Re: Fw: [HOn3] Figuring Grades

Dale Buxton

To John Cytron,

The south side of the Baxter Pass assent was actually 7.5% not 4%. True, long ruling grades of 4% were not the norm. But, here in Colorado, they were all over the place. 9 miles of the accent to east side of Dallas Divide on the RGS were a steady 4%. Almost all of the RGS grade on the Enterprise Branch was 5% or better.  The Crystal River Coalbasin branch had about half of its 12 miles on a 4.4% grade. Several of the Branches of the DB&W exceeded 4% for several miles as did the Argentine Central and lets not forget the "Three Little Lines" out of Silverton. They all  had stretches of 4% too! And on all of these lines, these steep grades made for made for operating hardships. To duplicate these grades In HOn3 means the cars must have super-free-rolling trucks and less than NMRA recommended car weights. HOn3 locomotives just don't have the scaled down mass on their drivers which translates into the tractive effort that their full sized counterparts had.

D Buxton

On Thu, Sep 26, 2019 at 5:29 PM Stephen Silver via Groups.Io <> wrote:
John,  I tested a 4% grade with both of my Blackstone K27s.  Both pulled six unweighted BS cars (a mix of 6 different cars) and a caboose but only under some heavy throttle. Double heading they pulled 10.  I don't have a 4% grade but something much closer to 3% on one section of track.  We will see what happens in reality when it gets built.

Life is mostly attitude and timing

----- Forwarded Message -----
From: John Cytron <rgsjohnny@...>
Sent: Thursday, September 26, 2019, 4:21:13 PM PDT
Subject: Re: [HOn3] Figuring Grades

I think you all have figured this incorrectly. Bob asked for the final elevation.

If the plan is ½” to the foot, then 8 inches on the plan is 16 actual feet. Think of each 1% grade as equal to 1/8th inch per foot in the real world.  (⅛” = 1/96th of a foot or slightly  more than 1%.) A 1% grade would rise 1/8th inch over 1 foot and 16 times that over 16 feet, or a rise of 16x1/8th which is 2 inches. Over 16 actual feet, the rise would be 16 times 1/8th or 2 inches. 

The calculations made by the earlier posters is correct to the scale of the drawing; that is, 0.32 inches.  So what is 0.32 inches to 0.50 inches, the scale of the drawing?. It is  0.32/0.50 or about 0.64. 0.64 is almost ⅔ and what is 2/3rds of a foot? —8 inches.  More precisely it is 0.64 times 12 inches per foot or 7.68 inches in the real world, that is, if the ½” to the foot plan were at full scale.

I still like to figure 1/8th rise in 1 foot as equal to 1%. It makes for easy figuring.

Anyway, why would you want a 4% grade as that is really rare even in narrow gauge (except for a few places like Baxter Pass on the Uintah RR and some others.Today's HOn3 locos could barely make that grade with 2 cars and a caboose.


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