Dynadrive mechanism (DSB MZ)

[47137]

For everyone who likes things mechanical and out of the ordinary - this is a Lima DSB MZ I just bought:

 

Inside:

 

And underneath:

 

The dimensions of the bogies match up with those of a GM Class 66, in H0 scale, so there is a future project for me if I find a Mehano or Heljan class 66 non-runner. Or, built up the class 59 kit from Worsley Works.

 

I've never seen one of these mechanisms before. All four buffers are missing, but it's fab to drive :-)

 

- Richard.

[Horsetan]

I see the tell-tale signs of Formil (John Lythgoe) having supplied it originally. He took on the Dyna-Drive concession in the UK after Starline Design (the original UK agent) dropped it.

 

For non-DCC operators, Dyna-Drive's great asset was that you had to learn how to really drive it, because of the physical mass that it was designed to convey. A very great shame that Brimalm Engineering stopped making the centrifugal clutches, though they still make the final drive gearboxes on and off.

[KalKat]

That must take a while to change direction.......................

 

 

 

 

Emma

[47137]

That must take a while to change direction.......................

 

 

 

 

Emma

Well - it has inertia like a real engine, but no brakes :-). Even if you close the throttle at a scale walking pace it trundles on another foot or so. If it is running at top speed, it takes about six feet to stop but there is some friction here because my track is a loop not a straight line.

 

- Richard.

[Horsetan]

That must take a while to change direction........

 

If you were running out of road, you could put it in reverse, but at the risk of not doing the final drive any favours. The original final drive was bevel-and-spur, and if the wheels were unable to slip, then the geartrain could be stripped very quickly, which was the reason why Brimalm replaced it with a multi-start worm and wheel (almost crossed-helicals) to try to retain the back-driveable characteristics.

[47137]

I've tried lifting it off the track, it's a bit unerving seeing all that energy unwind itself.

 

This is indeed marked as one of the Fourmil models.

 

The bogie mechanism does drive backwards (moving the wheels by hand), but I can't see inside what sort of gear it is, worm or bevel/spur. It 'feels' very smooth, no backlash.

 

- Richard.

[Horsetan]

....The bogie mechanism does drive backwards (moving the wheels by hand), but I can't see inside what sort of gear it is, worm or bevel/spur. It 'feels' very smooth, no backlash.

 

That box is the worm and wheel generation that you have there. It was a multi-start worm, with an overall ratio of 15:1. (A 26:1 was also available, according to my old Formil list, but that needed considerable running-in before it would show any backdriving ability, whereas the 15:1 would do that from scratch.)

[griffgriff]

I drove one year's back and it was a lot of fun running the loco on its own but as soon as some stock to shunt was introduced it became an amusing nightmare (you know the kind - frantic in the moment but hilariously funny afterwards) with stock literally flying everywhere.

 

Griff

[Orange Cat]

I think I have the bits for one of those drive systems. I had it in a running chassis at one time and it was great fun to drive.

[47137]

This one came with a spare mechanism too. So I have one running engine (above), and also the motor, clutch, flywheel and bogie from another engine. The spare motor runs, and if the clutch is good (it seems to work if I twiddle it in my fingers) then it seems I might get a different bogie, and choose another prototype.

 

- Richard.

[Horsetan]

I have three clutches for experiments, and have always wondered what would happen if you put one at each end of a double-shaft motor....

[47137]

I have three clutches for experiments, and have always wondered what would happen if you put one at each end of a double-shaft motor....

I suspect they would engage and release at different times, and the running would be too difficult, especially with a load on. However, it would make for an impressively long engine - Garrett anyone?

 

- Richard.

[47137]

Thinking of something a little more practical, the wheel centres of the MZ bogie are identical to those of a Class 66 in 1:87 scale. So if I ever stumble upon a non-running Mehano or whatever specimen, there is an interesting future project. I suspect I should begin with some kind of spare trailing bogie (anything really) and build up an experimental chassis to try out the spare mechanism.

 

- Richard.