In the days before DCC came along....

[Horsetan]

....there were quite a few attempts to replicate acceleration, coasting and braking via mechanical means. Some of us will be familiar with DynaDrive, an expensive system involving miniature centrifugal cutches, indecently-big flywheels, reduction gear cradles, driveshafts and some very efficient bevel-and-spur final drives to replicate the mass and inertia of the real thing.

However, there was another ingeniously brave attempt that was produced by Rivarossi some time in the 1980s. They called it "S-Drive". I didn't even know it existed until earlier this year, when, during one of those distracted Google searches that I sometimes get trapped in, the attached advert came up.

"S-Drive" seems to have been quite simple in the sense that a standard motor drove a worm and wormwheel. However, butted-up against that was a cradle carrying three spur gears. Running the motor and worm stage one way caused the cradle to flip in one direction and engage with a final drive gear, allowing the model to move. Whilst on the move, if you cut the power, the motor would stop and the cradle would disengage so that the model would coast to a halt. Applying power the other way caused the cradle to flip the other way, engaging the final drive and allowing the model to reverse. Again, cutting power to the motor would disengage the cradle and the model would coast in reverse. If you got your braking distances a bit wrong, you were free to apply power in either direction.

Turns out the system was so successful that Rivarossi only fitted it to one model: their ex-Bavarian S3/6 Pacific. It doesn't look like they tried it on any other. The advert suggests it was built using plastic spur gears; this may have been more to do with cost than anything else.

Anyhow, for those not entirely familiar with German, their advert is roughly translated as follows:

"Haven't you always wanted to drive realistically?

S-Drive offers automatic engagement and disengagement of the gearbox

- Continuous acceleration
- Traction-dependent sliding travel
- Individual determination of the braking distance through additional traction current pulses
- Realistic, mass-dependent coasting to a standstill
- Full braking by counter-control on the driving console
- Possibility of towing another locomotive with S-Drive in case of separate traction current supply (overhead contact line / outside contact line) or individual control with electronic multi-train systems

The Br.18 will be the first locomotive to be equipped with S-Drive by Rivarossi. It is planned to equip further locomotives with this new drive concept in the course of the model update.

Should one or the other brake sections of existing layouts not be sufficient for Rivarossi S-Drive - too bad! But then this modern drive concept can be switched over to the conventional type of drive at any time.

S-Drive. Now you can!"

Nowadays, there is DCC and almost everyone who gets used to that takes all the clever things it can do for granted. But for those of us who find DCC a bit beyond the pale, the mechanical methods are still out there and could still be messed with.

Edited September 10, 2022 by Horsetan