Whole Body Vibrations during Fully Mechanised Logging

This paper seeks to answer the question of whether the magnitude of vibrations affecting the whole body of the harvester operator (WBV) that are generated by the harvester boom is affected by the size of the processed trunk volume, to specify closer, the magnitude of WBVs generated during forest logging, and to localise these WBVs in individual partial operations. For these purposes, the production process, i.e., forest logging, was divided into six partial operations (Searching; Felling; Processing; Unproductive time; Machine movement; Stationary position). WBVs were scanned in the respective partial operations according to standard ISO 2631-1:1997 and the European Directive 2002/44/EC, and then the values were mutually compared. Volumes of processed trunks were recorded, which were then assigned to the given WBV during the respective operations. Research results did not demonstrate a correlation between the size of the transmitted vibrations and the volumes of cut trunks in the partial work operations of Felling and Processing. Neither a difference was found between the individual partial operations with two exceptions: Searching and Felling/Processing and Unproductive time. The research further showed that the average WBV of three partial operations did not meet the daily limit of 0.50 m/s2 permitted by European Directive 2002/44/EC, within a range from 12.20% to 27.02%.O

Suitability of Using Mechanization Means for the Maintenance of Grass Stands by the Method of Mulching

This study aims to provide comprehensive and practical information on particular mechanization means used in the maintenance of permanent grass stands, namely grass cutting technologies without the collection of cut grass biomass - mulching. A sample consisting of six machines classified into three categories (uniaxial tool carriers, single-axle small tractors, cutting machines with a zero turning radius) was tested in practice and functional and operational aspects of the machines were studied on different localities of permanent grass stands. Data measured in the individual machines were used to calculate consumption [l/ha], consumption [l/mth], consumption [l/l of cut biomass] or performance [ha/hour]. The measurements took place on two sites: a site with the permanent grass stand unkempt for a long time and a site regularly maintained by mulching. The study was conducted in the cadastral area of Ostrava City situated in the NE part of the Czech Republic. Results of the study show that the total fuel consumption [l/ha] in the individual mowing machines always at all times higher on plots that were unkempt for a long time. The overall comparison of fuel consumption [l/mth] of the individual types of cutting machines between the localities showed that nearly all tested cutting machines had a higher consumption on sites with permanent grass stands unkempt for a long time. The performance [ha/h] of all cutting machines was higher on the sites that were regularly maintained by mulching in the past.O

Analysis of Occupational Accidents in Tree Climbers

The work of tree climbers is a hazardous activity during which many risks of occupational accidents must be faced. Numerous injuries happen during the performance of this professional activity. This is why our research was conducted, and the principle of which was to gather and evaluate, on the basis of the questionnaire method, injuries occurring to tree climbers during their work. An anonymous online questionnaire was prepared in order to obtain data about the rate of accidents recorded amongst tree climbers working in the territory of the Czech Republic. There were 121 tree climbers participating in the collection of data. The questionnaire was divided into seven sections, each section including questions focused on possible injuries related to the work of tree climbers and first aid. Answers of respondents indicated that the highest number of injuries were caused by cutting with the manual saw. Burns caused by the power saw and damage to eyes by sawdust or dust during sawing followed. The results also showed that nearly 30% of tree climbers work alone, and 47% of tree climbers collaborate with a ground worker who is not able to rescue them from the tree in the case of an exceptional unexpected situation. The research also revealed surprising results as to carrying first aid kits. Only 62% of tree climbers have a personal first aid kit on them in the tree crown. However, a positive finding appears in the fact that 75% of tree climbers are graduates of some medical course.O

Analysis of Field View from Tractor and Trailer Units Using the Method of Terrestrial Laser Scanning

Having a proper view from the cabin of agricultural and forest machines is one of the main factors affecting work safety and efficiency. In forestry, machine operators very often perform working activities also in the rear of the cabin. Requirements, criteria and test procedures for the field of view from the tractor cabin are stipulated by the international technical standard ISO 5721. This study evaluates field view parameters from the cabin of the tractor (Valtra T 6300) and trailer (STS 12T) unit. In accordance with the test procedures, prescribed parameters were evaluated for the forward field of view; values for the rear field of view were determined in addition to outside the standard. In order to achieve more accurate measurements and faster evaluation of data, one of the latest methods-using laser pulse reflections (method of terrestrial laser scanning)-was employed. The results of our study demonstrate that even the construction of machines manufactured before the above-mentioned standard came to force can meet the current requirements, except for minor deviations.O

A Unique Grubbing Head Prototype for Environmentally Friendly and Sustainable Stump Removal

Stumps left behind after the felling of trees represent an important source of renewable energy that could be used for fuel mixtures as a sustainable solution. The subject of this research was to determine the influence of tree species, stump diameter size, and subsoil on the time required for stump processing. Evaluated parameters included the mean time for one stump's processing; the stump processing time based on the stump diameter; different soil types and tree species; and the tree species type (coniferous, broadleaved). The research was conducted in the territory of the Czech Republic in 2020/2021. There were 287 stumps and 6 tree species in total. The stumps were uprooted using a new prototype of grubbing head, developed at Mendel University in Brno, attached as an adapter on the boom of a JCB JS 220 LC excavator with a tracked undercarriage and was controlled remotely from an excavator cab. Research results confirmed that the processing time of one stump depends on the stump diameter (GLM), and the time needed for the processing of one stump increased with an increase in stump diameter in all experimental sites. An equation was suggested to predict the time needed to work on one stump.O

