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It is generally recognized that the dilution of crankcase-oil with water and unburned fuel tends to accelerate the wear of engine bearings, cylinders and pistons. The author traces the engineering development of a rectifying device and system designed to combat this problem. In this system, diluted oil that tends to work-up past the pistons, in company with the water vapor and unburned fuel that tend to work down into the crankcase, is drawn from the cylinder-walls and pistons by vacuum. This diluted oil is conducted into a still or rectifier where it is subjected to heat from the engine exhaust. The heating action is just sufficient to volatilize the fuel and water, the resulting vapor being returned to the intake-manifold and thence to the engine where it is burned. The lubricating oil that remains behind is conducted back into the crankcase. The system functions automatically.

Describing the three ways in which water may reach the oil-pan, the author says that the danger-point for water accumulation is reached when an emulsion becomes too highly viscous or when an accumulation of free water reaches the pump intake. The effect of using an emulsifying oil is explained and consideration is given the quantities of water actually deposited because of cylinder-wall condensation. An emulsion of oil with water up to 5 or 6 per cent differs hardly at all from the pure oil so far as film-forming and lubricating qualities are concerned. On the other hand, with an oil that is absolutely non-emulsifying, the tendency is for the water to segregate and collect in comparatively large globules. The ability of an oil to absorb a small percentage of water has the advantages of minimizing the danger of complete failure of oil circulation when starting in cold weather and of reducing somewhat the rate of piston-ring and cylinder-wall wear.

This paper deals with progress in the Cooperative Fuel Research since the last report was presented to this Society. Previous tests had shown that the temperature of the jacket water exerted a major influence on the rate of dilution of crankcase oil. The reason for this influence was investigated and it was concluded that it was due to differences in the rate at which diluent was added to or eliminated from the oil-film upon the cylinder-walls, the temperature of this film being dependent upon the temperature of the jacket water. Experiments failed to show that changes in the temperature of the piston head or changes in the viscosity of the oil upon the cylinder-walls exerted a major influence upon the rate of dilution. These conditions were investigated as being probable consequences of a change in the temperature of the jacket water. Evidence is presented which demonstrates that under certain conditions the diluent may be eliminated from the oil at a fairly rapid rate.

An independent study of a similar nature to that made by the Bureau of Standards on fuels in 1923 was conducted by the company the author represents, and the paper presents first the results of the tests made on five 7½-ton trucks during the regular course of business deliveries. Curves plotted from the data thus obtained are presented and analyzed in considerable detail. These data were then utilized as a basis for a series of dynamometer experiments in an attempt to explain further the effects of the many temperature and mechanical variables on the rate of oil consumption and oil dilution when only one factor was allowed to vary at a time. The dynamometer apparatus and the engine used are described, together with the test routine, and an analysis is made of the result of wear of the test engine. The “standard” conditions under which the test runs were made are stated.

The importance of the development of a light alloy for use in parts that are subjected to elevated temperatures has already been emphasized in many papers, among which that by S. D. Heron on Air-Cooled Cylinder Design and Development4 should be particularly mentioned. It was with this purpose in view that the foundry of the Engineering Division of the Air Service at McCook Field undertook a brief survey of the alloying, the casting, the heat-treatment, the physical properties and the metallography of an aluminum-copper-nickel-magnesium alloy of the Magnalite type as sand-cast under ordinary foundry conditions. It was found that the alloying involved no particular difficulty. The casting, however, showed the necessity for proper pouring temperatures, gating and placing of the chills and the risers. Several photographs are shown illustrating satisfactory and unsatisfactory methods of molding pistons and air-cooled cylinder-heads.

A brief summary of the history of motor rail-car equipment on the railroad represented by the author is given in his paper. Three gasoline-driven rail-cars were put into operation in 1910. The engine used for each car was a six-cylinder, 10 x 12-in., slow-speed, four-cycle reversible-type having overhead valves, an open crankcase and a 200-hp. rating, but experience has proved that the four-cycle reversible-type engine equipped with an air-operated starting-apparatus makes rather a complicated unit that is the cause of many difficulties. Details are given concerning these first three cars, their performance and the changes made in their equipment. In 1922, a two-car train consisting of a motorcoach and a trailer was installed. The coach is 28 ft. long, has a 12-ft. baggage-space, carries 30 passengers and weighs 28,000 lb.; the trailer is 32 ft. long, weighs 17,000 lb. and seats 36 passengers.

