Drag/Inertia Car

Fred2179G

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20 Apr 2017
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This little beast turned up today, from Peter K's estate. It's essentially a flywheel car that makes a live steam loco work harder to accelerate or slow down, thus simulating the interia of a real train.

20200812_171933_drag-car.jpg


20200812_171941_drag-car.jpg


Those look like solid steel flywheels and the ends of the 'box' are solid cast iron. The thing weighs a ton - intentionally to make sure the wheels grip and it doesn't just get dragged. One flywheel was disconnected (the gear was moved on the shaft so it didn't get driven.) That may be a way of making it work with only 1/2 the inertia!

I have no idea who made it but it is a nice job. I will be taking it to Jerry's SC&M to see if (a) his track can handle the weight and (b) whether it works. I have a little english train of Thomas stuff with a 'Countess' to pull it. If it works, I'll have to find a Thomas box van to hide the internals.
 
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AndrewK

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6 May 2019
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This little beast turned up today, from Peter K's estate. It's essentially a flywheel car that makes a live steam loco work harder to accelerate or slow down, thus simulating the interia of a real train.

20200812_171933_drag-car.jpg


20200812_171941_drag-car.jpg


Those look like solid steel flywheels and the ends of the 'box' are solid cast iron. The thing weighs a ton - intentionally to make sure the wheels grip and it doesn't just get dragged. One flywheel was disconnected (the gear was moved on the shaft so it didn't get driven.) That may be a way of making it work with only 1/2 the inertia!

I have no idea who made it but it is a nice job. I will be taking it to Jerry's SC&M to see if (a) his track can handle the weight and (b) whether it works. I have a little english train of Thomas stuff with a 'Countess' to pull it. If it works, I'll have to find a Thomas box van to hide the internals.

I really like this! Particularly as it will work independently of the locomotive.

I wonder how easy it would be to make a replica. I think all the parts in the photos would be quite easy to source (I already have lead weights). The only challenge would be the flywheels - but what about toy gyroscope flywheels?
 
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DGE-Railroad

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I really like this! Particularly as it will work independently of the locomotive.

I wonder how easy it would be to make a replica. I think all the parts in the photos would be quite easy to source (I already have lead weights). The only challenge would be the flywheels - but what about toy gyroscope flywheels?


It looked to me as though the flywheels were just a sliced piece of steel rod, as Fred suggested

It'd be interesting to get the flywheel dimensions plus the diameters of the 3 'distribution' gears. They look pretty familiar. Could they be Meccano?

Edited to say the 'distribution gears' appear to be:
Main shaft gear - 64T
flywheel shaft gears - 28T

The toothed pullies and belt are readily available from bearing suppliers (and more, given the prevalance of 3D printers these days!)
 
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Paradise

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28 Jan 2010
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You can also get the slo-mo and put it in a tender or car for the same effect. There is a kit available for that although fairly pricey.
The one above is a nice build for the do-it-yourself type of person on a budget.
http://smallsteamperformance.com.au/



IMG_4425.jpg
 
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DGE-Railroad

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You can also get the slo-mo and put it in a tender or car for the same effect. There is a kit available for that although fairly pricey.
The one above is a nice build for the do-it-yourself type of person on a budget.
http://smallsteamperformance.com.au/



IMG_4425.jpg

A very good point and well worth mentioning. As you say though, the cost does become pretty steep for a non-loco-specific option once shipping and import are factored in. There's no doubt the SSP units are beautifully made and great quality though.

I contacted Terry this year about the wagon kit but he's moving house at the moment and is therefore tearing down and rebuilding his workshop environment. I believe he's still taking orders but from what I remember, nothing's shipping until next year.
 
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Fred2179G

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Ernie Noa, who made this drag/inertia car, posted on MLS:

"I made 19 of these inertia cars in the late 1990s. Bob Paule help with some of the cutting on the steel. Most everything was cut with a hacksaw and file. Turning the round weights was a challenge on the Taig lathe I had. Some were made with dual flywheels and some with just one flywheel. The project used all the material. They were all sold at Diamondhead about 1998. The first one was made from an old film processing unit that was scrapped. The plans were published in Small Scale Steam Hobbyist in the early 2000s As John said they were based on an inertia car the Bob Paule, Kevin O'Conner and Larry Bangham "
 
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tac foley

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You can also get the slo-mo and put it in a tender or car for the same effect. There is a kit available for that although fairly pricey.
The one above is a nice build for the do-it-yourself type of person on a budget.
http://smallsteamperformance.com.au/



IMG_4425.jpg

It's a nice piece of engineering, but for a landed price of just under £300 - per each - so it should be,

The inertia wagon can go behind any loco....
 
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DGE-Railroad

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I was thinking some more about the whole inertia car thing. One of the main drawbacks with a mechanical solution is the noise byproduct of the geartrain and the rotating flywheel.

I remember there was a hard-disk platter, movable magnet solution devised by someone although I haven't witnessed the operation.

I wondered though if there was a simple-ish electronic solution to a momentum/inertia wagon.

