Relaxation and histereses of belts are two phenomena know only as terms, but experimentally quite unknown. In this paper, I have presented the results gained experimentally for relaxation and histereses of trapezoid belts. In the lab I have observed the relaxation of belt type AV10x725La in the case of acting of two forces with various intensities. In the same way, I have repeated the relaxation experiment in the same testing belt. The histereses has been researched for AV13x950La profile. The

more »

... esults gained for the relaxation and histereses have been presented in a chart and a table. 1. RELAXATION OF BELTS The transmitter's power conveyance with trapezoid belts is completed through the friction, which is created on the contact surface between the belt and the pulleys. In order to create the friction force the normal force F n must act on the contact surface. The normal force is realized through the tension of the belt with the force of installation tension-F pr. With relaxation it is understood the decrease of installation tension force by itself. Of practical importance is the determination of the value by which the force on the belt decreases by itself as well as the time during which this phenomenon occurs. The relaxation experiment has been completed in the research machine used for determining the cutting force of belts, respectively for the statistical research of trapezoid belts. The research belt relaxation has been completed according to the schema presented in figure. 1. The researched belt has been placed on the pulleys with same diameters. The top pulley is static and the bottom one is displaced from the acting of the researched force. When the value of the researched force is reached for which the relaxation phenomenon F h is analyzed, the acting of the load is stopped and the varying (decreasing) of the force is observed on the research machine. The decreasing of the force happens because of the belt relaxation. This phenomenon is called belt relaxation. Figure 1. The belt during the relaxation experiment 965