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ROLLS-ROYCE DOLLS -ROYCE ROLLS-ROYCE INTRODUCE AUTOMOTIVE RANGE ROLLS-ROYCE OF DIESELS

15th July 1966, Page 56
15th July 1966
Page 56
Page 57
Page 58
Page 56, 15th July 1966 — ROLLS-ROYCE DOLLS -ROYCE ROLLS-ROYCE INTRODUCE AUTOMOTIVE RANGE ROLLS-ROYCE OF DIESELS
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Specifically designed for vehicle applications and known as the Eagle, a sixcylinder in-line engine is announced today that is available with naturally-aspirated outputs of 205 b.h.p. and 220 b.h.p. and as a turbocharged unit developing 260 b.h.p.

By P. A. C. Brockingham AMIMechE QINCE the formation of the oil engine division of Rolls-Royce

Ltd. at Shrewsbury in 1950 and the introduction of the division's C range of diesels, vehicle makers and operators have successfully employed units in the range for road-vehicle propulsion, despite the fact that they were designed for industrial applications.

The Rolls-Royce Eagle range, announced today (Friday) was specifically designed to cater for current and future demands by operators of heavy freight-carrying road vehicles. And whilst the basic Eagle unit bears a close resemblance to the C6 diesel, it incorporates a number of advanced features that should provide the stamina and overall running economy required for automotive use, notably when operating at sustained high loads on trunking routes.

The Eagle is a conventional, six-cylinder-in-line, direct-injection type with the same bore and stroke dimensions as the C range. it is produced with naturally-aspirated outputs of 205 b.h.p. and 220 b.h.p. and as a turbocharged unit developing 260 b.h.p.

All the engines are based on the same crankcase/cylinder-block casting and, having common mountings, any of the units can be offered by the vehicle manufacturer without allowance for installation differences. Because of its conventional configuration, the Eagle is immediately suitable in a typical case for fitting in an existing chassis with the minimum of structural modification.

Approximate net dry weight of the Eagle 205 and Eagle 220 is 2,450 lb., whilst the turbocharged 260 engine weighs 2,562 lb. Overall dimensions of the naturally aspirated units include a length of 61.5 in., a width of 30.65 in. and a depth (excluding air cleaners) of 50.85 in. The length, height and width of the turbocharged unit vary according to the position of the turbocharger, any increase in any of these dimensions being small.

Prototype engines have been operating in South Africa, Australia and Canada, and in the two latter countries the vehicles have logged 300,000 miles and 250,000 miles respectively without overhaul. Covering an average of 15,000 miles a month, the 63,000 lb. g.v.w. vehicles in the Canadian operation normally travel at 60-65 m.p.h. and, on one section of the run, operate for long periods continuously on full throttle.

Ambient temperatures vary between —30°F and 90°F, and dust storms are a regular feature of summer running. Routine maintenance comprises changing the lubricating oil and filters at weekly intervals, whilst the fuel injectors are serviced every 60,000 miles.

A bore of 5.125 in. (130.2 mm.) and a stroke of 6 in. (152.4 mm.) comprise the common cylinder dimensions of the units, which give a capacity of 742.64 cu. in. (12A7 litres). The rated b.h.p. of the units is, in every case, the gross output at sea level at a temperature of 60°F and maximum power is produced at a crankshaft speed of 2,100 r.p.m. Whilst the 205 develops a torque of 560 lb. ft. at 1,400 r.p.m., the ratings of the 220 and 260 are respectively 607 lb. ft. and 730 lb. ft. at the same r.p.m. Both the 205 and 220 have a compression ratio of 16 to 1, the ratio of the turbocharged unit being reduced to 14 to I.

