On Feb 7, 2023, at 6:23 PM, Dave Parker via groups.io <spottab@...> wrote:

On Tue, Feb 7, 2023 at 02:43 PM, David wrote:

ACF did switch to 3-course 10k tanks in the mid-1920s.

My observations agree with what David is saying.  Flipping through all my Type 21 builders photos, it looks like the switch occurred from 1925 (4-course tanks) to 1926 (3-course).  Maybe not a hard shift, but I haven't seen an exception. (There is one oddball from 2/20:  Magnolia (MPCX) 618 looks like a 3-course 10-kgal car, but car 777 built one month later is 4-course).

The 1927-29 years embrace that period when ACF was building "Type 27" cars that looked just like Type 21s.  The longer frame seems to have come on line ca. 1930.  
 
-- 
Dave Parker
Swall Meadows, CA

Dave, Tim, Todd & others interested,

Just to share some info about this topic, over the span of about 5 years ACF developed 3 sets of drawings applicable to Type 21 & an early-version Type 27 tank cars as Dave accurately stated that were dimensionally very similar to the earlier Type 21’s. General arrangement drawings from the ACF drawing collection at the National Museum of Transportation all denote 9’-3” for the underframe width. Varying underframe dimensions are defined below. For the common 8,000-gallon & 10,000-gallon Type 21 & early-version Type 27 tank cars, the tanks were 28’-0” long. Tank inside diameters were 83” (8,000 gal.) and 92 1/2" (10,000 gal.). Viewing these drawings would likely spot various design changes in addition to the dimensional differences.

1. Type 21 general arrangement drawing 6569219, dated 9/5/1922 (generally used for ARA III & IV cars)

32’-5 7/8” over end sills

22’-8” truck centers

A Type 21 sample car built to the above design was lot 9468, ACFX 10032, built 1-23 (10,000 gallons, ARA III, 4-course tank). Two builder photos of ACFX 10032 are on the Barriger Flickr website. However, 3 slightly later lot numbers 9472, 9475 & 9476 show Type 21 cars built earlier than ACFX 10032. Three orders with 11-22 build dates are RBGX 102 (8K, ARA III), DAX 25-26 (10K, ARA III) & EJRR&TCo. 1210-1242? (33 cars, 10K, ARA III). Builder photos of all 3 of these lots are also on the Barriger Flickr website. Since the ACF lot list from this period provides only a cursory description of the cars to be built and in these cases didn’t identify the “type” number, I suppose it’s possible that these 3 lots built 11-22 could be late Type 20 tank cars rather than early Type 21. 

2. Type 21 general arrangement drawing 3577819, dated 2/8/1927 (generally used for ARA III & IV cars)

32’-5 5/8” over end sills

22’-9” truck centers

The final ARA III that I can determine was lot 547, MSWRY X1000-X1005 built 11-27 (7,000 gallons, ARA III, 3-course tank). 

3. Type 27 general arrangement drawing 3578849, dated 11/5/1927 (generally used for ICC-103 cars)

32’-5 5/8” over end sills

21’-11 1/2” truck centers

The earliest Type 27 with the short underframe that I have documented is lot 564, SHPX 10468-10469, built 12-27 (10,000 gallons, ICC-103). 

It’s noted that these initial Type 27 design came at the approximate time that the ARA roman numeral class designations were changed to ICC classifications such as ICC-103 that replaced ARA III. Production of these early-version Type 27 tank cars ceased with lot 1079, SHPX 10740-10761, built 10-29 (10,000 gallons, ICC-103). However, one last car assigned an earlier lot no. 1056 had a build date of 12-29 (PSMX 246-250, 7,000 gallons, ICC-103A).

Does anyone know if by chance the switch from ARA to ICC classifications had anything to do with the truck centers being shortened by 9 1/2 inches? 

Following are some approximate quantities of 8K & 10K-gallon cars built from the different groups of Type 21, 8,000 & 10,000-gallon ARA III and early-version Type 27 ICC-103 tank cars (all uninsulated, single-compartment). The quantities are approximate due to me not having photos or drawings that pertain to every lot number. Not in these counts are ACF tank cars of other designs lacking rolled channel side & end sills, designated as Type 25, 25A, 26, and 28. These cars used the same tanks as the Type 21 and early-Type 27 cars. 

Type 21, 8,000 gal., ARA III, 3-course tank - 1,926 cars, built 11-22 to 7-27, lot no. range 9472 to 10015 plus 14 to 519

Type 27, 8,000 gal., ICC-103, 3-course tank - 627 cars, built 11-27 to 10-29, lot no. range 566 to 1020 **

Type 21, 10,000 gal., ARA III, 4-course tank - 1,118 cars, built ca. 11-22 to 6-25; lot no. range 9468 to 9976, plus lot 13.

Type 21, 10,000 gal., ARA III, unknown if 3-course or 4 course tanks - 416 cars, 6 lots built ca. 12-24 to 4-25; lot no. range 9921-9948, 9982, 9990.

Type 21, 10,000 gal., ARA III, 3-course tank - 1,094 cars, built ca. 2-26 to 10-27; lot no. range 136 to 531.

Type 27, 10,000 gal., ICC-103, 3-course tank - 527 cars, built ca. 12-27 to 10-29; lot no. range 552 to 1079.

** While all cars in the above Type 27 groups denote ICC-103 stencils, some lots were specified as Type 21. It’s apparent the requirement for ICC-103 stencils occurred before all tank cars using ACF general arrangement drawing 3577819 were completed & delivered. Thus, some of these tank cars with ICC-103 stencils were built to Type 21 specs per the 2nd general arrangement drawing 3577819 instead of the 3rd general arrangement drawing 3578849.

Dave, as you noted the longer-version Type 27’s were first built in 10-29.  The earliest ICC-103 order of 8K & 10K-gallon cars I have documented is lot 1011, STLX 81-90, built 10-29 to 5-30 (8,000 gallons). Numerous other lots followed into early 1930 thru lot 1089, HPDX 401-410, built 1-30 (10,000 gallons, ICC-103). These Type 27 tank cars cars were nearly 4’ longer than the original design with the length over center sills of 36’-2 3/8” and 25’-8 1/4” truck centers. The tanks were accordingly lengthened and made smaller in diameter.

8,000 gallons - 78” inside diameter, 31’-6” length 

10,000 gallons - 87 1/4” inside diameter, 31’-6” length

Some may recall my two articles in RP CYC Volumes 2 and 3 that pertain to these longer-version 8K & 10K-gallon Type 27 tank cars built from ca. 10-29, thru the 1930s & into the 1940s. 

Regards,

Ed Hawkins