[Trivia] Refurbishments and modifications which have made previously compatible trains incompatible

[py_megapixel]

There as something about Greater Anglia 156s not being able to work in multiple with East Midlands 158s because they are fitted with a different passenger information system.
Are there any other examples where modifications have been made causing compatible stock to become incompatible?

 

[61653 HTAFC]

I can think of a few examples:
When class 141s were refurbished and had the couplers replaced, the refurbished units with BSI couplers couldn't work with unrefurbished ones which had Tightlocks.

DC-AC conversion of several fleets inc. 306s and 307s. Once converted the 306s could no longer work with the very similar 506s (though given the two fleets' rather different operating areas, the incompatibility was somewhat moot).

377s were originally specced with the same couplers as 375s (and were classed as 375s), when Connex lost South Central and GoVia took over they upgraded to Dellners and the units already delivered were reclassified as 377s. Later units came as 377s with Dellners out of the box. The SouthEastern units also had the couplers changed later, so now could in theory work with the SC units once again...but remained as 375s.

 

[cjmillsnun]

SWT 455 and ex SN 456 were made incompatible due to different PIS fitment. Amendments to the 456 were made to make them work together.

 

[Journeyman]

Isn't there a certain degree of future proofing in most multiple working systems? The original Southern Electric suburban units used 8-wire jumpers with all wires used, but the later EPB system used 27 wires, a number of which were spare. This was later used for public address, and apparently several wires were reserved for automatic door operation, although of course this feature was never used.

 

[JohnElliott]

Isn't there a certain degree of future proofing in most multiple working systems? The original Southern Electric suburban units used 8-wire jumpers with all wires used, but the later EPB system used 27 wires, a number of which were spare. This was later used for public address, and apparently several wires were reserved for automatic door operation, although of course this feature was never used.

Until the 442s.

 

[Islineclear3_1]

Couldn't the Renaltus Class 321's not work with "normal" 321s for a short while?

 

[TT-ONR-NRN]

SWT 455 and ex SN 456 were made incompatible due to different PIS fitment. Amendments to the 456 were made to make them work together.

Unrefurbished 456s were also unable to work with their refurbished classmates

 

[Journeyman]

Until the 442s.

Weren't they completely different to earlier stock anyway?

 

[JohnElliott]

Weren't they completely different to earlier stock anyway?

No, they used the 'classic' 27-wire system; there are pictures of them running ECS in multiple with older stock like 4-VEPs.

 

[Journeyman]

No, they used the 'classic' 27-wire system; there are pictures of them running ECS in multiple with older stock like 4-VEPs.

Ah, OK. I thought they were more like the 455s.

 

[CyrusWuff]

It may be an urban myth, but allegedly there's a 170 subclass with two of the train wires swapped, so if you couple them to a different subclass and put them in Forwards, the other unit will go into Reverse.

 

[py_megapixel]

It may be an urban myth, but allegedly there's a 170 subclass with two of the train wires swapped, so if you couple them to a different subclass and put them in Forwards, the other unit will go into Reverse.

Hmmm.. that sounds so utterly ridiculous that it's extremely hard to believe. But if it is true, who on earth thought that was a good idea?

 

[jopsuk]

It may be an urban myth, but allegedly there's a 170 subclass with two of the train wires swapped, so if you couple them to a different subclass and put them in Forwards, the other unit will go into Reverse.

I wonder if this is actually true with the Chiltern 168s & 172s versus 170s/other 172s?