Gradient for manual control live steam

[Richardcable]

Gradients for 32 mm live steam manual controlled locos.

Hi building a new raised level track. It might work to put a spiral in subject to gradients. 8 foot diameter is the most I can manage in the spiral. Question: if I go up to 1% gradient will a manual controlled loco run away down hill? The locos aren’t geared.

All help appreciated.

[tom_tom_go]

Hi and welcome.

This will help, however, it also depends on the loco you are running:

http://www.roundhouse-eng.com/faqs.htm#16

Personally, I would avoid gradients at all cost unless you plan to use inertia devices fitted in locos or rolling stock.

[bazzer42]

I've got an 8 ft diameter spiral and don't have any problems with any running away with a Lady Anne. The gradient is approximately 1:40. I have more problems with a Roundhouse Criccieth that stutters a little with the worm/gear arrangement, even after they fitted a flywheel. Essel chassis fine.

[angr607]

I run a purely manual fleet and I've never had issues with a train running away. That said, it depends on A, the loco and B, the kinds of train you want to run with it. Most trains I have don't tend to go beyond 4 coaches long which has never caused a runaway but I've never let the engine go unchecked when descending preferring to shut off steam when going downhill at the start of the hill!

Jon

[IrishPeter]

Eight foot radius and a 1% (1 in 100) gradient should not be a problem. I used to run over up to 3.5% gradients (1 in 28.6) with manual locomotives without a lot of problem. However, that line was all uphill one way, so it was fairly easy to manage trains so there was no risk of a runaway. You do need to be aware of the fact that operating over significantly fluctuating gradients with manual locomotives will mean that you will have actually drive them to some extent. On the steepest parts of my old line you ran with the regulator just off the face, but when the line levelled out a little - to 1.5% - the locomotives needs a little more steam to keep moving.

Cheers,
Peter in Va

[GTB]

8 foot diameter is the most I can manage in the spiral. Question: if I go up to 1% gradient will a manual controlled loco run away down hill?

What locos and rolling stock are we talking about?

You won't get enough clearance for normal SM32 locos and stock where the tracks cross with a 1% (1:100) gradient on an 8' diameter spiral.

An 8' dia. circle has a circumference of ~25', so on a spiral the rail to rail height where it crosses itself will be only 3" if the grade is 1%.

Roundhouse locos need around 6" of height clearance. Once you add in the rail height, sleeper thickness and girder height for the bridge, even with a through girder, you could need at least 7" minimum height rail to rail where the spiral crosses itself. Some Accucraft locos. are taller, so you may need more height between rail heads if you own one, or have them visit.

On an 8' dia. spiral, that means a grade of about 1:43, maybe steeper, to gain enough clearance. In my experience manual locos build up significant speed downhill on 1:50, although the 4' radius curve would increase the rolling resistance of the train and hold things back a bit.

With a grade of 1:43 you will need to be able to get at the spot where the spiral crosses itself, to adjust the regulator as necessary, on manual locos going up and down the spiral.

So, you can have an 8' dia. spiral, or you can have a 1:100 grade, but not both...............

Regards,
Graeme