Hornby live steam

"Rob K"

More to the point, which Rosemont?

There's probably dozens of them in North American alone.

-- Cheers Roger T.

of the Great Eastern Railway

Give us a report on the technical innards... a few of us on uk.rec.models.rail enganged in some wild speculation and arm chair physics about how they dun it. A fact or two would help us crawl out on a few more limbs.

-dave

I saw it. Was running at a fairly good clip on an oval. Was not able to get to talk to the rep about it. Every so often, some steam would emerge from the stack.

Kennedy

I'm sure that would interest a few folks.

-dave

The local hobby shop got a poster with a 'phantom' photo view of the loco's insides.

It still has an electric motor and gearbox, in somewhat the usual locations. There are several extra gears in strange locations. What follows is mostly speculation ...

The pistons and siderods are functional, but the external valve gear is clearly NOT (no valve chests). It's not at all clear from the photo, but I suspect the electric motor somehow drives the wheels AND the valve timing, which the steam propulsion portion then tries to follow. A sort of electric-steam servo system. This would allow something like ordinary speed control of the steam portion. Thus the drive may be combined steam-electric. The motor appears quite small for propulsion, so I guess the steam provides much of the power. Speed control of small live steam models has been one of the big problems with them previously. Many have been built, a few even in 'n' gauge, but performance was poor, and speed control almost non existent.

let's hope something neat comes from this. It's an interesting concept, to say the least.

Dan Mitchell ==========

Dave Curtis wrote:

Interesting that the leading coupled wheels and the flangeless driving wheels are off the track!

Without actually being able to take one apart I reckon that the "boiler" in the tender is there to get the water up to around boiling point where the very wet steam passes into a flash steam generator feeding a "reversing valve" that is controlled by the electric motor and gearbox. This gives direction and speed control. The valve gear looks like it's a rotary type driven by a gear off of the leading coupled wheels.

All very interesting.

Charles Kimbrough wrote:

snip

No, it is totally steam driven. Check Hornbys web site amongst other places

Rob K,

I didn't see any claim to "totally steam driven" on their website.

Can you be sure that the electric motor is not part of the drive?

Mike Sowsun Oakville, Ontario

OOPS...I just read this on the website.

"This is a real steam locomotive, operated purely by steam"

OK...If it is operated purely by steam, what is the electric motor and gears for?

Mike Sowsun Oakville, Ontario

As I said, my response was pure speculation. As someone else said, the valve appears to be a single rotary type, on center, driven off a driver axle. If so, what purpose does the motor serve ... to work the 'reverse' gear only perhaps? If so, it must somehow be timed into and synchronized with the valve motion. Without knowing more about the valving, it's hard to guess.

Dan Mitchell ==========

msowsun wrote:

"msowsun"

Servo motors for direction control?

-- Cheers Roger T.

http://www.highspeedplus.

The electric motor drives a gearbox that controls the position of a "reversing valve". The "reversing valve' has a series of ports that allow the exhaust and inlet pipes to be changed over, thus reversing the engine. This is a common and simple way of controlling a small steam locomotive - mamod used it for their steam locos. If the ports are carefully proportioned it's possible to control the flow of steam to the cylinders and get speed control. All this is old hat and has been done years ago. Even the heating of the water by current taken fom the track is old.

As the cylinders are fixed and not oscillating there must be a fairly conventional valve system for each cylinder and it could be that this is a rotary type driven from one of the driving or coupled axles.

What Hornby seem to have done is to productionise it!

Daniel A. Mitchell wrote:

snip

Sounds reasonable, but not necessarily good. I've seen similar, hand made, HO and O-gauge live steam, some with radio control. Speed control has been a HUGE problem, despite controllable valve and throttle settings. I've not seen one run with what I'd consider acceptable control. The best I've seen were some G-scale narrow gauge stuff at the national Narrow Gauge convention a few years back. Not to say the models are not NEAT, or fun to watch. I just can't hardly imagine trying to OPERATE a model railroad with locos having such poor control. It's be like having a momentum throttle with continuously self-reprogrammed momentum that you had NO control of. You'd never be quite sure where you were at, or what would happen next.

Even large scale live steam (7.5" gauge) exhibits some of this ... requiring the ride-on engineer/fireman to 'keep on their toes' every minute or risk stalling or overspeeding. heck, REAL, full sized, steam is similarly temperamental, but behaves erratically at a much slower easier to comprehend, and correct for, pace.

It'll be interesting to see if Hornby has improved on the control characteristics. If not, it'll just be a neat curiosity ... and I did say NEAT!

Dan Mitchell ==========

Dick Gandert>

From Hornby's press release............... .

"The launch of Hornby's 'Live Steam' range is the culmination of three years of research and development into the miniaturisation of components. The model trains are 1:76 scale (OO Gauge) and will run on standard Hornby track. They are powered by a miniaturised steam boiler that will replicate the driving action of classic steam trains."

I wonder what they meant by "replicate the driving action"?

Doesn't that sound suspicious?

No. After all, both straight DC and DCC as well as MSTS and Tranz "replicate" driving a steam loco.

-- Cheers Roger T.

of the Great Eastern Railway