Does anone remember Dynadrive?

[Horsetan]

.... some UK company was the distributor for Dynadrive in 1990´s — first time I saw Dynadrives in Imrex Exhibition in London maybe in 1993 or so ....

That was Starline Design Ltd. of Aspley Guise in Bedfordshire. The distribution later passed to John Lythgoe's Formil.

[34theletterbetweenB&D]

You can feel the mass of the model locomotive when you are driving with this chassis. The chassis is still driving about 30-50 cm after you have turn the electricity off (depending on the speed of course) — you have to learn driving again with Dynadrive You are able to glue 20 cm long tape on the rail head and nothing will happen — the chassis goes over it...

The irony in UK RTR OO is that just as Bachmann first brought to the UK the centre motor with flywheels arrangement with good coasting performance on DC, so also DCC started to make itself known, with fine electronic simulation of inertia. So now I have a fleet of fine running diesels from Bachmann, Heljan and Hornby all with mechanisms capable of coasting a metre or more thanks to the flywheels on the motors; but actually operated by DCC, and requiring the best part of a scale kilometre to stop from their maximum service speeds. I think even an experienced Dynadrive operator might need retraining to handle this!

[pauliebanger]

The irony in UK RTR OO is that just as Bachmann first brought to the UK the centre motor with flywheels arrangement with good coasting performance on DC, so also DCC started to make itself known, with fine electronic simulation of inertia. So now I have a fleet of fine running diesels from Bachmann, Heljan and Hornby all with mechanisms capable of coasting a metre or more thanks to the flywheels on the motors; but actually operated by DCC, and requiring the best part of a scale kilometre to stop from their maximum service speeds. I think even an experienced Dynadrive operator might need retraining to handle this!

 

What you need for your DCC simulation is another control a real loco has - brakes. 

 

My recent ZIMO sound projects (ActiveDrive from Digitrains) have progressive working 'brakes' (obviously,not actual brake block or discs on the model) which will apply a prototypical braking force to defeat (electronically simulated*) momentum effects. The longer the brake key is held 'on', the greater the force applied. The braking tonnage is user selectable, the sound project determines the different effects applicable for light engine or heavy train and for the class of loco.

 

Now you can have realistic levels of momentum but retain some control over stopping or slowing.

 

Kind regards

 

Paul

 

*  will have no effect on DynaDrive which employs physical momentum

[vitalspark]

I still have a Lima 47/7 in Scotrail livery with Push Pull set fitted with Dyna Drive.

3 large flywheels supported and driving through beautiful tiny ball race bearings to the brass bogie chassis.

It was before DCC and one of the main advantages was that it created its own sound with the coarse can motor…no need for a smooth Mashima as the clutch smoothed the take up in fact it was actually desirable to have a noisy motor.

It was unique in its day to hear the loco sound winding up and being held on the point of take up before the movement very realistically gently propelled the train forwards.

As said it took a bit of stopping but that was all part of the fun.

Planning to resurrect it and refit in an early green 47 to allow more flexibility of running on our 60s train set.

 

Dave.

[JDW]

Good to see other people still using DynaDrive, I have a couple of locos so fitted, including two chassis and a kit bought recently from another member of this parish.  The bodyshells maybe don't look quite as good as the newer models that they sit alongside, but I still like them, my Lima 66 conversion especially.  When I converted it, it was the first 'big' project I'd ever done, and was also one of, if not the, first class 66 kit Formil produced, other than their prototype.  Unfortunately, the 66 is noticeably different, mainly in colour, from the later Bachmann ones, so the two rarely get used together, whereas at least the 37s and 47s can stand together reasonably well (if you don't look too close!).

[Horsetan]

Good to see other people still using DynaDrive...

 

It was and is an excellent system for diesels / electrics, and it's a shame that Brimalm seem to have stopped making most of the components for it (the only bit still available from them direct appears to be the final drive gearbox). The only problem as I see it was that the price and, later, the availability didn't help sales. It really deserved to do better.

 

I'm still on the lookout for clutches.

 

The Australian ModelTorque system achieved much the same effects but in a different way.

[JDW]

Yeah, at the time the price seemed steep (especially to me on pocket money) though compared with a modern diesel loco, it wasn't that much more.  Mine don't get used that intensively, so I hope the clutches and gearboxes will outlast me!  The ModelTorque name rings a bell, but can't remember the details, how did that work?

[Horsetan]

...The ModelTorque name rings a bell, but can't remember the details, how did that work?

