Adding weight to tenders

Model Railroader General Discussion (Model Railroader)
1

Hello Railfans!

While reading another thread (bad electrical pickup on a Bachmann tender) I came across a procedure Ive known about, but dont do. Adding weight to a steam loco tender to enhance its electrical contact to the rails.

When i have this electrical problem I come at it from an electrical path problem view (fix the path) and that works. Im quite sure adding weight to the tender would work too, i just dont do that.

My questions are following, aside from it gaining better electrical performance, how does this added weight affect the pulling power of the model?

I sometimes use extraordinarily weighted cars (test cars not layout cars) to simulate the weight of a long train when breaking in or servicing locos. My loco fleet is unaltered, loco or tender, concerning added weight. I would add weight over the drivers to increase TE when a layout of size becomes available.

However, Im curious. When i use the loaded cars, i see how the model works under the load. Adding weight to your tenders would seem to decrease your pulling ability because the model now weighs more as a stand alone unit (no train). Thats more work on the motor than in its stock oem form and theres no train behind it yet.

Have any of you noticed this? Has this posed problems? Also consider, some of you may use correctly weighted cars too. Now thats more weight in tender, plus weighted cars. That HAS to drop the ‘tonnage ratings’ on your locos. Does it?

I know wre talking small weight amounts here, but it all does add up, and you can measure it on a volt and amp meters.

(I also forsee heat problems too… anyone?)

Thanks for the info!

PMR

2

I weight my tenders, but I also run short trains, 12 car maximum. I also have no grades.

Any reduction in pulling power does not effect me, but it makes sense that there would be some loss.

-Kevin

3

The tender forms part of the pulled load. More weight in the tender reduces the maximum available weight for the consist. Diesels had the advantage of fuel weight adding to traction. Steam locomotives with tenders lose net pulling power. Tank engines were popular for switching in part because they had more pulling power available than tender equipped locomotives of the same power.

4

I add weight to all my tenders but for a different reason. Most stock tenders are so light they wobble and I don’t like wobble on my tenders. I add about 4 to 6 ounces to my tenders but then again I add 8 to 10 ounces to my locomotives too.

A typical Rivarossi Cab Forward has about 2.8 ounces of drawbar out of the box. My weighted Cab Forwards have 5.8 ounces of drawbar or more. You can’t add weight to a Rivarossi using the original Rivarossi motor, it will overload and the heat from the motor will melt the plastic boiler or cab. I remotor all my locomotives with can motors.

The added weight to the boiler does increase the wheel contact to the rails but stopping the wobble was my primary reason. Good all wheel power pickup trucks work with out added weight.

Mel

My Model Railroad
http://melvineperry.blogspot.com/

Bakersfield, California

I’m beginning to realize that aging is not for wimps.

5

Mel’s got a point here. Let me elaborate a little more. Steam loco models tend to be front heavy, if you consider a standard tender behind. This was especially so with brass locos. More modern cast, mass-production steam should have tender weighted about right, if designed well. YMMV there.

I was a bit of a skeptic on this matter for the same reasons already mentioned. Life can be more complicated than theory. The extra mass and non-linear application of power in a typical steam model tends to horse the tender around, affecting contact. I suspect this is in part behind the “wobble” he discusses wanting to dampen.

An old timer first suggested trying it to me. It worked well to my surprise. I understand the sentiment to “fix all the contacts” but adding weight is much more convenient in many situations. Assessing a model to buy? You’ll not get a chance to go over the electrical paths and improve them, but you may be able toadd an external weight on your test run. If it improves contact, you know that some tinkering after purchase should fix it right up, an appropriate time to consider such a major cleaning or mods.

Made me a believer. Don’t use weight as a crutch, but you can find it helpful in many situations where it is a useful fix keeping in mind its limitations.

6

If you are concerned with the loss of pulling power in a properly weighted, pivoted, and ‘side-bearinged’ wobble-free tender, you could always adapt something like Stanton drives, put them on a control-only decoder for DCC and consist them with the locomotive, or do a little electronic ‘matching’ if on DC. Or otherwise motor some or all the axles for additional pull…

7

I run long steam powered trains, have done extensive pulling power testing, and I weight all my tenders.

Adding between two and four ounces effects pulling power in the obvious way, it reduces it by one car.

Why is adding weight necessary and good?

