Rolls-Royce Lifts the Veil
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DETAILS have at last been released of the Rolls-Royce oil engine fitted in the new Scammell Constructor 100ton tractor, described exclusively in "The Commercial Motor" on September 26. It is a six-eylindered fourstroke normally aspirated unit, which develops 155 b.h.p. at a governed speed of 1,800 r.p.m, The bore of the cylinders is Skins, and the crankshaft stroke is 6 ins., giving a total swept volume of 12.17 litres. The type name is C6. NFL.
A feature which applies to all engines in the Rolls-Royce C range of oil engines is a " handed " crankcase casting, which enables the flywheel housing to be mounted at either the forward or rear end, and all the externally mounted components either on the right or left side.
Easily replaceable wet liners are used in the cylinder block which is cast integrally with the crankcase. The nitride-hardened crankshaft is fitted
with an externally mounted torsion damper of the viscous type.
Push-rod operation is adopted for the overhead valves, of which there is one exhaust and one inlet to each cylinder. A recess in the piston crown provides a combustion space of toroidal form.
Built on the side of the sump is a heat exchanger, its purpose being to bring the engine oil rapidly to correct working temperature. When the engine is started the engine coolant by-passes the radiator and passes through the heat exchanger. When the coolant reaches a temperature of 73 degrees C. a thermostat control causes the coolant to circulate through the radiator.
The injection pump, which incorporates a fuel-lift pump, receives its drive from the timing-gear train. A triangulated belt drive is adopted for the dynamo, coolant pump and fan, and provision is made on the timing case for mounting a pulley to drive auxiliary equipment.
A 24-volt axial starter, and a 24-volt dynamo form the only two electrical units. Running on S.A.E. 30 oil, the engine is claimed to start readily at a temperature as low as —8 degrees C.