A Mobile Hydraulic Winch for Use in Small-Scale Forestry

Abstract

Winches have recently been used to extract timber from forests. Winches are often components of tractors, but tractors cannot be used on difficult terrain and are generally too expensive for small forest owners. The current study considers the use of an experimental winch for the extraction of timber from small plots with difficult terrain. The mobile hydraulic winch used in this study weighs 50 kg and has a pulling force of up to 53 kN, a 12 V motor, and a 64x224 mm drum. The associated power unit is a gasoline, single-cylinder, four-stroke, air-cooled KIPOR KG 390D (400D), 389 cm3 engine, with 7.7 kW of power, and a torque of 22.6 Nm at 2500 rpm. The engine powers a high-pressure oil pump with an output pressure of 3 MPa and a flow rate of 60 litres per minute. The input torque of the pump shaft is 25 Nm at 3000 rpm. The hydraulic winch can be fixed to tree trunks, stumps, or wooden pegs by lashings. The winch was tested at three locations with different assortments of wood. The results showed that the experimental winch was practical for timber extraction and that <250 kN of force was needed for successful extraction. At the test sites, the expense of lumber removal was on average 140% greater with the winch than with a horse but the advantage of the hydraulic winch is high pulling force. Because of its small size and low weight, the unit can be easily handled by two workers, easily moved at short distances in small plots with rough terrain, and easily transported among plots. With a one-man crew, the percentage of direct costs represented by wages dropped to 56%, and the percentage represented by fuel increased to 40%.