The Booster That Ran Backwards

By Fred Boland, Machinist 1928-1980
Bayshore Shops, Southern Pacific Railroad

During the war years anyone could come in and help overhaul locomotives. Instead of serving four years apprenticeship and picking up further knowledge and experience in the next few years, they were completely qualified as machinists in sixty days. As a result they would send me all over the locomotive to see that it was repaired correctly and was safe to run on the mainline. If I missed a cotter key or nut, it was my fault, for I knew better - they didn't.

A booster was a two cylinder steam engine of 10" diameter cylinders that drove a gear on the 45" trailing wheel through an intermediate gear. A few odd designs placed it on other wheels, but this was nearly universal. The steam pipe led from the cylinders down the left side of the locomotive to the trailing wheels under the cab. The exhaust returned up the right side into the stack, or sometimes to a 3" pipe ahead of the stack.

The booster engine was similar to a Climax locomotive design whereby the cylinder drove a 3 3/4 inch shaft placed crosswise of the frame, on which was milled an 8" gear, which engaged an intermediate gear. When used, this intermediate gear was meshed with the trailing axle gear, and when not used was disengaged.

The average booster added 10,000 lbs tractive effort to an average engine of 40,000 lbs to 86,000 lbs tractive effort, and was cut out when reaching about 12 miles per hour.

Engine 2422, a P4, or Pacific type came into the shop for overhaul. This locomotive had been converted from P1 about 1924 in a rebuilding program in Sacramento. Many had been rebuilt, many had not. The P1 had a simple trailing wheel with extended engine frames, inside motion, etc. The new P4 had new frames, new cylinders, a Delta trailing truck and Walshaert, or outside motion work.

A group of "MacAdoo" mechanics with a couple of floor men were hired on overtime to strip it's booster. They laid the parts in a pile on the floor, without a marking anywhere.

When it came time to put it together, my duty that day was in the roundhouse testing air equipment. I came back for something and heard John Mignosi ask foreman Andy Sherin if it made any difference which side of the cross shaft went where. "No" Andy said. This vaguely annoyed me at the time, but my mind was so full of air passages and where they went that I didn't pull up and reason out what was wrong with that answer then and there.

Well, needless to say, the fellows had their hands full when they tested the booster. And of course, even though I was assigned elsewhere that day, I had to straighten out the backwards running booster.

After I reasoned it out, I realized there is a left and a right arm, or eccentric crank. The new shaft made no difference, but once the arms are pressed on, the shaft has a permanent right and left side.

I'm glad I had thought about it then, because it was much easier to fix than if I had to figure it out from scratch.