Most steam locos have longer rigid lengths than their tenders, creating lots of side pull at the drawbar in curves. So like Mike said, tenders get horsed or bullied around.

Add to that fact the wires between the locos and tenders in recent decades which offer resistance to movement and can have lifting effects on tenders, and the need for extra weight is clear.

The extra weight is not just about electrical contact, it is about smooth, solid tracking which has the side benefit of more reliable electrical contact.

Given the dynamics of the coupling between the loco and tenders, most tenders are too light out of the box.

Sheldon

8

I add weight to all of my tenders, but I also add weight to all of my locomotives.
As Sheldon mentions, extra weight in the tender is basically equal to one freight car.

I don’t normally run long trains, as I have lots of grades (the major ones long and at about 2.8%) and lots of curves (reasonably wide-ish on the mainline at 34" radii or more). If the train is long or exceptionally heavy, I simply add more locomotives…perhaps doubleheading the front end, and, if necessary, adding a pusher (or two).

As far as I’m aware, pretty-well all decent-quality steam locomotives offered nowadays have all-wheel pick-up, and my for my older ones, both brass and cast metal, it’s not difficult to add it to them, too. In most cases, I also add all-wheel pick-up to the tenders. I also run all of my tenders with “live” coal loads.

Wayne

9

After re-reading the original post several more times, I have few more comments.

Like Mel, I have added additional weight to a number of locos to improve their pulling power with no ill effects. I do not have any old locos like Mel’s Rivarossi models.

My steam loco fleet consists of models from Bachmann/Spectrum, Proto, BLI, more recent Rivarossi, Mantua, some older brass and even IHC.

In addtion to additional weight to various locos and most tenders, many are kit bashed in various ways including a good number of tender swaps.

In fact, most of my steam locos are Bachmann/Spectrum and even more of my tenders are Bachmann/Spectrum.

While I have conducted lots of tests on the pulling power of locos and the rolling resistance of rolling stock, I have never bothered with measuring motor currents.

I have never overheated or damaged a motor with addtional weight or in use pulling trains. I run DC and my max voltage is just under 14 volts.

I know what my locos will pull and when that is exceeded, like Wayne, I simply add another loco. Most of my trains are double headed.

I have been known to redesign a drawbar or two to improve operation.

These kit bashed Bachmann locos have a draw bar that connects ahead of the attachment of the trailing truck to better deal with the offset forces of the long firebox and cab of thse locos.

Most of the time weight is the answer because the problem is bad tracking, not pooly designed pickups.

Sheldon

10

As most of you know I have a lot of Rivarossi articulated locomotives with oil tenders, the tender truck detail is very nice but for power pickup they’re very close to worthless.

I replaced all my Rivarossi tender Buckeye trucks with metal trucks, the Precision Scale trucks (32346) are very good at power pickup but constantly derail, I don’t recommend them. The Bowser Buckeye (35107) trucks look and work great.

I add 4 ounces to the oil tenders that stop the wobbles and most likely really helps with power pickup.

It’s been awhile but I think the Rivarossi tenders wobbled before any of the Mel mods.

This is a Mel kitbash Cab Forward to a Southern Pacific AC-9 with 10 ounces of added weight increasing the drawbar to a bit over 6 ounces, with dual Canon EN22 motors.

By using #8 birdshot it is easy to spread out the weight for proper weight distribution over the drivers.

Mel

My Model Railroad
http://melvineperry.blogspot.com/

Bakersfield, California

I’m beginning to realize that aging is not for wimps.

11

Kevin, this would be interesting to show, both in an ‘annotated’ side view (showing the line of the new drawbar and its ‘pivot axis’ both in the locomotive and at the tender) and in detail shots of the actual components. Note that as the drawbar moves from side to side, the trailing truck also ‘hinges’ under it so there is no fouling even on sharp curves.

This is interesting because it’s precisely the logic behind the American Arch articulated four-wheel trailing-truck design on the early Woodard Berkshires. And it leads to the perhaps ‘arch’ question: do you experience any difficulties backing these locomotives against a substantial load? This was a great problem for the Berkshires, as the truck would try to ‘cock’ sideways at the articulation points, and the steering at the abbreviated pivot point just at the rear of the driver wheelbase was much worse, with that l-o-o-o-ng polar moment of inertia out there behind, than what could be achieved in a Delta design at the extreme rear outside corners of the long firebox-and-cab overhang. (In practice I suspect your Delta trailer would have rear frame extensions on either side of the booster engine, and have progressive external rocker location devices right under the rear of the cab, radial to the swing, that would engage teeth on those extensions…)

12

I think you meant this for Sheldon.

