Another Ante-chamber Oil Engine
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A New German High-compression Product by a Manufacturer of Long and Varied Experience
ALTHOUGH it has built oil engines since 1908 the Carl Kaelble Co., Backnang, Germany, has only this year entered the commercial transport field with proprietary engines, a number ot which is now running in various German lorries and buses. The company has its own design, which was developed by the late Dr. Ing. Haselwander, who is said to be the originator of the pre-combustion chamber.
The pre-combustion chamber employed by the Raelble concern is centrally located in each cylinder head and is roughly drum-shaped at its upper extremity, from which a conical, funnelshaped section passes down to the main combustion chamber. The lower end is closed and projects slightly into the main combustion chamber. A number of radial orifices in the small projecting cap or dome affords the necessary communication. The injection valve is vertically placed on top of the pre-combustion chamber.
The compression .ratio employed is 17 to 1, and the resulting compression
pressure is 455 lb. per sq, in. The fuel is injected by means of a Bosch pump and through Bosch nozzles with a pressure of 1,140 lb. to 1,420 lb. per sq. in., and in the main combustion chamber the maximum pressure, as stated by the manufacturer, rises to 683 lb. per sq. in.
The company offers a four-cylindered and a six-cylindered unit with bores and strokes of 100 mm. and 120 mm. respectively. The engines weigh 990 lb. and 1,320 lb. and develop 55 b.h.p. and 85 b.h.p. at 2,000 r.p.m., their mean effective working pressure in each case being 92.4 lb. per sq. in.
Three other engines, a two, a four and a six-cylindered unit, have bores of 110 mm. and strokes of 165 mm., with outputs of 32 b.h.p., 65 b.h.p. and 100 b.h.p, at 1,600 r.p.m. These engines
weigh dry 880 lb., 1,320 lb. and 1,720 lb. The mean effective working pressure is 82.5 lb. per sq. in.
The largest engine has six cylinders with a bore of 125 mm. and a stroke of 180 mm. It weighs 1,870 lb., and develops 135 b.h.p. at 1,400 r.p.m., with a mean effective working pressure of 92.4 lb. per sq. in.
The fuel consumption of these engines averages 0.44 lb. per b.h.p. The water jackets are cast integral with the crankcases, and wet liners, of a special iron alloy, are inserted. The cylinders have individual heads, which are surrounded by a special frame carrying the inlet and exhaust pipes. The overhead valves are operated by push-rods and rockers, the whole of the valve mechanism being enclosed. In each case the camshaft is driven at the forward end, and the helical gearing is made particularly heavy so that it acts as a flywheel and counteracts torsional vibration. Light-alloy pistons are used, and it is claimed that mileages approaching 200,000 with the same set of pistons are not unusual.