Weighting Locomotives Traction vs. Wear

[brokenrail]

I just wanted to see some opinions we have about the benefits of added weight to our locomotives vs. wear and tear.I have added weight to a few of my Bachmann switchers and gained positive traction along with better electrical pickup in my Alco s4 and 70 tonner ,but  the same time both my s4 and s2 developed a wear ridge on the right rear wheel right down the center like the axles are not moving lateral since the axle gear is off center t words the  right rear under the cab where the odd wheel wear on both is occurring.The weight is behind each sideframe on that little porch between both wheels.You can get a quarter oz on each side along with a flat weight above the decoder and a some in front of the front headlight.These seem to help balance out the weight since the factory frame is very unbalanced with most of the weight in the cab area. Anybody know what material these wheels are made from that would wear so quickly? This wheel ridge does not seem to effect performance yet ,but the outside half of the wheel is probably a few thousands smaller now. Also does Bachmann have a opinion of adding weight to its locomotives ? Curious?
Johnny

[jward]

while added weight may be desirable in steam and diesel switcher type locomotives, I don't see the need for it in road locomotives. with diesels you can always do like the real ones do and add another unit if you need the extra pulling power. when adding weight you have to be careful not to overtax the motor lest you make it weak. this was a problem I had with some older athearns until I regeared them. changing from a 12:1 to a 32:1 gear ratio kept the motors from bogging down to the point the wheels wouldn't slip.

that said, in my 40+ years in the hobby I have never worn out a metal wheel tread.

[brokenrail]

Same here with the wheel wear issue.This is a first.I will see if I can get a pic of this to post. The wheels on the alco s2 an s4 seem to be unique to them. I installed a few of those super gear kits .One in a switcher with those metal sideframes.Remembered it really gave that switcher the correct gear  for switching cars, not top out at  150mph and bog at slow speeds that the stock gears created.Was not so good in a road engine unless all of them were done with the new gear.
Johnny

[rogertra]

while added weight may be desirable in steam and diesel switcher type locomotives, I don't see the need for it in road locomotives. with diesels you can always do like the real ones do and add another unit if you need the extra pulling power. when adding weight you have to be careful not to overtax the motor lest you make it weak. this was a problem I had with some older athearns until I regeared them. changing from a 12:1 to a 32:1 gear ratio kept the motors from bogging down to the point the wheels wouldn't slip.

that said, in my 40+ years in the hobby I have never worn out a metal wheel tread.

I agree with jward when it comes to the diesels, just add more, and generally with his comments regarding steam.

As my through train length, Vs wayfreight train length is, 20 cars + van, it's important that my heavy steam, my 2-10-2s and heavy 4-8-2s are able to pull 20 car trains alone after all, that's what they would have been designed to do.  

However, I usually, as a matter of course, add weight to all my steam no matter from what manufacturer.   I try to keep the weight balanced around the centre of the driving wheels as this improves traction and is less likely to cause derailments.  I do this by adding weight in inconspicuous places.  The roofs of cabs, inside domes and sandboxes, between the cylinders in the smoke box saddle and adding an air tank full of weight to the pilot deck of all my steam are the usual places.  You'll notice most GER steam have a pilot deck air tank as standard.

I think the only locos I haven't added weight to are the two Bachmann 2-6-0s as they are only used on one branch line hauling a two car passenger train and less than 10 car wayfreight.

The usually accepted limit for adding weight is the ability of the locomotive to spin its wheels.  If it cannot spin its wheels, then you've added too much weight.


Cheers.


Roger T.

[K487]

With one small exception, I fully agree with Jeffrey and Roger. 

The exception is that I like to stuff as much weight inside the engine shells that I can, and do it so I get the total weight of the engine equalized (50% over each truck) as much as I can (for the best pulling power.)  And in my 54 years of model railroading I have not been able to put enough weight under the shell to stall any any of the HO drive wheels or motors.  (I sort of feel like and sometimes operate as I have seen more than one Trainmaster/Dispatcher do - put the maximum tonnage permitted behind the engines, add 3 to 5% more, and go for it - i.e. let the engineer fight it out!)

PS - Once in a while I take one of my B'man SD40-2s that I've added weight to and equalized it, put it by itself on the head end of a 65 car train with 22" radius track curves, and run the train forward and backwards.  This engine handling comes real close to the mimicking the way I've seen the way (as a brakeman) the 1-to-1 scale engineers handle their long (120 to 150 car) trains successfully - including bunching the slack and being VERY careful with the throttle and the brake handle.

K487

[brokenrail]

I Have put together some mixed freight on the layout where the train spans a good 25 feet the layout runs mostly flat until it hits a s curve wit a 42 radius curve that peaks at the middle of the s curve then drops back down to the other half runs about 6 ft straight hit another 42 radius curve that is a 2 percent grade back up to the flat .So at cretin points in this layout the train will push itself if it is long enough to get through all that.It can be done without increasing the throttle most of the time .This took a wile to get right adjusting everything.Most of the time 1 good weighted loco running well can do it alone.This is a good test to see what they are made of. I will run doubles when not in the test mode to make it right, smooth and steady creeping along.Running sound locos that have that load sense change automatically really shows off how accurate they can be with the sound to load change in this section.If the loco is not weighted well we will have to send in a pusher/helper to get them through 
Johnny

[K487]

Johnny, it looks like you'd make a better engineer than me (and maybe have more fun too) - you have undulating track!  That's a fine train engineer teacher.  And I like your fix for a stalled train - send in a helper/pusher engine.

