Tuesday, April 27, 2021

SP Tender Swapping (Part 2) - "Tender Migration" Between Shops

In my previous post about SP Tender Swapping (Part 1), we looked at various prototype tenders, and ones that are commonly available to trade between models to get the 'right tender' to match a given photo.

Tender Migration




This time I'm looking at a different take on the "tender swapping" game.  How were tenders moved between the various shops?  What happened when engines were scrapped and the tenders migrated to other divisions to be put behind engines which were still in service?

During the various decades of service from the 1920s, through the 1930s, then the 1940s, and finally in the mid-1950s, the SP's steam engines tended to keep getting larger and larger tenders assigned as the smaller engines were scrapped.

An early photo of SP 5000 with the single 120-C-3 class tender.  Most of the SP-series of engines received 120-C-5 tenders. - Eddie Sims collection

It's hard to believe that the SP (4-10-2) class engines were delivered with 120-C-3 and -5 tenders, during the swaps of the late 1940s, they received 160-C types instead.  Many of the SP's F-class 2-10-2s also traded up their 120-C-series tenders for 160-C types during the 1950s.

A few SP 'Decks', such as F-4 class 3704, received very large square tenders from the AC-9s or foreign roads, for use in desert territories. - Eddie Sims collection.

In some cases, engines such as the AM and AC-1/2/3 classes were scrapped and their tenders filtered down to F-1, Mk-2/4, Mk-10/11, and various other engines.  As the AC-4s and 5s were retired even larger 160-C class tenders became surplus and were transferred to other smaller engines, then those tenders moved down to Mk-2/4 and 5/6s and C-classes.

SP 2771 with a 120-SC-series tender off an AC-3 or AM-series articulated.  This one still has the pressure cap on the oil bunker! - Eddie Sims collection.

These shuffles resulted in some weird combinations, such as C-class 2-8-0s receiving 120-SC-series "whale-back" tenders!

SP Tenders Away from their Engines


SP 4279's tender is set aside while the engine receives a new set of flues and rebuilt super-heater unit

Spare tenders for another AC and a GS also rest in the 'Garden' at Bakersfield while the engines are in the backshops.

The SP 'Malley Shed' at Bakersfield, which was used as a heavy car shop after the 1930s, usually had a half dozen or so tenders stacked into one of the open-air stub tracks being worked on or stored waiting for their assigned engine to come out of the backshop facilities at Bakersfield.  A few could also be seen over in the 'Whisker' tracks on the west side of the turn table at the electricians shed or stored for a 'quick' flue job, such as on the SP 4279 in one classic shot from the roof of the water tower.

The Prototype Photo


Here a set of F-units approaches Tunnel 2 with the (Mojave) "Shorts", notice the pair of tenders at the right of the photo. - E.K.Huller photo

In the photo above a pair of tenders are being moved from Bakersfield or west of Bakersfield to Los Angeles.  It is also possible that the tenders in the photo are set of tenders assigned to MW service.  The pair of tenders appear to both be 120-C-2, or possibly 120-C-3/6 class tenders.

Sunset 120-C-2 tender

These could be made with either Sunset, PSC, or (in the case of the 120-C-6 tender) Athearn-Genesis spare tenders.  - Unfortunately, most of the 120-C-1/2 tenders around my shop are all claimed for various engines.  

Athearn-Genesis 120-C-6 tender for SP 3266

A pair of Athearn-Genesis tenders would make a very nice starting point, but the $70+ list price per tender starts making that a bit painful.  Unfortunately the Athearn-Genesis tenders that are in 'the pool' are already claimed by other engines.  Some of those tenders could of course be 'borrowed' until their engines are finished and the DCC installed, etc.  However, I'd rather not have to retouch the numbers on the back of the tender.  From some photos in Robert Church's books on the Ten-Couple and 4-8-2 Mountains, these tenders when unassigned usually had their tender frame numbers painted on the backs of the tank. - I assume that during transfers between the shops, this would be the method used to keep track of them.  Of course any tenders in SPMW service would carry their own MW numbers.

SPMW 8241 built from an MDC/Roundhouse 70-C-1/2 tender

On with the Project!


The easiest... and probably prototypically lazy way to deal with the problem of where to get your 'spare tenders' from is to do just what the prototype did.  Use your supply of extra tenders you're not using with your engines!

Spare Sunset Models 70-C-9 class tender

In my current case, there are a couple of extra tenders from Sunset M-6/M-9 class 2-6-0s which could use new homes, but by the late 1940s and early 1950s, the super small 70-C-9/10 class tenders were mostly relegated to small 0-6-0s.

SP 2757 with 70-C-9 tender after WWII. - Eddie Sims collection

In some cases 2-6-0s and even 2-8-0s were assigned these small tenders when assigned to local yard work.

