I think I remember seeing a diagram showing the layout of the rollers on a Mk IV tank as a mix of light and heavy. I have drawing for the light roller in the Bovington Mk IV plans, but not the heavy rollers. Does anybody know what the differences are or have drawings of the heavy rollers they could share with me please.
I know this photo shows a Mark V (the one at the IWM actually) but it shows two types of roller. One is flanged on the interior faces and has a spring between the two halves of the roller. The other has no flanges and no springs either. I would presume that one is the "heavy" type and one the "light" type, though I hesitate to say which is which.
I think there may be some mix of information going on... just in case...
Early tanks had cast 'light' rollers, these tended to deform in use, so were replaced with solid versions. So basically they are all heavy rollers.
The tanks have a mix of flanged and unflanged rollers which interlock slightly. The flanged rollers are just the same but with two discs held apart by a spring. The discs/flanges keep the track from trying to slide off the rollers when turning and disabling the tank.
I can show you the arrangements for a MK1 but I'm unsure if it stayed the same for the later marks.
The photo I think is a MKIV with its sides missing.
Thanks Gwyn and Helen - that makes sense as the drawings I have show basically the same rollers either separated by a pair of larger diameter discs and spring or a spacer. The cross section I have shows the roller in both cases as hollow, which I guess would make them the light ones, I presume the heavy were solid (maybe still with the three elongated through-holes. I have the same photo of the Mk IV with side plates removed - I wish it was available in higher resolution as it holds a wealth of information relating to the construction of the tanks which really aides interpretation of the Bovington plans. These rollers are going to be my first attempt at a 3D CAD model so I can print them on my flashforge. Wish me luck !
regards
Andrew
Helen is right that originally rollers were hollow and that these tended to deform and so were replaced with solid rollers; I should have thought of that. I had thought that this problem was identified and solved early on though so I'm now a bit puzzled by the thought that some Mark IVs were built with hollow rollers.
The tank seen with the outer hull plates removed is a Male, BTW. I also think it a Mark IV.