Sunday, June 5, 2022

Modeling Blackburn Beet Racks (Part 1) - History & Evolution

This post will be discussing the 1924 Blackburn Beet Racks with a short overview of preceding designs.  In Part 2, I'll be covering construction of the OwlMtModels HO-scale model.

A string of Blackburn Racks roll westward through Caliente to Bakersfield in the closing years of the flatcar-mounted racks. Jason Hill - Jan 2020.

Research & a Cancelled SPH&TS 2020 Presentation

During the end of 2019 and the start of 2020, I was expecting to be doing a presentation on the Southern Pacific's Sugar Beets at the Southern Pacific Historical & Technical Society  2020 Convention in Sparks, NV.  Specifically, the development of the various 'Racks' on the SP.  The ensuing closures and inabilities to travel to do the rest of the research, followed by the cancellation of the Convention very much restricted the options for completing the research for the presentation.

Therefore, I will be discussing some of the information in this blog post.  I will preface this post with the note that I was unable to get a hold of any good roster data for the Southern Pacific's fleet of beet racks or corporate letters regarding the reasoning behind the design evolution.  From what I have been able to acquire over the last 3-5 years is mostly drawings of the various "beet racks".

Anthony Thompson's great series on Southern Pacific Freight Cars covers cars from the founding of the CP in the 1870s all the way up to the end of Southern Pacific's own designs in the 1960s when the company moved to outside company's designs (Pullman, Thrall, AC&F, Greenville, etc).  Southern Pacific Freight Cars Vol.3 has a few photos of the early sugar beet racks.  Sporadic additional photos have been found in later volumes in the back of the book's Appendix as new information was found.  John Signor's Trainline article also covers the operations of the Southern Pacific's Sugar Beet operations in California, mostly focusing on the 1950-1990 operations which he able to see.

Beet Rack History

Early Blackburn Racks

Allegedly Roseville, I suspect actually Sacramento Shops with beet racks stacked for storage. - Shasta Archives.

This would make since as the depths of the Depression would have put many of these older racks and cars into extra storage, such as the photo of stacks of beet racks in Roseville, Calif.  It would seem that these 2-Diaphragm racks were recycled with their hardware being reused in a 3:2 ratio to the longer racks.

Blackburn developed and patented his improvement on the early sugar beet racks around 1911.  I believe from my research that his patents had to do with the locking mechanism on the side-hung doors.

OwlMtModels drawing research pre-1924 Racks & Flatcars (click on image to enlarge)

This is a screen shot from my spreadsheet on the SP Drawings that I was able to acquire for the Blackburn Beet Rack project.  This first part is the designs leading up to the 1924 (4-board) Blackburn Rack that OwlMtModels has produced in HO scale.  

B-340, an earlier 34ft Blackburn Rack on CS-35 flat (36ft) with large side doors and one board extension. Note opening in end boards to access underside of rack. - Shasta Archives

I should note that the beet racks were designed to fit whatever CP and SP's standard flatcars were at the time, this resulted in the racks fitting designs in the 10-15 year old range.  The newest flatcars being kept for regular interchange service.  In the later years, extra T&NO flats were sent to the Pacific Lines for seasonal beet service.  The yellow lines in the spread sheet show the introduction of each New Class of SP Flatcar, then you can see the car length increase on the later classes, and the beet rack lengths also increasing a few years later to fit those once they have become the "Standard" flatcar for the era.  The other colors each represent a drawing, with the following revisions keeping the same colors throughout.

There are some holes in the research, because I wasn't able to find some of the drawings, but given what I was able to find and what photos exist, it is possible to make some logical connections of how the designs evolved.

SP New 1924 Blackburn Beet Rack for 40ft 10in Flatcars

Wrecked 1924 Blackburn Rack?

Interesting wrecked photo of F-50-series flatcars with early and 1924 (5-board) Blackburn beet rack - Eddie Sims collection.

The wrecked photo above shows two F-50-series flatcars with two versions of beet racks.  The one on the left is the as-built 1924 (5-board) Blackburn rack.  The one on the right is one of the earlier 1911 racks with X-braced doors, and only one sideboard added just above the hinge rod.  It would appear that a car over-rode the draftgear on the 1924 rack car and smashed the end of the rack, pushing the B-end panel almost to the 1st internal diaphragm.  Some of the A-frame appears to still be in place, which the end is folded back over the top of. - Thanks to Eddie Sims for sharing this photo with me!

Growth to New 40ft 1924 Design

Example of the 5-board (8'0" Height) Blackburn Racks with T-Diaphragms of Drawing 9013.

An example is the Drawing 9013, which were designed for 32ft racks, which were 3-bays, using 2 internal Diaphragms which were T-shaped.  

This 5-board version of the Blackburn design, using T-Diaphragms, suggests one of the Drawing 19968-662. (design concept 2018, OMM)

I believe that 16379, Revision-F, Feb 21, 1931 brings Drawing 9013 into alignment with the longer racks, which suggests the abandonment of the older 36ft flatcars around that date. 

Blackburn Racks in 1929 YouTube Video!

This is a video made from early sound-synchronized movie film from 1929.  So the background of the engines making their demo runs are a long string of mostly the 5-board 1924 Blackburn racks on SP F-50-series and other 40ft flatcars as well.  Earlier in the video there are more great shots of heavy SP steam engines "racing" for the footage.  (

Evolution of SP's 1924 Blackburn Beet Racks

SP's 1924 Pattern Blackburn Beet Racks riding F-50-series flatcars. - LMRC, 2020.

The Blackburn rack designs were improved on over the years.  At first, new board extensions were added above the hinge rod.  Finally in the 1924 "Improved" design, the whole rack was redesigned to have smaller doors, still hung from the same hinges but several feet shorter.  The upper board extensions were changed in 1924, to be a stronger X-braced panel with 5-boards above the hinges.

