General characteristics

Diesel, or compression ignition engines are similar to the spark ignition engines in principle. However, there are important differences. On the intake stroke of the Diesel engine air only enters the cylinder, and is com­pressed on the next stroke. At the end of the compression stroke the air temperature has been raised to approxim­ately l,200^oF. by decreasing its volume to about 1/16 of the original volume. This temperature is known to be high enough to burn heavy fuel that is sprayed into the compressed and heated air by a specially constructed in­jection mechanism. Since the Diesel engine operates with such high compression, its parts must be heavier and must fit more perfectly than in a spark ignition engine.

Although Diesel engines will theoretically operate on any oil that can be pumped through the injector, they operate much more efficiently on "Diesel Fuel" or fuel oil.

1. Study the following words:

next stroke, spray, in­jection, compression ignition, two-cycle, power stroke, blower

dust, plunger, care, volume.

2. Complete the sentences with appropriate words from the text:

a) Diesel engine …. with such high compression.

b) At the end of the compression stroke the air temperature has been raised to approxim­ately …

с) On the … … of the Diesel engine air only enters the cylinder, and is com­pressed on the next stroke.

3. Give antonyms to the words:

Raised, heavy, enter, clean, dirt, burn

4. Insert prepositions if necessary:

a) … the intake stroke of the Diesel engine air only enters the cylinder.

b) Diesel, or compression ignition engines are similar to the spark ignition engines … principle.

c) Since the Diesel engine operates …such high compression.

5. Exercises in translation:

I. When inspecting components in which the cause of any defect is suspected, care must be taken, in each case, not to jump to conclusions without careful consideration of the possibilities. 2. The principles to be followed in tracing these faults have been given in Ch. 8. 3. Opening the valves reduces the compression ratio from about 17 to 1 to approximately 5 to 1. 4. The routine maintenance required consists simply of following the tractor manufacturer's oil recommendations. 5. Before returned to service, an in­jector must fulfill four requirements. 6. Compared with (as compared to) an impulse-starter magneto, coil ignition timing is often found easier to check because there is no impulse. 7. Since each valve has to be actuated once only during two revolutions of the crankshaft, the cam­shafts are driven at half the speed of the crankshaft. 8. When the piston is at the right-hand end as a result of pumping, and the spring thereby compressed, the cylin­der is said to be "charged". 9. The shaft may be made to do useful work. 10. The temperature quoted is usually 200°F. 11. Both systems are fitted to the same vehicle, either system being capable of being put into action at the will of the driver. 12. The driver's responsibility for the efficiency of his vehicle (машина, автомобиль) must be emphasized throughout training. 13. When a driv­er can pass the test, he may be considered to have completed the recruit stage of his training. 14. The initial training of drivers must aim at satisfying the requirements in maintenance duties.

Text 7

FUEL INJECTION

То overhaul a 4-cylinder C.I.-engine's fuel system is a specialist's task. To prevent the need for such an over­haul is a driver's task which will not cost more than a few hours' effort per year. But first of all let us study basic principles of fuel injection common to such engines as Caterpillar, David Brown, International, Marshall, Per­kins (1) and others.

Naturally, there are differences in design, make and layout of the fuel equipment used on these engines, there being also engine differences: the Marshall is a horizon­tal, single-cylinder, two-stroke unit, the others are mainly 4- and 6-cylinder, vertical, in-line power units.

These differences do not affect the common fundamental principles of fuel systems employed, but they could Cause confusion if we attempted to consider all the engines under one heading. To avoid this we will deal only with the 4-cylinder in-line 4-stroke engines.

The fuel system is known to comprise three main assemblies: air cleaner, injectors and injector pump. The injectors, one for each cylinder, are situated in the cylin­der head. The injector-pump assembly incorporates four plunger pumps, and is mounted on the engine and driven at half crankshaft speed. Each plunger is connected to an injector by a high-quality steel fuel pipe.

The function of these main assemblies in the working cycle of the cylinder is as follows. The piston, on its inlet stroke, draws air through the cleaner into the cylinder. On compression stroke, this air is squeezed into about one sixteenth of its original volume and, as a result, its tem­perature rises to over 1,000°F.

