

Paxolin is an insulator and used in electrical applications to separate circuits. I believe it has been linked with cancer and may now have been banned.

 

[furnessvale]

Paxolin is an insulator and used in electrical applications to separate circuits. I believe it has been linked with cancer and may now have been banned.

Is ANYTHING not linked with cancer these days?

 

[323 Class]

Is ANYTHING not linked with cancer these days?

Yes, I take your point.
Im sat here typing and thinking about all the nasty stuff I came into contact with as an apprentice and the fact I have 3 children with S.E.N.

 

[Nym]

Paxolin is an insulator and used in electrical applications to separate circuits. I believe it has been linked with cancer and may now have been banned.

https://www.cef.co.uk/catalogue/products/507931-1200mmx600mmx6mm-paxolin

Nope.

It's a resin impregnated paper that uses phynolic formaldehyde resin to make it into a form of board.

 

[edwin_m]

I've never heard of any electric traction motor old or new that always rotated in the same direction and needed a gearbox to reverse it. While electric trains do have gearboxes or at least gears, these are just to match the rotational speed of the motor to the required speed of the axle. In some cases the motor is mounted longitudinally and the gears also turn the drive through 90 degrees.

No doubt someone will come along with an exception, but the above certain applies to the vast majority of fleets.

 

[alangla]

I've never heard of any electric traction motor old or new that always rotated in the same direction and needed a gearbox to reverse it. While electric trains do have gearboxes or at least gears, these are just to match the rotational speed of the motor to the required speed of the axle. In some cases the motor is mounted longitudinally and the gears also turn the drive through 90 degrees.

No doubt someone will come along with an exception, but the above certain applies to the vast majority of fleets.

Have a look on YouTube for some of the videos about the design & development of the class 91. The traction motors on them are pretty much in the last place you’d expect, mainly due to a desire not to repeat the mistakes of the 86s and the way they knocked lumps out of the track.

 

[D365]

Have a look on YouTube for some of the videos about the design & development of the class 91. The traction motors on them are pretty much in the last place you’d expect, mainly due to a desire not to repeat the mistakes of the 86s and the way they knocked lumps out of the track.

I was under the impression that the main design challenge for the Class 91 was that the motors are so bloomin' large!

 

[alangla]

I was under the impression that the main design challenge for the Class 91 was that the motors are so bloomin' large!

There is that as well! When they start reaching the scrapyards, I’d love to see one side on with the body cut off so you can properly see the layout. If the NRM was to take one, sectioning it wouldn’t be the worst thing to do

 

[73001]

Thanks for all the answers, very informative reading for me.

 

[edwin_m]

Have a look on YouTube for some of the videos about the design & development of the class 91. The traction motors on them are pretty much in the last place you’d expect, mainly due to a desire not to repeat the mistakes of the 86s and the way they knocked lumps out of the track.

I was under the impression that the main design challenge for the Class 91 was that the motors are so bloomin' large!

To simplify some very long stories:

Class 81-85 had various forms of flexible drive so the motor was sitting on the sprung part of the bogie but could still mesh with the gears on the axle despite the relative movement between the two. This was eliminated on the class 86, no doubt to save money. They had nose-suspended traction motors where one end of the motor effectively rested on the axle so there was no relative movement to be taken up. That meant about half the motor mass was unsprung, imposing high transient loads on the track which led to problems such as clay pumping through the ballast. For that reason the 87s had a more flexible drive arrangement - I think a hollow motor armature with another shaft through the middle linking to the gears, with the two being connected by a bush at the non-gear end so the motor could move around on the springs and the gears would still mesh. The 86s were either rebuilt to reduce the problem or restricted to lower speeds. In all these the motor was positioned crossways so the armature was parallel to the axle.

Something similar was done for the HST but with the 91 being specified for 140mph and presumably needing bigger motors for more power a different approach was needed. I believe the APT had put the motors lengthways within the body with cardan shafts down to right-angle gears on each axle. The 91 kept the same basic arrangement but effectively hung the motors below the body so they were within the bogie frame but not attached to it. Pendolinos and Voyagers have (I think) a motor lengthways near each end of the underfloor housing, with a cardan shaft to the adjacent axle.

 

[furnessvale]

To simplify some very long stories:
This was eliminated on the class 86, no doubt to save money. They had nose-suspended traction motors where one end of the motor effectively rested on the axle so there was no relative movement to be taken up. That meant about half the motor mass was unsprung, imposing high transient loads on the track which led to problems such as clay pumping through the ballast.

As an example of how bad the original 86s were. One weekend several common crossings at Euxton Junction were replaced under possession. Because no ballast etc was disturbed, the job was handed back at full track speed. Knowing what this would mean, we already had a possession booked for the following weekend to build up the battered crossing noses with weld! (Welded up noses are harder than the original steel so fortunately we didn't have to go back every weekend.)