Monday, May 10, 2021

Spring Switches on the SP - Tehachapi and Mojave Subs

 Following up to David Willoughby's excellent write-up on La Mesa Model Railroad Club's Spring Switch installations, let's have a quick look at where SP used spring switches on the Tehachapi Sub, mostly in CTC limits, and over the Mojave Sub, which was still Train Order-Timetable territory.

AT&SF 140 LAC, entering CTC at the end of Double Track at Bena.

The club installations of spring switches vary somewhat from the prototype due to several factors: the requirement to operate in several modes (TT/TO, CTC, ABS) for different eras or display running for the public.

Demo Video of Spring Switches in Operation


A clip starting at 8:00 of Jason demonstrating the operation of Bena's spring switch. - TSG Multimedia's Tehachapi Pass Tour video


Tehachapi Sub - Spring Switches, September 1955 ETT SI No.6


I have been looking through my Emplyoe Timetable Special Instructions No.6 from September 25, 1955, and pulled out the following bits of information on the use of spring switches.

    Rule 535. SPRING SWITCHES
    Spring switches not equipped with facing point locks are located as follows:
Location                                               Normal Position
Bena - West end siding                         Westward track
Caliente - West end westward siding    Eastward siding
Caliente - East end eastward siding      Westward siding
Bealville - West end westward siding   Eastward siding
Bealville - East end eastward siding     Westward siding
Marcel - West end westward siding      Eastward siding
Marcel - East end eastward siding        Westward siding
Tehachapi - West end No.2 Siding        Controlled Siding
Summit - East end siding                      Eastward track

Switch position indicator located at:
Bakersfield....Spring switch leading from back lead to inbound engine track.

Indicator does not indicate track occupancy.  When indicator displays red aspect, or is not lighted, careful examination of the switch must be made before passing over in eastward direction.

LMRC Notes:
The spring switches at the east end of Bena are installed for non-CTC operation on both the main and siding.  The main track switch is set for Westward track and the east siding switch is set for the westward main track.
During CTC operation, the springs switches function as regular switches, being reversed by the CTC Dispatcher and then the signals cleared.  After the CTC installation during the early years of WWII, 

West Bena's center siding's west main track switch was a spring switch, on the model we also have the inner switch at the west end set up as a spring switch allowing eastward trains taking the center siding to line the facing main track switch, then head into the siding without needing to line the inner switch.

The spring switches at Caliente have not been installed... yet.

The eastward siding at Bealville is not modeled, and the westward siding is combined with Allard, eliminating the need for any spring switches at Bealville as modeled.

The spring switches at Marcel need to be installed.

End of Double Track switch complex at Tehachapi with controls and track diagram. (Note switch to Nos.2 & 3 Sidings being rebuilt in this shot.)

The spring switches at Tehachapi as modeled include the pre-CTC spring switches at the west end on the main track and No.1 siding.  These two switches were made CTC controlled switches during the prototype's upgrades in 1943.  The end of double track switch on the main track in front of the depot is also a spring switch, allowing for movements onto the single track main west of the station.

Summit's east switch is also set up as a spring switch, which makes sense as it is entering a section of higher speed track, and the brakemen would have been busy cutting out the helpers at the wye near the west end of the siding for the last 20-30 minutes, getting air tests, etc.  Best to get the train moving again and down the hill to Mojave without leaving a tired brakeman 3 miles from Tehachapi or Monolith!

Bakersfield Engine Lead


Yard diagram showing the spring switch just above the word "Pullman"

This spring switch is set up on the "back track", with the normal position towards the inbound side of the engine house to direct eastward movements of engines into the inbound side of the engine house (obviously).  Westward engines coming off their trains, moving onto the back track can head down, spring through the switch next to the Pullman Shed, then back into the engine house without any manned throwing of any switches.  Making the fireman get down and line a switch in a yard where 'herders' are on duty would allow a time slip for the fireman to earn an extra day's pay for the violation!  Switching moves requiring an eastward movement on the back track must line the switch by hand for movement, then return the spring switch to normal operation.  This basically relieves the yard 'herders' from tending any of the light engine movements to "the house", especially this one commonly used switch which is 400-500ft out of the regular area where the herders and hostlers are working.

Mojave Sub - Spring Switches, September 1955 ETT SI No.6


    Rule 535. SPRING SWITCHES
    Spring switches not equipped with facing point locks are located as follows:
Location                                              Normal Position
Gloster - East end siding                     Main track
Ansel - West end siding                      Main track
Rosamond - West end siding              Main track
Lancaster - East end siding                 Main track
Lancaster - West end siding                Main track
Denis - East end siding                       Main track
Palmdale - East end siding                  Main track
Harold - West end siding                    Main track
Harold - East end siding                     Main track
Paris - West end siding                       Main track
Paris - East end siding                        Main track
Ravenna - West end siding                 Main track
Ravenna - East end siding                  Main track
Russ - West end siding                       Main track
Russ - East end siding                        Main track
Lang - West end siding                      Main track
Lang - East end siding                       Main track
Humphreys - West end siding            Main track
Humphreys - East end siding             Main track
Honby - West end siding                    Main track
Honby - East end siding                     Main track
Newhall - East end siding                  Main track
Sylmar - West end siding                   Main track
San Fernando - West end siding        Main track

Spring switches not equipped with facing point locks are located as follows:
Vincent - West end westward siding  Eastward siding
Vincent - East end eastward siding    Westward siding

Notes:


Mostly on the Mojave Sub we can see the example of basically every siding having at least one spring switch.  The end of the siding without the spring switch is usually going to be the end where the station is located and some stations had local operator controlled switch levers.  Saugus-Newhall is covered by Rule 605, Interlocking, which specifies the operations there in.

The heavy use of spring switches makes the rear brakeman's life so much easier, because he does not have to drop off, line the switch for the main, and then run after the caboose when the train is departing the siding.  When working on heavy grades, such as the climb from Palmdale to Vincent and down the Soledad Canyon to Newhall, especially at night.

In Closing


As far as the use of model spring switches go, they are nice to have in reverse loops, and other places which we want to have trains operate through and have regular routing selected, without needing the human operator to remember to throw the switch regularly at the right time.


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