Why the class 47 chassis changed for the 37 …

Look at an early class 47 chassis – and I mean early … very early … some of the first releases, and compare it against a later class 37 or 47 chassis. What is the difference you might ask. Indeed that is what I was asking myself. I looked … and looked … and looked … I just couldn’t “see the wood from the trees” as they say. Well, the mystery has been answered and before we explore why this was done, take a look at the pictures below;

  1. This picture shows us the section of the chassis we are talking about. It is just beyond the worm gear, at the outer corners of the top of the chassis, circled in red. This is the later, “chopped” chassis.
  2. This picture shows a close up of the two different chassis, side by side. Notice that the top chassis does not have the recess (or “chop”) that you can see in the lower chassis, which is circled again in red.
  3. Finally to the reason why. Here you see a class 37 body shell upside down showing the glazing, which fits from the inside. This glazing makes the clearance on the inside of the body narrower and the original class 47 chassis, designed for the January 1981 release, would not fit in the class 37 body with the glazing in. Hence the recess was introduced so that there was clearance for the glazing.

Interesting information if you are a Poole fan like me … just don’t put it forward as a question in your local pub quiz!