Class 378s

[Deleted]

378232 is out and about on the ELL

[tubeprune]

I was reading a blog:

leytr.blogspot.com/2010/03/driving-class-378.html

which describes driving a 378. The driver says that there are three power positions on the traction brake controller. Do these positions limit the maximum speed like the old "Shunt" "Series" and "Parallel" positions? I wonder because, on modern LU stock, movement from "Off" into the "Power" "arc" as it's called, sets the rate of acceleration according to the position of the handle. It caused much confusion for drivers in the changoever period from old to new stocks.

[dazz285]

378006 & 378007 heading back to Derby this morning.

[dazz285]

378203 and 378204 now back from Derby.

[Deleted]

Dec 3, 2010 9:48:00 GMT tubeprune said:

I was reading a blog:

leytr.blogspot.com/2010/03/driving-class-378.html

which describes driving a 378. The driver says that there are three power positions on the traction brake controller. Do these positions limit the maximum speed like the old "Shunt" "Series" and "Parallel" positions? I wonder because, on modern LU stock, movement from "Off" into the "Power" "arc" as it's called, sets the rate of acceleration according to the position of the handle. It caused much confusion for drivers in the changoever period from old to new stocks.

The 378s use the an Insulated Gate Bipolar Transistor to apply power to the traction motors. As I understand it, DC (third rail) or AC (Overhead) current is converted into 3 phase AC for the motors to use. There are 4 different power settings and yes in similar fashion they seem to equate to different rates of acceleration, but they apparently don't limit the maximum speed. Notch 1 will allegedly hold top speed on a level gradient!

[tubeprune]

Dec 16, 2010 14:51:57 GMT @notatraindriver said:

Dec 3, 2010 9:48:00 GMT tubeprune said:

I was reading a blog:

leytr.blogspot.com/2010/03/driving-class-378.html

which describes driving a 378. The driver says that there are three power positions on the traction brake controller. Do these positions limit the maximum speed like the old "Shunt" "Series" and "Parallel" positions? I wonder because, on modern LU stock, movement from "Off" into the "Power" "arc" as it's called, sets the rate of acceleration according to the position of the handle. It caused much confusion for drivers in the changoever period from old to new stocks.

The 378s use the an Insulated Gate Bipolar Transistor to apply power to the traction motors. As I understand it, DC (third rail) or AC (Overhead) current is converted into 3 phase AC for the motors to use. There are 4 different power settings and yes in similar fashion they seem to equate to different rates of acceleration, but they apparently don't limit the maximum speed. Notch 1 will allegedly hold top speed on a level gradient!

So, which is better? A power controller that limits the acceleration but always ends up giving maximum speed or one which allows the driver to set the top speed but provides a single maximum rate of acceleration?

[mcmaddog]

Had a strange situation last night at Surrey Quays where with the doors open the train rolled forward about 5 feet before abruptly stopping. Then just after the doors closed half the lights went out ... I could feel a cancellation coming but the train proceeded happily on after this little event.

[Deleted]

Had my first ride on a Class 378 today from Carpenders park to Watford High Street rtn. Overall impressed with them however I thought they were a little slow on acceleration; is this due to power supply limitations?

Also intrigued to see some of the former 4th rail at Watford High Street station still attached to the insulator pots!

Xerces Fobe

[Deleted]

They do seem a bit slow on that line. Try them on the (AC) sections of the North London line.

[Deleted]

Dec 22, 2010 11:34:29 GMT mcmaddog said:

Had a strange situation last night at Surrey Quays where with the doors open the train rolled forward about 5 feet before abruptly stopping. Then just after the doors closed half the lights went out ... I could feel a cancellation coming but the train proceeded happily on after this little event.

Maybe the driver forgot to apply the brakes after stopping and suddenly realised and slammed them on? Not sure about the lights thing. Which direction were you going?

[metrolander]

As a regular commuter on the DC (and almost always on LO trains as I go north of H&W), the difference in acceleration/speed is immediately noticeable even on the short section of AC heading from WJ onto the WLL. My travels on the NLL are usually between Willesden/Richmond which is of course mostly DC, and low-ish linespeed I guess due to a string of junctions on the AC stretch between Acton/Willesden.

[Deleted]

Hmmm yes there is no real opportunity for speed on the NLL westbound from Willesden. Going east however tirades Gospel Oak ....

[dazz285]

Transformer problems between H&W & Watford.. ie the lack of..
I believe that work is planned to fix this..

[mcmaddog]

Dec 27, 2010 21:50:43 GMT @notatraindriver said:

Dec 22, 2010 11:34:29 GMT mcmaddog said:

Had a strange situation last night at Surrey Quays where with the doors open the train rolled forward about 5 feet before abruptly stopping. Then just after the doors closed half the lights went out ... I could feel a cancellation coming but the train proceeded happily on after this little event.

Maybe the driver forgot to apply the brakes after stopping and suddenly realised and slammed them on? Not sure about the lights thing. Which direction were you going?

Re brakes, I just assumed the doors to be interlocked so they couldn't be released without the brakes being applied

Re lights, heading south towards New Cross Gate. Literally they went out as the doors had closed before we moved off and stayed off about half way to New Cross Gate.

[Deleted]

Jan 2, 2011 23:12:57 GMT mcmaddog said:

Dec 27, 2010 21:50:43 GMT @notatraindriver said:

Maybe the driver forgot to apply the brakes after stopping and suddenly realised and slammed them on? Not sure about the lights thing. Which direction were you going?

Re brakes, I just assumed the doors to be interlocked so they couldn't be released without the brakes being applied

Re lights, heading south towards New Cross Gate. Literally they went out as the doors had closed before we moved off and stayed off about half way to New Cross Gate.

Were you sitting towards the rear of the train? If so, the half lighting would have been as a result of the shoes for the rear coach being off the third rail due to the positioning of the stop marker board. (There is a considerable gap in the third rail on the Down Platform at Surrey Quays). Once the shoes are back on the third rail, full lighting should be restored which normally only takes a few seconds. This also normally happens if the train approaches the stop marker at a slow speed, the driver tends to get an alarm in the cab that the third rail voltage has been undetected once they release the doors.

[mcmaddog]

Jan 2, 2011 23:53:02 GMT @378driver said:

Jan 2, 2011 23:12:57 GMT mcmaddog said:

Re brakes, I just assumed the doors to be interlocked so they couldn't be released without the brakes being applied

Re lights, heading south towards New Cross Gate. Literally they went out as the doors had closed before we moved off and stayed off about half way to New Cross Gate.

Were you sitting towards the rear of the train? If so, the half lighting would have been as a result of the shoes for the rear coach being off the third rail due to the positioning of the stop marker board. (There is a considerable gap in the third rail on the Down Platform at Surrey Quays). Once the shoes are back on the third rail, full lighting should be restored which normally only takes a few seconds. This also normally happens if the train approaches the stop marker at a slow speed, the driver tends to get an alarm in the cab that the third rail voltage has been undetected once they release the doors.

a ha yes, I was in the last coach and didn't look further down the train! This was during some icy weather as well so I guess that might explain the slowness.
Cheers for the explanations!