Fitting and operating taper lock bushes and gear cases.

[Armortek]

Since we began fitting taper lock bushes to the drive sprockets, over four years ago, we have built up a good deal of operating experience due the feedback given to us by our customers. We have also gained experience on the durability of the gears in the gear case, in a number of operating conditions. Recently the topic was raised in the Panther forum, and we responded with our "official advice". This is an important issue, and the best advice is not the obvious solution.

When building the kit remember to clean the shaft and the bearing bores thoroughly and apply a high strength retainer when assembling the driven gear shaft into these bearings. This will prevent the gear from rubbing on the hull side.

The issue of how to deal with some slight rubbing of the driven gear against the hull side was raised, and we responded as below.

The idea of using a nylon, teflon or bronze thrust washer to act against the face of the gear wheel is a good one. The placing of a spacer between the back of the taper lock bush and the outer bearing is a real "no no". Taper bush manufacturers specifically instruct users not to do this, because it prevents correct installation of the bush as they recommend. You are supposed to tighten the screws and then tap the bush up the shaft and into the taper bore to fully seat it, before retightening the screws. Clearly you can not do this with a spacer behind the bush.

When we first started using these bushes we did not think that this was particularly important, however, experience has proved otherwise and we have had failures reported due to this very issue.

If you are going to fill the case with grease you must ensure that it is spotlessly clean and sealed where the drive gear goes in. If not, you will end up with a case full of grinding paste and the gears will wear prematurely. Once again we have seen this on a number of "high mileage" tiger 1. tanks. Much better to use a thin coat of dry film lubricant called DFSM or an open gear grease. Both of these products are available world wide from Rocol. Best advice remains simple. Unless you intend to do an awful lot of running, don't apply grease, leave them dry.

Mark