Gearbox lights on a 142 -

[Egg Centric]

I was on a 142 at a heritage railway today and gawping through the window in the door* to watch the driver. On a relatively sharp curve (15mph limit apparently for the curve only) the train (not local) gearbox light kept flickering on. I made a mental note to ask the driver about this. Then forgot about it.

Is this an actual sign of a fault, or is it something that 142s used to do "normally" on sharp curves? And if so why?


*Are there any remaining stock on "real" railways (i.e not light rail so not 139s, DLR, trams...) in the UK that you can do this with?

 

[Lurcheroo]

On other BREL Era stock such as 158’s it will illuminate under wheelslip. To the best of my knowledge, The Wheel slip protection (WSP) rack detects a difference in speed between wheel sets and illuminates the light.
With non-turning bogeys I wouldn’t be surprised if there becomes a difference in wheel rotation speeds and that is what causes the light to flash up.

 

[hexagon789]

I was on a 142 at a heritage railway today and gawping through the window in the door* to watch the driver. On a relatively sharp curve (15mph limit apparently for the curve only) the train (not local) gearbox light kept flickering on. I made a mental note to ask the driver about this. Then forgot about it.

Is this an actual sign of a fault, or is it something that 142s used to do "normally" on sharp curves? And if so why?


*Are there any remaining stock on "real" railways (i.e not light rail so not 139s, DLR, trams...) in the UK that you can do this with?

On other BREL Era stock such as 158’s it will illuminate under wheelslip. To the best of my knowledge, The Wheel slip protection (WSP) rack detects a difference in speed between wheel sets and illuminates the light.
With non-turning bogeys I wouldn’t be surprised if there becomes a difference in wheel rotation speeds and that is what causes the light to flash up.

Exactly as Lurcheroo states, it'll likely be wheelslip.

The equipment is set to detect a 7% difference in rotational speed between the speed probes, if it does then it cuts the throttle.

Wheelslip no longer detected, then throttle re-opens.

 

[D365]

Were any of the 14x/15x units ever fitted with ”locked axle” detection? E.g. a difference in rotational speed for >20 seconds.

 

[driver9000]

Were any of the 14x/15x units ever fitted with ”locked axle” detection? E.g. a difference in rotational speed for >20 seconds.

No. It was just the Wheel Slip detection and Throttle dip relay kicking in when the 7% difference in probe readings was detected. Sharp curves could sometimes cause problems on 142s with the relay cutting engine power (Accrington immediately springs to mind). Under braking a total slide was indicated by the speedometer reading 0.

There was a reset box under the drivers seat of a 142 should it cause problems.

Is this an actual sign of a fault, or is it something that 142s used to do "normally" on sharp curves? And if so why?

It was very common particularly at lower speeds and on rare occasion a 142 would get stuck on a sharp curve because the relay would keep kicking in as the rear axle (powered) would turn under power while the leading axle (unpowered) could be turning slower.

 

[coxxy]

No. It was just the Wheel Slip detection and Throttle dip relay kicking in when the 7% difference in probe readings was detected. Sharp curves could sometimes cause problems on 142s with the relay cutting engine power (Accrington immediately springs to mind). Under braking a total slide was indicated by the speedometer reading 0.

There was a reset box under the drivers seat of a 142 should it cause problems.



It was very common particularly at lower speeds and on rare occasion a 142 would get stuck on a sharp curve because the relay would keep kicking in as the rear axle (powered) would turn under power while the leading axle (unpowered) could be turning slower.

Exactly this! Accrington curve and the rose hill curve were awful at times, particularly after a light drizzle.

There was also a mod done to add a temperature sensor to the final drove assembly which also caused the gearbox light to flash intermittently- but that was a 5s flash if I remember rightly, rather than flickers.

 

[driver9000]

There was also a mod done to add a temperature sensor to the final drove assembly which also caused the gearbox light to flash intermittently- but that was a 5s flash if I remember rightly, rather than flickers.

Yes, it was a 2 stage temperature monitoring device fitted after a few instances of Final Drive failures. The Gearbox lights had a deliberate flash rate depending on which stage was activated and 5 seconds sounds familiar.