Why 1973 Stock first?

[Snow1964]

The new trains generate less heat than the old ones (mostly due to being lighter, and having regenerative breaking rather than rheostatic).

Rheostratic braking dissipates energy rather like those 1950s bar fires, heats everything around it.
Friction brakes also heat the air tunnels.

Being blunt when they built the old trains, the heating of tunnels was deemed acceptable byproduct of slowing them down

 

[computerSaysNo]

Rheostratic braking dissipates energy rather like those 1950s bar fires, heats everything around it.
Friction brakes also heat the air tunnels.

Being blunt when they built the old trains, the heating of tunnels was deemed acceptable byproduct of slowing them down

I wonder why rheostatic was chosen instead of returning the energy to the power rails? Was the shore power supply just not capable of absorbing what I guess would have been a sudden voltage spike?

 

[Snow1964]

I wonder why rheostatic was chosen instead of returning the energy to the power rails? Was the shore power supply just not capable of absorbing what I guess would have been a sudden voltage spike?

Yes, substations couldn't absorb it, even when another train on same electrical section wasn't drawing power. The dc motors with old camshaft control couldn't return current at rail voltage (at least not anywhere near tolerance of acceptable voltage)

It is only in much more recent times with electronic power inverters, that returning electricity to grid has been possible (although many sites are not equipped currently)

 

[Central]

Had regen brake on O & P stocks,not a success as sub stations couldn’t handle it.

== Doublepost prevention - post automatically merged: 10 Aug 2025 ==

They also had metadyne traction equipment which was not a success either.

 

[73Stock]

Is this flat wheel sound normal?

 

[Dstock7080]

Quite common on ‘73s, the rheo brake is quite primitive and snatches at the wheels causing them to lock momentarily.

 

[Mawkie]

Is this flat wheel sound normal?

It's not even leaf fall yet!

 

[73Stock]

There's actually some leaves falling already!

 

[Mr. SW]

Ahh! Flats on 73 stock! Such memories!

 

[73Stock]

Well the emergency alarms still work! Today was the first time I've heard it in use.