Operating Characteristics of a Timber Trailer with a Hybrid Drive

This paper deals with the design and operational evaluation of a timber tractor-trailer unit with a hybrid trailer drive. The source of electrical energy for the two induction motors driving the front wheels of the tandem trailer axle is a battery, which is recharged by an induction machine operating as a generator during periods of a lower demand for power from the tractor diesel engine. An electric drive was designed for the defined working cycle of the tractor-trailer unit, and its loading characteristics were tested in the laboratory. The parameters measured on the field tests during timber forwarding were battery voltage and power, and the energy balance. Three adjustment levels of the potentiometer controlling the trailer hybrid drive (50, 75 and 100%) were tested at three different forwarding distances of 100, 500 and 1000 m. Additionally, any slippage of the prime mover wheels and trailer was measured. The maximum peak power taken from the battery was ca. 33 kW during the field tests, whilst the drive was able to deliver a peak output of up to 72 kW for 10 s and permanently up to ca. 50 kW. Even in harsh terrain conditions, the electric drive assisted the combustion engine only when the loaded tractor-trailer unit was travelling uphill. The hybrid drive operation was sustainable for the whole working shift, without the need for recharging when the potentiometer was set to 50%. This appropriate setting of the potentiometer controlling the trailer's hybrid drive reduced the slipping of the driven wheels of the tractor-trailer unit whilst travelling uphill.O

Vliv intenzity pasečného hospodaření v dubových porostech na epigeickou faunu pavouků (Arachnida, Araneae)

The objective of the present study was to investigate the impact of intensity glade economy at oak forests on epigeic fauna of spiders. Specifically, there were two types of glade economy - mechanical and non-mechanical. The main target of was compare two types. Finding of the species richness, abundance and degree of rareness of spiders The spiders were cought in an individual way. Collect was held in six locations (3 mechanical and 3 non-mechanical) near cities Pasohlávky, Ivaň, Pouzdřany and Vranovice. Repeated five times, from May 2016 to September 2016, once a month. A total number 6915 individual spiders and 120 spider species. The research revealed a statistically significant difference in the species richness between mechanical and non-mechanical locations, where there was a significantly higher diversity on non-mechanical locations. Activit density was bigger on the mechanical locations. Non-mechanical locations a significantly higher incidence of rare and endangered species of spiders and overall, the arachnofauna in these locations was significantly more diverse. The results indicate the inappropriateness of large-scale milling of stump in forest management. The results can also serve as a basis for arboriculture practice in the care of scattered and public greenery

Whole Body Vibrations during Fully Mechanised Logging

This paper seeks to answer the question of whether the magnitude of vibrations affecting the whole body of the harvester operator (WBV) that are generated by the harvester boom is affected by the size of the processed trunk volume, to specify closer, the magnitude of WBVs generated during forest logging, and to localise these WBVs in individual partial operations. For these purposes, the production process, i.e., forest logging, was divided into six partial operations (Searching; Felling; Processing; Unproductive time; Machine movement; Stationary position). WBVs were scanned in the respective partial operations according to standard ISO 2631-1:1997 and the European Directive 2002/44/EC, and then the values were mutually compared. Volumes of processed trunks were recorded, which were then assigned to the given WBV during the respective operations. Research results did not demonstrate a correlation between the size of the transmitted vibrations and the volumes of cut trunks in the partial work operations of Felling and Processing. Neither a difference was found between the individual partial operations with two exceptions: Searching and Felling/Processing and Unproductive time. The research further showed that the average WBV of three partial operations did not meet the daily limit of 0.50 m/s2 permitted by European Directive 2002/44/EC, within a range from 12.20% to 27.02%

Analysis of Occupational Accidents in Tree Climbers

The work of tree climbers is a hazardous activity during which many risks of occupational accidents must be faced. Numerous injuries happen during the performance of this professional activity. This is why our research was conducted, and the principle of which was to gather and evaluate, on the basis of the questionnaire method, injuries occurring to tree climbers during their work. An anonymous online questionnaire was prepared in order to obtain data about the rate of accidents recorded amongst tree climbers working in the territory of the Czech Republic. There were 121 tree climbers participating in the collection of data. The questionnaire was divided into seven sections, each section including questions focused on possible injuries related to the work of tree climbers and first aid. Answers of respondents indicated that the highest number of injuries were caused by cutting with the manual saw. Burns caused by the power saw and damage to eyes by sawdust or dust during sawing followed. The results also showed that nearly 30% of tree climbers work alone, and 47% of tree climbers collaborate with a ground worker who is not able to rescue them from the tree in the case of an exceptional unexpected situation. The research also revealed surprising results as to carrying first aid kits. Only 62% of tree climbers have a personal first aid kit on them in the tree crown. However, a positive finding appears in the fact that 75% of tree climbers are graduates of some medical course

Srovnání diverzity vybraných skupin epigeických členovců v hospodářském nížinném lese s různou věkovou strukturou a typem managementu

The aim of this thesis is to investigate the species richness and abundance of epigeic arthropods (spiders, ground beetles, centipedes, millipedes, woodlice) in relation to different age structure and types of forest management. The arthropods were sampled from four different age classes (clearings, young, middle-aged and old forest stands), while within two of them (clearings and old forest stands) the influence of management was also evaluated. According to comparison of stages of forest succession most species were found in clearings without any mechanical soil preparation. On the other hand younger age classes hosted the least amount of arthropod species. The highest abundances of species were detected within young forest stands whereas the lowest in middle-aged stands. The results of forest management impacts indicate that soil milling is not suitable for any investigated group of organisms. The response to management of the old stands varied for different arthropod groups. The results reveal high importance of diversified silviculture in form of various age classes, a regulation is also necessary to restrict large area milling of clearings and for both managed and unmanaged forest stands the continuity must be maintained