Turntable Safety

[relaxinghobby]

This is the turntable project I'm developing for my Cake Box Challenge entry. The small loco I had dug out for the teenage modeller thread, it's my version of the small Sharp Stewart standard used by the Furness and Cambrian railways among others back in the 1860s. This gave me the chance of trying it out to see if it will fit on this small turn table which is a PECO n gauge one.

 

 

It just fits, the question is would this situation be allowed on the prototype?

 

Another problem of clearance is look at that front coupler, with the walls of the low relief building in place there is not enough clearance for the loco to turn. Mind you the draw bar is very long and could easily be shortened and I could remove the front coupling, but then the loco would be less useful.

 

 

The second photo shows a small tank engine with wagon which fits more comfortably, the wagon is a Slaters 19^th century era kit. So a wagon load of equipment could be shunted into the works.

 

[Caley Jim]

It's not just as simple as whether the loco physically fitted on the turntable, it also had to be balanced. The centre of gravity had to be over the pivot to make it easy for the crew to push it round, so the loco might not be sitting centrally on the 'table. So, quite apart from the overhang issue, I doubt if that loco could be turned on that size of 'table.

 

Jim

 

Edited to correct predictive text (again) :-(

Edited July 29, 2018 by Caley Jim

[Phil Bullock]

 

 

It just fits, the question is would this situation be allowed on the prototype?

 

 

Balancing the turntable is key to turning the loco. Cant find any reference on line at the moment but some turntables certainly had an extension bar arrangement - effectively rail extensions - which meant that locos longer than the table could be accommodated and balanced.

 

Phil

[34theletterbetweenB&D]

Overhanging the end of the turntable bridge, not a problem. (Some railways even used the expedient of bolt on extension rails to enable a slightly over long loco to be turned on a turntable otherwise physically too small.

 

There's another problem though. That is balance. Most UK tables had to be balanced on the centre bearing to be able to turn, and that frequently meant the loco and tender positioned 'off centre' visually. Typically the tender needed to be fully coaled and watered for locos which were large relative to the bridge length to be turned.

 

Your two examples won't turn if the turntable is of balance type. The 0-6-0 has the mass of the cylinders over the edge, no way will it balance (UK construction locos are typically 30% heavier per foot run than a fully loaded tender, so the tender is typically nearer the end of the bridge than the loco front end for balance to  be achieved. As for the 2-4-0T, even if the wagon were laden the loco will be more like 250% of the wagon weight, so again no balance possible.

 

Solve the problem by deciding the turntable is the more unusual type that took the load on the end bogies?

[Compound2632]

The Midland Railway had a very large number of 42ft turntables, a standard size going back to Kirtley's days and in particular the building of square roundhouses in the later 1860s. The total wheelbase of a Midland six-wheeled tender engine with the classic 8'0" + 8'6" locomotive wheelbase (i.e. all 0-6-0s and 2-4-0s) was about 38ft, i.e. just 4ft to spare. 

 

EDIT in the light of Regularity's post below, length over buffers around 50ft, so 4ft overhang at either end.

Edited July 29, 2018 by Compound2632

[Regularity]

Some wheel arrangements were more easily balanced than others. 0-6-0s and 4-6-0s tend to have the balance point roughly in the middle of the over-buffers length for engine plus tender, which is extremely useful for all concerned!

[Hroth]

In some cases, where a "large" loco (with tender) met a small turntable, it was the practice to separate loco and tender and turn each individually.  It took rather more time and was extra faff, but if the rule for tender locos was to run chimney first, then it needed to be done. 

 

In terms of the cakebox challenge, the rule is that it should be presented in a state that allows the entire model to fit in an 8x8x6 inch cakebox. If you align the loco on the diagonal, the couplings will fit inside the perimeter.  Choose the viewpoint you want the model to be seen from.  As it is a diorama, it doesn't have to be fully functional,  a degree of visual compression is ok.

 

You could always have a couple of figures standing by, scratching their heads; "She won't balance!".

 

 

edit 'cause one sentence didn't make sense.

 

Whaddya mean ONE sentence???

Edited July 30, 2018 by Hroth

[Compound2632]

With an engine on the table, you need only model the half of the pit. For extra interest, you could add a second engine...

[Hroth]

With an engine on the table, you need only model the half of the pit. For extra interest, you could add a second engine...

Oops!

 

"Right said Fred, got to turn the engine...."

 

Not as bad as the French engine that came through the Montparnasse station wall, though that would make a rather fine CBC!

 

https://upload.wikimedia.org/wikipedia/commons/1/19/Train_wreck_at_Montparnasse_1895.jpg

[Spitfire2865]

With an engine on the table, you need only model the half of the pit. For extra interest, you could add a second engine...

Shocking theres not more damage to the loco that took quite a nasty fall.  

[Killian keane]

In this view of Cheltenham shed c.1848 you can see the 0-6-0 'Alligator' has been turned separately from her tender, the same was done on the Liverpool and Manchester Railway for running around etc. Separating engines from their tenders was not taken as such a risk in those days, I've heard stories of engines travelling over a mile to collect their tender

Edited July 30, 2018 by Killian keane