None of my operating steam locomotives, except my Bachmann 2-8-8-4, have four wheel trailing trucks. The Bachmann EM-1 2-8-8-4 uses an amazing mount for the rear truck, and that locomotive can back through a 22 inch radius S-Curve with no problem.

My maximum train length is 12 cars, so no, I do not ever reverse against a substantial load.

Sheldon can probably answer all this better than I can.

-Kevin

13

I will take some pictures and answer the questions in a bit.

Sheldon

14

Hello Railfans!

Very interesting replys - thank you! Ok, lets review for a bit…

*Added weight in tenders increases electrical perfomance.

*Added weight in tenders decreases ‘tender wobblys’.

*Added weight in tenders drops tonnage rating by 1-2 cars.

The first one i think we can all agree on as its an obvious one to understand. Its been a long time fix.

The second i can also agree with. Though i have to admit, i find it suprising that so many of you have “wobbly tender syndrome”. I run mostly Riva’s in steam, IHC and a few old Mantua’s. None of which seem to have this problem. They track fine and therfore hardly ever wobble.

Sheldon raised a very good, unmentioned point - the wiring! And todays DCC models have alot more than their older ADC counterparts. I have run into this problem but it was easily fixed by relaxing and repossitioning the wires (both ADC or DCC). I didnt have to add weight. Good point though, as the wiring sometimes will ‘float the tender’!

Ive also never had a problem with drawbar swing. Matter of fact i usually pull mine closer for a more accurate look. So im not seeing any drawbar problems, luckily. Even on tight radii. Wiring can also hamper the swing - see above paragraph.

That leaves door number three above. And the reason i posted, mostly. It has been said the added weight only decreases tonnage by 1 car. maybe 2.

Given that i was reading 8 ounces for a tender alone i was thinking this would translate into about 5 to 10 cars lost in tonnage. Not one or even two maybe as stated.

Theres the amazement into this lil forray. In this, and the post this was based on, some of you add weight right out of the box just to be adding weight. And it seems like an atrocious amount too! 8 ounce tenders?? (on a side note, is this deterimental to turnout points? they are soft rail and easily bent under alot of weight.)

15

[quote user=“PM Railfan”]

Hello Railfans!

Very interesting replys - thank you! Ok, lets review for a bit…

*Added weight in tenders increases electrical perfomance.

*Added weight in tenders decreases ‘tender wobblys’.

*Added weight in tenders drops tonnage rating by 1-2 cars.

The first one i think we can all agree on as its an obvious one to understand. Its been a long time fix.

The second i can also agree with. Though i have to admit, i find it suprising that so many of you have “wobbly tender syndrome”. I run mostly Riva’s in steam, IHC and a few old Mantua’s. None of which seem to have this problem. They track fine and therfore hardly ever wobble.

Sheldon raised a very good, unmentioned point - the wiring! And todays DCC models have alot more than their older ADC counterparts. I have run into this problem but it was easily fixed by relaxing and repossitioning the wires (both ADC or DCC). I didnt have to add weight. Good point though, as the wiring sometimes will ‘float the tender’!

Ive also never had a problem with drawbar swing. Matter of fact i usually pull mine closer for a more accurate look. So im not seeing any drawbar problems, luckily. Even on tight radii. Wiring can also hamper the swing - see above paragraph.

That leaves door number three above. And the reason i posted, mostly. It has been said the added weight only decreases tonnage by 1 car. maybe 2.

Given that i was reading 8 ounces for a tender alone i was thinking this would translate into about 5 to 10 cars lost in tonnage. Not one or even two maybe as stated.

Theres the amazement into this lil forray. In this, and the post this was based on, some of you add weight right out of the box just to be adding weight. And it seems like an atrocious amount too! 8 ounce tenders?? (on a side note, is this deterimental to turnout points? they are soft

16

Here are some photos of the drawbar setup on my freelanced Mikes, built from Bachmann Bershires.

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17

Check your PM

Mel

My Model Railroad
http://melvineperry.blogspot.com/

Bakersfield, California

I’m beginning to realize that aging is not for wimps.

