Locomotive Testing on Grades and Curves

After I got a few more blocks wired up on the layout, I was doing some locomotive testing, just to see some trains run for a change. I found out some interesting things.

On a 2% woodland scenics grade with a 24" radius curve:
-an MTL F7 will pull 15 mixed type cars, but not 22. Double headed, no problems
-An MTL GP9 won't pull 15 cars, mu'd with a GP35, 22 cars is no problem
-An MTL GP35 won't pull 15 cars, mu'd with a GP9, 22 cars is no problem
-An AZL GP7 will pull 15 cars, but just barely with a lot of slip, and it won't push them up the same grade, didn't try it mu'd with any MTL GP's but it looks like it could be done.
-A Marklin F7AB combo will only pull 4 passenger cars, double headed with B unit in between, no problem with 6 cars

So it looks like to run 20 plus car freight trains trains and six car passenger trains, I'm going to have to double power everything. This is going to be kind of fun, trying to figure out the motive power combos to use for various trains.

Todd

Todd,
This is great information. It gives a realistic idea of the limits each engine or combination can handle. Good practical information I can use when planning my layout.

Thanks,
Jerry

Todd, Thanks from me as well. I've 'bookmarked' your post for further reference. This is valuable material for the users of this site. Cheers, Jim CCRR:)

After I got a few more blocks wired up on the layout, I was doing some locomotive testing, just to see some trains run for a change. I found out some interesting things.

On a 2% woodland scenics grade with a 24" radius curve:
-an MTL F7 will pull 15 mixed type cars, but not 22. Double headed, no problems
-An MTL GP9 won't pull 15 cars, mu'd with a GP35, 22 cars is no problem
-An MTL GP35 won't pull 15 cars, mu'd with a GP9, 22 cars is no problem
-An AZL GP7 will pull 15 cars, but just barely with a lot of slip, and it won't push them up the same grade, didn't try it mu'd with any MTL GP's but it looks like it could be done.
-A Marklin F7AB combo will only pull 4 passenger cars, double headed with B unit in between, no problem with 6 cars

So it looks like to run 20 plus car freight trains trains and six car passenger trains, I'm going to have to double power everything. This is going to be kind of fun, trying to figure out the motive power combos to use for various trains.

Todd

It's like the prototype: all this depends on grade value, curve radii and rolling stock's weight. Myself I'm doing tests on my in progress layout, where grades are 3% continuous and minimum curve radii are 14". Yesterday I was running a 18-car mixed freight consting of 9 MTL boxcars and flatcars, 1 Uncle-Will cylindrical hopper, 5 FR-Models 3-bay hoppers and 2 woodchip cars (heavier than average), and 1 brass tankcar from Kürt Luck in Germany (the fellow who runs Redrock Railroad).

3 GP35s or 2 SD70s are OK for this job, no wheelslip.

But as one can put as many engines as needed at the point of any consist, I guess the bigger problem comes from couplers. It's amazing the effort on them when running a train consisting of only 18 cars on such grades.... One of my initial goals was running 80-car trains on 2% grades, I guess this should every time lead to broken couplers....Unless you're running with DCC and having spare crewmembers at the throttle of helper units... Like the prototype, indeed!

Dom

Dom,

Sorry for the delay in replying here. I didn't realize you had posted on this thread.

80 cars would be quite a pull for this scale, I would think, especially up a 3% grade. That would be an 18-20 foot(roughly 5.8 meters) long train with a total train weight of 800-900 grams, depending on the size of the cars. That would be quite a bit of pressure on the couplers, especially up that grade. There could also be a couple of physics issues here especially with stringlining on curves due to the light weight of the cars and amount of force you would be putting on them from the weight of the train. I'm just guessing at this, but I understand the guys from the San Jose club run pretty long trains on their modular layouts and they may be able to provide more insight into this.


I'm looking at maybe 25 car long trains at the absolute longest. That would be about a 6.5 foot (2 meter) long train, which is plenty long enough for a 15 foot long layout. It looks like I will typically run 18-22 car unit coal trains, 12-15 car local freights, 20 or so car exchange freights from other railroads, and a couple of 6-7 car passenger trains. As I said above, it looks like everything except the smallest locals will have to be double headed.

Todd

Todd,

My general rule of thumb is to always double head locomotives. Even if your locomotive can pull 25+ cars, any slight stalling, or deviation can cause derailments and break aways. I have found double heading really smooths out the operation and keeps the trains running at a very constant pace. (Note this all based on analog operations). Plus it looks great!

