STUDYING THE RELIABILITY OF HYDRAULIC SYSTEM ELEMENTS OF GRAIN COMBINE HARVESTERS

Abstract

The article presents the results of scientific research on the main reasons for failure of KN 50.16.U1 pressure valve plunger and ways to restore it. The mechanism is used in the main hydraulic systems of “Nyva-effect”, “Don-680” “Don-680M”brands of grain combine harvesters, and also grain combine har-vesters of “Don”, “Vector” and “Acros” series. The chosen topic is relevant because in most cases, the con-sequence of the failure of KN 50.16.U1 is a complete failure of the main hydraulic system, or partial failure of its components with a significant operation slowdown of the of the hydraulic system cylinders. Moreover, an emergency case is the valve plunger seizing in the intermediate position. This case is usually accompa-nied by ruptures of high-pressure pipelines, ruptures or failure due to the formation of internal leaks of gear pumps such as NSh-32, NSh-28. Even being able to operate, but technologically incorrectly adjusted KN 50.16.U1 valve leads to accelerated wear of other elements of the combine main hydraulic system: gear pumps, sectional electrohydraulic distributors. During the study, the following methods were used: organo-leptic, direct measurement of absolute linear values, mathematical methods of processing the results of ex-perimental studies. According to the results of measuring the absolute dimensions of the diameter of the cy-lindrical part of KN 50.16.U1 pressure valve plunger in the zone of intensive wear, it was found that: 25 % of plungers in KN 50.16.U1 pressure valves need to be restored due to mechanical wear; about 20 % of plungers in KN 50.16.U1 pressure valves have traces of corrosion chemical wear; about 10 % of the studied samples have traces of both mechanical and corrosion wear. Thus, the repair of most of the investigated valves – about 55%, requires not only the replacement of rubber and plastic seals and rings, but also gal-vanic restoration of the working surfaces of KN 50.16.U1 valve plunger with subsequent grinding and pol-ishing of the working cylindrical surface to nominal size.