Abstract. In this paper are presented the power losses and sources of their occurrence in worm gear reducer. These are the losses that occur in the coupling of worm teeth and worm gear, losses in bearings, seals and oil churning power losses in the transmission. Power losses are determined for the actual model of worm gear reducer, on the specialized testing device AT200 at the Center for testing power transmission at the Faculty of Engineering in Kragujevac, Serbia. The total losses are determined for different values of input number of revolution, output torque and by variation of types of oil, according to the pre-defined experiment plan. The aim of the paper is an experimental proof of theoretical assumptions of the influence of various factors on losses in the worm gear reducer.
IntroductionThe transfer of mechanical energy (Figure 1) from the drive to the working machine is achieved by means of transmission shafts, couplings and gearboxes. In contrast to transmission shafts and couplings, gears can carry out transformations of the speed, torque, and sometimes direction of rotation [1].The gearboxes transmit the movement and torque from one shaft to the other by means of a link made by a toothed gear. During this transfer, there is a certain transformation of the number of rpm and torque. The gear pairs are the simplest form of a gear boxes composed of two gears. One gear is drive, while other is driven. The drive gear transmits movement and torque to the driven. The gears forming a pair of gears are called coupled gears [2].
This paper deals with the analysis of impact of various factors on power loss and efficiency of worm gearing. Factors that significantly affect the power losses are, principally, types of materials of meshed gears and geometry of worm pair, type and viscosity of lubricating oils, input rotational speed, worm shape, loading, temperature, etc. Results of experimental tests of worm gearing efficiency are also presented in the paper. Tests were conducted according to planned experiment schedule on specialized device AT200, where single-stage worm gearboxes with transmission ratio i=18 has been used. During the test stage, oils of different viscosities (ISOVG 220, ISOVG 460 and ISOVG 680) have been used and their impact on efficiency was monitored. The values of efficiency level are determined at different input rotational speeds (circumferential velocity) and output torques (loads).
ARTICLE HISTORY
Demands of today’s automotive industry are increasing; there is a constant tendency of weight reduction and higher reliability of constructions. Pistons and piston liners for vehicles are mostly manufactured from aluminum-silicon alloys. With different manufacturing methods and/or the addition of some chemical elements, base alloy properties can be modified. Methods for hypereutectic aluminum alloys and composites manufacturing and their influence on material properties will be given in this paper. The influence of Si percentage in base alloy and how an addition of some chemical elements affects the properties of these materials will be observed as well.
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