Analysis of the time efficiency of skidding technology based on the skidders

The time efficiency and principles of ergonomics related to timber skidding are based on the time consumption per work cycle as well as on the time consumption per individual work operations. Regarding the demands on the environmental requirements and ever increasing cost of work, it is necessary to objectively evaluate the inevitable time consumption required for timber skidding using all technologies. The paper summarised the results of time studies for skidder technologies. The time study compares the time consumption and productivity of cable skidders and cable-grapple skidders, with the main focus on developing time prediction models. The main aim of the study was to objectify the skidder time consumption and establish the impact of production factors on the time consumption of partial work operations of skidders. Within the time study 231 work cycles were measured, and 53 snapshots of work day with using methods continual time study. The overall time consumption of the work cycle and gross production rate of the monitored cable and cable-grapple skidders is affected by the following production factors: the skidding distance, volume of skidded logs and number of skidded logs. The impact of individual production factors on the overall time consumption of the work cycle is different for each group of skidders. Non-operation times of the skidder operators’ shifts represent 24.6% with the highest part taken by the technical operation of the work place. The mean gross production rate of the monitored skidders varied from 33.3 to 6.91 m³ h⁻¹.