What if axle 1 on a wagon drove a stepper motor to act as a generator, which in turn supplied current to a DC 'drive-brake' motor on a second axle.

Using a small potentiometer in the supply to the second motor would allow you to set the braking effect by reducing its speed.

Is that a feasible idea, or have I ignored something completely obvious (very likely!)?
 

tac foley

Registered
11 Apr 2017
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Near Huntingdon, UK
I was thinking some more about the whole inertia car thing. One of the main drawbacks with a mechanical solution is the noise byproduct of the geartrain and the rotating flywheel.

I remember there was a hard-disk platter, movable magnet solution devised by someone although I haven't witnessed the operation.

I wondered though if there was a simple-ish electronic solution to a momentum/inertia wagon.

What if axle 1 on a wagon drove a stepper motor to act as a generator, which in turn supplied current to a DC 'drive-brake' motor on a second axle.

Using a small potentiometer in the supply to the second motor would allow you to set the braking effect by reducing its speed.

Is that a feasible idea, or have I ignored something completely obvious (very likely!)?


Hmmmm, that way you could get the locomotive to provide the power to drive itself, and the more it slowed down, the more electricity it would generate, regeneratively-speaking, so that by the time it had come to a full stop, it would be generating enough power to drive it as fast as track and curves would permit!!

Maybe...............................:shake:
 
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DGE-Railroad

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Hmmmm, that way you could get the locomotive to provide the power to drive itself, and the more it slowed down, the more electricity it would generate, regeneratively-speaking, so that by the time it had come to a full stop, it would be generating enough power to drive it as fast as track and curves would permit!!

Maybe...............................:shake:

I think there's probably a big flaw in the theory somewhere but my electonics knowledge is far too lacking.

The whole thing needs boffins to turn such high-level, wavy-hand 'blue sky thinking' into something workable and to deal with all the difficult physics :D
 

PhilP

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Well, if you can make the whole system with superconductors (working at room temperature, of course) once you put a little 'kick' of current-in, it will run forever! :rofl::nerd::rofl:
 
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DGE-Railroad

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Well, if you can make the whole system with superconductors (working at room temperature, of course) once you put a little 'kick' of current-in, it will run forever! :rofl::nerd::rofl:


I'll take that as a no then... :D :giggle:
Cheers Phil!
 

tac foley

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Uh, Mr DGE - my response to your posit was in the nature of a gentle leg-pull, not a serious suggestion of how one might negate the laws of the conservation of energy. I thought you realised that.
 
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DGE-Railroad

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heh heh, Sorry Tac, yes I did. My reply was typed in humour. I should probably have added a few more chuckles :D
 

Fred2179G

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What if axle 1 on a wagon drove a stepper motor to act as a generator, which in turn supplied current to a DC 'drive-brake' motor on a second axle.

Using a small potentiometer in the supply to the second motor would allow you to set the braking effect by reducing its speed.
Well, nothing like re-inventing the brake-motor. When I was young and foolish, I raced slot cars and rewound the motors and controllers. One feature added during my years was braking - when you lifted off the throttle (potentiometer) it disconnected and placed a short circuit across the motor. It was spinning and generating back-EMF, so it had to work harder as it wasn't generating into an open circuit. The amount of braking was, of course, proportional to the speed. I even found a way to drive a generator in my hand controller (though I never buiit one,) that would apply reverse voltage and make the braking action stronger.
 
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Fred2179G

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I remember there was a hard-disk platter, movable magnet solution devised by someone although I haven't witnessed the operation.
Bill Allen in California, who builds fancy and outstanding live steam engines from scratch, had this to say:
"I have an inertia car that my friend Dennis made for me. It uses an Eddy Current with magnets between two hard drives. It works well, is adjustable, and is cool to watch.
I use it all of the time when testing engines.

But, the real gem is the governor car he made which has little sprung brake shoes that fly out and are adjustable for the speed. What is nice is that it works behind almost any engine as there is no resistance till it reaches speed. It allows almost the same speed uphill as down hill. Both cars have o-rings on the wheels for traction and some lead for weight.
Dennis also made a generator car for a friend that works well also. "


I think the question becomes: what are you trying to achieve? A "drag" car will make the loco work harder. an "inertia" car will make it work harder accelerating and slowing. A "governor" car will prevent runaways on hills.
 
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DGE-Railroad

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Dennis Mead came up with some fantastic prototypes. His rotary-telephone governer device with the mamod-type flywheel is a thing of physical AND mechanical beauty!

I added his disc-platter design to my list of projects purely out of interest.

20200829_100838.jpg

Personally speaking, I'm after a slo-mo style device: slow speed running and pickup by simulating a large load. I dont have any gradients to worry about. I'll probably just ensure I have a heavy set of stock to pull behind it. That'll tick the slow starts and noise boxes without additional hassle

I also reached out to Paul Bailey about David's mega-inertia wagon again purely because i was interested in the design but it sounds as though that has long since gone. I still have a picture of it - belt driven dual flywheels from articulated bogies, one flywheel had a fan and it required a strong engine to pull it
 
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