Figuring Gradient percent and Adding Weight to Engines

[Desert Rose]

Figuring Gradient percent and Adding Weight to Engines

For figuring grades with sidings for helper Engines, I use a standard of an 7000ft long unit trains in Nevada scaled down to 1:87 scale, 80 ft. ± long. Running fast freight. I put No. 6 switches and sidings for helper Engines 10 ft. before the bottom of the ramp. I put No. 6 switches and sidings for helper Engines 20 ft. past the top of the ramp with a 7-inch (.583) Rise in elevation.

I use Handy Converter for Model Railroaders Version 17 CD: https://stanstrains.com/SoftwareHandyConverter.htm

Using the software Handy Converter for Model Railroaders CD:
Gradient percent: 2%
Rise in elevation: .583 (7 inches)
Run in length is 29.15 feet.

So, the total length including sidings is 60 feet. Starting with 10-foot flat run on level 1, a 29.15-foot ramp with a Rise in elevation of 7 inches and ending with a 20-foot flat run on level 2.

So, adding weight should increase the pulling power, right?

Trains get traction because of the immense weight of the Engines, and the friction generated between the metal wheel and metal rail head.  More weight equals more traction which requires more horsepower. On model trains you have a set horsepower. Providing the model train has room for additional weight (some due most don't), a limited amount of weight can be added as long you don't exceed your power-to-weight ratio and center of gravity. Our power-to-weight ratio formula is for every Bachmann motor listed:
Weight: not to exceed 15.2 oz. per motor.

Model: H63525-1, Model: 6090X-8812A-FS, Model: 6090X-8812A-FL, Model: 6090X-8812A, Model: 621XX-8812B

On the DD40AX's we are using, it does have more traction from adding weight. Our DD40Ax's didn't pull very good, so we added DD40AX sound value decoder and added weight for a gross weight 24 oz. this gave the DD40AX acceptable pulling power, which now is close to our Geniuses DDA40X's which have a gross weight of 26 oz. Sometimes it's not how much weight you add, it is where you put it that counts. The center of gravity should be halfway in-between the forward truck and the aft truck. If one truck is lighter than the other truck the lighter one will brake traction first, then the second one will brake traction. Applying 12.0 oz. at the forward truck center and 12.0 oz. at the aft truck center for a total of 24 oz. at the center of gravity. Applying the traction evenly across both sets of D-D trucks it increased the pulling power for me.
Running consists with four DD40AX engines at 96 oz. total engine weight. Pulling 70 cars at 525 oz. total car weight. For a total train weight of 621oz at 98 SMPH on a flat run. Each Motor pulls 77.62 oz.



When weighing engine make sure the engine is level between scales. Its ok getting the weight and balance closes but not perfect but we don't exceed ± 0.2 oz. between trucks.



Is there enough room for this?

1). DD40AX, has room for additional weight.



2). GP40 does not have room for additional weight.



On our GP40's we use the alternate method for adding weight.  We add another GP40 (same motor same chassis with the same weight 13.2 oz. each) and we keep adding GP40 until the engines quit braking traction, then add one more. 6 Bachmann GP40's at 79.2 oz. total engine weight with NCE BACH-DSL Decoders P/N: 05240139 pull 60 cars total 270oz. at 62 SMPH. Each Motor pulls 58.2 oz. The decoders start voltage CV2 is set to a value of 30. This allows all the engine to start at the same time in this type of consist which is very important for maximum wheel adhesion and pulling power at low speeds.
We set the CV's on all of the GP40's at the same time sitting on the track. At step one at 9in. per 10 sec. travel standard.
CV116 torque kick rate to a value of 2.
CV117 torque kick strength to a value of 12.
CV2 start voltage to a value of 30.

3). SD40-2 does not have room for additional weight.



