Marty Wrote:
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> Could someone explain the need for a "yard braking
> sled." What was the need for extra brakes at
> Colton?

Be glad to. But first, I should point out that the unit pictured isn't a Brake Sled. Rather, it's an intact locomotive, albeit with an inoperative prime mover. More info can be found on this Trainorder's thread if you scroll down to the bottom and read "Topper's" post: [www.trainorders.com]

To understand why SP's Brake Sleds were created, one needs to have a little understanding of the West Colton Yard. Unlike a traditional hump yard where cuts of cars are pushed up a man-made hill and allowed to roll free once they've reached the crest, West Colton is a gravity yard. The yard consists of three primary units; the Receiving Yard is at the west end, the Departure Yard is at the east end, and the Bowl (that "humped" cars roll into) is in between. Because of the geography of the land that makes up the yard, the Receiving Yard is much higher than the Bowl and the Departure Yard. Thus, inbound trains are yarded in the Receiving Yard, carmen bleed off the air and perform an inbound inspection, then a Hump Job couples onto the west end of cars and shoves them eastward to the Crest, where they roll by gravity downhill into the Bowl. Thus, a Gravity Yard. Think of it like lining up a string of sugar cubes on a flat table and slowly pushing them over the edge.

Prior to the yard's opening in 1973, SP ordered six specially equipped SD38-2's from EMD, numbered 2971 thru 2976. They came with specially modified Extended Range Dynamic Braking, and two cast brakes shoes per wheel (as opposed to the more typical single Composition shoe per wheel arrangement). Additional, SP had three slugs constructed from retired six-axle Alco Century units. Hump sets thus consisted of two SD39-2's spliced by a single slug. Originally, two such sets operated on each shift, with the third set in reseve or out of service for inspections or repairs (heavy repairs and maintenance was done at Taylor Roundhouse in LA). Steve posted some pics of them in a previous thread.

While the hump sets worked well, it quickly became apparent that single-unit yard jobs had a very difficult time stopping heavy cuts of cars that were being shoved over the Crest. The Brake Sled concept wasn't new to railroads, and it was decided to design a sled for use at West Colton. Since the Train Masters were living out their last days, engineering work was done to use several of those retired units as platforms to build some sleds. Already retired 3028 was moved dead to West Colton where it was M.U.ed with one of the six-axle Alco Centuries to test the concept. As mentioned above, the 3028 had a failed prime mover; thus the engine couldn't be started. Rather, it was there solely for added braking effort. It proved successful, so additional conversions were authorized to be done by the Sacramento Shops, and several dead Train Masters were moved there. As envisioned, the work involved making major modifications. Basically, everything above the side running boards and end platforms was removed, and ballast was added. Like the Camera Car, the Brake Sleds were not considered by SP to be locomotives, and would have SPMW reporting marks.

As it turned out, only one Brake Sled was ever completed, using the 3027 as the platform. No more were done because it was decided to simply M.U. two six-axle units instead of going the Brake Sled route. My somewhat fuzzy recollection is that the decision was made because using a second unit was more versatile, the added weight of the sled made it harder for a single unit to pull cuts out of the Bowl, and the Train Master's lack of "switching steps".