Model trackwork, grades…..!

Grade

  • Discussion between Walter Orloff, Terry Smith, Peter Tuttle and Trevor Marshall – MaineOn2 2005/01/08, their discussions are included for the insight they provide.

This is one of those classic questions for which the answer is “it depends”. It depends a lot on what locomotive we’re talking, how well your particular model of it was built (brass is hand-built, so each one has the potential for its own unique blend of operational problems), how well your particular model has been tuned, the quality of your trackwork, etc.

Other factors also have to be considered, the rail material you are using, and material your loco drivers are made of,  this determines the coefficient of friction between the two materials, hence slippage  The rail cleaner you use can increase slippage. So the short answer is, the best way to determine this is to do tests with your own models. If you plan to pull any brass cars (cabooses or passenger cars come to mind) be warned that they could severely limit your grades.

For a very technical description of grades for the model layout visit http://webspace.webring.com/people/ib/budb3/arts/tech/grade.html

FAQ authors note, no track grade does not necessarily lead to a flat layout

Trevor’s approach – I’d like to be able to pull passenger trains with 3-4 cars for the occasional railfan trip, camp special, or running of the S&PCRR’s premier passenger train, “The Rusticator”, so I’m building my layout with a planned grade of ZERO. I’m sure that’s not the answer you’re looking for, but it at least explains why I’ve decided to not introduce grades on my layout. My advice – build some track – straight and at your minimum radius – on a portable board, prop it up to various grades (which you can calculate by using rise over run), and then pull some equipment with your locomotives and figure out what works for you.

Peter Tuttle – Allan Hanson, one of the pioneers in HOn2 and then On2, recommended a maximum grade of 0%, for all the reasons already mentioned. And Al’s scratchbuilt On2 engines were engineered to track and pull. (His SRR #15 had working leaf springs.)

Terry Smith‘s experience – I tested each of my locomotives for haulage capacity on the flat, round curves and up and down grades. Tests were done with freight cars. Most loco’s could pull 6 or 7 boxcars built from SRCS kits with grandt trucks and NWSL wheels. The bigger engines like the Sandy River Prairies and Bridgton 7 & 8 could handle 10 boxcars (all that I had running at that time). The track was Precision scale flex track with code 70 nickel silver rail. The tests originally showed me that the units tested could still pull a reasonable train up a 2% grade without too much slipping or other problems and my first iteration of my P&SR layout was designed with these figures in mind.

And then it all changed!.

I started using a PFM sound system, and had bought a set (#15/#16/#31) of Car Works Bridgton coaches/baggage. Because of the sound system I found that I needed to clean the track to avoid spurious sounds/signals etc. I ended up using Goo Gone, which is a fabulous cleaner, but the trains could no longer manage the 2% grade, so the P&SR was re-jigged to become as perfectly flat as realistically possible. 

It is only through discussions on another board that I have recently learned that rails should not be cleaned with Goo Gone as it leaves a deposit which is slippery. A pal of mine uses Rail Zap, and I have a sample to try, maybe more later.

I would also add that details on another site (see below) which deals with a number of technical issues for model railroads had an interesting section on haulage capacity and grades. It reminded me that different wheel materials will have different performances, and if I remember it correctly it more or less stated that nickel plated wheels on nickel silver rail was nearly the worse combination (lowest coefficient of friction, therefore lowest haulage capacity) and that turned steel drivers were better and powder metal iron drivers were the best. Interesting that the CB loco’s tested had different degrees of nickel plating, the Portland Products loco had turned steel driver tyres and I suspect that the Car Works Loco’s have nickel plated driver tyres or do they have stainless steel tyres? Technical site mentioned above, http://webspace.webring.com/people/ib/budb3/arts/tech/grade.html

 On2 Maximum grade tests done for P&SR;-

F&M #1 hauled two coaches up 5/8” rise in 48” (1.3%)

B&SR #7 hauled two coaches up 1 1/8” rise in 48” (2.3%)

F&M #1 hauled three freight cars up 1 1/8” rise in 48” (2.3%)

B&SR #7 hauled three freight cars up 1 1/2” rise in 48” (3.1%)

F&M #1 model by Portland Products, no modifications at test, except well run in. B&SR #7 model by Car Works, no modifications at test, very little running. Two coaches would be two from Car Works B&SR #15, #16, #31 Three freight cars would be SRCS kits equipped with Grandt Line Trucks and NWSL wheelsets. Freight cars in P&SR layout running condition weigh between 75 and 155 grammes. Estimated total weight of the three most likely freight cars is 240 to 290 grammes (8½ to 10¼ ounces). Track used was Precision Scale flextrack with code 70 nickel silver rail.

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