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= Most Common Agricultural Motors Used in Finland =
''By Eng. J. Kantola''

Previously, up until the outbreak of the world war, Finland used mainly motors imported from Sweden, England, and America, along with locomobiles as power sources for agriculture. Our own motor industry was still in its infancy; mass production was out of the question.

Sweden, which has a number of good specialized factories for motor manufacturing, supplied considerable quantities of agricultural motors to Finland. These were mostly vertical, two-stroke engines equipped with hot-tube ignition, running on crude oil or petroleum.

The Swedish also manufacture horizontal motors suitable for agricultural purposes, but as their price is somewhat higher, they were imported to our country in relatively small quantities.

From England, medium-sized and larger power machines were generally imported, mainly gas engines that were initially fueled by coal, later by sawdust and wood waste or peat. In their manufacture, England surpassed all other countries. Gas engines were extremely economical as power sources for mills, electrical plants, and combined mill and saw facilities where mill operation was the primary function. Steam engines are better suited as power sources for proper sawmills. Furthermore, relatively large quantities of small crude oil and petroleum motors were imported from England, mostly of vertical construction and equipped with magneto ignition.

American agricultural motors have a different construction from those mentioned above. Almost without exception, they use horizontal four-stroke engines with magneto ignition, and cooling is accomplished through an open water jacket surrounding the cylinder. Gasoline or petroleum is used as fuel. Operating reliability is usually good, but fuel consumption is relatively high.

Before the war, motors were imported from America in considerable quantities. However, during the war period, there was a fundamental change in the agricultural motor trade, as in many other things. As Finland's currency value declined, foreign motors became so expensive that hardly anyone could afford to buy them. At the same time, the price of domestic locomobiles rose proportionally much more than other machines, depending on the increase in boiler plate prices. This gave an impetus to domestic motor industry, and "motor factories" sprang up like mushrooms after rain.

Since the initial difficulties can now be considered overcome and weak and poorly managed motor workshops have disappeared, we can state that domestic motor manufacturing is on a reasonably satisfactory footing. We have several motor workshops whose products are of good quality and uniform, despite still relatively small production volumes. However, the manufacture of small motors must be mass production rather than individual production if it is to succeed properly. We are still far from achieving this. So few agricultural motors are used in Finland that they would not be sufficient for a single large motor factory, let alone several. We therefore have no choice but to export motors to other countries if we wish to maintain a proper motor industry. And export does not seem at all impossible.

In the following, we provide some brief information about the agricultural motors most commonly used in Finland. We first mention the most common domestic products.

== 1. B. M. W. Motors ==
The largest and most significant of our domestic motor factories is Björneborgs Mek. Verkstads Ab. in Pori. The B. M. W. motors it manufactures have achieved the greatest distribution in Finland, and they have been exported to other countries, for example Estonia. They are constructed according to the Swedish general type, being two-stroke engines equipped with hot-tube ignition, running on crude oil or petroleum, of vertical design.

[[File:1924 Fi Ill 1.png|frameless]]

'''[Figure 1. 8 HP B. M. W. motor]'''

For actual agricultural purposes, B. M. W. motors are now manufactured in 5, 8, 10, and 15 horsepower, mounted on wooden bases so they can be easily moved from place to place. Thus, the range is as complete as is needed in agriculture.

Previously, these motors were troubled by a slight tendency to vibrate. Last summer, the factory changed the arrangement of various parts of the machine, positioning the motor in the middle of the base between the fuel and water tanks, and strengthened the base. This eliminated the mentioned defect without making the machine significantly more difficult to access and maintain. During the past summer, the previous 7 horsepower motor was converted to 8 horsepower by increasing the cylinder diameter from 130 mm to 140 mm, so this size can now easily drive threshing machines equipped with rollers 600 to 700 mm long.

The B. M. W. motor speeds are quite high, being 750 rpm for the 5 hp engine, 600 for the 8 hp, 500 for the 10 hp, and 450 for the 15 hp. The piston mean speeds are thus 3.4, 3.5, and 3.6 meters per second. The motors' compression ratio is high (semi-diesel system). This has achieved relatively low fuel consumption, being approximately 275 grams per hour per brake horsepower when the motor is fully loaded.

By using the two-stroke system and high engine speed, the motor weight has been kept relatively small, which has some significance in agricultural motors. A 5 hp motor in full condition with base and cooling equipment weighs only 300 kg, the 8 hp weighs 460 kg, the 10 hp already weighs 800 kg, and the 15 hp weighs 1430 kg.