Just before the piston reaches top dead centre (T.D.C.) of compression stroke usually when the crankshaft is Within about 20° of it the pump begins, to inject fuel into the compressed air via the injector. As the self-ignition temperature of this oil is considerably less than I.OOO'F., the air temperature causes combustion. The fuel-lion period lasts through about 30° of crankshaft movement, and the piston is forced down by the expan­sion of combustion. Next comes the exhaust stroke, at the end of which the cycle begins again. The cycles of the remaining cylinders are arranged to produce a firing or­der of 1,3, 4, 2 or 1, 2, 4, 3.

The speed and power of the engine is varied by varying the quantity of fuel injected, but the volume of air drawn Into each cylinder remains the same at all speeds. Consider a 4-cylinder 4-stroke C.I. engine doing 1,000 r.p.m. and using a gallon of fuel per hour. As there are two firing strokes per crankshaft revolution, there must also 000 fuel injections per minute. This equals to 120,000 per hour. Consequently, the gallon of fuel used in one hour is pushed into the engine in 120,000 separate units.

The injection of each 120,000th of a gallon must begin when the engine crankshaft is a specific number of de­grees from (2) T.D.C and last through about 30° subse­quent movement. (3) Furthermore, the fuel must be in­jected in a uniform spray.

NOTES:

(1)Caterpillar, David Brown, International, Marshall, Perkins — названия фирм, изготовляющих двигатели

(2)is a specific number of degrees from... — находится на расстоянии определенного количества градусов от...

(3)last through about 30° subsequent movement — длится в течение последующего движения (коленчатого вала), приблизительно равного 30°.

1. Study the following words:

Overhaul, equipment, two-stroke unit, layout, injector pump, plunger, furthermore,

Squeeze, expan­sion, fuel pipe, gallon, mounted.

2. Complete the sentences with appropriate words from the text:

a) The speed and power of the … is varied by varying the quantity of fuel injected.

b) The … system is known to comprise three main assemblies

с) The fuel-lion period … through about 30°

d) To avoid this we will deal only with the …… in-line 4-stroke engines.

3. Give your own definitions of the words:

Overhaul, equipment, two-stroke unit, layout, injector pump, plunger, expan­sion, fuel pipe, gallon

4. Exercises in translation:

1. To satisfy the requirements of different designs of cyl­inder-head, many variations in design of injector-nozzles are seen. 2. To allow for the heavy work of starting large C.I. engines, it is usual to fit 24-volt electrical equipment to heavy C.I.-engined vehicles; once started, the C.I. en­gine does not require the same degree of warming up as does the petrol-engine. 3. To move the piston from T.D.C. to B.D.C., the crankshaft must turn through 180°. 4. To make an accurate comparison between different makes, three measurements are needed: overall diameter, bore diameter and width. 5. To check the pump, first (=first of all, MM) make sure, by disconnecting its feed pipe, that it is receiving an adequate supply. 6. To enable the sludge to be drawn off, the tank should slope about 1/2 in per foot of its length. 7. To prevent acidity, add lime at the rate of 1 lb. per 100 lb. of calcium chloride. 8. To prove whether a stoppage is in the feed line or the tank, disconnect the pipe at the top, and then work backwards or forwards according to whether or not fuel flows from the tank. 9. To bring about ignition by compression, ad­vantage is taken of the fact that, if air or other gas be compressed rapidly into a very small space, it becomes very hot. 10. To start the engine the fuel-pump control lever must first be moved into its closed position. 11. To get the best out of an engine, supply it with clean air, oil, fuel and water, keep it hot, work it hard, and abide by its maker's instruction book.

Additional texts

STARTING SYSTEMS

We know different starting arrangements to be in com­mon usage. Some of them are as follows: The Caterpillar C,I, engine is started by an auxiliary horizontally opposed I cylinder petrol engine (1) which drives the flywheel of the main engine. Provided the starter engine runs at I he correct speed and engages properly with the flywheel, the most probable causes of non-starting are faulty fuel supply and incorrect injection timing.

An International starting system no longer included in Mulish made models allows the C.I. engine to run as a S.I. unit until warm. In the cylinder head, above each cyl­inder, I here is a chamber closed to its cylinder (2) by a Valve. A spark plug is screwed into each chamber. A magneto is provided in addition to a carburetor and petrol manifold.

