I have seen discussions on this forum about layouts with a 2% grade. That seemed very low to me having just completed my first track using a HO hobby store pier set. The set rises 1/2 inch between piers which it shows placed at track joins, which are 9 inches long (EZ Track). To my calculations 1/2 to 9, is equal to 1 to 18, or 1/18 = 5.5555 or greater than 5.5% grade?
1.) Is this math correct and does this kit really build for a 5.5% grade?
According to greatesthobby.com a 2% grade will cause a loco to lose half its pulling power, with this power halved again for each additional 1% increase. Assuming this true, a loco pulling at say 5% grade would be pulling at 1/16th its power. My starter set Bachmann Diesel pulled 10 cars successfully over this 5.5% grade, but stalled near the grade top at 11 cars. 1/16 power times 10 cars = 160 cars at full power.
2.) Does this mean this loco should be able to pull 160 cars on a flat grade? Seems impossible to me.
I constructed a figure eight configuration with the grades starting at the mid points of the circles (top and bottom of the eight standing up).
3.) Would a curved grade help or hinder the locos power? Would centrifugal force help climb the grade since its coming off a circled curve?
A 2% grade would be 2’ rise over 100 linear feet. If you had a layout that was on a 4x8 sheet of plywood for instance, and ran the risers along the long side (96"), a 2% grade would be a rise of 1.92".
In your example, a 2% rise would be 0.36" for a run of 18". So indeed, with the piers spaced at 9" and rising at 1/2" per 9", you have a rise of 5.55%…far too much, and very impractical.
That’s supposed to be a 2’ (foot), not 2" (inch), rise per every 100’ forward.
The function of power lost over change in slope is not linear, your locomotive will not be able to pull its self let alone any cars at a 50% grade.
It is quite likely that the train set risers are 5+%, if you are only using the cars provided in the set it will not be a problem. At some point along the way the producer of the set expects you to upgrade from the figure 8 of track that comes with the set. 160 cars on the level is a bit optimistic for any locomotive (still possible for some) let alone one that came in a set. Don’t worry about the max power until you find it inadequate, there are a few things you can do to improve it but that’s for a different thread. You are also correct in that the curve hinders the locomotive’s power. When possible it is preferable to have graded track running straight and more importantly, the transition from graded to level should be straight. Finally, I am sure that your track can be laid to take advantage of centripetal force but when that is the case you are already pushing the limits of your models. Real railroads super-elevate the outside rail on high speed mainlines so that passengers and freight has a smoother ride. I am sure that this helps with power transfer too but on the model it is usually done for looks only.
In HO Scale a 3% should provide about 4 inches clearance over 12 feet of travel, a 2% can do the same job but requires about 16 feet to lift a train 4 inches or so.
Throw in curves and the situation gets rather complicated. I see a curve by itself as equal to a 1.5% grade. But that is purely MY thinking and is NOT based on any fact anywhere. It is speculation pure and simple. So if a 3% grade is on a curve it might become something almost 5% at the engine’s drawbar.
A engine does not really have room to “Swing” 160 cars on a typical layout. If you do know of one call me I would love to try such a train on my BLI F Unit ABBA set.
However think of a engine that pulls 10 cars on the level. Each % will steal approx 2-3 cars from the engine’s ability to pull it’s tran. So a 5% grade will make the engine cut down to maybe 4 or 5 cars at the most if that. 5% is quite severe and it is possible that the same engine can only spare enough drawbar pull to get one or two cars over that grade.
If my BLI PRR M1a Mountain 4-8-2 engine can handle 40+ cars by itself on level track, it will be reduced to about 16 cars or so on a 3% grade. I could make it do more on momentum but prefer to limit my engines to what they can start on the grade from a dead stop.
Yup, your math is fine. And so is your understanding of all those posts; 5.5% is horrendous for all but geared and specialty locomotives in industrial settings…most commonly.
The function is not linear, so a locomotive that can pull a maximum of 40 perfectly duplicated items of rolling stock on a straight and level track will be reduced by approximately 25% for every one percent of grade. Even then, it depends on other variables, such as how evenly the tracks are kept in terms of a constant grade (often there are substantial changes in rate of climb over a single grade,
Thanks, for all the feedback. I never imagined I’d get such a horrendous layout reccommended right on the box of piers from the hobby shop. I guess that 5-7 year old boy pictured next to the figure eight layout doesn’t know what he is in for.