The two-stroke system, which eliminates the inlet and exhaust valves and the mechanism driving them, which are necessary in four-stroke engines, along with hot-tube ignition, makes B. M. W. motors structurally simple and easily understandable. Later we will make more comparisons between two- and four-stroke motors, as well as between hot-tube and electrical ignition.

Since many Finnish and most Swedish agricultural motors are of the two-stroke system, and their structure is essentially similar, we describe below briefly the operation and structure of B. M. W. motors.

In Figure 2, 9 is the piston, which moves up and down in the cylinder. The crankcase 11 is completely sealed and functions as an air tank or more properly as a motor air pump.

The motor operates as follows:

When the piston moves upward, a vacuum is created in the crankcase, which causes the air valve 30 to open and admit air into the crankcase. When the piston comes down again, this air is compressed in the crankcase. As the piston approaches its lowest point, the air port B opens, allowing air from the crankcase to enter the cylinder, pushing out the remaining combustion gases through port C and filling the cylinder. When the piston moves up again, the air in the cylinder is compressed, and just before the piston reaches its highest position, the fuel pump injects the necessary amount of fuel through the vaporizer 4 against the hot interior wall of the ignition ball 2, causing the fuel to ignite, creating strong pressure in the cylinder and forcing the piston downward. Just before the air port B opens, the piston opens the exhaust port C, through which combustion gases escape to the muffler 19 and from there through the pipe 51 to the outside. Thus, the excess pressure in the cylinder dissipates before fresh air enters through port B.

This repeats with each revolution. The governor 46 regulates the motor speed by reducing the length of the fuel pump stroke as the motor load decreases or speed increases, and increasing it as the load increases or speed decreases.

The motor can be adjusted to run in either direction.

When starting the motor, the ignition ball 2 must be heated with lamp 18. Afterward, the lamp can be extinguished, as the ball remains hot from the heat generated by explosions, unless the motor is loaded extremely lightly.

The cleanliness of the cylinder and the motor's performance can be improved, fuel consumption reduced, and ignition timing and ball temperature controlled by introducing a small amount of water into the cylinder. This is done either through the drip tap 8 or pump 75. In the latter case, water flows through the ignition ball's pipe, which connects to the fuel vaporizer support.

The cooling of the cylinder and its cover is done with water, which in the smaller 5 and 8 hp motors circulates on its own without mechanical aids in such a way that heated water tends to rise and cold water flows from the water tank in its place (so-called thermosiphon system), and in larger motors by means of a pump. The main bearings are ball bearings.

Björneborgs Mek. Verkstad manufactures, in addition to the aforementioned, primarily agricultural purpose motors, also 7–50 hp fixed single-cylinder, 3–100 hp fixed twin-cylinder, and 8–200 hp 1–4 cylinder boat motors.

As already mentioned, many of the motors manufactured in Finland, such as Borgå Båtvarvin Alfa, Ahjon Simson, Grönlund's GG motor (production discontinued), etc., are of essentially the same construction pattern, so we pass over them here relatively briefly.

The same can be said of many Danish and most Swedish agricultural motors, Columbia, Bruzaholm, Phenix, Avance, Lysekil, Bergsund, and many others, which were once imported to Finland in considerable quantities.


[[File:1924_Fi_ill_2.png|frameless]]

[Figure 2. Cross-section of B. M. W. motor]

== 2. Alfa Motors ==
Alfa motors are used in Finland in relatively considerable quantities, and generally, with few exceptions, have functioned satisfactorily. They are two-stroke engines equipped with hot-tube ignition, running on petroleum or crude oil, of vertical design. In structure, they generally resemble B. M. W. motors. Fuel consumption should be considered relatively high. Motors for agricultural purposes are manufactured in 6–7, 10–12, and 20–24 hp.

[[File:19624 Fi Ill 3.png|frameless]]

[Figure 3. Alfa 6–7 HP]

== 3. P. S. M. Motor ==
The motor is a two-stroke engine equipped with hot-tube ignition, running on petroleum, of vertical design. In construction, it differs from the aforementioned mainly in that, instead of water cooling, air cooling is used; that is, the cylinder is equipped with wide fins into which a fan blows cold air. Thus, the risk of the cylinder and pump overheating has been eliminated and the machine has been made simpler. On the other hand, the cooling cannot be as effective and steady, especially in hot weather and in larger engines.

