Four-Stroke Or Two-Stroke Trimmer. What To Choose?

Trimmer is a grass mowing tool, performing work due to engine rotation. The trimmer’s task is to mow quickly, regardless of where to put the cut grass.


In the 60-70s of the 20th century, such giants as Huskvarna and Stihl made auxiliary equipment for the loggers. a prototype of the current trimmer. with which they cleared the area around the tree for felling. These trimmers (now they are called brush cutters) were very heavy but effective.
And at about the same time, on the other side of the world, George Bollas lived in the USA. a bourgeois huckster who was sorry to pay cheap labor for some grandmothers because he climbs on his knees and scissors he shears grass and. I attached two pieces of fishing line to a tin can, and the bank itself to some crap, after which he did many hours of work in a few minutes, thereby taking away the action from a dull workforce, and even cut the dough for it.
It is essentially the whole story, since later the usual engineering work began, connecting one solution with another and adjusting it to various user tasks, but still, the pioneers can be called Stihl and Husqvarna.

Principle of operation.

The principle of operation of all trimmers one: cutting tool. Moving at high speed collides with the grass. Due to the high impact energy that is transmitted during contact, the grass body breaks. The impact force is directly proportional to the speed and weight of the cutting tool, and inversely proportional to the contact area.
Put, the line/disc grooves through the grass with such force that it scatters. The faster the engine is spinning, the better it is hammering. However, the number of revolutions of the engine idling plays a minimal role, as the revolutions fall during operation. (see section Trimmer Power)
Also, a lot depends on the geometry of the cutting tool. However, the principle of operation remains the same.

Trim design.

Upper or lower motor.

The simplest design, of course, is the trimmer design with the lower engine, since after the engine there are practically no additional parts for transmitting torque to the coil. It is much cheaper, but it has its drawbacks:

  • The engine is located on a long lever that increases the force exerted by the engine up to about ten times.
  • Based on the first minus, the trimmers with the lower engine do not put powerful (read heavy) engines, so they can only mow the thin grass
  • The lower engine works as a vacuum cleaner, sucking up a lot of dust from the ground, which clogs the cooling channels, so it overheats and turns off / burns.

Two stroke or four-stroke engine?

The technology of the engine is not significant since at the end the operator, in any case, receives the same thing. If you do not take into account the maintenance, the only difference will be only in the noise of the trimmer. the four-stroke noise is less, which can be useful when mowing in places where nervous people live, there are no other advantages. The disadvantages of four-stroke engines include the high price and more complicated maintenance, especially the adjustment of valves.

The bogus advantages of four-stroke trimmers.

  • In the four-stroke trimmer it is impossible to make a mistake in preparing the fuel mixture. Yes, it is not possible, but this is not an advantage since a person who cannot pour the required amount of oil into a gasoline bottle will not be able to pour the necessary amount of oil into the crankcase. Also, in the case of a 2-T engine, there is no risk of forgetting to change the oil, but in 4-stroke engines there is.
  • Four-stroke trimmer easier to maintain in general, judging by the number of operations that need to be done, 4-T engines require more operations, so this statement is generally the opposite.
  • The four-stroke trimmer does not need to be cleaned of soot from oil Yes, this is true, but this is not an advantage, because now for 2-T engines there are excellent oils that burn almost completely and do not leave carbon, and in 4-T engines, if the oil gets into the cylinder, then it is very bad there burns, as resources are not invested in it (this is clear from the purpose of the oil)
  • The four-stroke trimmer eats less fuel from burning the same amount of gasoline you can extract the same amount of energy (read power)
  • Four-stroke trimmer weighs less it all depends on the power
  • The four-stroke trimmer turns faster generally nonsense
  • Four-stroke trimmer vibrates less depends on balancing