How to tell the difference between a C69/77

[Deleted]

Well.................what the title says! Are there ways I can spot a later built unit from the original batch or are they pretty much identical? I suppose one giveaway would be where 'Metro Cammell 19--' is written on the door trail (what's the right word for that?).

[Chris M]

ISTR reading somewhere (TubePrune's site?) that since the refurb the two builds are identical.

Chris

[Colin]

The C69's DM's are numbered in the 55xx/56xx series, while the the C77's DM's are numbered in the 57xx series. There is one exception, as a C77 DM was built to replace a C69 DM damaged in an IRA bomb at West ham, though i'm not sure of the number.

[Phil]

5585 ;D ;D ;D ;D ;D ;D ;D

Original destroyed by bomb as you say, an extra C77 was added to the build and given the number of the detroyed one

[trainopd78]

Pre refirb it was easy to tell as the C77's had the aerowalk trim in the doorways up to draughtscreen level whereas the C69 was only to around ankle height.

There are also a few clues in the cab, the console being the bigges giveaway with the 77's having 2 "MA" bulbs. The fan heaters are also different in the cabs between 69's and 77's. As a point of interest, the C77's cabs are being fitted with 1983TS style fan heaters so we will now be toasty warm in the winter.

[Deleted]

What are MA indicator lights?? I've always wanted to know that...

[q8]

sturdjos said:

What are MA indicator lights?? I've always wanted to know that...

Indicators in the cabs to show that the MA's are functioning correctly. Had them in my day but did not need them except on stock with DC lighting. AC lit stocks had the whine to tell you that all was well. 'R' stock and 59'62 stocks [not sure about 'A' stock] had an MG flag which was forever clacking up and down over rail gaps. Got on your tit after a while but you sort of blanked it out

[Deleted]

MA's are motor alternators??

[Christopher J]

sturdjos said:

MA's are motor alternators??

Yes, although on some diagrams/equipment they are shown as MGs (Motor Governors) but both MAs and MGs are the same thing.

[rpi]

Yes, although on some diagrams/equipment they are shown as MGs (Motor Governors) but both MAs and MGs are the same thing.

Errrrr I know I don't work for the Underground but MG was always Motor Generator?

[Deleted]

christopherjolly said:

Yes, although on some diagrams/equipment they are shown as MGs (Motor Governors) but both MAs and MGs are the same thing.

Close, but incorrect on this occasion. MG stands for Motor Generator, not Motor Governor.

Here is what an MG / MA is:

An M.G./M.A. is provided on each motor car and is referred to and labelled M.G. on the train. The M.G./M.A. provides a 230 volt (a.c) feed which is transformed into:

1. 115 volt (a.c.) for the main car lighting

2. 60 volt (a.c.) for the M.G./M.A. indicator light via the auxiliary rectifier

3. 60 volt (d.c) to the main rectifier which is now converted to 50 volt (d.c.) for the auxiliary circuits and charging of the batteries.

The only thing that would "govern" the motors is the Equipment Govenor which prevents train movement if the main line air falls below the 55 lbs p.s.i. needed to close the line breakers.

Hope that helps

[Deleted]

Met App, rpi said 'motor generators' - not 'motor governors'



***Met Apprentice was quoting Chris J, and was agreeing with the correction that rpi posted - Colin.***

[rpi]

Met App, rpi said 'motor generators' - not 'motor governors'

Yesterday at 4:42pm, Christopher J wrote:Yes, although on some diagrams/equipment they are shown as MGs (Motor Governors) but both MAs and MGs are the same thing.




Close, but incorrect on this occasion. MG stands for Motor Generator, not Motor Governor.

[Deleted]

wasn't the other way pre-refurb was that the C77 had a silver roof and the C69 had the black roof