The man behind it died, but the basic idea was like this

 

Here's someone who made his own version

 

A similar version here

[DCB]

From following Horsetan's links It seems to me that most of the advantage of Dyna Drive comes from the elimination of non reversible worm drives from the mechanism.   Some pre WW2 lorries had worm drive axles which had the same advantage / disadvantage that the wheels could not drive the engine.  You could not put them out of gear and push them or bump start them and worst of all could not knock them out of gear and let them coast downhill at 60 mph plus,

 

The Dyna Drive appears to work on  Eddy currents generated by a ring of magnets with alternating north and south poles acting on a disc of copper or aluminium.  The eddy currents generated ,make the disc turn in the same direction as the magnets.   The disc seems to be on the motor shaft in some applications and on output side in others.  What I can't understand is why the motors have a flywheel?  Surely all the flywheel should be on the out put shaft?  However I don't see the point of the Eddy current clutch unless you have a feeble motor,

 

A big fat (playcraft) motor driving a big flywheel with final drive through bevel gears should be every bit as smooth.  

 

So where do I get contrate or bevel gears for 1/8" axles so I can experiment with my West Country.

 

Where the clutch would be useful is for a banker, even a worm drive banker.

 

I'm pretty sure some Rover electric car door locks use a centrifugal clutch. I will investigate further.

[DCB]

My apologies form mixing up Dyna Drive with Model Torque.

 

Was there a wear problem with Dyna Drive and the centrifugal system?

 

 

I sort of like the eddy current system as it has no wearing parts.

 

I wonder if a small eddy current clutch could be made suitable for N gauge and also to fit non powered bogies on 00 0-4-4T chassis and trailing wheels on 0-4-2Ts or even Tender wheels to give some additional power without unrealistic wheel slip?

[Horsetan]

..... where do I get contrate or bevel gears for 1/8" axles so I can experiment with my West Country.....

Ultrascale makes two types of contrate-and-pinion assembly. I'm not sure if the infamous six-month wait also applies to gears, but assume that it does.

 

Failing that, you might be able to adapt Scalextric contrate-and-pinions (they come in varying ratios).

 

Bevel gears are produced by Grandt Line, but they are quite difficult to get hold of, and are quite rough.

 

Similar assemblies, referred to as mitre gears, are available from Gizmoszone. They are quite small and not suitable for 1/8" axles! Better, I think, to make them part of your own RG4-style final drive, i.e. with spur gears as well, and feed the shaft from the flywheels and clutch into that.

 

 

.....Was there a wear problem with Dyna Drive and the centrifugal system?....

 

The only known problem with DynaDrive occurred fairly early on, and it wasn't the clutch itself, but rather the momentum generated by the flywheel bank. So much momentum was generated that, if the model came to a sudden stop, the bevel and spur gears in the final drive would get stripped!

 

When John Lythgoe's Formil took over the distribution/sales from Starline Design, it took a while before Brimalm came up with a final drive with a worm (yuk) in it - this was in two forms: 15:1 which apparently would back-drive (suggesting that it was more of a crossed helical type), or 26:1 (which wouldn't back-drive). At this point, the original bevel-and-spur drive was withdrawn.

[DCB]

It sounds like Dyna Drive made the wrong decision in withdrawing the bevel and spur transmission when all that was needed was a clutch between flywheel and final drive to slip if excess torque was applied, either spring loaded or magnetic.  I think I found some suitable bevels in an old R/C car differential so it is game on for a bevel drive west country.

[Guy Rixon]

Clutches to cut the drive in an emergency (as opposed to clutches for smooth take-up of the torque) are standard parts in some science instrumentation. When I was associated with an instrument-building team, most of the lower-torque drives had a clutch about 15mm in diameter that was bought in rather than made in house. Unfortunately I never found out where they bought them.

[Horsetan]

It sounds like Dyna Drive made the wrong decision in withdrawing the bevel and spur transmission when all that was needed was a clutch between flywheel and final drive to slip if excess torque was applied, either spring loaded or magnetic.  I think I found some suitable bevels in an old R/C car differential so it is game on for a bevel drive west country.

 

In that respect, the ModelTorque / eddy current principle may have worked better if an emergency slip was required.

 

The only worm drives I have are in RTR diesels, since that's unavoidable, but if a bevel-and-spur drivetrain conversion were available for them which could be built into fully sprung bogies, that's the way I would go.

[shortliner]

 Re DynaDrive/Model Torque/Eddy currents etc - this may be of interest   http://model-railroad-hobbyist.com/node/15068

[Horsetan]

Yes, it's catching, isn't it?

[DCB]

I wonder if a couple of small cylindrical super neo magnets North pole to south pole along the driveshaft axis as part of the driveshaft would provide a drive but slip if excess torque was applied rather than stripping the bevel gears.  I found some crown wheel and pinion gears in an old Playcraft B B Diesel

so project uncontrollable 00 West Country is definitely game on!

[KalKat]

Any use to anybody?

 

http://www.ebay.co.uk/itm/141737553501?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[Pacific231G]

Did the free motor idea achieve a similar effect? Bob Symes and at least one other modeller fitted some early diesels with then and wrote articles about the results. AFAIR a second motor not connected to the drive spun up first and its back EMF supplied power to the actual drive motor. When the track current was interrupted the second motor, which had a large flywheel, effectively acted as a generator supplying power to the drive until it ran down. There would be no gear stripping momentum in the system as the drive motor would never get more than the normal 12 volts. I seem to recall that the system required some diodes to enable reversal and it wasn't quite as simple as just connecting the two motors in parallel.

