A NEW OIL-ENGINED
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Two -TONNER THE motor-vehicle division of the Dainder-Benz Co., at Gaggenau (Baden), in Germany, has just Introduced a new model with a carrying .capacity of two tons, which is offered optionally with a newly developed fourcylindered oil engine or a petrol unit. It is sold in Germany as a chassis at a price equivalent to 1302 (at par) with an oil engine and at 1239 with the petrol unit.
Except for the power unit, the chassis details are identical. The wheelbase is 12 ft. 1 in., the track is 5 ft. 5 ins., and the body has a pladorm area of 75 sq. ft. High-pressure 32-in. by 6-in. tyres are used. The general layout is conventional. Hydraulic four-wheel brakes of the Lockheed type, with internal-expanding bands, are employed. The hand brake acts on the transmission behind the gearbox, which is unit mounted with the engine, a single-plate clutch, 11 ins. in diameter, being interposed. The final drive is by helical bevels with a ratio of 4.86 to 1, and the maximum speed with either engine is 40 m.p.h.
The four-cylindered oil engine is a straightforward design, in which everything is avoided that tends to increase the price. In this respect it differs from the " six " of the same make, with its extensive application of costly light alloys. The four cylinders of 100 mm. bore and 120 mm. stroke are cast in a single block, together with the upper part of the crankcase, and have two detachable heads. The piston displacement Is 3,760 c.c.
The overhead valves, which have a diameter of 38 rum and a lift of 12.4 mm., are arranged in the head slightly to the left of the longitudinal axis. The head, as also the piston crowns, is flat, so that the combustion space is discshaped. The valves are operated by rockers and push rods, whilst the camshaft is inside the crankcase.
The axis of the pear-shaped antechamber, situated between the rockers
on each cylinder, is inclined, so the orifice is directed towards the centre of the piston head. The nozzles and the injection pump are of the Bosch type. A compression ratio of 17 to 1 is employed, the compression pressure being 512 lb. per sq. in. and the injection pressure 995 lb. per sq. in. The mean effective pressure is 96 lb. per sq. in.
The crankshaft runs in three plain bearings, axial thrust being taken by the central bearing. The connecting-rod bigends have centrifugally cast white-metal bearings. The pistons are made in an alloy and each has five rings, four narrow ones above and a broad ring of the scraper type below the gudgeon pin ; this is of the floating pattern.
The crankshaft is provided at the front end with a vibration damper, and it carries a belt pulley driving the dynamo and the fan, the last-named being combined with the water pump.
The 130-watt dynamo is mounted on an adjustable bracket, by means of
• which belt slack can be taken up. The electrical system comprises, in addition, a 24 h.p. electric starter and heater plugs, one for each antechamber. A special 2-volt battery is provided for heating the plugs, which are only required to facilitate starting the cold engine.
The Bosch injection pump is combined with the governor, which controls idling speed and limits the maximum speed to 2,000 r.p.m., at which the engine delivers 55 b.h.p. and exerts torque of 137 ft.-lb. The air intake pipe, which is equipped with a large air filter, is furnished with a throttle, constituting an additional means for rapidly stopping the engine.
The lubrication gear-type pump is situated in a central cavity of the sump and is driven off the camshaft by skew gearing. It delivers the oil through a filter to the main bearings, whence it travels through passages in the crankshaft to the big-end bearings. A
secondary oil line at each end of the engine leads up to the valve gear. In a branch circuit, a second on filter is inserted, so that two independent means for cleaning the oil are provided.
Our German correspondent reports that the engine is docile and quiet and has practically the same working characteristics as a good Petrol engine. There is stated to be no trace of smoke in the exhaust. Considering the piston displacement of this engine amounts to 8,760 c.c., the output of 55 b.h.p. kg good. It is equal to a -volumetric output of 14.6 b.h.p. per litre, a figure only 25 per cent. lower than what one nowadays expects of a good petrol engine.
The fuel consumption under full load is reported not to exceed .44 lb. per b.h.p.-hour. The vehicle will travel 21.7 miles on a gallon of fuel. The torque is highest between 1,100 and '1,700 r.p.m., when it averages .159 ft-lb., and
the power curve rises almost in straightline from 10 b.h.p. at 400 r.p.m. to 55 b.h.p, at 2000 r.p.m. Although the engine is rather robust in build, it does not weigh more than 940 lb., including the starter, so that the weight per brake-horse-power amounts to 17 lb: The new petrol engine is in most parts identical with the oil engine. It has the same crankshaft, camshaft, connecting rods and pistons ; also, the bore and stroke are the same: It has a one-piece cylinder head. The compression . ratio is 5.7 to 1 and its performance, even as regards torque, is surprisingly similar to that of the other engine. But, of course, it consumes much more fuel and has a mileage to the gallon of 12,8.
Having the same measurements and a similar performance to the oil engine, the petrol engine can be installed easily in place of the former and without the gearbox or rearaxle ratios having to be altered. This, naturally, reduces cost of production of the vehicles.