V.K. Tewari

Seating discomfort for tractor operators – a critical review

Abstract A large number of studies have been conducted and researchers have suggested several criteria for evaluating discomfort and the suitability of a tractor seat in a given working condition. The studies have led to various parameters, viz. the body pressure distributed under and supporting both the buttocks, thighs and the back of an operator, control of posture in static or dynamic condition, ride vibration, exposure time on task and other factors. But in the absence of a more definitive and the most logical criteria particularly from biomechanical viewpoint, the researchers will continue to design conditions and procedures to understand the seat dynamics and evaluate the seating discomfort. Therefore, this paper reviews the research information available in this regard and attempts to set the most appropriate procedure for assessment of seating discomfort during tractor driving. Relevance to industry This paper attempts to project the most appropriate method of assessment and selection of tractor seats from engineering and biomechanical view point which could be adopted by the tractor seat manufacturers. It is designed to enhance the feeling of comfort, safety, convenience, and results in higher work output from the operator.

Evaluation of three manually operated weeding devices.

Performance of three manually operated weeders was evaluated from ergonomics and mechanical considerations. Three operators were selected for laboratory and field trials; they represented the 5th, 50th and 95th percentiles of the operator population. Laboratory tests were conducted in a psychometric chamber to study physiological response under varying load and environmental conditions. From the data, relationships between energy expenditure rate and oxygen consumption rate vs heart rate were established. Field tests were carried out with the three weeders in a farm with Arhar crop (Cajannus Cajan L.) during August-September, when the average ambient temperature and relative humidity were 36 degrees C and 82% respectively. The results of this investigation indicated that weeding with the indigenous tools of a khurpi and a spade and with the improved tool (3-tine hoe) could be rated as moderately heavy work. However, a khurpi demanded less energy expenditure than a 3-tine hoe followed by a spade. The squatting posture with a khurpi appeared to be more comfortable than the standing posture with about 145 degrees erect position for the 3-tine hoe, followed by the standing posture with about 108 degrees erect position with the spade. For consideration of higher output, the order was spade, 3-tine hoe and khurpi, For weeding efficiency the trend was, however, just the reverse.

Ergonomic design of crane cabins: a case study from a steel plant in India

The study, carried out at the Batch Annealing Furnace (BAF) shop of Cold Rolling Mill (CRM) at an integrated steel plant of India, concerns ergonomic evaluation and redesign of a manually-operated Electrical Overhead Travelling (EOT) crane cabin. The crane cabin is a complex worksystem consisting of the crane operator and twelve specific machine components embedded in a closed workspace. A crane operator has to perform various activities, such as loading and unloading of coils, setting and removal of convector plates, and routine maintenance work. Initially, an operator had to work in standing posture with bent back most of the time. Ergonomically poor design of the chair and the controls, awkward work postures, and insufficient vision angle resulting in musculoskeletal disorders (MSDs) are some of the critical problems observed.. The study, conceived as an industry-academia joint initiative, was undertaken by a design team, the members of which were drawn from both the company concerned and the institute. With the project executed successfully, a number of lessons, such as how to minimize the anthropometric mismatch, how to improve the layout of the components and controls within enclosed workspace, and how to improve work posture minimizing risk of MSDs have been learned.

Injury severity assessment for underground coalmine workers.

An injury severity model is proposed for assessment of injury incidents in industrial settings. A classification scheme for injury incidents considering interactions is also developed. The injury severity model considers injury potential in the form of unsafe conditions and analyzes its transfer to actual injury of varying severity. A case study was conducted in an underground coalmine of eastern India. An observed reduction in risk realization is explained through the model. Presence of interactions is found to be the most significant incident attribute of injury occurrences. The classification scheme and the results obtained from this study will help in improving accident/injury investigation reporting and devising preventive measures for reducing injury severity.

Simulation of components of a power shuttle transmission system for an agricultural tractor

Simulation of the components of power shuttle system.System provides variable clutch engagement time so that same vehicle can be used for variety of operations.Variation in duty cycle of proportional valve changes the pressure building time of proportional valve.Slow increment in duty cycle of proportional valve cause smooth clutch engagement. The usage of tractors is widely extended to various non-agricultural and construction applications like with front end loaders, dozers, backhoe, etc. Tractors which are predominantly used in front end loader application requires frequent shifting of gear due to repetitive fore and aft travel requirements of the vehicle. In this application, tractors usually move forward and reverse direction at the same speed within a short duration by using a mechanical shuttle, synchro shuttle or by power shuttle transmission. This research article presents an idea on the simulation of the power shuttle transmission system of an agricultural tractor. A model of the individual component of power shuttle transmission system has been developed and integrated, to make it as a whole vehicle model, using MATLAB as a simulation platform. The model has been used to study the proportional valve characteristic, vehicle shift time and motion inversion time of modelled tractor and comparison was made between actual and simulated results. The model was validated with the help of an instrumented test tractor. The findings indicated that the time required to develop required actual system pressure was 1.85s whereas the simulated time was 3.1s which was optimized to 1.94s.The simulated shift time was 5s which was optimized to 3.1s. Similarly the actual and simulated motion inversion time of the tractor was 6.4s and 10s. The modification in the model was done to bring the resemblance between actual and simulated results by providing the actual simulation environment. Thus the simulation study presented here may be beneficial in the design and simulation of other types of power transmission systems used in the tractors.

