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Super Modulator
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Over on another forum, there is a heated debate on how blind drivers affect the pulling power of a model loco.

It brought some interesting points to light before several posts were deleted.

My friend, Ted Doskaris, posted some pictures showing how a 50 year old Lionel loco implemented a blind center driver, and illustrates the difference in tread width in this implementation.

Here's one of his pictures from the page on my web site:


Here is the URL for the entire page, showing the contact of the driver (or lack of) on the rails: Web Page on Lionel Adriatic with blind center driver[/b][/b]
The intent of this topic (which may wander of course
) is to invite discussion on people's experiences with blind drivers on their locomotives.

Regards, Greg
 

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Nicely

Often in models, not at all 'cause they're made smaller so they don't really touch the rail.
 

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I have/had three models with blind driver. Two are O gauge, one is G. The O gauge ones are a 1950s 2055 4-6-4 hudson. No problems, she's got magentraction. The other O gauge is a new MTH EP-5. Because it runs on tight curves, they made only 4 of the 6 wheels per power truck with flanges. It also has traction tires, so no problems. The third is a Bachman Big Hauler 4-6-0. Not much pulling power, but that'd be more attributable to the gearing not being all that great, rather than slipping due to loss of traction.

Frankly, until we see better, closer detail pictures, I think this is all pure speculation. What I can pull on my railroad will be a lot less than on most others, due to my grades. If a particular locomotive does not pull enough, I will add weight or decrease my train length. Not a really big deal. As I stated in the other thread, the blind wheels look wider than the flanged ones. It also looks like they are touching the rail head, but a real test should be simple enough. I think that in curves, yes, the flange will help increase the friction between the wheels and the rails. That can be a good and bad thing. If all wheels are flanged, that limits the minimum radius, a key factor in the marketing strategy of this particular locomotive.

It doesn't really matter, since the flanged wheels are to be included, so I can change them out if I really want. Actually, I really hope that Aristo makes the main driver have the right size counterweight!!
 

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Interesting.

Let's say you have 10 pounds of weight in the loco.
Let's say it's a 4-6-0.
IF you have center drivers blind and smaller diameter, the weight on 1 and 3 is 5 pounds if properly balanced.

If you have all 6 drivers flanged and in sprung contact, the weight per axle is 3.333 pounds (if properly balanced).

Which unit will have better tractive effort?
 

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Both will have the same tractive effort...tractive effort is only related to the weight on the driven axles.
 

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Havoc,"Both will have the same tractive effort...tractive effort is only related to the weight on the driven axles."

Soooo, since tractive effort is only related to weight on the driving axles, then doesn't that mean that the 4-6-0 with #2 axle blind and slightly off the rail thus have more tractive effort that a fully sprung, fully flanged 4-6-0? Since in TOC's post the 4-6-0 with #2 blind has 5lb traction with proper balance where as the 4-6-0 with full flange has 3.33lb traction with proper blance.
 

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Posted By Havoc on 10/07/2008 1:03 PM
Both will have the same tractive effort...tractive effort is only related to the weight on the driven axles.

What did I just say?
The issue is there is LESS weight on each driver when all three make contact.

Granted, the entire weight is on the rails, and with rod locos, the power is transferred, but you have gained nothing.

You still have the weight, which has remained constant.

Now, two trucks, like oh, artics, logging, diseasemals, then you've got balance issues.

Even then, I recall my days in 2-rail "0", we balanced the engines on a balance beam, and since the available weight was centered, they out-pulled those locos that simply had weight thrown at them.

I do that with some large-scale locos, and get impressive results.

If all drivers will break loose at a specific load with 3.3 pounds per axle, what will it do with 5 pounds per axle?

Here's an interesting tidbit:

A Bachmann 4-4-0 will out-pull a Bachmann 2-6-0 Centennial, same motors, gears, driver diameter and weight.
Used to do it all the time until I retired both units.
 

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My AristoCraft C-16s have both center axles blind. But, other than the flanges, the "tires" measure out the same diameter. They are a bit thicker in width at the tires. When the trains runs down the track, all tires appear to touch the rails and they are electrically conductive.

Seems to me that no train goes perfectly straight down the rails even when going straight down the rails so there will always be times when the flanges touch. With no flange to touch, this bit of tractive effort is lost. And because the weight of the engine is not sitting on the sides of the flanges, touching, or not touching, does nothing to change the weight on the wheel loading.

BTW, the real C-16 also used the two center axles with blind flanges for the same reason, tighter diameters are possible.
 
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What a timly thread Greg, after seein Jim C.s K-4 an Martys layout last week i went and dug out the 2 i have left and lube them up to run tommarrow. i noticed that there was a center blind driver on these? never saw that before that might explain why the dont pull 10 heavyweights?also you can see by the video that the center drivers are pritty clean, no wear marks. the enigines only have a hours run time on them but never noticed the blind drivers before. talked to Cliff at AML couple months ago about pulling power he said these were designed for speed not power. i said i want to pull a decent train with them? so Cliff sent me free of charge some new motors that are geared way lower than whats in there now. he said it should pull great but i will loose a little top end speed with it but thats ok...also if you or Jim are watching, notice the center gear box moving around? does yours do that? bolth of mine do, not sure why?
Nick..
 

