Class 91....

[Johnny_w]

I caught this last year at Peterborough,

was a bit surprised too see what looks like a prop shaft?

http://flic.kr/p/dUropj

anyone shed any light as I'd assume AC Locomotives would be thyristor controlled Traction motors.

Thanks,

JW

 

[Wikipedia]

IIRC the traction motors aren't axle hung so as to reduce the unsprung mass. They instead are mounted on the bogie frame so need prop shafts to connect to the axles.

I am happy to be corrected on any of the above!!

 

[starrymarkb]

IIRC TGVs have the same set-up. Pendolinos and Voyager motors are mounted in the body with a propshaft driving the inner axle on each bogie

 

[ainsworth74]

Isn't the technical term a cardan shaft rather than prop shaft? But either way the reason they have them is that the motors are mounted on the body rather than the axle hence they have to get the power to the gearbox/wheels somehow

 

[Johnny_w]

Isn't the technical term a cardan shaft rather than prop shaft? But either way the reason they have them is that the motors are mounted on the body rather than the axle hence they have to get the power to the gearbox/wheels somehow

Every day is a school day! Thanks guys, was surprised too see it.

JW

 

[Nym]

Most DC motored stock and stuff with either complex bogies, or high power output moved away from nose mounted or bogie mounted motors a while back.

2009 and S Stock have bogie mounted motors, but they're tiny in comparison to those on 1972TS and C Stock, and more powerful, and more reliable.

But they only go 50 or 60mph respectively, (while 72TS and C Stock won't realistically get over 40mph)

 

[DownSouth]

Isn't the technical term a cardan shaft rather than prop shaft?

Correct, the difference is that a Cardan* shaft has a u-joint on one or both ends while a propellor** shaft has one in the middle.

The proper technical term is simply driveshaft though, for the sake of clear professional communication any engineer worthy of the name would refer to driveshaft and specify where any u-joints are present.


* so named after Jerome Cardan, the first man to put a u-joint on the end of a driveshaft.
** so named for the original use in marine propulsion, where in some circumstances it has been advantageous to have the propellors angled down from the level machinery further inside.

 

[Johnny_w]

Minefield of information - Thanks guys!

 

[DXMachina]

(while 72TS and C Stock won't realistically get over 40mph)

Except C's when used to Amersham in the 1970s allegedly. Weak field still worked back then. According to drivers, 80+ on occasions to keep to the 75mph A-stock timetable despite slower acceleration, and at least one claim of an indicated 100

 

[yorkie]

This video from the documentary Running to Time will no doubt be of interest (also see Class 91 traction motor query)

Running to time (part 2 of 4)

[youtube]uwm4P-wKqgQ[/youtube]

"[Class 91]'s traction motors are suspended under the body, but within the bogie frame.

A short cardan - or drive - shaft runs into a transfer gearbox, again mounted on the bogie.

Two bevel gears take the power through a right angle.

A hollow quill shaft connects the gearbox to the wheelset with flexible rubber mountings.

The axel of the wheelset runs right through the hollow gearbox and quill shaft.

At the end of each motor is a disc brake. In this way, only the wheelset remains unsprung mass.

[Class 91] has 2 bogies with a traction motor for each of the 4 wheelsets...."

 

[zn1]

class 91 is basically the upgraded APT motor coach, without tilt package, hydro brakes and with the cabs fitted isnt it ??

 

[455driver]

Basically yes.

 

[zn1]

thanks 455, if only the punters realised they were using technically an APT, the 225 is a brilliant bit of fleet, and they still have the ability to push u in ya seat when they do put the power down...who cannot love em

 

[ainsworth74]

Why would the average passenger care that the locomotive propelling/hauling them came from a failed train design? Indeed I don't think most passengers care at all what their train is along as it turns up, runs on time and they get a seat!

 

[captainbigun]

class 91 is basically the upgraded APT motor coach, without tilt package, hydro brakes and with the cabs fitted isnt it ??

Mmm, not really. 91 was GEC design. APT was not, electrical equipment was from ABB.

Whilst there are some design similarities, they are just that.