Embedded digital draft force and wheel slip indicator for tillage research

A load cell based three pint linkage dynamometer is developed.A sensor based wheel slip measurement system is developed.An embedded system is developed to measure & display the draft force, wheel slip digitally.Developed devices helps in tillage research for researchers and educational needs.The device can be easily mounted in any make & model of tractor and implement. A mechatronic based embedded digital draft force and wheel slip measuring devices was developed. It includes a load cell based dynamometer to measure the draft force, hall sensor based magnetic pins mounted discs to measure wheel slip, an amplifier to amplify the sensing unit signals of dynamometer, and a microcontroller to process the received load cells, hall sensors data to calculate draft force, wheel slip and display on the LCD screen as well as record the data in SD card module. To compare and assess the degree of accuracy of the developed draft measurement system, wheel slip measurement system, a system involving instrumented three point linkages was developed to measure draft force simultaneously and a non contact type radar sensor was used to validate the wheel slip measurement system. It was observed that, a maximum variation of ź410N draft forces was observed between the developed and strain gauge dynamometer also found close to draft force values calculated by ASABE equation and a maximum variation of ź2.1% wheel slip was observed between developed and manual measured values. The developed devices are simple in construction and can be mounted on any make and model of agricultural tractor implements. The developed devices will be very much helpful for educational institutions and research needs in drawbar performance studies.

Oxidation Behaviour of Welded ASTM-SA210 GrA1 Boiler Tube Steels under Cyclic Conditions at 900°C in Air

Abstract ASTM-SA210-Grade A1 boiler tube steels were welded by shielded metal arc welding (SMAW) and tungsten inert gas processes. The oxidation behaviour of the welded steels was evaluated under cyclic conditions at 900°C. Visual observations and thermogravimetric data were measured at the end of each cycle. Finally, the scale was analysed using X-ray Diffraction, Scanning-Electron Microscopy/Energy-Dispersive X-Ray studies. A SEM Back scattered image analysis of the cross-section of the oxide scale thickness has been made to measure the oxide scales formed over the welded steels. SMAW welded steel showed the more oxidation rate (in terms of weight gain) as compared to TIG welded at the test temperature of 900°C and it was due to the formation of more cracks in oxide scale, and a thick oxide scale was found on HAZ and weld region.

Embedded digital drive wheel torque indicator for agricultural 2WD tractors

Abstract A microcontroller based embedded system was developed to measure and display the dynamic wheel axle torque and drawbar power of agricultural tractor for tillage research. The device includes a special transducer to measure dynamic drive wheel torque of tractor, an embedded wireless digital system to receive process and display data digitally as well as record in SD card module near the dash board of the tractor. The embedded system mainly consists of an amplifier to amplify the transducer signal, a transmitter unit to process the amplifier data, and a receiver unit to receive and display the transmitter unit data. The developed system was rigorously tested under laboratory and actual field conditions. It was found that, a maximum variation of ±320xa0Nm torque between the theoretically calculated and experimentally observed values under field conditions. With the developed devices the real time power requirement of various agricultural operations could be known to help the tillage researchers. The developed device and systems are simple and accurate and can be used for any range of agricultural tractors.

A Decision Support System for Design of Transmission System of Low Power Tractors

A decision support system (DSS) was developed in Visual Basic 6.0 programming language to design transmission system of low horsepower agricultural tractors, which involved the design of clutch and gearbox. The DSS provided graphical user interface by linking databases to support decision on design of transmission system for low horsepower tractors on the basis of modified ASABE draft model. The developed program for design of tractor transmission system calculated clutch size, gear ratios, number of teeth on each gear, and various gear design parameters. Related deviation was computed for design of transmission system of tractors based on measured and predicted values (simulated). The related deviation was less than 7% for design of clutch plate outer diameter and less than 3% for inner diameter. There was less than 1% variation between the predicted results by the developed DSS and those obtained from actual measurement for design of gear ratio. The DSS program was user friendly and efficient for predicting the design of transmission system for different tractor models to meet requirements of research institutions and industry.

Engineering innovation in developing rural load carrier operated jute seed drill for farm workers

Jute provides employment to 40 million farmers and 0.2 million workers in factories in India. Weeding and pesticide spraying are serious problems in the crop due to scattered germination and higher planting density, owing to the absence of effective planting mechanisms, which increase the cost of production and decrease the yield and quality. The current research relates to a self-propelled seed drill, derived from rural load carrier (RLC), which comprises of a self propelled device and a seed drill body. The machine was designed and developed to sow jute seed considering agronomic and ergonomic considerations. RLC used a 3.94 kW diesel engine allowing field work forward speed of 1.9 to 2.8 and 6 to 8.3 kmh-1 for rural transportation. The control levers were placed in accordance with the anthropometric data of the user population. Around 67% germination and plant establishment was found with the developed seed drill. The effective field capacity at the mean speed of 2.1 kmh-1 being 0.23 hah-1 and fuel consumption was 1.4 Lh-1. Ergonomic measured data also proved the suitability of the machine for rural workers with higher cost effectiveness. n n Key words: Jute, self propelled seed drill, rural load carrier, mechanical design considerations, workplace.