Multi-unit Diesel and Double Headed Steam Pulling Power

[cefinkjr]

What has your experience been with the pulling power of multi-unit Diesel consists and/or double headed steam? Is it equal to the sum of the cars the units/engines running alone can pull or is it something less?

My HO experience in this area is that double headed steam can be expected to pull about 80% of the cars that the two engines could handle alone. For example, if 2 Mikados are double headed and each can handle 18 cars, the 2 Mikes together can be expected to handle 28 or 29 cars (0.8*36=28.8). I don't know how this would apply to multiple unit Diesel consists or other scales but I suspect it would be somewhat similar.

Anybody have any other or better information in this area?

Chuck

[Anonymous]

I suspect hardly anyone has the room to test this out.

I have mu-ed a BLI M1a with a BLI Heavy Mike, both engines can handle a cut of 15 cars up a 3% grade. Under DCC both engines had no trouble with a 24 car consist. However space limitations kind of put a damper on what can this set really pull?

I have a A-B-B-A set of analog Life like Proto FA-2's all powered. There is no question that I can stack 100+ cars on this thing and get it started.

The biggest train in HO I have started to date is about 64 cars with a AHM 2-8-8-2 and a Riverossi Big Boy. Together these two locos managed to get the train moving but would need a REAL engineer to drive the train over hill and down dale.

[twhite]

I do a lot of double-heading with long trains, and find that I can almost double the number of cars I'd pull with one locomotive. Since I'm using DC and not DCC, it can be tricky with BLI locos--you have to make sure they're programmed to the EXACT same starting voltage. With my brass, it's not so crucial, just as long as the locomotives are within the same response by a volt or two. Of course with steam, you have to use common sense--you don't doublehead a Pacific with a Yellowstone--though you can certainly use a Consol with a Cab-Forward, which was common on the SP between Colfax and Norden over the Sierra. I try to use locomotives with relatively common wheel arrangements when I double-head non-articulateds, say 2 4-8-2's or a 4-8-2 and a 4-8-4, or a 2-8-2 with a 2-10-2. With articulateds on the point, I usually use a smaller loco, say a 2-8-2 or possibly a 2-10-2, depending upon the load and prevailing speed, though often just for show, I'll throw a compound 2-8-8-2 at the head of a 2-8-8-4. My trains usually average about 18-25 cars for a single locomotive, with double-heading, I can average about 50, and that's with 2.4% maximum gradient and 34" radius curves. The trick is getting locomotives that are relatively compatable as regards starting voltage.
Tom

[Anonymous]

i have DC (gonna get DCC) and somtimes double head two SD40s. my experiance is that they can pull about twice as much. also another experiance is that my mainline is about 1/3 of an HO scale mile (20 feet) so i can put about a dozen cars at max (so therefore double heading not as good as single). my layout is more of a branchline/switcher so i guess doubled heading isn't for me. but it can be fun.


Alexander

[Anonymous]

I double head two P2Ks Berks up a 3.1 grade hauling 28.
Separately, 14 a piece, it's a slower climb so I double head .

[Wdlgln005]

Double heading Nscale diesels yeilds about enough TF to pull 2 more cars than single. I regularly order & run 2 of the same type units together. That's why Atlas sells them in 2-3 road numbers each in each batch, or I just renumber the units. One of the best places to see this in action is on an Ntrak modular layout where the outside mainlines can easily handle 100+ car trains. An ABBA set of F units or some modern power can easily handle a train that size. It helps that these lines are planned & built with wide curves & no grades.

This was a regular feature in Model Railroader about 10+ years ago.

[Anonymous]

I've dot 2 P2K SD60's running DCC. I don't have the room, but they've been on a large club layout and could pull 100 cars on no grade with no problem. I also have 2 P2K GP30's that can pull about 50 cars together with no problem.

[bobjgroton]

I don't have formal test results for you but our club layout (New England Rail -- 9/2002 issue of MR) has some long 2% grades and we have run trains that span the entire length of the grades (probably 60 cars or more). I would suspect that your "each engine adds 80%" is a good guess since it's rare for ALL the engines to pull perfectly evenly ALL the time (e.g. a 4 unit lashup may effectively be only 3 locos plus one slacker at a given moment).

Cleaning your wheels and track for optimum electrical conductivity can be a BIG factor, especially when running command control (we use DCC now but used several other systems before). When we see a train starting to have trouble after several laps around the layout during a show, we automatically suspect dirty wheels even though we have a track cleaning car on most trains (and the wheels usually ARE dirty). Some diesels can also have trouble with dirty contact wipers on the wheels, although it's the wheel treads that pick up the most dirt. While I'm on the subject of dirt, we have a club rule that ALL cars must have METAL wheels -- plastic wheels are HUGE dirt magnets and can quickly pick up enough dirt on the wheel tread to increase the diameter of the wheel to be greater than the flange!

Our steam engines haven't been doubleheaded very often, if ever, so I can't give you any useful information there. I can ask the articulated-engine owners to do some testing. By the way, most longer freights on our layout will have 3 or 4 diesels on the point as a matter of standard practice -- we don't usually attempt to run with less than that unless a train is short or unusually light (most of our cars are within 25% of NMRA recommended weights).

[rrgrassi]

This is all really good information. I am just now getting to the point where I can build my own layout. I do not know of any clubs local to me. I live near Greenville TX. I do have one question. Currently I have four Athern locos SD45, SDP45, SD40-2, and U33C. I have a TECH II 2400, and it gets quite hot when I triple the motive power. I have not made the jump to DCC yet, and I was wondering what power packs both DC and DCC to get.

Thanks!

[Anonymous]

www.modelrec.com and click on the power pack icon, then tech 4

[orsonroy]

The region I model didn't see a lot of doubleheading, so I haven't done any real testing of my engines (with my grades, 20 cars is about the maximum for my train lengths anyway, with a single P2K Berkshire).

I have had doubleheaded Rivarossi Berkshires pulling a 110-car coal drag on our local HO modular layout. Looks impressive!

[Anonymous]

if you decide to go with a Tech 4, go to wholesaletrains.com. They sell the Tech 4 series at about half the price of other retailers.

[Anonymous]

In my expirence, depending on wether you're using dc or dcc two HO scale desels in dc should be able to pull double the number of cars they could pull by them selfs, and in dcc they should be able to pull about 3 times the number of cars they could pull by themselfs. For example lets say you have 2 SD 40-2's that can pull about 25 cars up a 3% grade in dc.If you MU them and give them the right voltage, they should be able to pull about 50 cars. In dcc they should be able to pull about 65 cars. My railroad is more of a shortline than a Class 1 railroad. The only reason I know this is from expierence on my dad's railroad

[Anonymous]

The pulling power of any consist depends on the quality of the motive power. Don't expect much from the lower end Athearn models. The Ready-to-Roll series run smoother but offer only slightly better pulling power. The Bachmann Spectrum line is only slightly better. The best pullers on my layout, which has 2% grades, are my Atlas and Walthers diesels. I can pull 40 cars up those grades with only 2 Atlas B40-8's or my Walthers GP-15 and B40-8 lash up's.