New Bachmann tank car

[PGE_Modeller]

From the Bachmann NE caboose thread,

Quote from: jmlaboda on December 18, 2011, 10:34:46 PM


    - snip -

    The tank car looks really good as well but it doesn't look like a 10,000 gallon car... the tank looks too small.  In comparing the model to Intermountain's 8.000 gal. model it looks like it is closer to it in capacity.
    - snip -
    If someone gets their hands on one of these models would you please post the diameter of the tank and the car length (scale or prototype measurements are fine... real measurements can be easily converted)... this will help to confirm if I am correct about the car or not.

Jerry,

I picked up one of the new Bachmann tank cars at Central Hobbies this afternoon.  The measurements are:

Outside diameter of dome  = 60"
Outside diameter of tank = 87 3/4"
Length over tank sheets = 31'-3"
Length over tank heads =  33'-6"
Length over end sills = 36'-3"
Length over strikers = 37'-6"
Truck centres = 25'-8"
Width over side sills = 9'-5"

Allowing 3/8" for the thickness of the tank sheets and 5/8" for the thickness of the heads, the volumes calculate out as follows:
Tank body (over head rivets)  9650 US gallons
Tank heads 205 US gallons each
For a total capacity of 10060 US gallons (8383 Imperial gallons)

The rivet detail is very fine and represents a car constructed of three longitudinal courses.  Wheels are all metal with a flange depth of 0.023".  Gauge, check gauge and back-to-back distances on my sample all match the NMRA standards gauge and the axle length is 0.556".  The tread width is somewhat excessive at 0.083".  The Horribly Oversize couplers will have to go.

Of particular interest to me is the fact that the dimensions of this car, except for the truck c-c distance being about 1'-6" short,  match the dimensions of a nominal 10,000 gallon British American Oil Company car,  BAOX 649, very closely - prototype dimensions: tank OD 87 1/2", dome OD 59", length over tank heads  33'-8 1/2", length over strikers 37'-9" and truck centres 27'-1 1/2".  Even the height of the dome is close: 21" compared to 23" on the prototype.

Overall, this car seems to very nicely fill the gap between the Intermountain 8000 gallon car and the Micro-Trains 12500 gallon one.   In terms of overall dimensions and tank size, the car is within a couple of scale inches of matching the dimensions given for two 10,000 gallon cars, CofG 32058 (ex GATX 26107) on page 471 and CofG 32028 on page 474, in the Southern freight car diagrams that Jerry referenced in his earlier post, http://southernmodeler.info/SRrollingstock/SR_FRT_CAR_DGMS_1982.pdf.  The main dimensional discrepancy is in the diameter of the dome as the CofG cars had a smaller (~52" diameter) dome with the safety valves mounted through the side of the dome with a double elbow fitting.

Cheers,
Greg Kennelly
Burnaby, BC

[bbussey]

Greg,

Have you verified the Micro-Trains car is a scale 12,500 gallon tank, or are you siting some previously-established literature?  I always thought the MTL car was 10,000 gallons.  I know the Atlas chemical tankcar is 11,000 gallons, and the MTL car appears to be slightly smaller.

I haven't seen the Bachmann car yet, but I concur that based on photos it appears to be a smaller capacity than the MTL car, and it obviously is a larger capacity than the IMRC model.

[jmlaboda]

"Outside diameter of tank = 87 3/4"...
Length over tank heads =  33'-6"..."

These measurements are in line with some diagrams I have for 10,000 gallon tank cars.

Thanks for answering my question (under the Bachmann caboose thread) about this model.  I do appreciate it!!!

[PGE_Modeller]

Greg,

Have you verified the Micro-Trains car is a scale 12,500 gallon tank, or are you siting some previously-established literature?  I always thought the MTL car was 10,000 gallons.  I know the Atlas chemical tankcar is 11,000 gallons, and the MTL car appears to be slightly smaller.

I haven't seen the Bachmann car yet, but I concur that based on photos it appears to be a smaller capacity than the MTL car, and it obviously is a larger capacity than the IMRC model.

Hi Bryan,

The Micro-Trains tank scales out as follows:

Outside diameter of tank = 93"
Length over tank sheets = 32'-9"
Length over tank heads = 34'-10"

With appropriate allowance for tank and head sheet thickness, these dimensions yield a tank capacity of 11371 US gallons plus 278 US gallons each for the tank heads for a total of 11827 US gallons.  This would be a nominal 12,000 gallon tank - not sure how I originally managed to sneak an extra 500 gallons in there.  There will be a small extra amount for the portion of the dome that extends down the upper curve of the tank, but not 500 gallons!

Here is a photo comparison of the Bachmann and the Micro-Trains tank cars:


With this car from Bachmann, we N-scalers now have a good selection of general service tank cars:

Micro-Trains 6000 gallon 3-compartment
Intermountain 8000 gallon
Bachmann 10000 gallon
Micro-Trains 12000 gallon.

