Farmall RegularIn the past, gasoline engines of varying sizes were started with cranks. The cranks were usually connected to the end of the crankshaft; however, on some machines they were connected to the crankshaft, flywheel or camshaft through a series of gears which reduced the effort required to turn over the engine.

Starting an antique tractor with a crank was an acquired skill. It was considered to be a rite of passage in some farm families. If night-time temperatures dipped to below freezing, it was necessary to carry warm water from the house and fill the radiator. Then, it was time to check the level of the oil in the crankcase and top it off, if necessary. The next step was to remove the caps from the smaller rear tank containing gasoline and the larger front tank containing tractor fuel (aka distillate) and either peer in or insert a stick to determine if there was sufficient fuel in each; if not, then the operator had to obtain some from storage tanks, lifting the cans to head level or above to pour the fuel in the tanks and using a funnel to reduce spillage. Following that, it was important to verify that the transmission was in neutral, so that the tractor didn't run over the operator when the engine started. This could be especially unpleasant if the tractor had steel wheels with lugs. The following steps were to advance the throttle, pull open the choke lever or rod, retard the spark to reduce the likelihood of a backfire, and turn the fuel valve to the position which allowed gasoline to flow to the carburetor. Then, the engine was turned over slowly to position one or more pistons on the compression stroke. Next, the handle of the crank was placed in its lowest position, so that the operator could pull it up to start the engine--not push it away. When grasping the handle, it was important to hold the thumb alongside the fingers--not over the handle. These last two steps were taken so that the crank would fly free if the engine backfired; otherwise, the operator ran the risk of broken bones--or worse. As soon as the engine started, it was necessary to immediately retract the crank or it spun and became a menace to the operator. If the crank was permanently attached to the tractor, this limited the danger; however, if the crank was loose, it could fly off in any direction and maim or kill the operator or a bystander. Cranks on the earliest machines had to be retracted manually; those on later machines were either retracted by a spring or designed in such a way that the crank automatically retracted as soon as the engine started. With the transmission in neutral, the throttle advanced somewhat, the choke opened, the spark retarded and the crank in its lowest position, the crank was given a quick and forceful upward tug, while simultaneously the operator stepped backwards out of the immediate danger zone.  When the engine was running, it was time to close the choke lever or rod, adjust the throttle, and advance the spark. When the engine had warmed up, the fuel valve was turned to the position which allowed tractor fuel to flow to the carburetor. Finally, the operator was able to climb aboard,  select a gear and get to work.

When starting an antique tractor with a hand crank, it was necessary to turn over the engine fast enough to enable the magneto to produce a hot spark. Slow rotation resulted in low voltage. Some tractors were equipped with an impulse coupler to assist with starting. An impulse coupler enabled the magneto to produce a hot spark equivalent to that produced when the engine was rotating at 600 to 800 rpm, when in actuality the engine was being turned over slowly with a hand crank. The impulse coupler also retarded the spark slightly to reduce the possibility of a backfire, which caused the crank to rotate at high speed in the opposite direction and was very dangerous for the operator. On some tractors, the operator was required to flip a lever to activate the impulse coupler.

Small engines may be started with a starter rope wound manually around a pulley on the crankshaft. In modern engines, the starter rope is attached to a mechanism which utilizes a coiled spring to rewind the rope when the handle is released. This system is common in lawnmowers, chainsaws, etc., produced by manufacturers such as Briggs & Stratton, Tucumseh, and Honda. A few small European automobiles have also incorporated this system in the past.

MotorcycleSmall engines such as the Maytag washing-machine engine and those on motorscooters and some motorcycles, may be started with a foot pedal.

The electric starter motor was first used in an English automobile in 1896. Charles F. Kettering and Henry M. Leland patented the electric starter motor in the United States in 1911. Cadillac introduced starter motors in its cars in 1912 and by 1920, most automobiles either were issued with starters as standard equipment or they were available as options. Case tractors had starter motors as early as 1936 and by 1939, starter motors were either standard equipment or options on most farm tractors.

Although electric starter motors became standard on automobiles during the late 1920's and early 1930's and on farm tractors during the 1930's, most retained provisions for cranks into the 1940's.

In older gasoline automobiles, when an electric starter motor is activated, inertia causes a pinion gear to slide out on the motor's armature shaft, engage the ring gear on the flywheel and turn over the engine. This Bendix system is found on most older cars. Once the engine starts, the greater speed of the engine causes the flywheel to override the speed of the starter motor and the pinion gear disengages from the flywheel. In 1967, the Chrysler Corporation introduced an improved system in which the starter motor engages a series of reduction gears which, in turn, engage the ring gear. The reduction gears increase the torque of the starter motor and permit the use of a smaller, lighter and less-expensive starter motor. When the engine turns over, a magneto, a generator or an alternator produces a spark to ignite the fuel and start the engine.