SP 2718 with 100-C tender by post-WWII era. - Eddie Sims Collection

However for my purposes the 2-6-0s and 'bigger' C-8/9/10 class 2-8-0s working out of Bakersfield generally had the larger 90-C and 100-C size tenders, and my little SP 1213 already has a little tender!

Tender book, that I used to find the tender frame numbers for these tender classes.

Looking at Southern Pacific Historical & Technical Society's Tender Book, I find that SP had only two tenders rebuilt to class 70-C-10, so these more rare tenders probably wouldn't have ended up coupled to each other in a transfer move as I'm considering modeling.  Ideally then, the spare tenders could be a 70-C-9 and a 70-C-10.

Painting and Weathering Choices


In the photos in Robert Church's books some of these unassigned tenders are obviously fresh out of the paint shops after rebuilding.  Some could have been stored for weeks or months before being assigned to a new engine or ordered to be transferred to another shop for assignment.

Here's an example of a traded tender, freshly cleaned, behind a dirty SP 3266.

The tenders probably would get a bit of running weathering en route, but would be given a quick wash down or steam cleaning before having their new engine number painted on the rear of the tank.

Tenders coming through this process would probably have a slightly different 'patched' appearance on the rear of the tank where the new road number is applied over the tender 'frame number'.  This is another detail which can be added to your paired steam engines and tenders.  As you change your engines and tenders around this prototype 'patch' painting work can be used to hide the fact that you've swapped tenders, without completely repainting a tender from scratch.

Painting the 70-C-9/10 Class Tenders



Sunset Models M-9 class 2-6-0 with proper replacement 100-C-1/2 tender.

Both of the 70-C-series tenders for this project came from Sunset M-6 and M-9 class 2-6-0s.  These tenders are too small for the prototypes my customer and I wanted to build them to be.

SP C-70-9 and -10 class tenders

Other side of the two tenders.

I mocked-up the two tenders with Tichy Andrews trucks.  For rollablity as cars and the fact that the metal trucks were needed to go under the Balboa 100-C-1/2 tenders.

SP 6855 & 7067 tender numbers in place of locomotive numbers. 

SP painted the tender frame numbers on the tenders when they were not assigned to specific engines.

Mechanical Changes


Mechanically the changes required will be very minimal.  On the prototype, obviously the stacked drawbars (one above the other) would simply be connected to the other tender instead of to the rear of the engine frame.  I'm sure the extra drawbars could be loaded onto the tops of the tenders or otherwise coordinated between the shops to have the proper number of drawbars at the receiving shop to connect the engines with their new tenders.

Tenders drawbarred in this version with a piece of PC-board.  I may replace this with brass section.

Generally the brass tender models have a threaded post at the front of the tender which slips through a hole in the engine's drawbar.  For this conversion I'll be swapping out the 1.4mm threaded rod-pin for a screw and a drawbar to keep the two tenders together.

The main consideration with using brass tenders in this way is that there is NO INSULATION between the tender frame and the drawbar pin.  Using a metal drawbar will cause a short between the two tenders.  One of two things must be done for this configuration to work: 1. swap the pickup side of the tender trucks to the 'wrong side' or use of a insulating drawbar or draft gear box for one or both ends of the drawbar.  Thankfully in most cases, converting these cars to plastic trucks should solve these electrical issues.

Truck Bolster Shims


Tichy Andrews trucks, 0.03" bolster shims, and some 1.4mm screws for the bolsters.

The Tichy trucks are lower at the bolster than the previous Sunset Models brass trucks, so I need to shim the bolsters up to fix the coupler heights.

Coupler Box Shims


SP 7067, 70-C-10, tender ready for the road.

I shimmed the coupler boxes with a small piece of 0.02" x 0.04" styrene cut to 21" long.  A little touch up paint could be used along the outer edge of the shim.


Coupler height adjusted on SP 7067.

A bit of adjustment was also needed to the rear pilot footboards, which looked like they got tweaked a bit somewhere along the line.

SP 6855 coupler height after shimming.

I may eventually put leaf-springs in the Andrews trucks, but for ow the cars will do.

In Conclusion


If for any reason in the future I might want to split up the tender transfer pair, ideally, this should be as easy as dropping the drawbar off one of the tenders, swapping back to the pin, and a quick patch job over the rear of the tank to reapply the new engine number to the tender.  Flipping the insulating side of the trucks on one tender is just asking to be forgotten about in 5-10 years when you might want the tender with another engine again, which is why I'm avoiding that option.


Hopefully this has been a quick fun project, and a way to 'use up' those spare tenders which aren't quite right for any engine in the current stable.

Jason Hill

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