New Thornycroft` 11.3-litre Oil Engine
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THE oil engine offered as an alternative to the petrol engine in the new Thornycroft Trusty SAR/GRN6 sixwheeler, a roadrtest report of which appears above, is of 11.3-litre capacity and develops a maximum of 155 b.h.p. at 2,000 r.p.m., with a maximum torque of 508 lb.-ft. at 1,000 r.p.m.
It is a six-cylindered unit of monobloe construction, having a bore of 4 ins. (121mm.) and a stroke of 6i ins. (165mm.). The R.A.C. rating is 54.16 h.p. There are two' heads each covering three bores, and the block is fitted with flanged cylinder liners.
The overhead valves are push-rod-operated from a single camshaft which is driven by a triple-roller chain provided with .automatie and jockey adjustment. The nitride-hardened crankshaft is carried in seven nre-finished copper-lead steel-backed bearings. Torsional vibration is absorbed by a viscous torsional vibration damper.
A rotary gear pump is responsible for oil circulation, the system working at a pressure of 50-60 lb. per sq. in. The oil passes through a cooler and filters to the main and connecting-rod bearings. The oil feed to the camshaft is at a pressure of 12-18 lb. per sq. in., the oil being forced through the hollow camshaft to its bearings. A low-pressure supply of lubricant is taken direct to the rocker eear..