Simulated 3% slope for testing

[jward]

the es44c4 is a special case. the goal here was for ge to eliminate the dc traction motor from their locomotives. ac motors are easier to maintain, and can outpull their dc counterparts by a significant amount.. ge has designed the es44c4 to replace the es44dc. bnsf so far has the only examples in operation, they were also one of the largest buyers of the es44dc and its predecessor the c44-9w. (720 es44dc and 1796 c44-9w) 

the sdl39s were actually a north american adaptation of an export design, other sdl variants have been sold to overseas buyers.

it should be noted that in the past 30 years or so, most of the older light rail branch lines which required lightweight locomotives have been abandoned. those whose traffic justified it were upgraded. the advent of standardized 288k cars has forced the hand of many smaller lines: upgrade to the larger cars demanded by shippers or die.

[Desertdweller]

I thought it was neat to pull an A-1-A locomotive for the last run.  It was the lead loco in a consist of C44-9W's.

The Dash 9's were my favorite loco to run, regardless of the railroad.  BNSF locos always seemed to be the best maintained and cleanest.

The Milwaukee Road SD7's with the light weight option had flexicoil trucks.  In an even more extreme example, we had a secondary line (ex-narrow gauge) that had bridges so lightly built that we had a special group of SW1's fitted with mu connections to run on it.  Four or five of these little guys would handle short trains.  I never operated a true switcher.  By the time I became an engineer, GP's were used for switching.  The smallest loco I ever ran was a GP7.

I remember working on small railroads where there was a controversy among the engineers over what was preferable, a Dash 9 or a SD70MAC.  I liked the GE's better, but I think I was in a minority.

Les

[jward]

I can tell you horror stories of the ge dash 7s, which I am told were a drastic improvement over the u boats. o dodn;t run them but I helped deal with many locomotive failures enroute. the line I was assigned to primarily had banned all 6 axle units except those with radial trucks due to track conditions. 4 axle dash 8s were rare on our line, and there were no 4 axle dash 9s so I can't say from personal experience if they were any good. but my experiences with earlier ges, along with the fact that railroads are choosing to retire the dash 8s rather than rebuild them has made me skeptical of any ge product.

the sd80macs we eventually ended up using were orphans on ns at that time, the only ac units and the only 20 cylinder ones, but they performed admirably given the circumstances. I've seen them do some amazing things in a service they were not intended for, and outside of software issues they were much more reliable than anything else I had to deal with.

note that the reason we were restricted to certain locomotives was due to the age and brittleness of the rail we were running on. a rigid frame 6 wheel truck was not flexible enough for track conditions but radial trucks were, and with 14.400 ton coal trains climbing 2% grades we needed all the power we could get. 4 sd80s were able to replace 8-10 4 axle units, and our risk of stalling due to locomotive failure, and doubling the hill and running the first cut 30 miles or so to the power plant because there were no usable sidings on the line became largely a thing of the past.

the ge's we used were everything from b23-7s to b40-8s and they were notorious for flameouts, occasionally setting brush fires along the line. a b36-7 or b40-8 is not a good puller even with a radar based wheelslip control. they and the gp50s would loose their grip on the rail, the wheelsips would catch the slip and throttle down, wheels would regain their grip on the rail, and the resulting tug could have a disasterous effect on the drawbars n that first car in the train.

[Desertdweller]

In my experience the B23-7 was a sweet unit to run.  A little slow to load, and tended to rock at 19mph on staggered joint rail, but otherwise a very good unit.

The B36-7, on the other hand, was not so good in my opinion.  Slippery and with a cramped cab.  For some reason, some of the larger units had pretty small cabs.  SD7's and 9's were surprisingly cramped.

The Dash 9's corrected the earlier problems encountered in big GE's.

SD40's and SD40-2's were both good models.  The cabs were larger than earlier SD's, and they seemed quite dependable.

I liked running the old Geeps, too, especially the non-turbo models: GP7, GP9, GP18, GP38's.  They were better switchers and low-speed luggers than GP20's and GP40's.

