Gear pneumatic motors belong to volumetric type motors. The working chambers are the hollows, and the pistons are the teeth of the mating rotors. The troughs and teeth have complex shapes and participate in complex planar reciprocal motions, making it difficult to understand the working processes of these engines.

Three-link screw mechanisms converting translational motion into rotational motion are widespread due to their compact design. They are used in pneumatic drilling hammers and perforators, the annual production of which for mining and construction industry only in our country counts' hundreds of thousands of units. Development of the national economy puts forward the tasks of increasing the productivity of this equipment and increasing the efficiency of mechanisms perforators.