UP Big Boys (the real things)

Model Railroader General Discussion (Model Railroader)
1

Can anyone tell me the story of the aftercoolers that were on the pilot deck when the Big Boys were built? I see photos showing the aftercoolers still on the deck while other photos show them relocated. Just wondering what units had them relocated and when.

Thanks Guys

2

Numbers 4000 through 4019 (built 1941) had them built with the aftercoolers on the pilot deck. They evidently had problems with them there and moved them into the pilot behind closed doors. Numbers 4020 through 4024 (built 1944) were built to this speck. Hope this helps.[:)]

3

Thanks Jonathon, any idea of when this was done?

4

If I remember correctly they froze up in the cooler temps/higher altitudes.

Fergie

5

Looking at the Big Boy pictures, most were modified in the 1950 to 1951 era and looked like the 4020 series.

6

According to the info on the Pentrex Union Pacific Big Boy Collection DVD, The aftercooler Change was conducted in 1942. 4000-4019 Were deliverd winter of 1941-1942 and as fergie states. Tended to freese up in the often Harsh WY winters. (40 Below is not unheard of and 30 below is common during night time lows) So in Summer 1942 they were all changed to underneath the pilot deck. 4020-4024 were all deliverd in the modified arrangement.

James

7

You can believe what you choose about the change, but the pictures in the Big Boy book from Kratville and several other books on the Big Boy that I have show the change over in the1949 to 1950 era on the first series of Big Boys. I doubt if the UP would have repiped the after coolers and left the old ones out in the open for all to see.

Pictures of the Big Boys clearly show the after cooler on the early series engines up to about 1950 era in the Big Boy book and several other UP books that I have. The second series were delivered with the coolers behind the shield for sure.

The DVD from Pentrax included some of the orginal NBC and UP film of the Big Boys and all were shot from 1953 and later. All of the early series had been modified by that period that the film was shot.

I also have the DVD from Pentrax and there are other errors in their reporting. Check out the facts.