Cutting duration and performance parameters of a harvester’s sawing unit under real working conditions

Prinz, Robert; Väätäinen, Kari; Routa, Johanna

doi:10.1007/s10342-020-01320-5

Cited by 7 publications

(3 citation statements)

References 22 publications

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“…In their study, tree delimbing accounted for more than 40% of the cycle time. A recent study by Prinz et al (2020) has shown that effective cutting may take as little time as milliseconds, depending on the diameter at which the cuts are performed.…”

Section: Nl Nc Nfmentioning

confidence: 99%

Performance of a Double-Grip HYPRO 775 Machine in Processing Small-Sized Pine Wood

Pérez

Vintimilla

Borz

2020

FWIAFE

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In forest operations, productivity studies represent one of the central topics because their output is frequently used to develop predictive models, to compare alternatives or just to set production rates and to make informed decisions needed to reach a balance between the work effort and payment. Ecuador has started to change its technology in forest operations by a transition towards the increment of mechanization to procure wood from forests planted for timber production purposes. Nevertheless, the change has brought no new research approaches to check the performance of the new machines. A particular case is that of tree processing operations at the landing by means of double-grip processor machines. This study aimed to evaluate the performance of these machines in processing timber from thinning operations and to estimate, by a check study, the sample size needed for a full-scale study. For this reason, a number of 57 processed trees were included in the study and a detailed time-and-motion analysis was implemented to check the variability and central tendency of the data, a fact that also enabled the operational description. Based on the study outcomes, basic statistics were computed to characterize the performance of the operations under the assumptions of a preliminary study, and the number of observations for a full-scale study were estimated. On average, close to 4 logs were recovered from a tree which resulted in an average work cycle time of 45 seconds that was characterized by a succession of very fast events such as gripping, feeding, and cutting. Elemental cuts, for instance, accounted for a number of 228 observed events and they averaged close to 1.5 seconds. The estimation of the sample size based on a confidence threshold of 95% and on an assumed precision of 5% revealed a rather low number of observations (127) needed at the work cycle level. However, factors such as the variability in some work elements, as well as the occurrence of other work tasks on a regular basis should be considered in the attempt to adopt the sample size and to conduct a full-scale study. Until conducting a full-scale study, the results given herein could serve as reference in the performance of tractor-mounted double-grip processors in

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Section: Nl Nc Nfmentioning

confidence: 99%

Performance of a Double-Grip HYPRO 775 Machine in Processing Small-Sized Pine Wood

Pérez

Vintimilla

Borz

2020

FWIAFE

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“…The harvester head's main function and power-consuming functions, chainsaw, and feeding roller drive are hydraulically operated for the time being and will be for quite some years to come and therefore, using a hydraulic energy storage system such as a high-pressure accumulator is advantageous in terms of minimizing energy conversions. As the CTL forest harvester is a critical piece of equipment in this kind of forestry, its work cycle has been studied in time studies [9] as well as performance evaluations [10].…”

Section: Introductionmentioning

confidence: 99%

Hydraulic Hybrid Cut-to-Length Forest Harvester—Evaluation of Effects on Productivity and Fuel Efficiency

Einola,

Kivi

2024

Actuators

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A cut-to-length (CTL) forest harvester is a purpose-built, hydraulically actuated mobile work machine used for felling, delimbing, and cross-cutting trees into dimensions and assortments. In such a machine, the diesel engine load is known to fluctuate greatly over the work cycle. To manage these changing power demands, a hydraulic hybrid system is implemented into a full-scale proof-of-concept machine to discover its functionality and to collect experimental results in real operating conditions. The hydraulic hybrid system installed on a CTL harvester machine was tuned to enable the collection of two actual datasets of timber harvesting, and data collection over a period of production use was carried out. In addition to updating the state-of-the-art research into heavy non-road mobile machinery regarding hybrid systems, this paper discusses the two tests carried out in actual production conditions with the studied hydraulic hybrid system. The adaptations and modifications to the studied and tested system since earlier papers are discussed—especially the improvements in the system dynamics and response as well as the control of the hybrid system. In conclusion, the tested system can be said to operate satisfactorily and shows clear advantages over the conventional system, even though it still has some limitations. The results show that the system has the potential to increase the productivity of the machine through the demonstrated higher peak power, as well as showing improvement in fuel efficiency under highly fluctuating loads, especially with heavy or large-volume tree stems.

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“…Several studies have been carried out in different parts of the world to check the performance of single-grip harvesters and processors in forest operations, with the aim to provide an informed ground on equipment capabilities as a baseline for its selection and use in operations, performance modelling and cost estimation [13][14][15][16][17][18][19]. Recently, important steps were taken to improve our understanding on the human-machine interaction [20], fine-scale performance of process mechanics [21] and human exposure to harmful factors [22]. However, mechanized tree processing at the landing was less addressed by scientific studies, and work organization and operational environment in such work places are different from those typically found in the forest stands.…”

Section: Introductionmentioning

confidence: 99%

Processing Small-Sized Trees at Landing by a Double-Grip Machine: A Case Study on Productivity, Cardiovascular Workload and Exposure to Noise

Vintimilla

Pérez

Borz

2021

Forests

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To be characterized as sustainable, forest operations need to be studied and validated from many points of view, including their productivity, ergonomics and costs. In most of these areas, performance enhancement was found to be sustained by the development and use of mechanization, including that of landing operations done to process small-sized trees. For these, an affordable and sustainable alternative could be that of using double-grip processors. However, there is a lack of information characterizing their capability and performance, which was one of the main reasons for carrying on this study. Observational data were collected over four operational days for a HYPRO 775 double-grip processor to estimate the productivity, exposure to noise and cardio-vascular workload in processing small-sized trees at landing. Miniaturized dataloggers and video recording were used to document close to 28 h spent at the workplace and 15 h of operation, respectively. A time study was used to estimate the productive performance and the commonly used metrics were computed to evaluate the exposure to noise and cardio-vascular workload. A delay-free work cycle was framed around a processed tree and it took, on average, ca. 45 s. Based on 901 processed trees (average height of ca. 12 m and average breast height diameter of ca. 12 cm), the net productivity rate was estimated at ca. 65 trees per hour (ca. 224 logs of 2.4 m produced per hour). While the cardiovascular activity indicated light work, exposure to noise seems to be a concerning problem to be addressed in the future, given the figures found (A-weighted sound pressure level higher than 85 dB(A) and the sound pressure level normalized for a nominal day of 92.79 dB(A)). This becomes even more important as this study found a machine utilization rate of ca. 60%, therefore an extension of productive time could increase the exposure to noise. We conclude that double-grip processors represent a valuable technical alternative in processing small-sized trees at landing if supplementary precautions would be taken against exposure to noise. These may rest very well in the awareness and behavior of the operators as well as in wearing protective equipment.

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Cutting duration and performance parameters of a harvester’s sawing unit under real working conditions

Cited by 7 publications

References 22 publications

Performance of a Double-Grip HYPRO 775 Machine in Processing Small-Sized Pine Wood

Performance of a Double-Grip HYPRO 775 Machine in Processing Small-Sized Pine Wood

Hydraulic Hybrid Cut-to-Length Forest Harvester—Evaluation of Effects on Productivity and Fuel Efficiency

Processing Small-Sized Trees at Landing by a Double-Grip Machine: A Case Study on Productivity, Cardiovascular Workload and Exposure to Noise

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