Southern Region EMUs Mk1 no Mk2

[Terry Tait]

I have always wondered why SR emus post 1963 were not built to the Mk2 design despite the rest of the railway going with it, Veps could have been built as 310s but with end gangway and CIGs could have used the same basic design as the Mk2 Irish DEMUs, by the time phase 2 CIGS were being built they could have been aircon, compatibility with the pre 1963 stock could have been easily achieved.

 

[30907]

The first Mk2 passenger coaches were barely in service before the CIGs so the derivative design would have taken a while, and for the SR compatibility with existing standards was paramount (though I remember they were criticised at the time for their plain front end - unlike the Clacton stock - and "pack-em-in" layout).
The 310/312s were rather a niche product, and came a bit later (Wikipedia says 1963, which must be when the order was placed).
As for aircon, that was for InterCity stock only!

 

[Helvellyn]

The opportunity might have come with Bournemouth Line electrification. The REPs, TCs and VEPs were pretty much built at the same time as the AM10s (same EE traction motors in a REP and AM10, plus Class 73) and the first Mk 2s for the West Coast electrification. The issue was that the Bournemouth Line was done a very strict budget, hence the REP trailer cars and the TCs being rebuilds of Mk 1 coaching stock, with only the REP motor coaches and the VEPs being new build. VEPs and the Phase 2 CIGs then followed, and for compatibility they went with existing designs, culminating in the 1974 batch of REPs and TCs.

 

[AM9]

... The REPs, TCs and VEPs were pretty much built at the same time as the AM10s (same EE traction motors in a REP and AM10, plus Class 73) ...

I don't thing that the 310s had the class 73 400hp (~300kW) motors. They had 270hp (~200kW) motors which were derivatives of the standard EE507 that had been fitted for years before. The 400hp version was intended for the Electro Diesels, so the class 432s (4-REP) had a total of 3200hp in a 4-car unit.

 

[Helvellyn]

I don't thing that the 310s had the class 73 400hp (~300kW) motors. They had 270hp (~200kW) motors which were derivatives of the standard EE507 that had been fitted for years before. The 400hp version was intended for the Electro Diesels, so the class 432s (4-REP) had a total of 3200hp in a 4-car unit.

The were all fitted with EE546 traction motors, albeit at different ratings, according to the Platform 5 combined volumes (albeit the 73/0 locomotives had EE542 motors). There was an article on the Class 73s in either the RM or Rail in the last year or so that also had this information.