Study on reduction of hand-transmitted vibration in self propelled vertical conveyor reaper by isolators

The self propelled vertical conveyor reaper is commonly used for harvesting wheat, rice etc. It has become a main or the sole of mechanical power source on small and medium size farms in India. The operators of VCR are exposed to a high level of vibration arising from single cylinder engine during field operations. The vibration from the VCR is transmitted from handle to hands, arms and shoulders. In the present study, experiments were conducted to reduce the vibration extent in VCR for two operational conditions i.e. transportation on bitumen road and wheat harvesting operation by using isolators in between engine and chassis. The vibrations were measured at engine speed 2200 and 2800 rpm. In this study it was found that the vibration magnitudes decreased with increase in engine speed from 2200 to 2800 rpm in both operational conditions. The highest vibration values were observed in x-direction. The maximum frequency-weighted vibration acceleration (rms) in x-direction was 18.76 and 22.8 ms-2 in transportation and wheat harvesting, respectively. After incorporation of isolators the vibration total values reduced at 2200 rpm form 22.8 ms-2 to 9.63 ms-2 and 28.11 ms-2 to 12.57 ms-2 in transportation and wheat harvesting, respectively (Fig. 1 and 2). Whereas at 2800 rpm the vibration total values reduced form 12.93 ms-2 to 5.85ms-2 and 17.86 ms-2 to 8.42 ms-2, respectively. The average increment in 8 hour exposure time for occurrence of white finger syndrome from 1.16 to 2.88 year and 0.93 to 2.17 year for isolators in transportation and wheat harvesting, respectively.

Assessment of hand-transmitted vibration in self propelled vertical conveyor reaper

The self propelled vertical conveyor reaper is commonly used for harvesting wheat, rice etc. It has become a main or the sole of mechanical power source on small and medium size farms in India. The operators of VCR are exposed to a high level of vibration arising from single cylinder engine during field operations. The vibration from the VCR is transmitted from handle to hands, arms and shoulders. The detrimental effect of the prolonged exposure to hand-transmitted vibration on the operators has been known for a long time. In the present study, experiments were conducted to assess the vibration extent in VCR for two operational conditions i.e. transportation on bitumen road and wheat harvesting operation. The vibrations were measured at engine speed 2200 and 2800 rpm. In this study it was found that the vibration magnitudes decreased with increase in engine speed from 2200 to 2800 rpm in both operational conditions. The highest vibration values were observed in x-direction. The maximum frequency-weighted vibration acceleration (rms) in x-direction was 18.76 and 22.8 ms-2 in transportation and wheat harvesting. One third octave band frequency spectra were also obtained. The peak acceleration appeared around 50 Hz for both transportation and wheat harvesting at engine speed 2200 and 2800 rpm. The average 8 hour exposure time for occurrence of white finger syndrome was 1.16 and 0.93 years at transportation and wheat harvesting operation.

Mathematical Modeling of the Weight of Grain Straw During Conveying in Vertical Conveying Reaper Windrow

Analyzing the total weight of cut straws inside the conveyor is important in a vertical conveyor reapers machines to optimize the supply energy into the lugged belt conveyor system. This weight was mathematically modeled by considering the working mechanism of vertical conveyor reapers machines, corelating feeding rate of cut straws from cutter to conveyor and conveying rates of lugged belt conveyor. Then the mathematical model for total weight was defined by determining numbers of cut straws in front of each cutters or knives. The defined equation shows that the feed rate of cut straws into the conveyor is in arithmetic sequence fashion with equal initial value and common difference. The total weight of cut straws equation is an arithmetic series with positive common difference. The equation also shows that the numbers of cut straws in the conveyor increased in arithmetic progression when the numbers of cutters or knives increased. In general, the weight of cut straws in conveyor depends on mass of straw, gravitational acceleration, numbers of cutters or knives, forward speed of reaper, spacing of lugs, angular speed of conveyor pulley, diameter of conveyor pulley and diameter of straw.

Mathematical Modeling of The Weight of Grain Straw during Conveying in Vertical Conveying Reaper Windrow

Analyzing the total weight of cut straws inside the conveyor is important in a vertical conveyor reapers machines to optimize the supply energy into the lugged belt conveyor system. This weight was mathematically modeled by considering the working mechanism of vertical conveyor reapers machines, corelating feeding rate of cut straws from cutter to conveyor and conveying rates of lugged belt conveyor. Then the mathematical model for total weight was defined by determining numbers of cut straws in front of each cutters or knives. The defined equation shows that the feed rate of cut straws into the conveyor is in arithmetic sequence fashion with equal initial value and common difference. The total weight of cut straws equation is an arithmetic series with positive common difference. The equation also shows that the numbers of cut straws in the conveyor increased in arithmetic progression when the numbers of cutters or knives increased. In general, the weight of cut straws in conveyor depends on mass of straw, gravitational acceleration, numbers of cutters or knives, forward speed of reaper, spacing of lugs, angular speed of conveyor pulley, diameter of conveyor pulley and diameter of straw.