Howthe Mk III performs
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by Gibb Grace I WAS able to examine and drive Atkinson, Guy, Foden, ERF, Seddon and Scammell vehicles fitted with naturally-aspirated and turbocharged versions of the Mk III Eagle at the time of the announcement — though unfortunately the test ground was restricted, and the short routes available made accurate measurement of fuel consumption impossible.
There were some interesting installation details to be seen. Fodens' application of the Eagle 220, for example, included a metal blanking plate at the rear of the cab, backed by 2in-thick foam to reduce exterior noise levels. Seddon had used a large-capacity Farr filter on their 220-engined tractive unit, while the Atkinson Borderer with the 220 had a heat shield mounted over the exhaust manifold.
A single loaded trailer was available to make up an articulated outfit and I ran it first with a Scammell Handyman 4 having the 220 bhp engine and then with a 280-engined Scammell Crusader.
The Handyman, with six-speed gearbox, felt like a very typical 32-tonner, with 220 bhp on tap, but the 280 bhp Crusader, with a Fuller nine-speed box, was a vehicle of altogether superior performance, and should be really lively on the road at 32 tons. On tick-over the cab and fittings were practically vibration-free in the best European tradition, and only the clutch seemed prone to shake. The big engine made correct choice of gear ratio much less critical, and this led to far fewer changes.
The 280 unit is turbocharged but the whine normally associated with a turbocharger was not evident and the noise level generally was very good. An exhaust brake was fitted to the 280 unit and this proved very effective in the lower gears. This brake is mounted downstream of the turbocharger now, with the Garrett unit, instead of upstream as was the case with the Holset turbo.