One of the mechanism and machine theory important problems is to reduce the rotation irregularity of the cyclic machines input link. A traditional way to solve this problem is to install a flywheel, but for equipment with high peak values of cyclic loads, the moment of inertia of the flywheel can take on large values, which leads to an increase of the overall dimensions and weight of the machine. In this paper, using a piston compressor as an example, the possibility of reducing input link speed fluctuations is investigated using a pair of non-circular gears, which is installed between the motor shaft and the input shaft of the cyclic mechanism and allows non-linear transmission of torque, increasing its value during the working stroke and decreasing it during the idling of the machine. The dynamics of a piston compressor is considered, and non-circular gears are synthesized based on the law of motion of the drive link. An experimental stand of a piston compressor crank-slider mechanism with non-circular gears was developed and tested. Real law of motion of the drive link was obtained, which showed a reduction in rotation irregularity from 2.45 to 1.78 with the use of non-circular gears.