Search Results (5)

The objective of our research was to ascertain the time intensity of timber skidding with a prototype ATV Salamander 600 4 × 4 micro-skidder and to characterize the operator’s field of view. The time intensity of skidding amounts to approximately 20 min/m³ at a distance of 20 m when skidding timber from the forest stand and approximately 10 min/m³ when skidding along the skid trail for a distance of 80 m, which is comparable to other machines of this type, despite reported problems with raw material causing jamming on rugged terrain in the first phase of the skidding process. The significant discrepancy (6%) in wheel slippage between the front and rear axles was particularly pronounced during the process of pulling timber up to the skid trail. This can be attributed to the transport hitch being positioned excessively high, thereby relieving the force on the hitch and causing the front axle to be affected. The observed difficulties in skidding resulted in the need to scan a wide visual scene when working in the stand. The initial phase of timber skidding in the forest stand exhibited a deficiency in its smooth flow, which led to an augmentation in mental workload, as indicated by the elongation of saccades. On average, these saccades were approximately 80% longer compared to those in work conducted on the skid trail. Full article

Damage to the residual stand caused by forest operations can have detrimental impacts on the biological processes of stand growth. This study shows the details from monitoring damages related to manual motor ground-based timber operations in a mountain mixed hardwood forest. The harvesting system was cut-to-length, and logs were extracted by wheeled cable-skidders. Data were collected from the remaining trees immediately after logging and 10 years after the logging session. The parameters assessed included stem injury, radial growth increment and wound healing rate for five hardwood species of commercial interest. The number of injured trees represented 15% of the residual stand, 23% of the wounds were related to the felling operation and 76% to extraction. Wound height, wound size and damage to bark, due to felling, were larger than those in extraction, while wound width and damages to cambium and wood caused by extraction were larger than those triggered by felling. Ten years after harvesting, average longitudinal and radial growth increments were reduced by 38% and 24%, respectively. Wound healing rates ranged from 12.90 mm yr⁻¹ for extraction wounds to 19.70 mm yr⁻¹ for felling ones within 10 years. On average 73% of all wounds were still unrecovered and 17% of these were decayed, while only 10% were fully healed within a 10-year recovery period. The analysis showed that the best recovering performance among damaged trees was mostly achieved in shade-intolerant species with a diameter less than 40 cm, located in the dominant canopy layer with a wound size smaller than 100 cm². In addition to the significant effect on log quality, the ecological longevity of residual trees has major implications for pre-planning harvesting operations that can preserve the quality and value of residual trees. Understanding the damage inflicted upon residual trees is essential to reduce economic losses, improve planning of harvest operations and, ultimately, ensure a sustainable harvest of mixed hardwood stands in mountain regions. Full article

The article is focused on the static stability of a vehicle with a 2000-liter water tank behind the rear axle. The purpose of the research is to evaluate the influence of the tank on stability. The vehicle is composed of a forestry skidder, a water tank, and equipment. To equilibrate the tank a ballast weight of 500 kg in front of the skidder is used. The influence of various combinations of the full water tank, half-filled water tank, and ballast weight is evaluated. The stability is determined as the distances of vectors of a stability triangle and a gravity vector, that is placed in a center of gravity of the whole vehicle. A Python programming language is used to implement the solution. The results are displayed in form of heatmaps. For the analyses, a slope angle of ${18}^{\circ }$ is used. The results show that the longitudinal stability is decreased and lateral stability is increased. The tank also makes the vehicle unstable in some positions. Full article

Soil surface is directly affected by heavy traffic of machinery during harvesting operations. Machine traffic often causes damage to forest soil which is visible on the surface (ruts) and invisible changes in, for example, bulk density, penetration resistance, etc. Close-range photogrammetry is the state-of-the-art method used for recording and evaluation of visible changes. This study aims to analyze soil surface changes caused by traffic of three types of wheeled skidders without a load on Cambisol soil in Central Slovakia. We use the Structure-from-Motion (SfM) close-range photogrammetry to record and evaluate depths of ruts and their volumes after 40 passes of individual skidders. We compared Root Mean Square Errors (RMSEs) of dense point clouds created from various numbers of images taken for individual plots. Rut volume changes calculated by the SfM method and from the manual measurements were compared for one skidder. The final values of RMSE did not exceed 10 mm except for the plot with the lowest number of photos. The final rut depths varied between 0.026 and 0.050 m, and their final volume fluctuated from 0.021 to 0.089 m³. The skidder type and the terrain slope had significant impacts on magnitudes of soil changes. The results of the manual and SfM methods assessing soil changes were correlated. Based on the presented results we can conclude that the SfM method can be applied to detect soil surface changes after traffic of forestry machinery. Full article

The presented article presents an innovative solution of a fire-fighting adapter based on the basic hypothesis: to provide sufficient technical support in difficult terrain conditions for water transport logistics in order to quickly prevent the spread and destruction of forest fire. At present, when forest fires begin, it is often quite complicated to provide sufficient technical support for the quick prevention and elimination of fires. This fact is largely eliminated by the designed fire-fighting adapter. The mentioned fire-fighting adapter can be used as a fire-fighting mobile device with a base machine of a forest wheeled skidder (LKT), part of the long-distance transport of water in difficult terrain (lake system), a water tank in difficult terrain with the possibility of filling the Bambi bag with a helicopter, part of the long-distance transport of water in the case of a difficult water source without a forest access road network, and a mobile device for emergency transportation of materials in difficult terrain. In addition to the use for fighting forest fires, the fire adapter can also be used to provide for transport of water for forest nurseries (irrigation), freshly planted areas in the event of prolonged drought, the filling of watering-places for forest animals and filling puddles in the dry season. When designing the supporting frame, we used and imitated the evolutionary approach of nature in the form of generative design. The presented paper deals with the use of modern composite materials in the design of superstructures for base machines, which gradually acquire meaning. The main reason for the increasing use of fiberglass is to achieve higher strength and safer weight reduction. This adapter is designed for forest wheel tractors that reach 40% slope availability, are able to work on the stand area, overcome obstacles and are available in sufficient quantities in all Slovak forest areas. Full article