Okay, here is my totally non scientific test from this past weekend. Our train club was operating two trains. One was a single MTL F7 Christmas train with 13 cars. The other was a pair of AZL SD70Ms with over 20 high cubes. The club was packed with small children and the layout was getting quite a bit of shaking and bumping. The MTL train was derailed every few minutes. The AZL train never derailed. This may be a number of factors for this. I have been trying to figure it out myself especially since the high-cubes can be top heavy, but I am wondering if the smoother double headed action of the AZL SD70s keep the train at a regular pace where as the single F7 was really getting jostled. Other factors, AZL couplers and metal wheels may also have come to play. All and all, it was interesting to see the difference between the operations of these two trains.

Rob

My rule of thumb is to buy all my mainline locos in pairs. I will get 2 GP9's, GP35's,etc.

Carbody units like the F7 will outpull GP's. The extra weight in the carbody makes a huge difference. I wish Z scale had some Alco FA's to pull with, similar to F's. The FA2 is slightly longer than the FA1.

Single locos can have too many stutters, stalls & other hickups that can cause derailing in curves & turnouts. The stutter introduces an unwanted viabration.

Double locos should lower the starting speed as one unit nudges the other. It would be better to have some way to MU the consist so you have more electrical contact.

Double locos may pull about 10% more than just having 2 single units. This is true for most of the scales. So if one unit pulls 10 cars, 2 should pull 25 or more.

It sure would be fun to find out what the Zscale pulling champ is.

GWoodle, Very good posting. This all make sense. Thank you, Jim CCRR:)

It sure would be fun to find out what the Zscale pulling champ is.

\\

It should be (I wish) the new AZL "Challanger". Imagine, a huge 12mm Faulhaber motor in the tender, six driving axles, lots of weight... If so, I'll buy two. My only problem, I have only 26 PFE reefers.

Lajos:)

GWoodle wrote:

It sure would be fun to find out what the Zscale pulling champ is.

That is easy! AZL's brass F45 is a legend for pulling power. It has a heavy, solid chassis and a powerful 8mm Fualhauber motor. A single F45 has been found to pull 50 car trains. The next runner up is MTL's F7. These classic locos are pulling machines.

Rob

Rob, I thought the F45 had a 10mm motor.

I also like to add the F59PHI. Even thought its not a freight engine, it pulls like one. It used to pull my freight trains before the GP35 and the SD70.

Lajos-- if you need more PFE's I have one set of four and maybe another set- never run- won't even charge storage;)
Never run. new in box
Fred

Lajos-- if you need more PFE's...

Yes. I would take all, send your invoice to This email address is being protected from spambots. You need JavaScript enabled to view it.. What about trade?

Lajos:cheer:

Ok Lajos- These 4 are yours and I'll try to find the other set. I'll contact off site.
Fred

Fred, I'm afraid, your Z Central e-mail address is not working, I've responded to your e-mail two days ago.

Lajos:unsure:

I answered about 2 days ago. I'll Try again.. Let me know if it works,
Fred:S

Just Posted- Did it come thru the wires yet??

Lajos-- I've sent 6 different msgs from 3 starting points- none have been sent back as undeliverable. Plus your site. May have problem at your end.
Fred

This is a very good post and will use it as referance.
Fred

Well since you guys are on the subject of car pulling power, i thiught i would add this. Our Z club, the Wasatch Z Club, here in Utah is working with the show coordinators of our fall show in Salt Lake City to stage an all scales car pulling competion. At next falls show (this year's was several month ago) the organizers will be getting a second building with an addtional 25000 sf of floor space, so we talked with them about setting up this pulling event as a new show display.

What were talking about doing is to setup a long line of display tables against one whole wall of the new building, and layout various guges of snap type track to form several guages of long straight level track to pull on. Each track will be hooked up to a seperate tranformer, and we will have car pulling sessions. We'll try varoius single locos and MU'ed consists with all sorts of numbers of cars behind them. Were hoping to have a scale to be able to weigh out the car load as well, so both total car number, and total gram weight can be figured out for each pull test. Should be fun!!!

I don't have any idea how Z scale will compair with the other scales, but if nothing else, we will be able to do some real testig on the capabilities of Z, and have fun with the public at the same time.

Tony B...
Wasatch Z Club