If the engine in the lawnmower is out of order, and this fact is beyond doubt. it is time to change the engine to a new one. You cannot continue working until the motor is replaced. And to change the engine yourself, find out what type and type it is on this device.
Types of engines for mowers
Currently, lawnmowers with a motor are widely used. On machines of this type and class, electric and gasoline engines are used. Among the first here are synchronous and non-synchronous, collector and brushless, and even stepper motors. Among the second. two-and four-stroke.
A gasoline engine converts the internal energy of a fuel into heat, and then into mechanical. The continuous operation of the gas engine is ensured by a constant and slow supply of fuel and oil into the combustion chamber (carburetor), where they mix with air and ignite from sparks ignited by candles. The number of cylinders in a gas engine of a lawn mower is only 1. This distinguishes a lawn mower from a car where 4-8-cylinder engines are used. The fact is that one cylinder is enough to not only mow the grass, but also, for example, ride a snowmobile alone.
Lawn mowers and trimmers use a two-stroke or four-stroke engine. The second of them is the most effective, it is easy to refuel. individually, gasoline and oil are poured into different tanks. For the first, it is necessary to mix gasoline with oil and pour the resulting fuel into a common tank. A two-stroke engine does not burn it to the end. a little unburned gasoline remains in the exhaust.
For gasoline engines, power is not limited to two kilowatts. If you convert the horsepower of the most powerful lawn mower to kilowatts, then the power will increase to 5 or more kilowatts. A gas engine can work for an hour or more without problems, without stopping for a break. Noise is also paid for increased power. not 30-45 decibels, but 55-80.
For a long mowing on gasoline you need headphones that drown out the roar of the engine.
Features of electric motors
An electric motor converts electrical energy into mechanical energy, producing torque. Through the gearbox, this kinetic energy is transmitted to the knives or drum with fishing line (or cord), which cuts the grass.
The motor itself is economical. It is not necessary to choose whether to burn gasoline, a liter of which for 2019 is approaching 50 rubles, or for the same money to consume 10-15 kilowatts. And the price of an electric motor equivalent to the same 5 “horses” is much lower. The electric motor can operate from a wall outlet and from a battery. It is ideal for owners of small cottages with a plot of no more than a few hundred.
The electric motor must be turned off every 15-20 minutes for at least 20 minutes. this will allow it to cool. Under load from mowed grass, it heats up much faster than without it. If you ignore the breaks, then for a long time such a motor will not work. Overheating motor windings will gradually burn out.
The name of this type of motor speaks for itself, and the principle of operation is as follows: a rotating structure. the rotor. exactly falls into the vibrations of the induction field generated by the stator windings. The speed of the field coincides with the speed of the rotor.
Video: How to Mix Gasoline With Lawn Mower Oil
Power consumption of a synchronous motor is more than a kilowatt, which is explained by its complicated scheme. The rotor winding is designed for a single phase. The winding itself is powered by a direct current source, and sliding contacts. rings and brushes. are brought to it. Even with a significant load on the rotor axis, this motor does not reduce the rotor speed (number of revolutions per minute).
In lawn mowers, the engine shaft is vertical. this allows it to transmit maximum torque through a gearbox or belt drive to the working drum.
When starting, the synchronous motor does not immediately switch from asynchronous to its normal mode, but it justifies its real characteristics by 100 percent.
Vertical Shaft Asynchronous Motor
Asynchronous motor, compared with the previous view, is much simpler. The rotor is also equipped with external field windings. In general, the operation of the engine is not tied to changes in the induction field produced by the stator. Rotor speed does not coincide with the rate of change of the magnetic field.
The advantage of an asynchronous motor with a vertical shaft is the absence of a gearbox or belt drive. Knives or drum with fishing line are fixed on the axis, rigidly connected to the rotor of the engine.
- the engine itself slows down with a significant increase in load;
- its power and output are noticeably lower than that of a synchronous motor.
The speed adjustment when mowing grass in an induction motor occurs not only with the help of natural deceleration under load, but also with the help of an electronic divider that produces different supply voltages. On some models there is a smooth regulator or a switch for several positions.
This helps extend the operating time of the electric lawnmower where grass is rare and high revs are not needed.
What to choose?
For large. 20-60 acres. areas suitable lawn mower on gasoline or diesel fuel, and not on electricity. If the choice still fell on the electric mower. lawn mowers with an asynchronous engine are cheaper than similar models that have a synchronous motor. Asynchronous lawn mowers are mainly equipped with direct drive.
The most popular electric mowers of the following companies:
So, Honda engines expensive. the motor itself costs from 5 to 30 thousand rubles, depending on power. American Briggs engines&Stratton, not inferior to the engines from the same Honda, put in devices from Snapper, Ferris, Simplicity and Murray.
For example, if you change the engine on a lawnmower where an asynchronous motor with direct drive is used, check if there are any compatible models with your engine and drive. This method is good when your model is already 5 years old or more, it is discontinued. You can try to restore the old device without acquiring a new one. Self-propelled lawn mowers require more powerful engines than non-self-propelled mowers. part of the energy is spent on the fact that the lawn mower “rides” itself during operation.
Possible problems and motor replacement
For example, instead of the regular 3000 rpm, the engine gives, say, 2200, 1700. such a decrease gradually. This drawback often affects DC brush motors with almost worn brushes. The fact is that the graphite rod on the brush is slowly but surely abraded.
Finally The exposed terminal, displaced by the expanding brush spring, spoils the copper paths on the rotor. one of the ends of a winding approaches each track. The motor stalls more and more often and does not start even after complete cooling. To make the motor work properly, users change the brushes to new ones.
Buy a model of a mower with a brushless motor, the resource of which is tens and hundreds of times more.
The main causes of engine failure:
- hitting a car on an abandoned unit;
- storing the mower in a damp, dirty room or outdoors in winter, in the rain;
- untimely cleaning and lubrication of the engine and drive;
- long. more than 20 minutes. work without interruptions;
- garbage and stones on the territory, tuberosity of the soil;
- contact oxidation, brush wear and other minor motor damage.
In the service center for the repair of electrical and motor equipment, the masters will replace the motor. They will pick the exact same or compatible one from another model.
See how to choose an engine for a lawn mower.