gingerfold:
The original designation of what became the TL12 engine was AV770. Extensive testing of the prototype engines was carried out night and day, 6-days weekly with two concept tractor units, specially built in AEC’s Experimental Department’s workshops. One of these tractor units was a 6x4, which had been a concept and test vehicle for the AEC V8 engine, the other was a 4x2 unit. The 6x4 was granted special dispensation to run at 44 tons gvw, with a test weight payload of 31.5 tons on a flat trailer. The engines were driven for 50,000 miles then removed from the chassis and completely stripped down and measured for wear, then re-built and refitted into the chassis for another 50,000 miles to be accrued.AEC vehicle test driver, Robert Smith who has provided these details, was one of the night drivers whose shift commenced at 8.00 pm and finished at 7.00 am. His route was from Southall through Hayes End to junction 3 on the M4 and down to the Severn Bridge, then back along the M4 to junction 8/9 Maidenhead, turn round, back to the Severn Bridge then back to Southall. A total of 385 miles per shift. Motorway cruising speed was maintained at 60 mph, unless balked by slower lorries.
From the photos below it can be seen that the 6x4 cab has gained a “snout” compared with its V8 engine testing days. This was to accomodate the longer length of the TL12 engine.
Click on photo twice to enlarge
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There were some articles regarding these vehicles in an AEC Gazette a few years back but i cant remember if it was the V8 or the TL12 they were testing . What i do remember is the driver saying how well they performed , i think the article was covered over several issues