[HOsteam] Transmission

Jon Miller <atsf@...>

I doubt this would work well on steam, it's designed for diesel I think.
Years ago there were a couple of types of torque converters designed. One
had rubber fingers inside a drum and the other was oil filled with vanes, I
think. Never saw the oil one but heard it leaked a lot. The rubber fingers
one worked ok but not great. The ones I saw were on Hobbytown drives. This
was in the late 50's.

Jon Miller
For me time has stopped in 1941
Digitrax DCC owner, Chief system
NMRA Life member #2623
Member SFRH&MS

Arved Grass <a_grass@...>

On Tue, 26 Sep 2000 05:35:12 -0700, "Bruce Pryor" <bpryor@pacifier.com>

I wonder how this would work on steam engines for double-heading and mid-train helpers.

Interesting. From it's functional description, I'd guess it's some sort of a clutch, possibly centrifical. They used to be popular when I was a small kid, back in the '60s. I had a Hobbytown of Boston RS-3 with a centrifical clutch, and it was more problem than it was worth. I ended up taking it out and relying on the flywheel.

However, it's called a transmission, and there's one shot of the internals showing a gear on one shaft, and what looks like a hole for the axle of a mating gear. This looks suspiciously like some sort of modified planetary gear system. That would only help by making the locomotive run slower. That might not be a good thing. (I have nightmares that include diesels with Ernst regear kits, where the motor is screaming away faster than a Formula-1 car's engine, and the model is still creeping from tie to tie like a shay).

Pricey, though. I certainly can't afford to retrofit all my existing locomotives with this "tranny."

As for speed matching your double-headers and/or helpers, I think DCC is the way to go. I'm not there yet, but I'm at the edge getting ready to take the plunge. With multi-function decoders costing less than lighting effect modules, the only thing really holding me back is the cost of all the supporting electronics.

But that's for another thread, on another list :-).

- Arved
Modeling the Southern Pacific, from AC-4s to AC4400CWs.
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Nelson Kennedy <nelsonk@...>

From a follow up enquiry I can tell you that the Modeldrives transmission is
NOT a clutch. It is probably best described as a torque converter. It is
NOT a fluid drive. It has been described to me as two sun gears with two
planetary gears running on a coaxial shaft with one sun gear firmly attached
to the motor shaft and the other to the output shaft. It seems to be
simplicity itself. The motor starts turning and meets the resistance of the
drive train of the loco and causes the transmission unit to rotate in the
opposite direction to the motor. As the torque builds it overcomes the
resistance of the drive train and begins to drive it. I'm told that starts
are awesomely smooth and the principle behind the design enables precise
equalisation between locos of different characteristics (although there are
presumably some practical limits to that). The price reflects the close
tolerances to which the parts are made, in an industry which, by its very
nature, works to much finer tolerances than we modellers are accustomed to.
The product is said to be of superb quality.

Before we head off in speculative directions, like comparisons to quite
different products from the past might I respectfully suggest that asking
questions about the product by using the 'Contact Us' button on the Model
Drives website might be more useful?

BTW, guys, I have no connection with this product but I have been impressed
by what I have been told and I can see I'm going to have to try one.

Nelson Kennedy
Christchurch, New Zealand
Ferrymead Trams, NZR 0 gauge and some Espee H0 at:
Products suitable for 1:32 models are at http://ninemill.railfan.net