They do, however, all appear to be later (Type 21 or Type 27) AC&F cars so the prototype modellers among us still have a need for cars from Union Tank Car and Standard Steel Car as well as early (Type 4, Type 7 and Type 11) cars from AC&F.  The available cars will, however, serve very nicely as stand-ins until other cars either become available or can be kitbashed

The M-T 6000 gallon car can be readily converted to a single compartment car by removing the two outer domes, filling the resulting holes and sanding off the four lines of rivets that represent the head rivets of the individual compartments toward the middle of the car.

Cheers,
Greg Kennelly
Burnaby, BC

[bbussey]

Greg,

Excellent reporting, thanks.  It's also nice to see that the Bachmann tank is of a distinctly different capacity than that of the MTL car.

I guess that also means I have a few MTL tanks that have to go, as most of the schemes painted on it are of the 10,000-gallon variety.

bb

[PGE_Modeller]

You're welcome, Bryan.

I originally became aware of the true size of the M-T tank when I realized that it was the correct diameter but about 5 feet too long for a specific series of 10,000 gallon (8367 Imperial gallon) PGE tank cars that I wanted to model.  The dome was also too large in diameter but that has been solved since removing the dome from the 12000 gallon car leaves a hole that is almost exactly the size needed to fit in one of the domes removed from the 6000 gallon 3-compartment car - that dome just happens to be within one scale inch of the the size I need!  I do need to fabricate the "double elbow" safety valve mounting for those cars - unfortunately that detail part is only available in HO scale.

Cheers,
Greg Kennelly
Burnaby, BC

[Mark5]

So the MTL is a 12,500? All this time I was thinking it was a 10K. 

I picked up a MTL to strip and paint for N&W Co. service, now I have to go back and revisit that plan.

Thanks for the info!

Mark

[Philip H]

Greg,
Outstanding reporting. Since I need a lot of tank cars to feed the refinery, what's the operating time frame for these?
Thanks,
Philip

[PGE_Modeller]

Hi Philip,

There are others much more knowledgeable than myself regarding tank car timelines, but I'll see what I can do.  As I indicated in my earlier post, the new Bachmann tank car, the two Micro-Trains cars and the Intermountain car all appear to be models of American Car & Foundry cars, most likely of Type 27 (the Intermountain car has certainly been advertized as a Type 27 car).  The definitive reference work for AC&F tank cars is the book "AC&F Tank Cars" by Ed Kaminski, published by Signature Press.  Unfortunately, my copy seems to have developed legs and left home, so I'll try to remember what I can from my perusal of the book a few years ago.

AC&F "Type Numbers" generally refer to the year the underframe was designed and various sizes and styles of tank could be built on the same underframe and, in fact, the same design underframe could be built in different lengths.

As Jerry indicated, many early tanks are distinguished by rows of rivets around the upper part of the tank since they were built using a bottom sheet approximately 80" wide and three or five overlapping bands that formed the upper part of the tank.  AC&F Type 4 and Type 7 cars are examples of this type of construction, although I have been unable to see the horizontal rows of rivets between the bottom sheet and the radial courses on the few photos I have seen of Type 4 cars.  Type 4 cars are characterized by having wooden blocks at both ends of the steel underframe to prevent the tank from moving longitudinally - a carry-over from the days of wood underframe cars.  The bands around the tank only serve to hold the tank down onto the frame - they don't stop it from moving lengthwise.  A major change with the introduction of the Type 7 car was the centre anchor which connected the tank to the centre sill of the car.

By the teens, tank construction had evolved from the earlier radial course design to the more modern longitudinal course design, which is characterized by, typically, three logitudinal double rivet rows - one at the top centre of the car and the other two at the junction between the upper courses and the bottom sheet.  The four tank car models under discussion all represent this type of construction.  The Micro-Trains 6000 gallon 3-compartment car also has four circumferential rows of rivets - two between each pair of domes.  These rivets mark the location of the two pairs of tank heads that separate the car into three compartments.

After the preceding long-winded discussion, let's get back to your question of when these cars were used:

These four models represent a type of construction that indicates they would be unlikely to have been built before the mid 1920s.  I haven't paid much attention to tank car rosters after my own modelling cut-off date of 1952, but I know that some high-walkway Type 7 cars built for the Union Oil Company of Canada in 1908 & 1910 were still being operated by the British American Oil Company in the mid-1950s and a group of low-walkway Type 7 (or maybe Type 11 - I am unsure what the distinction between these two types is) were being operated by Pacific Great Eastern in  diesel fuel service until at least the mid-late 1960s and went on into MOW service after that, with the last one being sold for scrap some time in the 1990s.  British American Oil Company was having cars very similar to the Micro-Trains 12000 gallon car (albeit of welded construction rather than riveted) built as late as February 1954.  These cars were absorbed into the Canadian General Tank Car Company (CGTX) fleet in 1961.

Hopefully, other forum members can add to or correct what I have written and provide information regarding how late cars of this type were still in general use.

Cheers,
Greg Kennelly
Burnaby, BC