To start the engine, the fuel-pump control lever must first be moved into its closed position. Movement of a sec­ond lever (3) opens the cylinder-head chamber valves and also allows petrol to enter the carburetor. Opening the valves reduces the compression ratio from about 17 to 1 to approximately 5 to L This enables the engine to be turned easily either by hand or electric motor, and also allows an air/petrol mixture to be drawn into the cylin­ders and to be ignited by the spark plugs.

When the engine has become warm the driver, by re­turning the lever, closes the chamber valves and isolates the carburetor. The compression ratio is thus raised to that necessary for compression ignition.

The injector pump is brought into action by movement of its control lever.

NOTES.

(1)horizontally opposed 2-cylinder petrol engine — горизонтально оппозитный 2-цилиндровый бензиновый двигатель

(2)closed to its cylinder — отделенный от своего цилиндра (зд.)

(3)a second lever — декомпрессор (зд.)

COLD RADIATORS AND COLD STARTS

Cold radiators and cold cylinder walls are found to en­courage corrosion, wear and tear. Corrosion in engine is less likely to occur at cooling water temperature about 176°F. than at lower temperatures. A test which is refer­red to was carried out by the Standard Oil Company in America which showed the cylinder wear of a petrol en­gine, after 60 hours' operation, to be 38 times greater at a cooling water temperature of 114.8°F. At the same time the engine output is reported to have been smaller by 3% while fuel consumption was greater by 20%. Another test referred to and carried out by the Marine Experimental Division of the U.S. Navy on four-stroke Diesel engines showed a cylinder wear to be 20 times greater at 122°F than at 185°F.

Starting engine from cold also has bad effects. A Ger-mm test showed that cylinder wear after one hour's operation and after starting from cold (cooling water tem­perature 59°F.) was 55% greater than when starting with a cooling water temperature of 140°F. After 2 hours' operation the difference was still 35%, and only after three hours' operation did cylinder wear figures reach their normal level. The writer recommends filling radiators with hot water before starting an engine in the morning.

FREEZING UP

It was so cold last winter that some Diesel fuels were affected and could not feed the engine's injection system. In extreme instances, engines could not be started be­cause of this.

Protection can be provided either by keeping the trac­tor and fuel away from frost, or else by diluting the fuel with a 20% addition of lamp paraffin— not vaporizing oil. It should be noted that the lamp paraffin must be added before the fuel has been affected by extreme cold.

Protecting Cooling Systems. The best method of pro­tecting the water cooling system of an engine is the subject of controversy. Some prefer to drain the system each lime the engine is shut down; some rely on a good brand of antifreeze, while others fill the cooling system with Diesel oil.

In my opinion the best method is a good brand of anti-freeze. But it must be used at the right strength and in a system that does not leak. If_}the system leaks, the strength of the solution may be reduced by the addition of water and antifreeze will be of no use. If the leak is internal it may allow the solution to enter the engine with disastrous effects on the crankshaft and cylinder walls.

Before using antifreezes, flush the system; see that the cylinder head nuts are tight and that the water hoses are sound.

If draining the system is preferred, the cylinder block as well as the radiator must be drained. Insert a wire in the taps to make sure they are not blocked by dirt.

When filling the system and starting the engine, keep the radiator covered until the engine is warm. If this is not done the fan will draw cold air through the core, and the water in the radiator may become frozen while the thermostat restricts the circulation of warm water to the engine cylinder block until it reaches a predetermined temperature.

I am in two minds about (1) the use of Diesel oil as antifreeze.

Electric Batteries. A battery that is exposed to frost should always be topped up immediately before it is to be charged. If it is topped up after the machine to which it is fitted is shut down, the distilled water may freeze before it has mixed with the acid solution in the cells.

Starting a cold and stiff engine puts a great strain on an electric battery. This strain can be eased ‘by using the correct grade of oil, turning the engine once or twice by hand and by disengaging the engine clutch when using the starter.

Do not engage the starter motor of a spark-ignition en­gine for longer time than three to four seconds at a time. The starter of a Diesel engine may be engaged for long­er periods, but not exceeding 20 seconds because of the strain.thrown on the battery.

Keep batteries well charged' at all times during frosty weather. The electrolyte of a discharged battery will freeze in 25° of frost, but it takes about 50° to freeze a battery that is three-quarters charged.