P. M. S. motors, manufactured by Oulun Rautateollisuus Oy., have naturally spread mainly in Northern Finland depending on the manufacturing location and climatic conditions. Motors are manufactured in two sizes, 6 and 9 hp, both portable. As in most other Finnish motors, this one also had some small errors and irregularities in manufacture initially, but most of these have likely been corrected.

[Figure 4. P. S. M. 19]

== 4. English Petter Motors ==
Before the war, English Petter motors were sold in large quantities also in Finland, and it must be admitted that few motors have been made with such extreme precision and of such selected materials. Excellent operating reliability and long life have always been reliable characteristics of these motors. But this is not surprising. Although Petter factory production has decreased since the war, annual production is nonetheless 50,000 motors. Such mass production makes the use of all conceivable technical equipment possible.

Previously, Petters Limited manufactured both four- and two-stroke motors, but from 1915 it completely discontinued four-stroke motor manufacturing and now manufactures exclusively two-stroke system motors of two models, brands S. and M.

The Petter motor, model S, is a hot-tube ignition-operated crude oil or petroleum motor, sturdily constructed and essentially similar to the B. M. W. The bearings are extremely generous in size. Ball bearings are not used, as is generally the case in English machines. The main bearings are equipped with ring oiling, the crankpin and connecting rod pin and piston with splash lubrication. Excess oil runs into the crankcase, from which air pressure forces it through a screen into the oil tank. Thus, no oil is wasted. The lubricator is fully automatic, operated by the pressurized air in the crankcase, so it requires no adjustment when starting or stopping the motor. In newer engines, three-way cocks can be used to check the operation of each oil feeder. The governor regulates fuel consumption according to load. The motor speed can be easily changed during operation. Air is drawn into the motor crankcase through the base, so it can be obtained cleaner than directly from the motor side.

A special feature of Petter motors is cold starting. In hot-tube ignition motors, engine starting is relatively difficult. The ball must be heated 15–20 minutes with a lamp before starting. Petter's cold starting device, which received the highest award from the English Agricultural Society last year, makes it possible to start the engine in half a minute. This is done as follows:

The pipe in the motor's ball is unscrewed, a charge of special substance is inserted, ignited with a match, and the pipe is screwed back into the ball. After this, the motor is started in the usual way. The entire procedure takes about half a minute. The required substance is inexpensive. Starting is further aided by a valve that can reduce compression.

Petter motors run without any adjustment, either loaded or unloaded.

[Figure 5. 5 HP Petter Motor]

[Figure 6. Cross-section of Petter Motor]

Four-stroke motors are also manufactured in our country in considerable quantities. Of these, at least in this writer's opinion, the most notable in quality, if not yet in production volume, is:

== 5. Olympia Motor ==
Olympia is manufactured by Ab. Finska Motorfabriken in Vaasa. Practical men generally give Olympia such a review that hardly any complaints ever come from it, and that it should therefore be considered one of the most reliable Finnish motors in use.

Olympia runs on petroleum and is equipped with electrical ignition, of vertical design. The cylinder is L-shaped. The crankcase and cylinder are cast as separate pieces, and the crankcase is closed for lubrication purposes, as the main and crankpin bearings receive oil through splash lubrication. The main bearings are white metal bearings.

The motor has dual electrical ignition, which thus increases its operating reliability. It has, namely, first the usual battery ignition and, in addition, a Bosch high-voltage magneto; both have their own spark plugs. The carburetor is of Schebler design and the intake air can be taken as needed either cold or heated through the exhaust pipe.

The governor is located in the flywheel, as is common in American agricultural motors. The governor acts through lever arms on a butterfly valve in the gas intake pipe, which increases or decreases the amount of gas the cylinder receives.

[Figure 7. Olympia Motor]

The four-stroke motor operates as follows.

The piston moves from its highest position downward, creating a vacuum in the cylinder that draws the gas mixture into the cylinder (first stroke). When the piston turns to move upward again, the gas mixture is compressed (compressed), with both intake and exhaust valves closed (second stroke). When the piston has reached near its highest position, the gas mixture is ignited. The force of the explosion forces the piston to descend (third stroke, power stroke). When the piston has passed its lowest position, the exhaust valve opens and the burned gas escapes as the piston moves upward, after which the same process repeats.

Olympia agricultural motors are manufactured in two different sizes, 9–10 hp and 4–5 hp. Engine speeds are quite high at 550 and 750 revolutions per minute. Fuel consumption is normal. Starting is quick and maintenance is easy.

Olympia motors have gained a foothold in many foreign countries as well. As an interesting note, they have even been exported to the Congo.