Employing valves of larger diameter in the two-valve cylinder heads accounts for the higher rating of the 220 unit compared with the 205 engine, the diameter of the inlet valves being increased from 2.075 in. to 2.216 in. and that of the exhaust valves from 1.95 in. to 2.031 in. The turbocharged engine is based on the 205 unit with the smaller valves, and the engine is available with the blower mounted centrally on the exhaust manifold or at the rear according to installation requirements. No details can yet be given of turbocharger type or performance.

Notable features of the Eagle that differ from the C-range details include sodium-cooled exhaust valves (these are fitted to the naturally aspirated units as well as the turbocharged engines) dynamically balanced crankshaft, modified piston-liner combinations and straight-sided toroidal combustion chambers in ston crowns. Employing sodium-cooled exhaust valves was by the need to provide a long life at continuously high by increasing heat dissipation from the stems.

ilst the exhaust valves are of KE965 austenitic steel, which is -faced and tipped, the inlet valves are of EN52 silicone steel, the guides being of cast iron in each case. Replaceable, hromium iron inserts are employed for both inlet and exhaust , the two cylinder heads of the power unit being castings of rade alloy iron.

gasket fretting

lough the purpose of counter-weighting and dynamically ing the crankshaft of the Eagle was to provide smooth g throughout the speed range, particularly at higher speeds, ;e of counter-weights also has been found to minimize .1r-head gasket fretting, which can occur after a long period ning. The crankpins are of 3.25 in. diameter and the shaft d as standard with a Holset viscous-type vibration damper a. diameter at its forward end. The crankshaft is made of material and nitride-hardened after grinding.

'erential hardening is applied to the wet-type cylinder liners, tie under the top flange being heat-treated to give ductility in m, which reduces wear and erosion rates to a minimum. The are finish-honed by a special process which ensures rapid g-in of the piston rings, reduces blow-by and wear and ;. efficient oil control.

Is-Royce technicians favour wet liners because they give heat dissipation from the pistons, compared with dry liners, the cylinders to be spaced at reduced centre distances, y replacement and afford greater latitude in the shaping of

the between-bore water passages.

The upper ends of the liners are flanged and located in recesses in the top of the cylinder block, the flanges standing proud of the block face. This aids sealing of the cylinder head which is augmented by a thin steel gasket. At their lower ends, the liners are sealed by rubber rings of special composition designed to last the life of the engine between major overhauls.

It is claimed that the use of Wellworthy W62 aluminium alloy . for the pistons gives complete immunity from cavity cracking at high temperatures, the toroidal combustion chamber being, as mentioned earlier, of the straight-sided type. Each piston carries three compression rings and one oil-control ring, all the rings being located above the gudgeon pin.

An insert of Ni-resist iron is provided for the top ring, whilst the oil-control ring is of the chrome-rail spring-backed type and the top compression ring has a molybdenum inlay. The 2 in.-diameter gudgeon pin is fully floating and is retained by cirelips; other dimensional details of the piston include an overall height of 6.6145 in. and a pin-to-crown height of 3.981 in.

The injectors are located diagonally in the head in water-cooled, copper-alloy sleeves at an angle of 200 to the vertical and are flange-mounted on the outside of the heads to facilitate replacement. The injectors are of the four-hole type and the fuel-line pressure is 240 atmospheres. Injection timing is 34' before top dead centre.

Setbolts are employed in place of studs for attachment of the heads because they afford assembly advantages, improved mechanical strength (by virtue of the single thread engagement per bolt) and easier head removal. The bolts have a diameter of 0.5625 in. and a total of eight setbolts is fitted round each bore.

The seven journals of the crankshaft are carried in Vandervell Tr-metal, steel-backed, lead-bronze bearings which are leadplated and indium-flashed. The first, fourth and seventh bearing caps are retained in place by four vertical bolts and two transverse bolts, the remaining caps each having two bolts. Bearing diameter is 3.9 in., all the crankshaft thrust being taken by the centre bearing. The cylinder block and crankcase are formed of a one-piece casting of close-grained iron.

