Animation of the crankless rotors


A new efficient mechanical transmission

The cleaner and better engine for the future

Crankless is a start-up company, and a patented innovative mechanical transmission.

We propose an alternative to the widespread crankshaft transmission, replacing the crankshaft by a much simpler mechanical drive. Crank-less. And also valve-less.

Main applications are combustion engines, compressors and pumps. Advantages of the crankless technology include better power-to-weight ratio, lower production and maintenance costs, higher efficiency, lower fuel consumption and wasteful emissions. An important step towards a cleaner world.


The crankless drive is an innovative mechanical transmission that efficiently transforms a uniform rotation into a non-uniform rotation, or vice versa.

For example, the crankless drive can transform a uniform rotation of a machine axle into a non-uniform rotation at different phases of two rotors that rotate in a fixed housing.

Animation of the crankless rotors

As a result, the chamber created by the volume between two successive rotors and the fixed housing will periodically increase and decrease.

Alternatively, the same new mechanical transmission can be used to transform a non-uniform rotation of two rotors at different phases into a uniform rotation of a machine axle. The non-uniform rotation of the two rotors could be the result, for example, of the periodic volume fluctuations of a (rotating) combustion chamber of an internal combustion engine.


The technology is innovative, but practical. The base concepts are easy to understand, and implement. Please see drive technology

The crankless drive that we are promoting can be designed very flexibly. The relation between the rotation speeds of the machine axle and the rotors can be engineered according to specific requirements, as can the periodic volume fluctuations of the rotating chambers. This is illustrated on the figures below:

Please refer to drive technology for more information about its operation.

Rotation speeds in function of time for a simple implementation

Fig: Rotation speeds in function of time for simple implementation

Rotation speeds in function of time for a more sophisticated implementation

Fig: Rotation speeds in function of time for more sophisticated implementation


The crankless drive can be used in many applications. Almost any mechanical machine that uses a crankshaft transmission can be redesigned to work with the crankless drive.

Typical applications include:


The crankless drive has many advantages over a traditional crankshaft transmission.

No back and forth linear movement

A traditional crankshaft transmission transforms a back and forth linear movement into a rotation of a machine axle or vice versa. The inherent disadvantage of machines with a crankshaft is the back and forth movement of masses, with their continuous acceleration and deceleration. These inertia effects inherently result in high mechanical loads, limit revolution speeds, and induce vibrations.

It is well known, for example,that by eliminating the back and forth linear movements, the Wankel engine can achieve much higher revolution speeds with low vibrations. However, the Wankel engine suffers from other disadvantages, such as a difficult sealing of the combustion chamber. The crankless drive that we promote does not have these sealing problems, and offers the same advantages of the Wankel engine, without sealing losses.

Better geometry, simpler device

The crankless concept has 4 working chambers in one toroid. This geometry is very efficient, and has a very good power-to-weight ratio.

Our crankless design is also valveless, and therefore uses much less moving parts.

This results in a significant improvement in production and maintenance costs, as well as less vibration, quieter operation and higher revolution speeds.

Higher revolution speeds in turn lead again to a better power-to-weight ratio.

Increased efficiency

Since there are no valves, no pressure is lost during intake or exhaust. Supercharging becomes easy. And the turbulence in a rotating chamber results in excellent combustion dynamics.

All this leads to better efficiency and lower wasteful emissions.

Path to market

We are promoting the crankless technology through a program of selective licensing.

For more information, please refer to the licensing section.

Copyright © 2015 Crankless