The paper presents the construction of a device designed for cross-cutting of conveyor belts. The device is equipped, among others, with a pneumatic drive in the form of a double acting piston rod. This actuator ensures reciprocating movement of the circular blade mounted on a non-rotating axis. The axle is built into the frame guided by a trolley-rail assembly. The paper also presents the results of the pressure changes in the working chambers of the actuator as a function of displacement, recorded during the working movement of the knife carried out during the cutting process. The purpose of the tests was to evaluate the pressure level in the cylinder chambers during the cutting of belts of various constructions. These values were converted into cutting force values. It is relevant for the evaluation of changes in the value of cutting force of belts characterized by a different internal structure (composite belts made of different materials) and total thickness.