On our SD40-2 we also use the alternate method for adding weight.  We add another SD40-2 (same motor same chassis with the same weight 15.2 oz. each) and we keep adding SD40-2 until the engines quit braking traction, then add one more. 6 Bachmann SD40's at 91.2 oz. total engine weight with NCE BACH-DSL Decoders P/N: 05240139 pull 80 cars total 440oz. at 65 SMPH. Each Motor pulls 88.5 oz. The decoders start voltage CV2 is set to a value of 30. This allows all the engine to start at the same time in this type of consist which is very important For maximum wheel adhesion and pulling power at low speeds.
We set the CV's on all of the SD40-2's at the same time sitting on the track. At step one at 7in. per 10 sec. travel standard.
CV116 torque kick rate to a value of 2.
CV117 torque kick strength to a value of 12.
CV2 start voltage to a value of 30.

NOTE: For maximum wheel adhesion at low speed, NCE uses CV116 torque kick rate and CV117 torque kick strength.

NOTE: For maximum wheel adhesion at low speed, The Bachmann SD40-2 Sound Value Upgrade (SoundTraxx TSU-BH1 Digital Sound Decoder) uses:
CV3 Baseline Acceleration Rate to a value of 29.
CV4 Baseline Deceleration Rate to a value of 2.
CV10 EMF Feedback Cutout to a value of 126.
CV211 Low speed Compensation to a value of 255.
CV212 BEMF Feedback Intensity to a value of 126.
CV215 BEMF Reference Voltage to a value of 125.
CV220 Constant Brake Distance Rate to a value of 2.

NOTE: The Bachmann GP40 Sound Value engines run just fine out of the box, just set the CV2 start voltage The same as the NCE start voltages, they run with pack just fine.
 
NOTE: The Bachmann SD40-2 Sound Value engines:
CV116 Engine Exhaust Control to a value of 2.
CV3 Baseline Acceleration Rate to a value of 29.
CV4 Baseline Deceleration Rate to a value of 2.


NOTE: Resalts will Vary.

[trainman203]

I always thought that gradient percent was a factor of the rise at any given 100 feet of track.  I.E., 1' rise in 100 feet of track = 1%. 

I'm no civil engineer.  Is this incorrect?

[jward]

I always thought that gradient percent was a factor of the rise at any given 100 feet of track.  I.E., 1' rise in 100 feet of track = 1%. 

I'm no civil engineer.  Is this incorrect?

You are correct. It is a measure of rise vs run. That formula can be manipulated to Rise = Run x .01 per percent of grade. Thus in Benjamin's case, 29.15 feet equals 349.8 inches of run, rounded to 350 inches. 350 X .02 = 7 inches of rise.

On a related note, I am working on an evaluation of my fleet's pulling power on a 4% grade using a 20 car test train made up of Silver Series cars. When I get all my Bachmann units evaluated I will post the results here. I will note that my evaluations are for unmodified units other than the possible addition of DCC. I will also note that Steam doesn't pull as well as diesel, and that Bachmann products are all over the map when it comes to pulling power. So far my Atlas units are consistently the best pullers, but some Bachmann units also compare favorably against the Atlas units.

[trainman203]

I am very interested in seeing the results of your steam locomotive tests on the 4% grade.  I don't have any diesels to readily compare with my steam engines.  I do know that my decapods and consolidations all haul 15 cars up a straight 2%, no prob.

[Len]

I wish I had 60 feet of space to dedicate to an entire layout, never mind one elevation change.

Len

[trainman203]

I'd like to see a track plan of the layout these 7000' long unit trains run on.

[trainman203]

I have also wondered if this is the 10,000 square-foot union pacific layout in Sedona Arizona that I've heard about.

[Desert Rose]

Answering your question. We are in the high desert of southern Idaho, and the layout is only 592.75 feet of track.
13 Left turnout #5, 11.5". (remote)
13 Right turnout #5, 11.5". (remote)   
3 Left crossover #6, 21.25". (remote)   
3 Right crossover #6, 21.25". (remote)   
2 Bridges spanning 5.25 feet each.

[trainman203]

Nice railfanning plan.  Thanks.