Positive lubrication

Vandervell Tr-metal-type bearings are also used for the big ends of the connecting rods which (in common with the crankshaft) are forgings of EN19 material, two-bolt attachment being used for the caps. Lead-bronze little-end bearings are employed which are fed with lubricant from the big end by a drilled passage. Cross drillings give positive lubrication of the cylinder bores, which is claimed to minimize wear, particularly in the event of frequent cold starts. The length of the connecting rod is 10.8 in.

Carried in seven plain pre-finished lead-bronze bearings, the hollow forged camshaft has carburized cams and is driven by a straight-spur gear. End float is controlled by a phosphor-bronze thrust plate located between the driving gear and the wheelcase backplate. Chill-faced iron tappets relay the thrust to hollow steel push rods, thence to forged rockers conventionally mounted on a longitudinal shaft. The valves are timed to give inlet opening at 12° B.T.D.C., inlet closing at 50° A.B.D.C., exhaust opening at 60° B.B.D.C. and exhaust closing at 19° A.T.D.C.

Features of the wet-sump lubrication system include a geartype pump driven direct from the crankshaft, oil being delivered to the block through two full-flow filters mounted in parallel at the back of the rear cylinder head and circulated through an oil-water heat exchanger. Aluminium-alloy sumps are offered of various shapes to suit differing applications.

The in-line fuel-injection pump is of CAV or Simms manufacture, driven in tandem with the compressor from the main gear train, and it is noteworthy that the cam box is pressure lubricated from the engine system. A fuel-lift pump, mounted on the side of the injection pump, delivers fuel to the latter through two C A V paper-element filters.

Driven by a triple V-belt in conjunction with the generator, the centrifugal water pump has an impeller of 6 in. dia. and at its forward end carries an eight-bladed fan of 24 in. dia., which absorbs about 8 h.p. at 2,100 r.p.m. Temperature control is provided by a three-stage, wax-capsule thermostat which gives progressive warming-up characteristics, the response of the thermostat being such that the valve starts to open at a temperature of 78°C and is fully open at 96°C. Alternatively, a thermostat can be supplied which opens over a temperature range of 72°C to 83°C.

The 24 V electrical system is produced by CAV Ltd. and a d.c. or a.c. generator may be specified, the standard starter motor being of the pre-engaged type with a diameter of 5 in. With a nominal output of 10 cu. ft./min., the standard compressor is a Clayton Dewandre twin-cylindered air-cooled unit.

The inlet manifold, which is an aluminium-alloy casting, is mounted on the right of the engine and can be supplied with one of a number of alternative inlet positions to suit the particular application. Whilst the normally-aspirated Eagle engines are equipped with a conventional cast-iron exhaust manifold, the unit of the turbo-charged engine is cast in Ni-resist corrosion-resistant iron which safeguards the turbocharger against damage by scaling. Provision is made in all the engines for an exhaust brake, which is fitted to the 260 engine between the exhaust manifold and the turbocharger.

A detail of importance in some applications and one that represents a change compared with the C-range engines, is the installation of all the auxiliaries, other than the starter motor, on the left side of the cylinder block, which is of particular advantage in the case of forward-control, right-hand-drive vehicles as it provides clear access to the auxiliaries from the passenger side of the cab. The mounting of the exhaust manifold on the left has the merit that it reduces the heat dissipated from the engine on the driver's side.

The new Eagle engines carry the normal Rolls-Royce guarantee, which applies for 12 months irrespective of mileage. Also applicable, the usual service exchange scheme provides for complete reconditioning at the Shrewsbury works and incorporation of the latest modifications. The reconditioned units carry a six-month guarantee, again irrespective of mileage.

Comprehensive sales, parts and service facilities will be available on a world-wide basis, backed by factory-trained area representatives and service engineers.

As an historical footnote, it may be recalled by some older readers of the journal that the name "Eagle" was given to the company's first aero engine built in 1914, which did yeoman service in the First World War.

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