Water Ballast. A solution of calcium chloride should be used to prevent the water ballast in tyres (2) from freezing. Use 2 lb. of chloride to each gallon of water and add lime at the rate of 1 lb. per 100 lb. of chloride to prevent acidity. This mixture will give protection against 32° of host.

When mixing, always add the chloride to the water— never the other way round. Allow the solution to cool be-putting it into the inner tube. Never use the chloride solution in a radiator.

Slush and Mud. Slush and mud can cause breakdowns if allowed to freeze around certain types of mechanism overnight. The damage occurs when power is applied to the frozen components. This frequently happens to trackers which have become frozen to the ground. Clean the machine at the vulnerable points before leaving it exposed to frost and park the tractor on stones or pieces until re sure that all is well.

Wheels, track rollers and all moving parts which operate in slush and mud and have to be lubricated regularly should be oiled or greased twice as frequently as normal when there is a likelihood of the dirt entering the bearings.

NOTES:

(1) mi in two minds about — я сомневаюсь, я не уверен в

(2) water ballast in tyres — водяной балласт в шинах (для усиления их веса в целях улучшения сцепления с почвой)

TOP OVERHAULING A FORDSON MAJOR DIESEL

The top overhaul of the Fordson Diesel engine, as described in this article, includes decarburizing, grinding the Wives, cleaning and testing the fuel injectors. It is not always easy to determine when an engine needs a top overhaul. The symptoms calling for it are loss of power and sometimes black smoke, misfiring and bad starting. But these symptoms can also arise from faults in the air and fuel system and the exact cause should be determined by special equipment including an injector tester, otherwise there is always the chance that a top overhaul will prove to have been unnecessary.

All carbon should, of course, be removed from the valves, the head and from the interior of the exhaust manifold. The pistons and tops of the cylinder liners should also be decarbonized. Before doing this, plug the water and oil passages in the face of the cylinder block with clean non-fluffy cloth.

To make a thorough job of decarburizing a Diesel en­gine the injectors should be cleaned, tested, and, if neces­sary, adjusted. This cannot be done without special equip­ment.

Before returned to service, an injector must fulfil four requirements: 1) it must begin to spray at 185 atmospheres; 2) not allow a pressure of 150 atmospheres to drop below 100 atmospheres in less than six seconds; 3) the four sprays of fuel from the holes should be uniform, well atom­ized and free from.streaks and distortion (1); 4). after a nozzle has been wiped dry, the tip must remain dry after delivering three or four injections.

The air cleaner is a most important accessory on the Diesel engine and it should be inspected during the over­haul. Remove and clean the pre-cleaner. If dirt is lodged between the louvres, remove it gently so as not to damage them. Misguided enthusiasts (2) have been known to prise the louvres apart with a screw-driver; this upsets the air flow and reduces the efficiency of the cleaner.

NOTES:

(1)well atomized and free from streaks and distortion — хорошо рас­пыленными, сплошными и прямыми

(2)misguided enthusiasts — некомпетентные энтузиасты

RECONDITIONING A PERKINS DIESEL

Perkins sell Diesel engines. They have a "Perpetuity Plan’’ which provides Perkins users with factory reconditioned engines in part exchange for (1) those requiring a major overhaul. The reconditioned engine carries a guarantee similar to that of a new engine.

The plan works as follows. When a user decides that Ml engine is nearing the time for a major overhaul, he orders a reconditioned engine from Perkins. The old en­gine roes back to the works to be reconditioned and then passed to another user.

Improvements that have been made in design since a particular engine was produced are incorporated in the reconditioned version. There is no limit to the number of times that an engine can be reconditioned—hence the title "Perpetuity Plan". To see what a user gets for his money, I spent a day idling engines being reconditioned. First, the engine is completely dismantled—even to the femoral of cylinder-head studs from the cylinder block. Pistons, rings, main and big-end bearings, valve springs, gudgeon pins and similar items are scraped. Then the com­ponents that are likely to be used again are steam-cleaned or chemically degreased. Manufacturing standards pre­vail. Testing and inspection takes about 50% of the time for reconditioning. For instance, the crankshaft is put through a crack detector twice: once before it is reground and once after.

