PRR 6 trailers

The following are the 6- trailered experimental locomotives used by the Pennsylvania railroad in the immediate post war era. More here.

1. K6 class 4-6-6.
This class was originally built by Lima as a high speed passenger locomotive. However, it was found the locomotive had frequent problems with adhesion. However, it still was a decent enough of a runner to warrant continued production. With them largely being used on sections of the various train. Despite the adhesion trouble, the class did perform well on coal trains. Which gave them other life as a freight class.

2. S3 class 4-8-6
Following the adhesion problems with the K6. The PRR went for a solution by adding an additional set of driving wheels to the engine. This proved to work fine, and the S3 was soon working sections of various trains and fast freight. They were also proven to be good branch-line runners. As such, they were assigned to pull connecting trains from places like Peoria, grand Rapids, and South Bend, to parks along the PRR mainline. But they were not very fast for the railroad's liking. Which lead to...

3. S3a class 4-8-6
The PRR had leased some T1 4-4-4-4s to the C&O. When they were proven to have problems on grades, the C&O turned to Lima, which responded by using the T1 as the basis for the 3rd of C&O's 4-8-6 types. The PRR saw what they did, thus, deciding to do it for themselves. Though they were originally planned to replace the T1s. The S3as instead spent much time along the duplexes. Even double heading at times.