I've run SD45's, and they seemed to be a lot like SD40's.  The 20 cyl. engine led to some reliability problems, but they never gave me any trouble, just four extra cylinders to blow down.

Something I would have liked to try, but never had the opportunity, would be to run a set with slugs.
I think they would have been excellent low-speed haulers.

Something else I would have liked would have been to run an F unit.  I've ridden in lots of them, but before I was able to run them.  Never even ran a CF7.

What I thought was really cool was running an ex-ATSF wide cab unit in red and silver warbonnet.  It was like a Lionel fantasy!

Les

[rbryce1]

OK, testing is complete and problems are solved.

I set up 8 feet of Woodland Scenic 4% slope foam, put 8 feet of Bachmann track on it, one Bachmann GP40 and it went up the grade fine with no problems. 

I attached one of the McKinley Explorer passenger cars, and it went up and down fine. 

Then two of the passenger cars, and it went up and down fine. 

The third car went up, but the wheels on the GP40 were slipping slightly.

Adding a second GP40, they all went up and down fine.  Added another passenger car and they went fine, but the 5th car made the locos slip again.

Added the third loco and another car and it went fine.

Then I removed the GP40's and inserted one of the Bowser F7a units, and it pulled the five cars fine.  The Bowser started slipping with the 6th car, and when I added the second Bowser, it pulled fine. 

I added 8 more feet of track (level) and the two Bowsers pulled all 9 cars without difficulty up the 4% slope.

Conclusions:  I can use the 2 Bowser F7a's to pull the 9 McKinley Explorer cars and the 4 Bachmann GP40's to pull the 5 Princess Cruise Line cars up the 4% grade.

Moving forward again!

[jbrock27]

Would I be incorrect to assume the Bowser units are heavier than the Bachmann ones?

[rbryce1]

You are correct, they are a bit heavier.

HO DCC Bowser F7a:  18.15 oz.

HO DCC Bachmann GP40:  14.40 oz.

Bowser is sound equipped, Bachmann is not.  All have 2 axle trucks.

[jbrock27]

Thanks Rob.  Your test results make all the sense.

[jward]

something seems a little off here. both locomotives have all weight on the drive wheels. the gp40 weighs 80% as much as the f7, yet it only pulls half as much. why is this? according to the weight, it should be able to pull 3 cars up that grade. what is causing the loss of traction in your gp40s?

[Doneldon]

Jeff-

This isn't a linear relationship for either models or the real thing. A locomotive's ability to pull is determined by a number of factors. You could have two locomotives with the same motors, weights and wheel numbers which pull different numbers of cars (also matched). Or perhaps they pull the same number on level track but not on a grade. Or conversely.

What could explain this? Well, here's just a short list of possibilities: different wheel materials, different balance shifts (front to back and left to right) on grades or curves, different bearings or bearing design, drive mechanisms which bind under certain conditions of curvature or grade, different gear materials or different electricity delivered to the motors due to different conductors used in building the locomotive. You can also have different results based on who is operating the locos, just as different drivers get different performance and mileage from identical vehicles.
                                                                                                                                                                                                    -- D

[jbrock27]

Here's a thought: The Bowser F7As are better pullers than the B'mann GP40s

[rbryce1]

I would agree that there is probably not one single item causing the engines to pull differently, maybe one motor has better torque, maybe 2 poles or 4 poles, maybe different gears in the trucks themselves, don't know.

I do know each of the 4 Bachmanns pull the same load as each other and both Bowsers pull the same load as each other.  I was lucky this week and found another Bowser Alaska F7A with sound on Ebay and it will arrive today.  Now I have a 3rd engine to compare with.

Still have the same plans, The McKinley Explorer with the Bowsers and the Princess Cruise Line cars with the Bachmanns.

[DAVE2744]

I had a stock B'mann S4. Could just barely push 4 B'mann modern ore cars up an 18R 4% grade.  Had the unit replaced by B'mann under warranty ( dcc issue ), thank you B'mann.  Here is the interesting part. The new unit, completely stock, pushes 6 of the same cars up the same grade. Go figure.

[jbrock27]

I figure, a functioning locomotive, pulls/pushes better, than a defective one (short of other factors not made aware of).