Mallard in black

I think the answer is corridor tenders have balance weights on the corridor side to offset the weight of the water ,so when moving it about water needs to be added to keep the weight even.

 

Sorry, Keith. Mallard does not have a corridor tender.

Peter James

 

Interesting theory given that Mallard is fitted with a non corridor tender.
By filling the tender with water it will increase the weight and help to prevent skidding wheels when the brakes are applied.

 

I think I should have waited for Anthony .

 

Wouldn't the springs be set up for it to be full of coal and water? Quite a lot of extra weight. So if it were to be run empty, then the springs wouldn't work in quite the same way. I'd guess that travelling over point work, or rough joints could potentially cause a derailment?

 

The only trouble with that idea is that, at the end of a journey, a tender will generally have little coal or water remaining (especially on the non-stop) so it needs to be acceptable as a vehicle in the empty condition. I've asked the question because I can't think of a logical reason and I'm intrigued. No doubt the answer will be simple!

 

I'm probably going to look like a complete moron here but is it to do with brake force perhaps?

 

Mallard is vac braked throughout and, although the A4's had a very high brake ratio, I can't see the vac brake being in use for the trip.

 

Could it be something about a 4 axle tender needing a minimum axle weight to safely negotiate points and tight corners in yards etc ?

 

As I said earlier, empty tenders would not be uncommon is steam days, whether 6wh or 8wh rigid. That would be even more likely around depots and sharp curves and indifferent track were far more prevalent then than they are today. What's also puzzling me is that it's a bit unusual for Anthony to not respond to queries about NRM activities.

 

Sorry - I'm not on here as much because I'm frantically trying a) to get our allotmentready for chickens and b) to finish the steam roller for Beamish at the end of the month and c) trying to spend less time on the interweb as I used to. Mallard's tender was filled with water to add weight a) for the brake force and b) to get it to ride better on the springs. Mallard was moved to and from Shildon as a braked vehicle and came back on its own behind 5972 - thus the loco and tender were the only braked vehicles as well as the Hall. On the last bit of the journey south, the water valves were opened to drain the tender which caused some lineside speculation then.

 

Thanks Anthony. You've taken the time to explain why but it still begs te question 'why'? A tender should still ride satisfactorily when empty and the brake force/adhesion weight ratio is more significant on the loco part of an A4 I'm betting that you didn't fill the boiler as well in order to optimise this?
I can see the reasohs why it was done but I can't see the necessity of it.