I'm more of the laid-back "engineer" - let the trains slowly move around on flat track - except every once-in-a-while I do come down with a bad case of brain-belch and HAVE to crank up the power packs and let 'em rip.

K487

[brokenrail]

I don't know about being so better or worse.It took about 5 years and  many adjustments to get one area figured out after I really botched phase one that did not allow progression in the design of the tables and the grades and after finding the formula of 30 degree angle in a 5 foot span to grade down using a 29 radius curve at the top of the s curve to drop grade .This is also the end of the we call it a bent dog bone layout design. Once in a wile I will open the throttle ,but try to keep within reason to check if it works at all speeds.Using a pusher for a stalled train in a tunnel  beats crawling under to the access holes to fool with it .Let the pusher go to work for you. Just have to be careful not to push to hard .Dcc makes this kind of fun possible with the independent control of the pusher. NMRA  weight specs for rolling stock seems to make them heavy ,So a well weighted loco is important. Is center of gravity in weighting effect traction?? Never could really grasp that one.
Johnny

[electrical whiz kid]

On some of my brass locomotives-some of which have been around quite a while-I have noticed wearing on the drivers; evidenced by brass showing through the nickel silver.  Now, I am not really sure if the drivers are nickel silver plated, or if it would be a thin tire-I am 71, so the eyes-you know?

On curves:  a long time ago-around 1970, there was an article in 'Model Railroader' by Linn Westcott dealing with radii.  He brought the concept of 'easement curves', which works very well.  I think that, in use with super-elevation-especially towards the apex-this might be a pretty good idea.  The only thing I would be  hesitant to do is use turnouts on that type of curve.

Rich C.

[K487]

Rich, just a thought about your, "I think that, in use with super-elevation-especially towards the apex-this might be a pretty good idea." -  If you run long trains with super-elevated track, be very careful - you can string-line trains real easy this way (just like some of the 1-to-1 trains do.)  Don't ask me how I know this.   So, I don't have any super-elevation at all.

K487 (Doug)

[jward]

I have never built a layout without grades and curves, I don't think i'd be interested in running a layout without them. I am also not a fan of superelevation. it is very easy to roll a long train over on a superelevated curve. what I have found instead, is that proper operation of your trains requires careful attention to the lateral elevation of your track. sudden changes, or twists, in the relationship of the elevation of the two rails can and will cause derailment problems. the longer the wheelbase of the engine the more likely this is to occur. where the wheels hit the ties and where they actually climb the rail may be quite a distance apart. usually, if you have problems they can be traced back to the point where the wheels climb the rails, not where they fall off onto the ties.

I have also found that the use of grades helps keep my train lengths manageable. longer trains mean more problems, just the same as on the real ones.

[ebtnut]

Re:  Worn tires.  Many brass locos had nickle-plated brass tires.  Depending on the quality of the plating process and the thickness of the plating, some wear much better than others.  Driver tires have been made in brass, nickle-plated brass, nickle silver, and steel.  Plain brass has the same issues as brass track - the metal oxidizes quickly, affecting electrical contact.  Nickle silver is much better.  Nickle plating, if done well, is also good.  Stainless steel is OK; plain steel can oxidize (rust) over time. 

[rogertra]

I have never built a layout without grades and curves, I don't think i'd be interested in running a layout without them. I am also not a fan of superelevation. it is very easy to roll a long train over on a superelevated curve.

[Snip]

I have also found that the use of grades helps keep my train lengths manageable. longer trains mean more problems, just the same as on the real ones.

I do use superelevation and transition curves on all visible trackage and always have done.  Strictly for looks mind you as really, in the small scales, they do nothing to assist running.  After all, you can run an HO train set around 18" set track curves at near warp speed and it will stay on the tracks.  My staging yard radii are around 30" so no superelevation nor transition curves. 

Mind you, 20 cars is the longest train I run.

And I agree about grades.  They not only keep train lengths under control (ruling grade) but also make the railway much more interesting to operate.

20 car through freights are powered by two diesels (One possibly a dummy) or one 2-10-2 or one heavy 4-8-2.  Every now and then an eastbound steam powered freight of 20 cars or so may be powered by a light 4-8-2 or even a 2-8-2. Then they get a 2-8-0 head end helper added at Farnham (Modelled Yard).  West bound, any helpers are removed at Farnham.  Somewhat following CPR practice in the area I model.   Only in southern Quebec,  the helpers were added and removed a little further down the line.   Ads some twists to an operating session. 

Cheers


Roger T.

[brokenrail]

Roger,
I  like that interesting twist in your description. I think it  adds a great dimension to the operation, to be able to make it keep er simple ,but work it a little with the imagination adding and removing helpers. Sometimes  mine is not done purposely  adding those helpers ,but it does make it look like I know what I am doing in my case found a way to make it look good when I overload my train ,or load it the wrong way ,or hit the grade at the wrong speed so that the trains momentum will get it out the other end of the tunnel with the least amount of power at he head end.
Johnny

[jward]

where I live helpers are a way of life, both major railroads use them to get trains over the mountains. so it is natural to try and model this. it really helps to have flawless trackwork when you are pushing on the back of a train.

one thing not commonly known is that the real railroads use helpers to keep slack under control. if you are running long trains in an area with a lot of short up and down grades, the slack action in the train can wreak havoc on the equipment unless it is somehow controlled, running the helper with just enough power to keep the slack bunched saves a lot of time and money spent on broken coupler knuckles. during my time on the railroad I witnessed firsthand the awesome power that slack runout can cause, including one case where it broke a locomotive's underframe.