[AndyID]

Did the free motor idea achieve a similar effect? Bob Symes and at least one other modeller fitted some early diesels with then and wrote articles about the results. AFAIR a second motor not connected to the drive spun up first and its back EMF supplied power to the actual drive motor. When the track current was interrupted the second motor, which had a large flywheel, effectively acted as a generator supplying power to the drive until it ran down. There would be no gear stripping momentum in the system as the drive motor would never get more than the normal 12 volts. I seem to recall that the system required some diodes to enable reversal and it wasn't quite as simple as just connecting the two motors in parallel.

 

I've tried it. It sort of worked, but not as well as I had hoped. I think the problem is you lose too much power to voltage drop in the brushes, although the motors I was using may not have been very well matched. I didn't use any diodes.

 

EDIT: The free motor with flywheel is effectively a lossy non-polarized capacitor 

[Brian Harrap]

Yes I remember the Dynadrive system. Have a few locos so equipped. Excellent simulation of (or rather real) momentum. I love it.

A few small observations though, if I may.

 

1. The Dynadrive clutch is not, as often assumed, centrifugal but rather the Bendix type. It operates by a 'cam' following a helix on the input shaft of the drive, thereby moving (forcing) the brass faceplates towards the bell housing of the output shaft. The helix is of the 'twin or double' type allowing the whole lot to operate in either direction. With this system it is, by definition, the torque produced by the motor that gradually engages the drive, not the speed (motor revs). A bit academic I know and has little effect on the play value of the thing. A point not enjoyed though by other systems referred to is that as soon as current is removed and the motor stops turning the 'connection' between the input and output shafts is removed allowing all the momentum of the flywheel (bigger the better) to be used moving the loco along and not some (small I agree) amount being wasted turning a 'dead' motor.

 

2. I also have locos equipped with eddy current drive systems. I find little to choose between Dynadrive vs good old Eddy, other than that eddy current clutches do incline to allow the motor to race away somewhat alarmingly given half the chance - train too heavy or trying to start up a train the wrong way against buffer stops or similar.

 

3. Some of my locos (see Continental Modeller April 2001) are equipped with Squires Transmission (not the tool people) of a permanently meshing gear system using a sun and planet type setup but not arranged in the conventional way. This method has the 'advantage' that there is no (extra) loss between motor output shaft and the wheel/rail interface. Hardly important in our toy trains I know. This system was produced in Raleigh USA and sadly no longer available, I mention it here as someone may wish to resurrect the idea. It works very well and enjoys the fact that most of the mass of the gearcasing is also added to the output side of the device which adds to the momentum effect which is what we are after after-all with these gadgets.

 

4. I am often asked which system is best or which I prefer and I just cannot form any reasonable conclusion. It depends on my mood at the time, whether I'm shunting a few wagons, positioning something precisely on the hoist or the like or the type of loco the device is in. I find I am forever changing them around from loco to loco just to play with their varying characteristics. All benefit from, or require a nice big flywheel (several ounces) or all is lost. The large flywheel and its mass also give the clutch of whichever type something to work against for a nice smooth start as well as momentum for carrying on. And that's the rub - all this equipment requires a big loco to fit it all in, the very locos that probably require it the least but still all great fun. All these drives can be played with using the 'shove it in reverse and throttle up to slow down quickly' method. Not prototypical but a great feeling of being in control. For small shunting types electronic inertia is likely the only way to go.

 

5. Part of the fun of these drives is that they have to be 'driven'. A bit of extra throttle will have to be given when entering a sharpish curve or perhaps of bit of complicated pointwork with lots of check rails and things to hinder progress - something which back emf throttles (they have their uses) deny one the pleasure of. 

 

6. I hope I'm not speaking too soon, but I've never been able to strip a gear as they say. How do you do it?

 

Regards, Baron

[Horsetan]

......Squires Transmission.....This system was produced in Raleigh USA and sadly no longer available, I mention it here as someone may wish to resurrect the idea......

 

Not much chance of that if people don't know what it looks like! 

[Pacific231G]

I've tried it. It sort of worked, but not as well as I had hoped. I think the problem is you lose too much power to voltage drop in the brushes, although the motors I was using may not have been very well matched. I didn't use any diodes.

 

EDIT: The free motor with flywheel is effectively a lossy non-polarized capacitor 

Indeed but a rather enormous one  (qv the Parry People Mover) and it would need to be of a type with little internal friction  that would run down very slowly.

[Horsetan]

Here you go . . .

 

http://www.rmweb.co.uk/community/index.php?/topic/38591-quai87/page-7&do=findComment&comment=789699

This sparked off a bit of cyber-digging, and after a while I stumbled across this patent application

 

Could this be it?

[Grovenor]

Could this be it?

Yes, that's it.

Keith