I believe you are incorrect. A 3-cylinder simple locomotive (like a UP 9000 or an SP 5000) have cranks 120 degrees apart. If I knew how to attach it I have a good recording of a 9000 starting a heavy train. All the exhausts are the same distance apart. When it starts to get a roll and hooked up it starts to go goofy. The problem with the Gresley motion was it worked off the valve stems of the outside cylinders. So, any lost motion in the regular Walschearts gear got transmitted to the Gresley gear, which had its own bunch of bushings that got worn out pretty quick. the end result was the center cylinder usually had some pretty wacked out valve events.