Your explainations and rules of thumb seem to make much more sense than some of the erroroneous information I got from greatesthobby.com. I never believed that 160 cars thing. If I can pull 20 cars (all be it light, starting set rolling stock), on level land I’d be happy with my entry level locos. And I’ll fix my layout once I get into more serious engines.
Granted that the toy train trestle grade is, in fact, 5.55%, it is also very short. Trains, like aircraft, can trade speed for altitude - also referred to as, “Taking a run at the grade.”
More legitimately, for a long, winding just-about-continuous grade that has to rise a total of 555mm, 5.55% would be horrendous. Think two Y6b’s taking fifteen cars to the end of the branch. A total rise of 400mm, while still way steep at 4%, is somewhat more workable and not nearly as ugly. Reduce the rise to 220mm (approximately 7.5 inches) and you’re in the ball park for ordinarily steep mainline grades with 2.2%. Or build along the Hudson River or across the flats of West Texas on a grade of one foot per mile and get to drag preposterous trains with minimum-power locomotives.
If your prototype climbed 8% grades, rounded 100 foot radius curves and still couldn’t get up the mountain without tunnels and switchbacks, don’t feel bad about modeling it that way. After all, it IS the prototype! (Specifically, the Hakone Tozan line south of Fujisan in Japan.)
Chuck (modeling Central Japan - north of Fujisan - in September, 1964)
I had a 18%'er in Vermont way up north near the border and it was two miles straight down. I think I had tingles of terror backed by lots of courage in a bottle for that run. Empty.
Getting back over the grade with a load grossing just 40 tons (Thanks Eathan Allen! For the FINE furnature) or a tiny bit more on a 320 Cat hurt the truck because halfway up the wheels were barely turning and it was a matter of which would win first, caterpiller or the hill; uh. Mountain. Caterpiller won that day but it sustained some damage.
Regarding the twisties in and on grades it adds so much to the required effort. I think I recall a ridge near Altoona called “Babcock” That was a grade including a hairpin turn that like doubled in grade coming out near the bottom. I recall my flatbed with lumber would require a two shift down on that Cummins big cam 4 just to pay for the increase in grade coming out of that hairpin. The only positive thing was at 7 mph it was right where it can get down and haul that low down in gearing.
I do a bit of flying on the computer on a game called FSX Deluxe and understand that going up into altitude with a airplane is kind of like climbing a mountian with a train. I could get a fully fueled virtual 747 to about 34,000 feet and eventually to 42,000 if the flight is long enough (Trans pacific flights 8+ hours) but it is so much easier to dump the fuel to what is only needed for that flight and float the thing to 45,000 in less time, less distance and less stress on the engines.
One other thing about trainsets, I associate trainsets with plastic wheels, truck mounted horn and hook couplers and engines with just one powered truck that also has to pick up electricity to run. Yes you might get 4 cars over that 5+ % grade on the block set figure 8 track but it will not be fun.
There is a forum member here who likes to run a 2-6-6-2 with 20 cars out of his yard up a “S” grade that had a photo to boot and he would say that it was about as much as he
We were in VT this summer, and took a road over one of their ‘hills’ that was signposted ‘Not recommended for tractor trailers’. I’m glad we wre in a car instead of a truck. It was narrow, twisty, steep and no places to pass - Safety Valve would have not been a happy camper at all!!
There are roads out west where you lean out of your left window of the cab and look straight down at your steer tire to keep it on the pavement or there is a 1000 foot drop to your death while your trailer wheels rub the mountain on the right.
Those little bitty eastern roads that signs not recommended for TT’s are actually meant to keep RV’s out of there with thier monster 60+ feet long and 13’ high bodies that just cannot manuver.
That one hill in VT was legal for TT’s on that two lane state road. I remember the long nose in my rig totally blocking the view coming over the top going down Northbound. It was also one of the few times Ive smoked brake shoes despite jake braking and bobtailing to get a loaded trailer at the Canadian Border at the Ethan Allen Plant.
There are some roads that were marked or otherwise restricted against TT’s that I took anyways. Those usually resulted in a angry policeman yelling kindergarden school words into my cab scolding me for my hard headed refusal to obey the signs =) Those I keep for another day as these tickets were rather costly.
There are true mountain grades in Canada and out west that are marked with minimum horsepower/torque requirements. No cheap company crappy 350 horse/1350 pound feeter need apply here, break out the big 650 cat let’s go!
I guess that 5-7 year old boy pictured next to the figure eight layout doesn’t know what he is in for.