Grade percentage


T

trailrider

Well-Known Member
Wow! I never quite managed to measure the ruling grade on my layout and finally decided to measure it, using a 24-inch long carpenter's level, laying on the track, and measuring the rise with a steel tape, which came out to 1-1/8" rise = 1.125". Running the numbers on a model railroad grade calculator I found on the 'net, I come out with 4.69 %! Yike! I always thought it was about half that. Not only that, but I have 22-inch radius curves at both ends. No wonder my 2-10-4's (both the older one running on DCC and the latest one I haven't changed over can only pull six ounce-and-a half hoppers plus its tender and a caboose. Interestingly, an old Athearn blue box GP7 with handle two more hoppers with no apparent slippage or strain! What I find even more interesting is the comparative tractive effort of the prototype M-4 (83,000 lbs) versus a single unit GP-7 (starting) 65,000 lbs. My 2-10-4 models only have the end drivers flanged and in contact with the track, whereas the GP-7 has 8 wheels in contact. It would be interesting to see what the 2-10-4's would pull on level track, but I don't have enough straight-and-level on my layout to truly measure, plus I don't really have a means of determining the "tonnage" of the freight cars due to rolling friction of their trucks. Maybe someday when I can try them on a club modular layout...
 
The sintered iron wheels on the blue box engine grip better because they are rough, instead of the smooth nickel of the newer wheels.
 
bnsf971 said:
The sintered iron wheels on the blue box engine grip better because they are rough, instead of the smooth nickel of the newer wheels.
Click to expand...
So if I could find a way to...naaa! Sounds like a great way to ruin the model. A traction tire would work, but I don't know where I'd find a 63" Mantua driver with a traction tire. Oh, well, thanks for the information.
 
If you live near northern Virginia area, you could bring your locos over to my full basement empire and stretch their legs out on this 6 1/2 scale miles of track.
 
As a rule I try to stay around 2%. With my Kato track I use the 248mm straights as a measure for 0.4-0.5cm rise. And for the 45deg curves put 0.6 to 0.7 Which is a tiny bit over 2%, but seems fine. Some of my single loco trains will struggle a bit on more than that when pulling a prototypical load.
 
Last edited:
My Deutsche Bahn (and ÖBB and SBB) main lines are at 3.5% effective grade with a 24" and 22" radius curving incline at the top. Most all of my European locomotives have traction tires which helps a lot. My average locomotive will pull seven 76' stake wagons loaded with lumber, nine empty 45' gravel hoppers, or six 303mm full-length passenger coaches. I've pulled as many as nine, but it doesn't look good on my size layout.

Ironically, the Bemo locomotives that run on the 6% effective grade do not use traction tires, but still have no problems with that grade hauling as many as five coaches and two freight cars. I normally don't run Rhätische Bahn trains that long though, but the locomotives climb right up those grades without problems.
 
You must log in or register to reply here.



Back
Top