ACL P5a/b 4-6-2 Question : LUSENET : ACL and SAL Railroads Historical Society : One Thread

A quick question for any mechanical engineering types out there. A review of the P5a/b 4-6-2 technical data in the society's ACL steam locomotive diagram book provides tractive efforts for "the pin mounted in the middle hole vs. the pin mounted in the front hole". Does anyone know what "pin" and "hole" these entries are referring to? Thanks in advance for any input.

-- Buddy Hill (, January 03, 2002


Hugh, Thanks for solving this mystery. Very much appreciated.

-- Buddy Hill (, February 23, 2002.


I'm pretty sure this refers to the placement of a pin in the equalizer bar between the springs for the drivers and the springs for the trailing truck. Depending on which hole the pin was placed in, it would change the distribution of weight between the drivers and the rear axle. In one position, the engine would have more weight on the drivers, and therefore more useable tractive effort, at the expense of a higher maximum axle load. In the other position, the weight on the drivers would be slightly less, and the maximum axle load would be slightly less. This would be beneficial for running on lightly built branchlines.

Please feel free to e-mail if you need more info.

Good Steaming, Hugh Odom The Ultimate Steam Page- ACL 1800's-

-- HughOdom (, February 23, 2002.

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