In this picture you can see the pin holding the two frames together on a GG1.
I have a better picture somewhere, I just have to find it.
7j43k Don't forget that the PRR Q's were not articulated, either. Or the S1, either. And then there's the B&O EMERSON. By definition, a "duplex drive" is not articulated. While the BLI HO model of the T1 is non-articulated, I was surprised to find the Bowser/Penn Line WAS. I also noted in the photo of the latter that it was a pretty awful model. Not back when it was created, but now. Say, compared to the BLI. Ed
Don't forget that the PRR Q's were not articulated, either. Or the S1, either.
And then there's the B&O EMERSON.
By definition, a "duplex drive" is not articulated.
While the BLI HO model of the T1 is non-articulated, I was surprised to find the Bowser/Penn Line WAS. I also noted in the photo of the latter that it was a pretty awful model. Not back when it was created, but now. Say, compared to the BLI.
Ed
So if the Pennsy's 4-4-4-4 had been articulated it would have been classified as a DD. Presumably a DD3 since they had DD1s and a single DD2 electric.
Dave Nelson
Unless I'm very mistaken, Chuck is correct. The Pennsy engines were rigid-frame engines, not articulateds. Good catch!
Selector: Interestingly enough, the Pennsy electric GG-1 was called that because they considered it's 2-C-C-2 wheel arrangement to be like two G class 4-6-0 steam engines together, hence "GG".
Chuck, I'm going to take a different way to appreciate the wonderful, if short-lived, T1 Duplex. The land steam speed record for N. America, at least the officially recognized one, was achieved during a brake test on a Canadian Pacific Jubilee Class passenger locomotive, some of which had 82" drivers. I believe the speed was 112 mph before they clamped on the binders.
The Jubilee was a 4-4-4 configuration. A T1 is 4-4-4-4. So, simply because I feel it convenient, I claim that the T1 was actually two Jubilees under one boiler.
Looking at the May 2017 Model Railroader, I found a caption on page 19 that identified the PRR T1 as an articulated.
Granted that most model T1s are articulated - the one early brass model that wasn't had a minimum radiius requirement of 32 inches. However, the photo is a 1:1 scale locomotive - a rigid-frame duplex drive with no hinge between the driver sets. Looking only at the wheels, frame and engine trucks the T1 is a Northern with divided drive _ and would have been a better locomotive if the two driver sets had an internal linkage to keep them synchronized 180 degrees out of phase. That was the method Bill Withuhn proposed to drastically reduce dynamic augment and driver slip. Unfortunately, the T1s went to scrap two decades before Withuhn's ideas were published.
T1 models get the same result by having both driver sets geared to a common shaft driven by a single motor.
Chuck (Modeling Central Japan in September, 1964 - with nothing that even resembles a T1))