PERFORMANCE EVALUATION OF ANTI-VIBRATION MEASURES FOR REDUCING HAND TRANSMITTED VIBRATION IN SELF PROPELLED VERTICAL CONVEYOR REAPER
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Date
2018-07
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Publisher
MPUAT, Udaipur
Abstract
The self-propelled vertical conveyor reaper is commonly used for harvesting wheat, rice and
other cereal crops. It has become a main 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. 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. The symptoms which include effects on
peripheral circulation, the peripheral nerves or the musculoskeletal system have also been
recognized as important occupational disease. To reduce the detrimental effect of the handtransmitted
vibration two types of anti-vibration measures were developed. Styrene-
Butadiene Rubber and Neoprene rubber were used to develop anti-vibration measures. The
materials used for these anti-vibration measures were modified into cylindrical isolators
based on the load acting on the engine. To prevent the transmission of vibration to handle the
cylindrical isolators were provided in between engine and chassis.
In the present study, experiments were conducted in two operational conditions i.e.
transportation on bitumen road and wheat harvesting at engine speed of 2200 (half throttle
speed) and 2800 (3/4th throttle speed) rpm. In this study it was found that the vibration
magnitudes increases with increase in engine speed from 2200 to 2800 in transportation and
in wheat harvesting the magnitude of vibration decreases with increase of engine speed. The
vibration total values without anti-vibration measures at 2200 rpm were 13.91 and 19.90 ms-2
in transportation and wheat harvesting respectively. Whereas at 2800 rpm, the vibration
magnitudes were 27.98 and 15.55 ms-2 respectively.
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 of 2200 and 2800
rpm.
The vibration magnitudes were reduced after installation of developed anti-vibration
measures. The observed vibration reduction in transportation by isolators made up of
Neoprene at 2200 and 2800 rpm were 48.22 per cent and 81.2 per cent and for isolators made
up of material SBR the observe vibration reduction in 2200 and 2800 rpm were 18.18 per
cent and 81.3 per cent. The observed vibration reduction in wheat harvesting by isolators
made up of Neoprene at 2200 and 2800 rpm were 59.39 per cent and 55.11 per cent. For
isolators made up of material SBR the observe vibration reduction in 2200 and 2800 rpm
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were 46.08 per cent and 60.90 per cent. It was found that vibration magnitudes were reduced
more in case of x-direction. However in y and z direction the vibration magnitudes were also
reduced. Maximum vibration reduction was observed with Neoprene isolator at 2200 rpm
(half throttle speed). There was no significant difference between SBR and Neoprene in
reduction of vibration at 2800 rpm (3/4th throttle speed).
Description
PERFORMANCE EVALUATION, ANTI-VIBRATION MEASURES REDUCING, HAND TRANSMITTED VIBRATION, SELF PROPELLED VERTICAL CONVEYOR REAPER
Keywords
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Citation
Nag, R.H. and Mehta, A.K.