OwlMtModels drawing research pre-1924 Racks & Flatcars (click on image to enlarge)

Looking at the drawings and the revision dates, the beet racks seemed to immediately need changes as the new March 1924 design increased the height and the cubic capacity.  This increase in size, I believe, exceeded the strength of the wooden members making up the beet racks.  This is Drawing 16379 from 3-28-1924.  Then a series of revisions to the designs seem to occur repeatedly about every 9-12 months into 1929.  The Racks covered in Drawing 16379 are 36ft 11.5" long, 8;0" High (5-board) and used three H-Diaphragms between the doors, as built.

Diaphragms with H-style construction, connecting the two posts of the car.  Also notice the tie-rods connecting the middle of the X-bracing inside the upper sides.

16379, Revision-A, in November 11, 1925:  The top and bottom side boards were changed from 1" to 2" thickness.  5/8" Tension Rod added through slat stiffeners and center door hinges, adding Washer Plates for Roller Bracket Bolts.

I submit that these changes were attempting to keep the beets from breaking these boards.  Note, that during this time the racks were using 37ft long 1x6s.  When those broke, new 37ft long 1x6s were needed.  Obviously this is painful in the material costs, so the SP was trying to solve this problem.

16379, Revision-B, Sept 2, 1927:  Adding slat reinforcing Cleats, Post Tire Rods, and various minor details to agree with racks built at LA in July and August 1924.  Ref to Drawing of Application of Roller Bar Keeper eliminated.

16379, Revision-C, November 30, 1928:  Reduce overall height of Rack from 8'0" to 7'3", Cubic Capy from 1966 to 1711 Cu Ft and minor changes to spacing of slats to agree with decreased height (in end panel, along with one fewer grab irons).

16379, Revision-D, April 27, 1929:  Added not specifying change to class of lumber used in the rack. - I believe this was another attempt to "fix" the breaking board problems from 1925 and 1928... It would seem that the SP was still having a large number of broken boards.

16379, Revision-E, May 16, 1930:  Relocated Longitudinal Top Rods and shortened Diaphragms to agree with Drawing 16380, Book 662. - Drawing 16380 revision the next day, Change Height of Diaphragm from 6'9.25" to 6'6.5".

This change allows the diaphragm to match the side-board height reduction.

16379, Revision-F, Feb 21, 1931:  Change to design of Diaphragm to agree with detail drawing.  Eliminate Cross-tirerods at Posts.  Added Slat to Splitce Plate and minor changes to Wrough-Iron Details from Drawing 9013, Book 662 (32ft-5in, 6ft-5in height 3-bay rack, T-Diaphragm) to Drawing 19968, Book 662.

Unfortunately I don't have a copy of Drawing 19968-662, but I believe this is the increase in length of the rack to match the Drawing 16379, while retaining the T-Diaphragm and parts from the Drawing 9013.

Ted Waterhouse'sbeautiful scratch-built beet loader topping off an OwlMtModels 1924/31 Beet Rack on F-50-8. - Ted Waterhouse's modeling and photo, used with permission.

It appears that Feb 21, 1931 is the date when SP's designers finally gave up on the 37ft long upper slat boards.  They seem to just continue breaking and with the depths of the depression taking deep hold on the SP's purse strings.  Metal splice plates are added at the Diaphragms, allowing the slat boards to be cut into sections long enough to span the distance between the Diaphragms.  These boards were not replaced all at once with shorter ones, but it would seem that it was an add-needed basis.

The photos show that some cars only have a couple of spliced boards... other cars have maybe 50-80% of the possible joints spliced.  The disadvantage of the splice joints is that the joint looses longitudinal strength, allowing the slat board to flex outward under the load of beets.  It would seem that the cross rod through the center of the X-brace in the upper sides would loosen up, allowing the boards to flex too much, causing them to break at the diaphragm.  Thus the splice plates give up on trying to keep the boards from breaking there, but instead allow them to flex if needed.  Therefore, many of these cars with spliced slats have sides that bow outwards when loaded, and may even collapse inward when empty.

No further changes of note were made resulting in large visible changes to the beet racks after the Revision-F on Feb 21, 1931.  The racks remained in service, with basic repairs until replaced in 1948 & 1949 by the 2500 new composite GS gondolas.  I have not found any photos of these Blackburn racks after 1949, although similarly designed pulp-wood racks did last until roughly the same time, perhaps a little longer.

Beet Racks on the V&T?

There's also some photos taken on the V&TRR, suggesting that some of the SP beet racks were used to ship cord-wood in to the V&T, probably with the A-frame boards removed.  Some beet racks also seem to have been used without their A-frames as extra stock cars for sheep movements!  I'm not sure if another false floor was installed over the basic frame of the rack for this operation.

V&T 26 with Blackburn Rack "B-747" circa 1941 - from Ryan Blake capture off Ebay - Cropped

The above photos shows that the Beet Rack door latch levers are pulled to the released position (i.e. away from the end of the bunk at left).  Interesting to see the car being moved with the doors unlocked.  The Rack is carried in this photo on an early F-50-1/2/3 class car with the PSC deep pressed steel sidesills.  This is one of the few photos that shows a B-number clearly, as B-747.  Also of interest is that the right side of the close end doesn't show a B-number stencil, which means that this rack probably has the end B-number stenciled vertically on the center post.

In Closing

Four OwlMtModels Blackburn 1931 cut-down beet racks under construction.

I'll be covering construction and tips for building the HO scale model in Modeling Blackburn Beet Racks (Part 2) - Construction with OwlMtModels Beet Racks.

Jason Hill

Related Articles:

OwlMtModels Blackburn Sugar Beet Racks - Link to sales page (and combo kits with F-50-series flatcar)

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