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Ach, blind drivers are not the problem with traction effort. Tractive effort is the force that a locomotive is capable of exerting, though its coupler, to pull a train. This is affected by the number of drivers and the weight of the locomotive. Tractive effort is NOT affected by blind drivers. Locomotives do not move by the friction of the flange to the rail. The flange should not even touch the rail. Yes, the flange does touch the rail, but it is due to the car sliding side to side. The tire of the locomotive is what moves the locomotive. The tire is the flat part of the wheel that makes direct contact to the rail. I should add that the tire is not completely flat (like what our G-Scale wheels are), infact the tire is tapered with the flange side being a wider diameter than the non-flange side. This taper is what keeps the locomotive, and rolling stock, on the rails. The flange is their for added safety.
 

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Nick,
The K-4 pulled nine of Marty's USAT UP streamliners without even breathing hard. I have the 19.5:1 geared motor installed. Like yours, it came with a 11:1 gear. Traction was not a problem at any time on Marty's layout. I have steeper grades and tighter curves on my layout than Marty. With the original gearing, the K-4 would slip the drivers pulling 14 freight cars. With the present gearing, it has no problems. The biggest difference is in startup. With the previous gear, sometimes the loco would pop the polyswitch on the throttle. With the new gear..... NO Problem. Whether I needed it or not, I added 1.5 lbs of additional weight to the boiler over the front driver.

The biggest problem I have encountered with the blind drivers is for the driver to drop on the inside of the rail if a curve/switch tighter than 8ft diameter is attempted. Exiting the curve, the driver then "pops" up and usually takes other drivers with it in derailing.



JimC.
 

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Discussion Starter #12
Hey Nick you old troublemaker! Ha ha ha!

Yes, blind driver, but all drivers are sprung and contact the rail well. I noticed the pulling power on mine was not what I had hoped.

First, the stock gearing was way too high, 11.5 to one (the motor has an integral planetary gearbox) . Jim Carter got a 25:1 motor and he's happy. I got the 38:1 motor and now the loco will pull stumps.

Also, you can add 3-5 pounds of lead into them easily, and it makes a **** of a lot of difference.

See my site for what I have done to mine, there are several things you want to do.

I believe that the major thing that worked against traction, besides the way too high gearing, was the stainless drivers are very smooth and slippery. Nothing to be done about that.

See my pages:
[url]http://www.elmassian.com/trains-mainmenu-27/motive-power-mods-aamp-tips-mainmenu-35/aml--accucraft-mainmenu-242/k4-mainmenu-243 [/url]

There are 3 pages, see the menu on the left side... Be sure to visit at least the K4 misc info and tips...

I added 5 pounds of lead to mine, and with the lower gearing it works great. You really cannot add weight to the stock gearing, you will actually overheat the motor.

Regards, Greg
 
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Jim, Greg,
AAAA you guys left me hangin on this one, i didnt know about how much improvment there would be by changing out the motors? i have them so i will put it on the to do list, So tommarrow i guess my job will be to see if i can burn up the old motors and see how much they can pull?? he he he but i will also be bringin one of the new hudsons as well and i know that will pull stumps, should be a great run day. i have the new k-4 motors in my hand how do i tell whitch ones cliff sent me? all thou either should be a great improvement .... OK so now im goin to go some were and cry
cause you guys held out on me ... HE HE HE......
Nick..
 

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Super Modulator
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Discussion Starter #14
Nick, the gear ratio should be on the label on the motor, take a look... if you can't find that, then send me the model number of the motor and we can look it up.

Regards, Greg

p.s. you should have read my site first!!!! All this info was there all the time... ha ha ha... just poking ya!
 

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Nick,
When you decide to change the motor, after you take the old one out, go to the hardware store and replace the motor attachment screws with hex head bolts. I guarantee that you won't regret it. Of the three motors I had in the K4 while I was experimenting, two used ASA bolts/screws and one used metric screws. I would suggest a place like Ace Hardware or Lowes to find the correct replacement bolts.

JimC.
 

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Posted By Curmudgeon on 10/07/2008 12:32 PM
Interesting.

Let's say you have 10 pounds of weight in the loco.
Let's say it's a 4-6-0.
IF you have center drivers blind and smaller diameter, the weight on 1 and 3 is 5 pounds if properly balanced.

If you have all 6 drivers flanged and in sprung contact, the weight per axle is 3.333 pounds (if properly balanced).

Which unit will have better tractive effort?

I always hated "Story type" math problems. The always started out "Farmer Brown has six cows."
 

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Did you ever get to Physics?

"Consider a spherical cow of uniform density..."
 

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The physics calculation that always baffled me was the problem where they PROVED that tire size and width makes absolutely NO difference in automotive handling... (except that in the real world it does... go figure)
 
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