The Big Boy couldn’t miss in my collection so I built a replica of Jayhurst's model because I think is the best Lego conversion of this iconic steam engine.


Since Easter I have been involved in the creation of this goliath to give my tribute to the American railroads.
My model is a little bit different from Jayhurst’s master copy because this version has lights, the cab has rear doors and the arrangement of the tubes near the boiler is more similar to the real thing (from my point of view).





Big Boy histoty & technical data
The Union Pacific wanted a locomotive that could pull a 3.600 ton train unassisted over the 1.14% grade of the Wahsatch.
The designers determined that to pull a 3.600 ton train, a tractive effort of 135.000 lbs would be needed. Assuming a factor of adhesion of 4,0 the weight on drivers would have to be 4,0 x 135.000 = 540.000 lbs. Given an axle loading of 67.500 lbs each, this would require 8 drivers or an x-8-8-x wheel arrangement. The designers agreed upon the 4-8-8-4 design. Next, the horsepower and cylinder sizes were computed based on 300 psi boiler pressure. Although they weren't planning to pull these freight trains at 80 MPH, the Department of Research and Mechanical Standards designed them for 80 MPH in order to have a sufficient factor of safety built into the design. What resulted is considered by many to be the most successful articulated steam locomotive ever built.


My Big Boy respects original proportions and is inspired to the exemplar 4023 in Kenefick Park, Omaha Nebraska.
The locomotive is powered by 4 PF medium motors hidden in the boiler.
In the tenders are placed the battery pack for the motors and a 9 volts battery to power lights
It has been a challenge assemble the front light but it wasn’t a waste of time: I am satisfied with the final result!
Now enjoy the show









































During the weekend I hope to post more pictures and may be a video.


