In diesel engines in automobiles and tractors, in similar fashion to gasoline engines, an electric starter motor is activated, causing a pinion gar to engage the ring gear on the flywheel and turn over the engine. When a diesel engine turns over, the fuel in the combustion chamber is compressed to the point where it ignites and the engine starts. In direct-injection engines, the fuel is injected directly into the combustion chamber; in indirect-injection engines, the fuel is injected into a small prechamber next to the combustion chamber. 

Diesel engines have been notoriously hard to start--especially in cold weather--and a wide variety of methods have been used to get them running. Glow plugs are often used to preheat the combustion chamber to facilitate the process. In the past, common techniques have included starting the engine on gasoline and then switching over to diesel fuel or soaking a rag in diesel fuel, setting it on fire and sticking the burning rag into the air intake while the engine is turned over. The Perkins P4 diesel engine used in an early Land Rover and other vehicles incorporated the Ki-Gas system in which kerosene was sprayed onto a hot glow-plug in the intake manifold. George Jendrassick, a Hungarian, patented a system in which diesel fuel was suddenly injected into the combustion chamber. The sudden release of the fuel increased its temperature by as much as 300 degrees and assisted starting.

AutomobileMany diesel engines--antique and modern--have a manual or automatic system to relieve some of the pressure in the combustion chamber and reduce the effort required to turn over and start the engine. This system is also used in some high-compression gasoline engines.

If a stationary engine doesn't start, it can be belted to a different engine. If the engine is mounted in a vehicle, the vehicle can be pulled by a different vehicle. Vehicles with automatic transmissions or those with alternators can't be started by pulling.

In the case of most models in the John Deere Letter Series of farm tractors, the operator may simply rotate the flywheel manually to start the engine. In other models, the operator has the option of removing the steering wheel, holding it against a special receiver on the end of the crankshaft on the outside of the flywheel, and rotating it to start the engine. When the engine starts, the steering wheel is then returned to the end of the steering shaft.

On some antique stationary engines, a handle may be permanently mounted on the flywheel for use when cranking the engine. To reduce the likelihood of injury to the operator, this handle is usually hinged so that once the engine starts, inertia causes it to automatically retract into a recess in the flywheel.

When gasoline engines are reluctant to start, a small amount of fuel may be poured into the sparkplug hole or the throat of the carburetor to ignite immediately when the starter is activated. A more volatile substance such as diethyl either may be used; although, if overdone, this can cause damage to the engine and/or injury to the operator. Some early automobiles had Prestolite tanks which transported acetylene under pressure through regulators and piping to their intake manifolds. Other automobiles had small onboard generators which produced acetylene for starting and for lights.

In a large engine with so much compression that it is difficult to turn over, a small one or two cylinder engine (pony engine) is linked mechanically to the large engine, with a clutch between the two. The small engine is started and when it is running up to speed, the clutch is activated and either a friction mechanism or a pinion gear engages the flywheel of the large engine and causes it to turn over and start.

Waterloo BoyWhen an engine is designed to run on an inexpensive fuel such as kerosene or crude oil, which doesn't ignite readily at an ambient temperature, the engine may be started with a more volatile fuel such as benzine or gasoline and then switched over to the inexpensive fuel after the engine has reached operating temperature. Some early tractors were started on kerosene and then switched over to crude oil. Likewise, some diesel engines were designed to start on gasoline and then be switched over to diesel fuel. 

Some antique tractors had a mechanism in which a clockwork-type spring was coiled manually by means of a crank or lever and then released to turn over the engine. A lever was used to press a small, rotating wheel against the rim of the flywheel. A similar aftermarket device was available for Model T Ford automobiles.

A small engine may be connected to an air compressor which builds up pressure in a tank. When sufficient pressure is built up, a valve is opened and the air enters the cylinder of a larger engine and turns it over, causing it to start. In a different system, the compressed air activates a starter motor, which then starts the larger engine. In an interesting variation, an antique two-cylinder Avance tractor (Sweden) simply had an air tank. After the air was used to start the engine, one cylinder continued to run while the other was isolated and used to compress air and replenish the air in the tank. In an early design by H.P. Holt, a reservoir was filled with exhaust gases under pressure, which later was used to start the engine.

