Open AccessThe paper proposes a technique for accelerated life benchmark tests of tractor friction clutches, imitating real mode loading. A loading diagram of a tractor unit, constructed by this technique, is common for all friction clutches of a given class and purpose. However, specific clutch loading is determined not only by a loading diagram, but by the design parameters of a friction unit as well (geometric dimensions, a value of the reserve coefficient and a moment of inertia Je of the engine shaft, terms of heat sink, the number of friction pairs, an irregularity of their loading, etc.). Therefore, when assessing a durability of friction pairs of clutch, a loading diagram of tractor is reconstructed into the loading diagram of a particular friction clutch. At life benchmark tests a loading mode is close to the operating mode, and a convenience of the experiment is provided by logging load levels and by using the minimum number of bench changeovers. Thus, each specific clutch, in a common diagram of operating loads of the tractor, will meet an individual loading diagram that determines its durability. The paper presents the model loading diagrams for three types of tractors and clutches, used in their transmissions.
Conclusions: The proposed technique for accelerated life benchmark tests of clutches is based on the principle of simulating a mode of loading to be equivalent to that of the operating mode. Thus, benchmark test acceleration is achieved by increasing the cyclic of clutching in comparison with an operating mode. Using the proposed technique allows 6 ... 10 times benchmark test acceleration as compared to the operating one, depending on the design, code of friction material and loading conditions under operation. Good convergence (error of 11% at most) of the results at bench and field tests allows us to recommend the proposed technique to evaluate a resource of tractor clutches.