When the crack detector is used on a crankshaft, the lull is first magnetized and then bathed in a special fluid, i(h owing to the action of the magnetic lines of force, forms a dark line or lines over any crack that may exist. Faulty shafts are scrapped and sound shafts are demagnet­ized land reground 0.010 in., 0.020 in. or 0.030 in. under­line, l hen they are again crack detected, demagnetized and Inspected.

The sizes, date of reconditioning and other data are then stamped on a brass plate which is fitted to the camshaft side of the cylinder block (2).

Connecting rods are tested for cracks by a slightly dif­ferent technique from that used for the crankshaft, the fluid being poured on while a 500-amp. current passes through the rod. This treatment causes the cracks to turn green and the color shows up when the rod is inspected in a special chamber.

Rods which pass this test are then checked for align­ment and fitted with new big-end and gudgeon pin bear­ings.

The water-jacket of the cylinder block is sealed and test­ed under pressure for leaks. Blocks that pass the test are then fitted with cylinder liners and main bearings.

Dry liners are used in the P series engines (3). They are forced home (4) by an hydraulic press, they are then bored and finally honed. Wet liners are a hand-push fit (5) and require no further treatment.

Water pumps, lubrication oil pumps and similar acces­sories are reconditioned and tested individually before being fitted to an engine. The completed engine is given a five-hour running test. Finally, it is painted the color that is normal for its application to a given machine.

NOTES:

(1) in part exchange for — в частичный обмен на. (2) is fitted to the camshaft side of the cylinder block — прикрепляется к блоку цилиндра со стороны кулачкового вала

(3)the Р series engines — двигатели серии Перкинс

(4)are forced home — устанавливаются на место

(5)are a hand-push fit — устанавливаются вручную

PART II. MACHINERY FARM

THE MODERN FARM TRACTOR

Text 1

Тractors may be classified according to type of engine, i.e. how the fuel gets into the cylinder. An internal com­bustion engine is one in which the fuel is burned, and the power is generated within a closed cylinder.

An external combustion engine is one in which the fuel • burned outside of the cylinder, and the power generated is confined in a separate space to be released through the cylinder.

The engine used may be two or four cycles; single or multiрІе cylinder; manifold or solid injection; low, medium', mi high compression; but it is still an internal combustion engine. As such, it requires constant, systematic care and maintenance to insure greatest efficiency and long life.

The modern farm tractor is the result of many years of development. Its present efficiency is possible because of engineering progress in design, metallurgy, fuels, lubricants, manufacturing methods and in many other respects, і he modern tractor may be said to be very closely related to the modern automobile, truck, airplane, all of them hiving one feature in common: the internal combustion engine.

The farm tractor is capable of working long hours at capacity loads in the heat and dust of summer or in the Cold mid snow of winter. Long continued good performing is known to depend upon the operator.

A careless operator can allow a tractor motor to ruin itself in a few minutes, whereas a careful operator can pro long indefinitely the useful life and efficiency of a similar motor. Small difficulties are to foe prevented from becoming large ones which may be time consuming and expensive.

TRACTOR ENGINE FUELS

The tractor engine cannot burn both gasoline and distil­late. The tractor engines are to be designed specifically for either one fuel or the other.

Need for Tests. We were asked 1) to develop instru­ments and test methods which would permit accurate testing of tractors under all conditions of operation and 2) to explore the power and economy possibilities of dis­tillate and gasoline.

As it was entirely possible for engineers to sit down with pencil and paper and figure out the relative efficiency and economy values of these two fuels, we did that. We knew in advance that distillate contains more heat units than gasoline, but we also knew that the number of heat units is not the true test of the efficiency of a fuel. Tar, for example, has more heat units than either gasoline or distillate, but it is totally unsuited for internal combustion engine fuel.

The high manifold temperatures required to vaporize low-grade fuels have the effect of reducing engine power by raising the temperature of the air in the fuel mixture. The heavy parts of these fuels often do not vaporize and simply run down the cylinder walls, washing away the lubricating oil, and diluting the oil in the crankcase. Tak­ing all these factors into consideration we figured out that, theoretically, gasoline should develop 29.6 per cent more power than distillate.

Laboratory tests. The next step was to take a tractor into the laboratory and see how theory stood up under actual operating conditions.

We spent a considerable amount of time designing and Installing measuring instruments. First, there was an electric dynamometer to test the power at the belt under conrolled conditions. Thermometers were installed to measure the temperature of cooling water, crankcase oil, and lubricants in the transmission and differential.