In the first part of the paper, a general quantitative comparison of air, water and oil-cooled cylinders is given as it relates to the subject of heat-transfer and temperature drop. Unfortunately, the discussion does not include experimental data, but the assumptions are stated clearly and a large range of values is covered in Table 2 so that any desired values can be chosen. A thorough and comprehensive discussion of the steam or the radio-condenser type of cooling is given under the headings of Steam Cooling Systems, Characteristics of Steam Cooling Systems, Cooling Capacity of Radiators Used To Condense Steam and Present State of Development. In the second part, an attempt is made to give a thorough but brief discussion of the performance or of the operating characteristics of radiators from the point of view of the car, truck or tractor designer. The cooling of aircraft engines is not considered.

The efficiency of internal-combustion engines increases with the pressure of the charge at the time of ignition. Therefore, a compression at full load just below that of premature ignition is ordinarily maintained. But when such an engine is controlled by throttling, the efficiency drops as the compression is reduced, and as automobile engines use less than one-quarter of their available power the greater part of the time, the fuel consumption is necessarily high for the horsepower output. On account, also, of the rarefaction due to throttling, more power must be developed than is necessary to drive the car; automobile engines in which the fuel is introduced during the induction stroke, would be more efficient, therefore, if the maximum compression were constant during all ranges of load.

Definite knowledge as to the behavior of gases and liquids in the manifold of an internal-combustion engine being lacking, an attempt is made to answer the questions: (a) How bad is the distribution, (b) how do the different types of manifold compare, (c) why is the liquid distribution in some manifolds poor and (d) how shall we proceed to correct the trouble? The solution of the problem is affected by the facts that, in extremely cold weather, nearly all fuel is delivered to the engine, at the time of starting, as a liquid; that all cars perform poorly under such conditions, some engines, when cold, “hitting” on only one or two cylinders; and that, because of inferior distribution, many multi-cylinder engines are outperformed by single-cylinder engines of similar design.

Supplementing a paper by another author that treats of the theoretical balancing of this engine, Mr. Anderson presents the practical methods that have been devised to accomplish the results desired. Since this crankshaft is not in running or in dynamic balance without its piston and its connecting-rod assemblies, it is necessary to apply equivalent weights on each of the crankpins when balancing it on a dynamic balancing-machine, and details are given of how these weights are determined. The selection of parts to obtain equal weights is also necessary; a description is given of how this is made. A combination static and dynamic balancing-machine that can be set for either operation is used for balancing the crankshaft. Details of its operation are presented. Service conditions to secure parts replacements within the weight limits specified are outlined, and flywheel, universal-joint assembly and other unit balancing is discussed. The method of testing the completed work is stated.

Remarking upon the progress made by the builders of machine-tools in providing equipment for locating and correcting the unbalance of rotating parts, the author divides into three major groups the units of a motor car that require particular attention and treatment to assure a smooth-running mechanism and gives details of the actual methods employed by the company he represents to balance the parts that constitute each group in the vehicles it produces. Representatives of the engineering and the manufacturing departments of this company studied the subject intensively and determined the types of balancing-machine and the methods to be employed, and special balancing equipment was devised also. Details of the balancing practice for crankshafts, flywheels, connecting-rods, clutches and propeller-shafts are presented and the subjects of impulse balance and the maintenance of balance for assemblies of parts are discussed.

References to previous theoretical discussions of engine balance are cited prior to consideration of vibrations in four, six or eight-cylinder engines that may either be felt or heard in the car and result from lack of balance. Dynamic arrangement of the engine, unequal forces set up by the unequal weights of moving parts and vibration arising from elasticity or yielding of the parts themselves are the major causes of unbalance, of which the unequal weights of the parts are within the manufacturer's control. Unbalance of the conventional four-cylinder engine is of considerable magnitude, due to the angularity of the connecting-rod that produces unequal piston motion at the upper and lower parts of the stroke, the unbalanced force reversing itself twice per revolution and acting in a vertical direction. The actual magnitude of this force varies directly with the weight of the reciprocating masses and as the square of the speed.

Very few data seem to be available on the frictional losses in automobile engines caused by the failure of the oil to perform its function as a lubricant. The researches of the Lubrication Inquiry Committee in England indicate that the friction of a flooded bearing is proportional to the speed of the engine, the area of the bearing and the viscosity of the lubricant and is independent of the pressure and of the materials of which the opposing surfaces are composed. The principal sources of friction in an engine are the crankshaft, the camshaft and the connecting-rod bearings, which rotate; the pistons and the valves, which slide; and the auxiliaries, such as the generator, the pump and the distributor.

