AT THE HEART OF THE ROAD TRANSPORT INDUSTRY.

Call our Sales Team on 0208 912 2120

AIR-COOLED DIESEL APPLICATIONS

16th November 1962
Page 80
Page 85
Page 80, 16th November 1962 — AIR-COOLED DIESEL APPLICATIONS
Close
Noticed an error?
If you've noticed an error in this article please click here to report it so we can fix it.

Which of the following most accurately describes the problem?

pOSSIBLY one of the most interesting aspects of the development of a six-cylinder automotive air-cooled engine by Ruston and Hornsby Ltd., Lincoln, is that the freedom it provides from radiator plumbing troubles would be of particular benefit in underfloor applications This point was made by a number of leading .goods-vehicle operators who attended a demonstration of the unit in Lincoln recently (and also by p.s.v. operators at a demonstration in September), and it is noteworthy that the makers would consider the production of an underfloor engine if demand were sufficient.

Although the suitability of the engine .has been fully established for vehicle applications, the makers are seeking opportunities to obtain extended service experience in a variety of conditions before going ahead with production plans. The engine is basically similar to an industrial type which has been on the market for some years, and production of the automotive unit could be expanded progressively with the minimum of planning.

Known as the 6YDA, the unit is of 7.39-litre capacity and has a bore and stroke of 41 in. (111 mm.) and 5 in. (127 mm.), respectively. In its original automotive form the engine developed 110 b.h.p. at its governed speed of 2,200 r.p.m. and a maximum torque of 301 lb. ft. at 1,450 r.p.m., and this unit has been used in a Leyland doubledecker bus of the North Western Road Car Co. Ltd for a mileage well in excess of 160,000. * It has also been applied to an Atkinson maximum-load articulated outfit, converted by Transport Vehicles (Warrington) Ltd., and operated by North Cheshire Ivfotors Ltd., which has covered over 55,000 miles carrying a load of around 14 tons, mainly on the very hilly route between Sheffield and Warrington.

fly employing plain inlet valves in place of the masked type and by modifying the inlet ports to give .directional air flow, it has been possible to increase the output of the engine to 120 h.h.p. at 2,200 r.p.m., and the uprated version of the unit is fitted to a Guy Arab double-decker operated by Lincoln Corporation. Records of fuel consumption indicate in every ease that it is about the same as that of an equivalent water-cooled engine.

One of the most interesting features of the engine is the low power consumption of the fan. Whilst the industrial engine is fitted with a fan of 12-in, diameter, the air ramming produced by the forward motion of the vehicle has enabled a fan of 9-in: diameter to be used, and r.p.m. to be reduced by 25 per cent. Fan losses at maximum output have been reduced from about 8 h.p to approximately 3 h.p., which compares with the power consumption of an equivalent water-cooled engine fan of around 5 to 6 h.p. Using a smaller fan at a lower r.p.m. has also reduced fan .noise.

The fan is driven by triple belts controlled by a tensioner, and it is claimed that the belts have an indefinitely long life. A device can, however, be incorporated in the system that would give a warning of excessively high cylinder temperatures. In addition to obviating corrosion (and freezing) troubles, the cooling system has the advantage that it tends to be self cleaning if muddy water is inhaled into the ducting and is very much less susceptible to blockage than a radiator. Moreover, it can be cleaned out in a few minutes with the help of a water hose.

Although operating conditions affect the working temperature of the engine, it is claimed by the makers that temperature variation is considerably less than that of a water-cooled type, and the value of the short warming-up period is particularly emphasized. All engines in the Ruston

ranges are designed, to run at temperatures up to 125°E (51.5°C).

The installed weight of the unit, with all auxiliaries, is 1,900 lb., which affords a saving of. say, 400 lb. compared with a water-cooled counterpart. Sound damping has been applied in various ways and it is confirmed-by a member of The Commercial Motor staff, who travelled in the Lincoln Corporation bus and the articulated outfit, that the average sound level of the installed engine is about equal to that of a conventional unit.

In part, operating noise has been reduced by a specially stiffened crankcase and the application of " dispersal patterning" to the sides to prevent drumming. A further reduction in noise is obtained by lining a series of louvres in the air-duct system in line with the fan with acoustic insulating material and by using the same type of material for lining the engine housing.

Each cylinder assembly comprises an aluminium head of Y alloy and a shell-moulded barrel of B.S. Grade 14 cast iron. Toroidal-cavity pistons are employed of siliconaluminium alloy and the top rings are chromium-plated. The main and big-end bearings are of the pre,finished thinwall copper-lead type plated with 0.0015 in. of lead-tin flashing. Vertical valves are push-rod operated, a special feature of the latest units being the use of stiffened valverocker boxes as rocker-mounting members, the boxes being fitted with inspection covers. The layout of the head is such that there is a free flow of air past the finned shrouds of the fuel injectors.

Four through bolts secure each head and barrel to the crankcase and any cylinder can be , removed without disturbing the remaining assemblies.

According to the makers, a vehicle should cover at least 100,000-120,000 miles before a top overhaul is required and a distance of 250,000 miles should normally be exceeded before a major overhaul is required. The six-cylinder industrial version of the engine is available as a turbocharged unit, and it is stated by the makers that the automotive engine is suitable for turbocharging. The cost of the standard engine is-about £800.

Heating and demisting equipment is being developed based on an exhaust-type. heat exchanger.

Tags

Locations: Sheffield

comments powered by Disqus