Re: Locomotive Coupler Question

Think that over a bid: ", a larger one on the tender and a smaller one on the pilot? or vice versa". The coupler is to match up with cars and cars are all the same so they match. So the coupler on the locomotive is the same size as all other on that railroad and matches with the cars.
Now, there are different sizes of couplers and different style designs. Standard gauge as full size MCB with a style design of "E" or "F" generally.
The 2' narrow gauge lines in Maine used one 3/4 of this size, and many of the eastern 3' lines did as well. But most western 3' lines like the D&RG used full size couplers on the narrow gauge cars.
They also are at different heights. There is also a 1/2 size MCB (Master Car Builders) design that was used on industry and smaller cars.
The 3/4 size will not coupler to a full size as the hands will not mate, but a casting was made to fit in the smaller coupler that presented a hand that fit the full size car. That was where the SG car had the wheels switched and run over the ng track.
Federal Law never required the elimination of the link and pin on the engine and tender, as the Federals never had authority to do so as the engine did not carry interstate or foreign commerce. The ICC Act covered CARS carrying commerce. Many states did enact laws requiring MCB automatic couplers on locomotives. Some states, like NH never did.
The notched coupler knuckle that handled the pin and link was common into the late 1920s