New Motor of the Hvid Type
The new type “M. V.” heavy-duty marine oil engine manufactured by the Pittsburgh Filter & Engineering Company of Pittsburgh, Pa., and illustrated on this page embodies the well-established and successful method known in Europe for many years as the Brons principle and in the U. S. as the Hvid principle. These motors Combine the economy of the Diesel type with mechanical simplicity and their use is particularly recommended where service and economy are expected. The compression is carried to approximately 500 lb. per sq. in. and the motor is started from cold without pre-heating and put under full load in a few seconds. These motors will burn any grade of the cheaper fuels, from kerosene to the heaviest of fuel oils; the same fuel serving for starting the motor.
The engine is of the inclosed type, and the design has adhered as far as possible to the thoroughly tested practice of modern high speed Diesel engines. Not only is the crankcase inclosed, but the camshaft bearings, roller levers and gears run in a bath of oil. The camshaft can be removed by taking off the front cover. Accessibility of the crank pins is provided by very large openings in the crankcase. Air to the cylinders is admitted through slotted mufflers. Exhaust ells and header are waterjacketed.
Starting is accomplished by means of compressed air at about 125 lb. per sq. in., each cylinder being provided with an air starting valve. The starting is assisted by compression relief valves. Starting and relief valve rockers are mounted on eccentric shafts and a single turn of the control lever brings the engine from starting into running order. This operation of the control lever also shuts off the fuel to the cylinders during the starting period. Compressed air for charging the starting tanks is supplied by a compressor driven off the engine shaft.
The amount of fuel required is regulated by a “Johns” governor mounted on a vertical shaft. Independent from this automatic regulation of a constant engine speed, a hand control lever permits of slowing the engine down while running. The lubricating system is complete and entirely automatic, no attendance being required.
Main bearings, crank and piston pins are at all times flooded with a copious stream of clean oil by a plunger pump driven off the engine shaft. The oil is initially forced under pressure into the main bearings, and through drilled passages of the crankshaft into the crank pins, thence through the drilled connecting-rod to the piston pin. The oil after leaving the bearings is collected in the crank pit, flows to a strainer and from here a small plunger pump delivers it to a Richardson-Phenix filter. Leaving the filter the oil passes through a cooling coil and is again used.
The base or bed plate is of a rigid box section cast integral with the crank pit and seats for main bearing shells. These shells are of cast iron lined with babbitt metal. The main bearings are provided with shims for adjustment. The shims are composed of layers of brass firmly held together by a metallic binder. An adjustment of .002 in. is made possible by this method.
The crankshaft is of open-hearth steel, forged from the solid and for engines including the four-cylinder size is made in one piece. The six-cylinder shaft is made in two half units. The cylinder frame and crankcase for engines including the four-cylinder size are cast in one piece; for the six-cylinder unit two three-cylinder frames are bolted together.
This type of prime mover is of interest to water works engineers particularly for small town plants owing to its high fuel economy and low cost for maintenance.