== 6. Vickström Motor ==
This motor, manufactured by Bröderne Vickströms Motorfabrik in Vaasa, resembles Olympia in construction quite greatly, of which it is actually the "older brother." The motor's speed is high and the piston mean speed is also very high.

[Figure 8. Vickström Motor]

== 7. Tikka Motors ==
Tikka motors manufactured by Tikkakosken Rauta- ja Puuteollisuus Oy are four-stroke, petroleum-burning, vertical motors equipped with both electrical and hot-tube ignition. They have been manufactured in two sizes, 9 and 11 hp.

[Figure 9. 11 HP Tikka Motor]

In these motors, the cylinder is L-shaped, and its cover is removable. The main bearings are ball bearings. Lubrication is by splash. The carburetor is of the factory's own manufacture, extremely simple. The ignition is combined hot-tube and electrical ignition. The latter is used until the ignition ball heats sufficiently, after which only this can be used. The capsule governor is connected to the camshaft.

Fuel consumption in these machines is high.

== 8. Sirkka Motor ==
Tykö Bruks Ab. has for several years manufactured a small 4–5 hp, petroleum-burning, magneto-ignition-equipped vertical motor called Sirkka. More recently, the factory has also manufactured a larger 8–10 hp Sirkka motor.

In structure, Sirkka differs from the aforementioned first in that the cylinder and crankcase are one piece, and rest on a wooden base on cast iron flanges on the side of the crankcase. The cylinder cover is removable and water-cooled. The motor uses splash lubrication system.

The intake air is heated by exhaust gases. The main bearings are bronze bearings. The crankpin bearing is a bronze-white metal bearing. The governor is in the flywheel. Moving parts are encapsulated.

Fuel consumption is quite high. Engine speed is relatively high, 670 times per minute in 4–5 hp machines. The piston mean speed is, however, moderate. Especially the newer model Sirkka motors can be considered fully good agricultural motors.

The same manufacturer previously manufactured an 8 hp two-stroke crude oil motor called Talous, which is generally of the same construction as other aforementioned vertical two-stroke motors.

[Figure 10. Sirkka Motor, 4–5 HP]

== 9. Alligator Motors ==
As an example of American-style agricultural motors, we can mention the motor manufactured by Alex. Sjöholm's machine shop, to which some dealer has given the name Alligator. These are manufactured in 6–7, 10–12, and 13–14 hp.

It is a horizontal, four-stroke, electrical ignition-operated petroleum-gasoline motor. The carburetor is American-made Schebler. The magneto is Mars. Bearings are lubricated with vaseline. Maintenance is easy, as in a horizontal engine all parts are well visible. Petroleum consumption is low. The motors run slowly and reliably. The cylinder is surrounded from above by an open water jacket, into which more water is added as it evaporates. The motor is therefore better suited for outdoor use than for use in a closed room.

If the machine were to be used extensively in a closed room, it would need to be equipped with additional devices to prevent water vapor formation.

[Figure 11. 6–7 HP Alligator Motor]

== 10. Waterloo Motor ==
is essentially of the same construction as the Alligator. In addition to the aforementioned, many different types and brands of agricultural motors have been built in small machine shops in Finland, mostly as experiments.

= Comparison of Two- and Four-Stroke Systems =
Which is more advantageous, the four- or two-stroke system in ordinary agricultural motors, is a question to which it may not be good to give a direct answer. Both have their advantages and disadvantages.

Two-stroke motors, in which combustion occurs with each piston stroke, are much smaller in size and therefore cheaper than equally powerful four-stroke motors, in which combustion occurs only on every other stroke. Similarly, in two-stroke motors, valves and their control mechanisms are eliminated, so the machine becomes not only cheaper but also simpler. In most of the two-stroke motors in practical use here, crude oil can be used as fuel, which at least before the war came considerably cheaper than petroleum, and fuel consumption is also lower. The hot-tube ignition used in them is very understandable for the ordinary layman, and any faults are more easily corrected than when electrical ignition is used.

On the other hand, the cylinder of a two-stroke motor never becomes as clean of exhaust gases as is the case in the four-stroke motor, and therefore the former never develops twice the power of an equally sized four-stroke motor operating at the same pressure and speed. The crankcase of a two-stroke motor must be tight, otherwise the motor will not run. So if, for example, ordinary bearings wear loose, the motor may start running poorly because the necessary compression cannot be achieved in the crankcase. The disadvantage of hot-tube ignition is its fire hazard, that starting takes about 20 minutes, and that an inexperienced person easily overheats the ball, causing it to burst.