In some antique diesel engines, an uninsulated iron bulb extends horizontrally from the cylinder head. Cotton waste soaked in oil is placed in a small iron tray beneath the bulb. When this is ignited and left to burn, it heats up the iron bulb to the point where when fuel is injected into the cylinder, the hot bulb ignites the fuel and causes the engine to turn over and start. In large engines of this type, a long lever may be used to rotate the flywheel and place a piston in the combustion (power) stroke position, ready to start. In later hot-bulb engines, a torch (blowtorch) is used to heat the bulb. 

In some antique tractors, a blank shotgun shell is inserted into a receiver in the head. When a firing pin is struck, the explosion causes the engine to turn over and start.

In a few antique tractors, igniter papers are clipped to the end of a spark igniter, which is inserted into the top of a horizontally-operating cylinder head. Striking the firing pin at the base of the device causes the papers to catch fire and ignite the fuel. An example is the Field Marshall Mark 1 tractor.

Traction EngineSteam-driven stationary engines or traction engines are started using the general procedure. After verification that there is a proper amount of water in the boiler, a solid fuel such as wood, coal, straw, etc. is inserted into the firebox and ignited. A period of time ensues during which the water heats up to the boiling point and steam builds pressure in the boiler. When a sufficient "head" of steam is achieved, a valve is opened to release steam to the cylinder and operate the engine. Steam engines may be single-action or double-action. In a single-action engine, a valve admits steam to one side of the piston. In a double-action engine, a sliding valve injects steam alternately to both sides of the piston. A modern steam engine may use a petroleum product or solar energy to heat water and create steam which drives a piston engine or a turbine. 

Propeller-driven, piston-powered aircraft have employed a variety of starting methods. The oldest method--still used with some small planes--is to swing the propeller by hand. In planes with larger engines, a crank may be connected to the engine through a gear-reduction system to reduce the effort needed to turn over the engine. In an inertia starter system, a hand crank or an electric motor is used to rotate a flywheel; when the flywheel is up to speed, a clutch is engaged to turn over the engine. A crank or lever may also be used to wind up a spring, which then is released to turn over the engine. Modern airplanes normally have electric motors which turn over the engines to start them.

Some older aircraft use explosive cartridges to rotate the engine. The B-52 is an example of such an airplane. 

An auxiliary power unit (APU) may be installed in an airplane or on a mobile device (start cart) moved next to the airplane at an airport. Depending on the design of the aircraft, this device may export compressed air, a gas under pressure or electricity to power a starting motor. Some helicopters utilize a geared hydraulic motor on a mobile device (start cart) to engage a mechanism on the aircraft and start the engine. 

If an engine turning a propeller stops during flight, the airplane may be placed into a steep dive to build up speed and cause the propeller to "windmill" fast enough to restart the engine. 

Interestingly, during wartime, engines on large airplanes have been started with ropes. On a multi-engine aircraft, a rope may be wound around the propeller dome of one engine and then extended over to and wound around the propeller dome of a second, adjoining engine. The "live" engine is then turned over with its magnetos turned off. An engine on a DC-3 has been started in a somewhat similar fashion by winding the rope around the engine dome and then attaching it to a pickup truck. This method is also said to be successful if the rope is pulled vigorously by "two snowmobiles or five men and three little boys."

BomberAttempts have been made to start an engine by moving a second aircraft in front of the first and using the backdraft to spin the propeller of an engine on the rear airplane; this has seldom, if ever, proved successful. Likewise, attempts to start an engine on a multi-engined plane by taxiing fast enough down a runway to make the propeller "windmill" and start the engine have usually met with catastrophic failure.

In aircraft with jet engines (normally turbojet or turbofan), a variety of auxiliary power units (APU's) are used to start the engines. Isopropyl nitrate may be injected into the engine and then ignited to rotate the fan and start the engine. Compressed air may be injected into a small starter motor which spins the fan and starts the engine, or a compressed air system may power a generator which produces electricity to run a starter motor. An onboard, ram-air-drive turbine engine may be coupled to an electrical generator which, in turn, is coupled to an electric starter motor. The ram-air-drive turbine may be replaced by a fuel-cell or battery to power an electric starter motor.

Boat and ship engines are started using the same systems as those in land-based vehicles. Engines may be inboard or outboard and they may be fueled by gasoline, diesel fuel or electricity. Likewise, they may be piston-powered or incorporate turbines, jet engines, electric motors or hydraulic motors. Accessories such as bilge pumps, generators and ventilating systems add to the complexity of their design and operation. Diesel engines on large ships may be started by having compressed air admitted to their combustion chambers through separate, dedicated valves.