18

Note that this is precisely the rationale for the American Arch four-wheel articulated truck, that it carries the drawbar force straight between the abbreviated chassis holding the driver pedestals, at just about axle height, under the ashpan to a tender drawbar connection at the rear of its frame. This parallels contemporary electric practice of taking the entire buff and draft through the articulated underframe (as on the GG1) with that reasonably closely following the line of the curve to preclude lateral force.

With the documented issues about trying to back up that arrangement (which apparently was more difficult than with your system) Lima went to a Delta-style trailer… and encountered difficulties. There is a specific relationship between pivot, wheelbase, and axle spacing that produces a two-axle trailing truck that acts as a proper Bissel in curve following, and the axle spacing needed for weight-bearing effectiveness was NOT the geometric spacing needed; in fact with the rear axle used for a booster (and hence needing to be reasonably tangent to curves at all points it was running) the lateral required for the forward axle was substantial. Timken addressed this with a weird expedient: the journal boxes of the forward trailing-truck axle are free to shift laterally to some extent, and their load is carried by a pair of hardened-steel rollers on hardened surfaces below and above so the axle ‘floats’ laterally in the frame while remaining fully weight-bearing. This might be thought of as an extremely-long-frame two-wheel Delta truck, with the long tongue being carried by ‘helper’ wheels. &nb

19

Sheldon)

What type curves/switches do i run? Right now im on essentially 2 test tracks. One loop for continuous (break in) running, and one switching module (for testing short S curves, electrical contact over frogs/points, coupler swing/trip pin drag etc etc).

While the layout I intend to build will feature 32" or broader curves and #8 or higher switches, right now i use 24" on the loop, and #4s on the module. If I can get anything running on these tight constraints - im figuring they will have no problem on the future layout.

And when that layout is built, my collection will be built (kits), broke in, and ready to go. Mostly this post was to get a good idea on what you, those that have already moved further ahead in this weight thing, are doing. Again, i am rather suprised at ‘all the weight being thrown around’. [(-D] - pun intended. From the other post i mentioned at the top of this thread.

Concerning switch rails and points: I might have questioned an 8oz tender and not the 20oz loco pulling it or the heavy passenger, never the less, the question at all was how does this affect anyones switches/infrastructure per se?

I have noticed personally with Atlas (of all manufacturers!) alot of differences in their track (becuase of different contractors they use to make it). Same piece matched to same piece. One switch can handle the load while another, the point rails bend or twist under most loads (yes, i removed it from use).

Remember, my rolling stock isnt weighted (more on this below). But im experienced enough to know to look for these things. Someone rather new to hobby that just adds weight to a tender to fix an electrical problem… now all the sudden might get track problems. I remembered the problems ive seen with this and it got me to thinking about it. As in - how much is too much? Wheres the bar now?

Drawbar swing) I am totally follo

20

OK, physics does not scale down, we know this.

And, everyone’s layout goals are different. I model a freelanced line that interchanges with the C&O, B&O, and WESTERN MARYLAND. And I am not building a multi deck layout with a long helix. But I do have grades, not a flat table…

My grades are 2% and less. Most of my grades only change elevation 2" and then have a level stretch.

In real life, whatever a Mikado might pull would be cut in half by a 2% grade.

Two of my Mikados will pull those 37 cars up a 2% grade, even on a curve, since all my curves are 36" radius and larger. All my 35-40 car freight trains are double headed, or have much bigger power than Mikados.

I don’t obsess over every car being spot on the NMRA RP, and I often err slightly below the formula. But cars that are too light are a string line risk when you are pulling 35-50 car trains. My experiance says long trains need cars with similar weights and slighly heavier is better than slightly lighter.

I do use a special freight truck on most equipment - Kadee sprung metal trucks with Intermountain code 110 metal wheels.

Reasons:

  • Equalization is important.
  • Metal trucks and metal wheelsets put weight down low for better tracking.

Testing revealed this combination to be exceptionally free rolling. More free rollling than any other equalized or rigid truck I could find.

I will not use semi scale wheels or couplers.

Maybe, just maybe, My Mikados (and my other modified locos) pull more, and pull more up hill, because of low rolling resistance?

Your rolling stock is not weighted? Well do you take out the factory weights? I find most cars are close to the NMRA RP out of the box, and by the time I add metal trucks they are even closer.

I know this, when this new generation of locos started showing up, diecast frames with plastic boilers, plastic tenders with metal floors, wir