The magnitude of the business of the American Railway Express Co. requires that careful consideration be given to the details necessary for economical operation. The equipment comprises 12,755 vehicles, of which approximately one-third are motor-driven and have a carrying capacity of more than one-half the total. On July 1, 1918, when all the express companies were merged into one organization, it was found that the motor-vehicle equipment included 59 different makes and 131 different models. Among the 377 trucks built by one company were 21 different models. Diversity of equipment, of course, complicates the maintenance problem and adds to the cost. Additional expense is incurred frequently by purchasing and experimenting with parts offered by makers of accessories such as carbureters, spark-plugs, wheels and the like. Careful inspection, adequate lubrication and the adoption of “stitch-in-time” methods will save needless expense.

To install conveyors in a going automobile manufacturing plant of moderate size, without interrupting production, and with a minimum amount of rearrangement of the plant and an investment commensurate with the saving to be effected, was the problem, the solution of which is herein described. The conditions that determined whether power-driven or gravity-actuated conveyors should be used are discussed and the various types required for handling raw stock, for machining operations, for sub-assemblies and for finished assemblies are indicated.

In production grinding the progress made during the past few years has been along the line of grinding multiple parts simultaneously, such as piston-rings, ball and roller-bearing cups and so forth. This kind of grinding brought about the use of wider wheels to cover the entire surface of the work, whereas formerly narrow wheels had been used with the traversing table method. With the development of these operations came the cylindrical grinding of square and distributor cams; also square shafts, using the oscillating cam-grinding attachments; piston-relief grinding with the same attachments; and two-wheel or double-wheel grinding for such parts as steering-knuckles and pinion shafts of different diameters or where two diameters are separated by some protrusion, as in steeringgear worm-shafts.

Wire wheels, having been used exclusively on bicycles, naturally were adopted as standard by the builders of the early types of automobile. But as the automobile soon increased greatly in weight and as its builders believed that the best results could be attained by wheels of large diameter, wire wheels were found to be lacking in strength and were discarded in favor of wood wheels of the artillery type, which at that time were being imported from France. When a few years later, wire wheels again appeared on some of the English models, the prejudice against them still remained and it was not until about 1914 that they began to find favor in the industry. Drivers of racing cars, however, continued to use wire wheels because they obviated the flywheel effect and lent themselves to quicker braking and accelerating.

Stating the fundamental characteristics of the modern motor-car under the headings of performance, safety, economy, comfort and taste, the authors define these terms and discuss each basic group. The specifications of the car in which the single-eight engine is installed are given, and the reasons governing the decision to use an eight-cylinder-in-line engine are enumerated. Following a somewhat lengthy discussion of the components of engine performance, the design of the engine is given detailed consideration under its divisions of crankshaft design and the methods employed, gas distribution, the operation of the fuelizer, cylinders, valve gear and the arrangement of the accessories. Transmission design and the wearing quality of gears receive similar treatment.

Present-day fuels are stated to be the cause of crankcase-oil dilution, due to their high end-points, and the author presents tabular data to show how end-points have risen since 1910, together with data showing the effects of various percentages of fuel dilution with relation to the Saybolt viscosities and pour-points of high-grade oils. Three divisions are made of the dilution due to mechanical defects. Contamination, not dilution, necessitates oil drainage, and this statement is elaborated. The rise of heavier-bodied oils is decried. Six specific divisions of how to avoid crankcase-oil dilution are made and emulsification is discussed, together with demulsibility and crankcase service. Five specifications are made with regard to how to avoid oil-sludging, and carbonization is given lengthy consideration. Proper oil-specification is treated, and instructions on how to avoid oil-pumping and carbon deposit are presented in eight divisions.

The author believes that the universal power unit will be direct air-cooled, but states that the direct air-cooled engine is now in the minority because, until very recently, there has not been a sufficiently broad series of established engineering facts and development work available to form a foundation for improvement. The satisfactory air-cooling of an 8 x 10-in. cylinder has been reported, and the development in a smaller cylinder of 138 lb. per sq. in. brake mean effective pressure; also, in a three-cylinder, air-cooled, radial-engine, a brake mean effective pressure of more than 125 lb. per sq. in. was developed and the engine endured beyond the ordinary expectations for water-cooled engines.