About the Märklin/Trix Big Boy, good write up but what will it PULL? I’ve been repeatedly disappointed with some recent engine releases. Some look very good but can’t pull much. Please let me know in ounces or in approximate number of HO cars what this engine will pull.
Francis Tepedino
San Diego, CA
MRN has in development a test bed that will measure the pure pulling power of a locomotive in ounces. Generally, you can reasonably predict that a locomotive’s weight on drivers without traction tires will yield about 25% of that weight in the form of pull. Thus, a 16 ounce diesel with all axles pulling should produce around 4 ounces of pull. Traction tires raise the efficiency from 25% to around 33%, but tires may roll off or fail at any moment. Track conditions and variations between units as they come off the assembly line will further complicate the issue. Don’t forget temperature and humidity.
Once we know the pulling ability in ounces of a given locomotive, we will still need to develop a way of determining the rolling resistance of a given train in negative ounces. Since we have no way of knowing your car weights, axle journal conditions, grades, curves, or any other factors that contribute to rolling resistance on your layout, we will never know how many of your cars a given locomotive can pull. We hope that we will provide modelers with a fair comparison so that they can do the rest on their own.
As to the Märklin/Trix HO Big Boy, we currently cannot put more than 25 cars on a string due to track length (see the Athearn F3-F7 Burlington review this issue for a different approach) but we can superweight some cars. Due to the unusual weight on the journals, this increases their rolling resistance out of proportion, but the bottom line is that the Big Boy pulled such a train weighing 207 ounces, not including the locomotive’s weight, around 27 and 30 inch curves, only slipping a little here and there. I would estimate that to be about equal to 60 or so 40 foot NMRA-weighted 4 ounce cars on the straight and level.
— Ed.
I wonder at the implication made by your Big Boy reviewer that “they (the Big Boys) could then pull a train five miles long at speed!” That would be a train with a length of 26,400 feet. At a conservative 45' over the pulling faces, that would be a train of about 590 cars. Are you getting suspicious? At 50 tons (loaded) for each car, that would be a 29,500 ton train. What do you think? Maybe a bit too much?
Bill Metzger
Forest Grove, OR
Into all of this I’d like to add a note from World’s Greatest Steam Locomotives by Eugene L. Huddleston, reviewed a couple of issues back. He states that the Guinness record for longest train was held by an N&W 500-car coal train in 1967, pulled by a trio of diesels and helped by three remote control units back in the train. The current Guinness record holder dates to August 1989 on the South African 3’ 6” gauge Sishen-Suldanha Railway which pulled a train of 660 wagons, a tank car and a caboose, the entire train being 4-1/2 miles long.
— Ed.
I have the new decapod WM and am pleased with the unit, except it tracks okay thru #6 turnouts, both forward and reverse but is prone to derailing in reverse through #4s. The pilot comes off, and I have tried it on several #4s, including a brand new one. I will try weighting the pilot. The switches are Atlas. A new section of layout will have all Peco so I hope they handle the Russian better. My club has Peco but since I haven’t installed a decoder yet, testing it there will have to wait.
Since I’m near Philadelphia, I called Lee Riley, Bachmann Product Manager, and he was kind to respond to my voice mail stating that he had no problems like I did. He offered a new unit if the problem persists. I would like to see if another unit does the same.
Alden Smith
— Jeff Saxton
I enjoy Michael Pratt’s reviews in Model Railroad News as well as those of Mr. Saxton. Although I am committed to HO scale I usually read those that you publish in other scales, and this brings me to the point of this letter.
Mr. Pratt, in your review of the Kato Budd Rail Diesel Cars you mentioned that the power came from updated WWII engines. This is not quite correct, although close. I do not want to be known as a “nit-picker” but because I believe you are interested in accurate information, I thought the following might be of interest to you.
The Budd RDCs were powered by two General Motors Detroit Diesel model 6-110 two stroke cycle diesels. The six indicates the number of cylinders (in line in this case), the 110 is the cubic inch displacement of each cylinder. They were manufactured between 1950 and 1965. Even though they had a gear driven Roots type blower they were still considered to be naturally aspirated rather than super charged in the eyes of SAE (Society of Automotive Engineers) since the engine would not operate without it.
The Detroit Diesel Division of General Motors sold this engine with horsepower ratings of from 250 to 325 depending on the application. Marine use, (especially in pleasure boats) would have larger injectors and governed at a higher RPM than would a continuous duty generator set on a construction site.
When mounted in the RDC the engine was on its side with a slight incline of about 20°. The drive to the wheels was through an Allison automatic transmission in the same manner as an automobile. Using an automatic transmission behind this much horsepower in 1950 was state of the art engineering. At about this time General Motors was building 2 -1/2 ton trucks for the army with automatic transmissions but it had a small six cylinder 302 cubic inch gasoline engine of 130 horsepower.
