34 J. FOR. SCI., 57, 2011 (1): 34–40 JOURNAL OF FOREST SCIENCE, 57, 2011 (1): 34–40 Energy consumption of a chipper coupled to a universal wheel skidder in the process of chipping wood J. Kováč, J. Krilek, M. Mikleš Department of Forest and Mobile Technology, Faculty of Environmental and Production Technology, Technical University in Zvolen, Zvolen, Slovakia ABSTRACT: The chipper for chips is an energy consuming machine. Many factors influence the result of chipping which influence the whole process. The paper deals with the process of wood chipping by a chipper in order to deter- mine its energy consumption. The main purpose was the determination of input power and comparison of revolution frequency on the outlet shaft of a skidder regarding the dimension of the torque depending on variable parameters which characterize the process of wood chipping during the measurement and the analysis of energy consumption of a chipping machine was carried out. Keywords: chip; chipper; chipping; energy consumption; power of cutting Chipping machines are used for the process- ing of inferior wood and wooden waste like waste from sawing which are produced by the processing of whole tree stems for assortments in the forest or main wood stocks and waste from timber produc- tion (e.g. branches, tree stumps, coniferous topwood, etc.) Output products of these machines are small particles of wood called chips. Chip production can run directly in the scrub, on the skid road and in the factory. ese are input materials for subsequent in- dustrial delimbing, e.g. in chemical industry for the production of cellulose and paper, in wood-process- ing industry for the production of chipboards and fibreboards and in power industry biomass (fuel) is used for the production of heat ( 2001). According to the purpose the chip will be used for it must have required dimensions and shape. For the production of fibreboards the fibres should be from 20 to 30mm in length and from 3 to 5 mm in width. For the production of brown coal the chips should have the length from 80 to 120 mm. e length of chips is given by the type of grate in the furnace and stoking equipment in automatic burning machines. If the chips are blown, the required length is from 6 to 10 mm. If there is a mechanical transport of chips, the required length is from 12 to 20 mm. In the chemical processing of chips by a sulphite process the length of chips from 20 to 30 mm and the thickness from 3 to 6 mm are recommended. In a sulphate process the length of chips is from 10 to 25 mm and the thick- ness from 3 to 5 mm (STN 48 0057; STN 48 0058). In practice we can find more names of these ma- chines like chipper, cutting machine and grinder of wooden mass. All these names are characteristic of a machine which uses mechanical way of cutting knives for taking small particles from wood and it is called a chip. Chipping machines are machines for the chip- less cutting of wood by a knife across the fibres and also for necessary thickness along the fibres. Nowa- days, there are more and more people who know that chipping is a real way of wooden mass utilization and that it enables to obtain the pureness of forest. Technological operations which prevent waste wood utilization involve timber production, con- centration into lines, skidding to transporting plac- es, its dimensional homogenization, e.g. chipping, grinding, etc. Wood for energy production can come from either waste from technological processes of wood production and primary wood processing or goal-directed production of fuel wood. eoretical principles of wood chipping by a chipper First, we have to say that wood chipping is a very difficult process. is is the reason why simplifying