London Banter - View Single Post - reliability of NNL and district line richmond branch

Colin Rosenstiel · August 13th 06, 12:16 PM posted to uk.transport.london

In article . com,
(MIG) wrote:

Neil Williams wrote:
Colin Rosenstiel wrote:

The 313s are 35 year old technology.

The units themselves are only about 30 years old though... (the
507s and the 508s are the same age as me, 27).

But the design first appeared in the the PEPs, about 35 years ago.

They were also designed for a
maximum speed of 30MPH on DC (series only motors).

Really? Do they differ substantially from 507s and 508s? I
assumed they were the same but with a 25kVAC-750VDC transformer
on the middle coach. The Merseyrail units are top speed 70mph,
though I don't know if they ever reach that, perhaps they do on the
bit out to Chester.

There was a discussion about this in the past. I think the 30 mph
restriction only applied to the Moorgate line.

Indeed. But the only /designed/ DC use of the stock was on the Northern
City (Moorgate) line. The wider DC use came much later when it was
decided that some of the units were surplus on the GN.

I think the 313s maximum on AC is 75. But the point is that the design
was for series only operation on DC, presumably to simplify the control
gear.

They were fitted with extra shoegear for the Silverlink routes,
presumably because of gap problems that didn't arise on the Moorgate
line.

I can't remember whether or not this had any bearing on the top
speed.

Different top speeds on AC and DC occur on other stock. Look at the
Eurostars.

--
Colin Rosenstiel