FIRST OIL-ENGINED MORRk .7,0MMERCIALS
Page 30
Page 31
If you've noticed an error in this article please click here to report it so we can fix it.
AS announced In " The Commercial Motor" last week, the directinjection oil engine to be fitted to the new Morris-Commercial 5-ton models is an . alternative to a petrol engine,details of " which are not yet available.. One of the new models will be shown for the first time at the Amsterdam Motor Exhibition at the end of this month.
The chassis will be available in two wheelbase lengths and weigh under 3 tons. The smaller vehicle for building work will have a body capacity of 5 cubic yds., and the other will have an inside body length of ft. 6 ins, and width of 6 ft. 7i ins.
Maadactured at the Birmingham works of Morris-Commercial Cars, Ltd., the engine, which is made under licence from the Swiss Saurer Co., bears little outward resemblance to the Saurer engine which has been displayed at continental shows.
With a bore of 85 mm. and a stroke of 125 mm., the engine, a six-cylindered unit, has a capacity of 41 litres and has an output of 75 b.h.p. at its governed speed of 2,400 r.p.m. Torque of 167 lb.-ft. is developed at 1,750 r.p.m. A relatively high compression ratio of 19 to 1 is employed. The injectors are located vertically in the cylinder head and spray directly into the toroidal cavity in the crown of the piston. injectors. are of Saurer design and C.A.V. manufacture and have nozzles which will require little attention. Maintenance should be negligible, as the atomizer is of a poppet pattern, and there are no holes to become clogged. The injector operating pressure is 150 atmospheres. Care must be taken when fitting the injector and its feed pipe to ensure that the faces are meticulously clean.
There are no soft metal washers to make a seal on the high-pressure side of the fuel supply or prevent leakage from the joint between the injector and cylinder head. The fuel pump, also of C.A.V. Tanufacture, incorporates a standard pneumatic governor which is connected by a flexible pipe to a venturi throat valve fitted to the air induction manifold. The pump is located high up on the right-hand side of the engine, where it may be quickly removed for inspection or adjustments.
The crankcase and cylinder block form an integral casting made from heat-treated aluminium alloy, thus reducing the overall weight of the power unit. The detachable wet liners of centrifugally cast iron are fitted in a manner similar to those of the Swiss engine and have a 0.011-in, shim under each liner, permitting 0.0080.010-in, pinch. Ample water space is provided around the liners and the interior of the block is easily .accessible for removing any sludge or scale that may collect.
Made from alloy steel, heat-treated and hardened on its journals, the crankshaft is retained in position by seven main bearings, which have half-steel shells lined with lead bronze. A similar-pattern bearing is used for the connecting rods, the small-end bushes being made from phosphor bronze, ,End thrust of the crankshaft is controlled from the rear beating, 0.003-in, end play being permitted. The flywheel, which is fitted to run within 0.002 in. true at its periphery, is provided with a replaceable starter ring.
The camshaft, mounted high up in the cylinder block, runs in five plain bearings and is located at the front end by a ball bearing. All the cams are hardened and run partially submerged in an oil bath, which serves a dual purpose of providing lubrication and reducing tappet noise.
Drive to the camshaft and fuel pump is by a triplex roller chain incorporating an automatic chain tensioner. Jets of oil are sprayed on to the chain to ensure long life and silence in operation. Camshaft timing may be adjusted to a fine degree by a vernier wheel located to the front of the camshaft.
The cavity-type pistons, made from heat-treated aluminium alloy, have fully floating gudgeon pins of large diameter. Four compression and two slotted scraper rings are fitted. The one-piece cylinder head, which covers the six bores, also carries the overhead valve gear, of 12 rocker arms.
The inlet and exhaust valves, operated by the rocker arms and push-rods, differ in size and, therefore, are not interchangeable. The inlet valves, are not screened, sufficient turbulence being created by the formation of the airinduction manifolding and pistoncavity design. Six decompression taps are fitted to the cylinder head, as in the Swiss engine. • , The water-pump and fan-bearing bracket is attached to the front of the head and the exhaust manifold to the kit-hand side. A Vokes air cleaner is mounted directly on the air intake manifold. An aluminium-alloy casing, open at the top, surrounds the valve rocker gear and incorporates the airinduction manifold. This casing is enclosed by the easily detachable top Cover.
Driven by means of a vertical shaft from the centre of the camshaft, the submerged gear-type lubrication pump supplies oil to a gallery cast in the cylinder block, and by means of drilled passageways to the main and crankpin bearings. A cover is provided over the lubrication pump driving gears, so that they may be inspected for wear without need for removing the sump.
A Tecalemit full-flow oil filter is located on the left-hand side of the engine adjacent to the drive of the lubrication pump. The crankcase is ventilated through a large-diameter pipe attached to the oil-filter body bracket and the crankcase fumes are conducted away below the engine. • • Four-point rubber suspension is provided, the fore end of the engine being carried by a bracket from the timingcase cover and .on each side of the clutch bell housing at the rear.. Provision is made to offset the line of the engine according to the position of the steering in the chassis. On home models, with right-hand steering, the engine is carried slightly to the left of the frame, and vice versa with lefthand steering. This may he seen in the head-on view of the cab, where it may be noticed that a rubber fillet surrounds the radiator filler cap, and t h e starting handle receiving bracket has an elongated hole.
A C.A.V. 24-volt axial starter is fitted, Complete weight of the engine and its components, including the clutch but without gearbox, is 826 lb.
The single dry-plate clutch has a spring-drive centre plate, and its total friction area is 118.5 sq. ins. Of unit construction with the engine and clutch, the gearbox provides four forward speeds and one reverse. The gearbox casing, made from cast iron, houses conventional straight-tooth gears, with a constant-mesh double helical gear and dog engagement for the third speed..
The chassis frame has not been altered, and, as in previous 5-ton models, the split-centre rear axle incorporates a spiral-bevel drive, with a four-star differential and fully floating axle shafts.
The bonnet cover takes up part of the cab, although not to the detriment of the driver. All controls are well placed to require the minimum of effort, and the instruments are easily read. Two 12-volt batteries, located in the cab and to the rear of the engine cover, are coupled by a series-parallel switch, which provides 12-volt lighting and 24-volt starting current.
On test, the oil-engined chassis has shown an excellent fuel consumption, and it is claimed that 18 m.p.g, may be expected when carrying a full load.