The 6-110 engine was developed to be a larger version of the famous 6-71 that performed so well during WW II in landing craft and 35 ton tanks. Here again, the six for cylinders, 71 for cubic inch displacement. This engine, with from 160 to 180 horsepower, became very popular after the war and in 1948 GM started making it in four cylinder and then three and two cylinder designs to power all types of pumps, tractors, and industrial equipment. GM saw the need for a larger engine, but nowhere near as large as the locomotive 567 cubic in per cylinder used in locomotives.
I know of no production highway trucks that were powered with the 110 although there were many pieces of construction equipment that used this engine. In 1958 the 8V-71 engine was introduced, after that the 12V-71 and then the 16V-71 in 1960. These larger engines were overshadowing the 110 series and GM devoted their engineering resources to improving the 71 series and eventually dropping the 110 in 1965. You might say its replacement was the 149 series in the late 60s.
It seems that the 6-110 engine powering the Budd RDC was a marriage made in heaven. There was not previously — and in my humble opinion has not been to this date — a better power plant for the RDC. The two cycle was very smooth, just like the 6-71s in most busses of the 50s, 60s and 70s. There were no 275 hp diesels that would have fit under a coach prior to the 6-110. A “V” engine’s envelope size would have been to high. GM put a number of power packages together out of 6-71s, two side by side twins and two side by side and end to end quad units but these would not have fit under the RDC. The 660 cubic inch displacement was in a class all by itself when compared to four stroke cycle engines it was the equivalent of close to 1000 cubic inches.
In the mid 1970s the Boston MBTA was investigating repowering its fleet of RDCs with Cummins Diesels and Twin Disc torque converters. The engine used as a trial was an 855 cubic inch in line six tubrocharged to about 300 hp. In 1950 a similar Cummins engine would have been 672 cubic inches and turbocharging an engine of that size was in development stages. Three hundred horsepower was hard to find in an automotive diesel. I say automotive because of the size requirement and the high rpm needed so gear changes could be minimized between starting and top speed.
It is interesting to note that these two cycle engines nick-named “Jimmys” are simply a smaller version of the 567 and 645 series manufactured by the EMD division. The EMD engines turn at the rate of 900 RPM while the 6-110 was governed at about 2100 RPM. The two cycle design, with a power stroke every time the piston went down, was smooth running with quick acceleration. The 6-71s, used on most around-town and highway buses in the 50s, 60s and 70s, had a distinctive sound that was exactly like the 6-110. Detroit Diesels did require a large muffler which in the case of the RDCs was located in the mid-mounted dome with the radiator.
Two cycle automotive Detroit Diesels are seldom seen today on new equipment. They are not fuel efficient and have trouble with emissions. They had almost nothing to do with railroads with the exception of the Budd RDCs
Keep up the great work. Please send an advertising rate card; I’m thinking about doing some for my new line of solid urethane 1940s and 50s trucks. Some of these will only be sold direct, and I may use media like MRN to get the word out in addition to my web site (when I finally get it designed)
George Barrett
Sheepscot Scale Products
— Ed.
This is the first part of Bill’s letter. RBL type car = RailBox ownership? I don’t think so. RBL is an AAR classification for insulated box cars with adjustable loading or stowing devices. The symbols are derived from: R=Refrigerator B=Bunkerless L=loading devices. Although the RBLs had no reefer units, their insulation could hold interior temperatures much better than a standard box car. Those standard box cars were AAR class XL; X=Box car L=loading devices.
In the next few lines, your author makes reference to a photo on G. Elwood’s site of a very different car from the one in the review. The photo IS of an XL class, plate E car (very TALL!) but it is a very different design than the Evans car he is reviewing.
Bill Metzger
Forest Grove, OR
— Ed.
I’m happy with the publication now. If it’s not broke, don’t fix it.
Cliff White
Pittsfield, MA
— Ed.
Peter Hewitt
Derbyville, VT
— Ed.
Jack Moser
Oaklawn, IL
— Ed.
My dad was a teenaged soldier in 1945 and missed seeing action in the Pacific Theater by only a matter of weeks. He recalls the troop trains he rode to and from the West Coast. Has any manufacturer made an HO model of a troop train? I would love to know. P.S. I am willing to pay a little more if you expand your publication.
Paul E. Housworth
Oreland, PA
Between his memories and your research, you should have some idea what you want. Locomotives were assigned from the various railroads over which a troop train traveled. With such a list in hand, you can either search the Walther’s Catalog at your local hobby shop or on line at www.walthers.com As a writer, I encourage you and your father to write up the story, including anecdotes, as you build your train. You will then have a story — complete with props — to share with younger generations in your family.
— Ed.
