The Mystery of the Rim Maxarets

The Axle Maxaret problem was one occasion where a swift answer was found to a hitherto unrecognised problem. On the other hand, there were repetitive problems that just never seemed to go away. One such was the constant stream of Rim Maxarets that landed on my desk from the RAF.  This bit of kit had been around for a long time, bolted onto the legs of RAF aircraft almost since time immemorial. Rather than being hidden neatly inside the axle the rotating lump of lead was driven by a small rubber-tyred wheel running on the aircraft wheel itself, opening and closing a hydraulic valve to control the deceleration.  These would arrive on my desk with a label from the RAF maintenance depot "Brakes failed. Pilot called for nets" or something on those lines. I would send these 'defective' items to the test house, and they invariably came back with a clean bill of health. After a few months of this, I discussed the recurring nature of the issue with one of the ex-Navy matelots in the office, learning that the Navy had never liked the idea of the indicator pin that protruded from the casing on the RAF versions, and the naval version was always supplied without it.
PING!
A light lit up in my head. The pin was OUT when the brakes were OFF. If it froze OUT, might the brakes stay OFF? Even in summer, a Lightning patrolling for an hour at forty or fifty thousand feet would arrive back at the airfield cold-soaked, freezing and possibly wet from cloud or rain. I picked up the Maxaret sitting on my desk and set off for the laboratory - where the cold-test kit lived - and which, in the months I had been at Dunlop, I had yet to visit. Down Swallow Lane and through the small door in that vast featureless wall - and found I had entered a different world: a world of a distant past.

Stunned, I stopped and stood taking in an astonishing sight (and feel).  The vast earth-floored space was filled with BIG machines driven by belts - BIG belts - from shafts high above, turning machines spinning wheel-rims of all sizes. The whole place was shaking with a low-frequency vibration, and had the feel of a previous century. This was one of the earliest surviving parts of the Dunlop empire, and, as far as I know, is still there, having had several new owners and a management buy-out. Surely it doesn't still have that archaic works?

The Laboratory was on the far side of that building, and after a good deal of discussion involving sighing on their part ("but we did this years ago") and insistence on mine, my 'failed' Rim Maxaret was set up in the test rig with an agreed program of wetting and freezing.  On my return the following day a small group of us gathered to see the result, and Bingo! The indicator pin froze OUT and the brakes failed. Whoops! Talk about egg on faces. The Assistant Chief Designer was summoned and shown the result. Unlike that earlier experience where I had been silently accused of showing everyone up, I was thanked for spotting the problem and we established a warm working relationship that was to produce more useful results later on. Another case of fresh eyes seeing things in a new light.

 This wasn’t the end of the Rim Maxaret story. There was another twist still to come.