A revolutionary new take at an old problem

LESS is a patented innovative mechanism that converts rotary to reciprocating motion and vice versa.

It is a replacement for the traditional crankshaft mechanism, which is found everywhere around us.

From Internal Combustion Engines, to Pumps, Compressors, and Expanders, the LESS Mechanism offers a host of unique advantages, depending on the application.

How it works

Basis of operation

The most basic LESS mechanism consists of two ring-like components that slide on top of each other. Using certain mathematical properties and the right configuration, the components can be arranged so that when one part rotates, the other one has to reciprocate and vice versa.

The kinematic connection between reciprocating and rotating motion can be completely sinusoidal, resulting in a smooth and natural movement. It can also follow a polynomial equation, or a variety of different functions, depending on the application’s requirements.

Here is an example of the basis of operation in a planar fashion, as well as a setup with two ring-like components.

Full Reciprocation

The example above is the most basic version of our mechanism, but it requires the existence of some force to keep the individual components in contact. A more complete mechanism uses an additional component to do that in a completely self-contained fashion.

This mechanism comprises of two symmetric annular undulated stators (red items in the next figure) and an annular undulated rotor (white item). The upper and lower undulated surfaces of the rotor are symmetric to those of the stators respectively. The rotor slides on both stators simultaneously, with every point of the rotor conducting a smooth undulated move.

As you can see in the animations below, when the middle component rotates relative to the edge components, it also has to reciprocate. Note that motion is relative between the white and red components. If we look at it from an external static reference point, we can have a rotating and reciprocating moving middle part (white) as seen on the left, or we can have rotating edge parts (red) and a reciprocating middle part (white) as seen on the right.

LESS is more


LESS can be used in a variety of Internal Combustion Engines where it can replace the traditional crankshaft mechanism to convert the reciprocating motion of the piston to rotary motion in the main axle.

LESS can also work conversely and turn rotary movement to reciprocal, and it can be used in several types of piston Pumps & Compressors.

It can either replace the crankshaft that drives the piston, or it can use the area between the individual LESS components as the chamber, with the working liquid being compressed in-between the moving parts.

Overall, our design has LESS:

  • size, weight, and mass
  • components & maintenance
  • material & manufacturing costs
  • vibrations & noise
  • power losses
  • fuel consumption & emissions (ICEs)

Unique Advantages

In most cases, the LESS mechanism itself is smaller in size than the crankshaft mechanism. It also has a unique advantage in that the kinematics of the movement can be set to fit the particular purpose. More info on that can be found in the Kinematics section.

What’s more, the LESS mechanism can be balanced by connecting two units directly opposing each other, similar to the Boxer style engines. Unlike the Boxer engines, the two units are coaxial and can be completely balanced.

Whether it’s used in an ICE, Pump, or Compressor, this provides a unique advantage in terms of vibrations, fatigue, and noise.

Another unique feature of the mechanism compared to the traditional crankshaft design is that it makes more than 1 reciprocation per rotation (compared to 1 reciprocation per rotation in the case of the crankshaft). The default design has two valleys and peaks in each component, and it is easy to see from the animations that this results in 2 full reciprocations per rotation. The design can change to 3, 4, or any number of valleys and peaks which would result in the same number of reciprocations per rotation.

Performance and Efficiency

The LESS mechanism has fewer moving parts, therefore it has less mechanical wear and tear, and maintenance costs. And thanks to the hydrodynamic lubrication of the sliding surfaces, it has minimal friction and wear.

It has no side forces on the piston, eliminating friction between the piston and the cylinder wall, rocking movement & clanking noise, and produces better sealing. On top of that, using a sinusoidal and fully symmetrical design of the undulated surfaces, the piston makes a smooth, fully harmonic movement.

Last but not least, in the case of Internal Combustion Engines, we can introduce a delay at the Top-Dead-Center of the piston and create an isovolumetric combustion. That increases power and efficiency and decreases pollutants and by-products of incomplete combustion.

Application-specific advantages

You can find a detailed description of all the advantages and a more in-depth analysis of the mechanism for each particular application on the dedicated page.

Target Markets

With its unique advantages, the LESS mechanism has extreme potential in many aplications and markets. For example:

  • In motorbikes & marine applications, where it can replace 2-stroke engines with a 4-stroke of similar size without consuming oil & polluting.
  • In handheld power tools such as chainsaws, lawnmowers, etc, reducing both the cost and weight.
  • In light & ultralight aircraft and UAVs. In all aircraft that use reciprocating ICEs, it significantly redudes the weight and increases the efficiency of the aircraft.
  • In industrial pumps and compressors, increasing efficiency and decreasing maintenance costs.
  • In professional and hobby/home use compressor units, decreasing noise and wear, and increasing efficiency.
  • In refrigerator and air conditioning compressors, decreasing noise and wear, and increasing efficiency and lifetime.

We are actively looking for collaborators and licensing partners. If you are interested, please contact us.

Current Status

Patent Application

Behind the LESS operation and benefits lie a set of mathematical properties. We have already been issued a patent in Greece by the Hellenic IPO, a patent by USPTO (#US11220907B2), a continuation patent by USPTO ( #US11414992B2), and we have filed patent extension applications in and various other countries.


As part of the work done under the grant (see below), two academic publications were created and showcased. The first one was a paper that was presented at ICE 2023, 16th International Conference on Engines & Vehicles for Sustainable Transport, and the second one was a published paper at the MPDI Energies open access journal.


We are at TRL5 stage with working prototypes both as a compressor and as a 2-cylinder, 4-stroke, gasoline-powered ICE. Our prototype already proves LESS’ size benefit with a 50% reduction in volume and a 60% reduction in weight vs a conventional engine of roughly comparable power output. We are also building a prototype of a deep well pump using our mechanism.

We recently (Aug 2020) received a €500K grant by the Greek government to further the development of our engine prototype, and create a second TRL6 prototype.

The project is co‐financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH – CREATE – INNOVATE (project code: Τ2EDK-02566).

To learn more about our current designs and get detailed information about our prototypes, please visit the Prototypes section.

Contact us

For inquiries, please contact info@less-engineering.com.

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