Engine speed was checked by means of an electric tachometer indicator. A flashing neon-tube continuously indicated ignition timing, Fuel and air consumption were ensured too.

Great care was exercised in the selection of fuels, particularly distillate. The best distillate available was used, if should be pointed out, however, that there is a consid­erable variation in the quality of distillate throughout the country. The gasoline used for testing was the regular grade and samples were uniform.

Each fuel was put to work under engine conditions best suited to it. For distillate, hot spark plugs, hot manifold, and cylinder head of 4.32:1 compression ratio were used. For gasoline, cold-type plugs, cold manifold, and a com­pression ratio of 6.14:1 were used.

Under the same loads and at the same engine speeds gasoline was found to develop slightly over 26 per cent Wore power than distillate. The fuel saving amounted to approximately 20 per cent by weight.

Under various other conditions the difference between the efficiencies of the two fuels were even more marked.

The program next called for tests in the field.

The site selected for the field tests was Murve Dry Lake on the Mohave desert, in California.

Load was applied by towing another tractor. Additions and modifications in instrumentation had to be made for exact measuring of power at all times under new condi­tions. In general, the test methods were the same as those Lined in the laboratory, same engine speeds, compression ratios, fuel mixtures, and so on.

After months of work in all kinds of weather we came to the following conclusions: on the average, gasoline developed 27 per cent more power at the rear wheels than distillate; gasoline did each unit of work on 21 per cent less fuel, by weight.

1. Study the following words:

distil­late, unsuited, instrumentation, rear wheels, Installing, low-grade, consid­erable, amounted, lubricants, tachometer, explore

2. Complete the sentences with appropriate words from the text:

a) The site selected for the field tests was ….

b) The tractor engine cannot … both gasoline and distil­late.

C) …. were installed to measure the temperature of cooling water.

d) The … used for testing was the regular grade and samples were uniform.

3. Give your own definitions of the words:

distil­late, rear wheels, Installing, low-grade, amounted, lubricants, tachometer, explore

4. Insert prepositions if necessary:

a) Tar, for example, has more heat units than either gasoline or distillate, but it is totally unsuited … internal combustion engine fuel.

b) The next step was to take a tractor into the laboratory and see how theory stood …under actual operating conditions.

c) … the same loads and at the same engine speeds gasoline was found

d) The heavy parts of these fuels often do not vaporize and simply run …the cylinder walls, washing away the lubricating oil, and diluting the oil … the crankcase.

Text 2

MECHANIZATION PLOUGHS

Before 1947 the tractors reported in this paper were all old-type Fordsons (1) which averaged less than 15 acres of ploughing (2) per 50 hours. Today with three-furrow ploughs and tractors with multi-ratio gearboxes the ploughing output had been raised to an average of 27 acres per 50 hours.

When discing, as big an acreage could be covered with a light tractor as with a heavy one but the latter pulled a very heavy disc which would generally do better work in one run than could be done in two or more runs with light discs.

When cultivating, the rate of work done by either size of tractor was the same if mounted cultivators were used and there was little difference in the quality of work. If a trailed cultivator was used, however, the heavy trac­tor showed greater advantage, but it was only in excep­tional circumstances that a trailed cultivator was prefer­red to a mounted one. With the present mixed team (3) of large and small tractors the same equipment was often used for rolling, harvesting and drilling because the smaller tractors could pull the loads on moderate slopes while the larger machines with their extra gears, could pull them on the steeper ground.

NOTES:

(1)Fordson — марка тракторов

(2)averaged less than 15 acres of ploughing — в среднем вспахивали менее 15 акров

(3)team — состав (зд.)

1. Study the following words:

Ploughing, discing output,rate,circumstances, loads, excep­tional,trailed, gears.

2. Complete the sentences with appropriate words from the text:

a) With the present mixed team of large and small tractors the same equipment was often used for …. …..

b) Today with three-furrow … and tractors with multi-ratio gearboxes the ploughing output had been raised to an average of 27 acres per 50 hours.

С) If a trailed … was used, however, the heavy trac­tor showed greater advantage

3. Give your own definitions of the words:

4. Find antonyms for the words:

Furrow, slopes, covered, heavy, light

Text 3