Ergonomic Design Modification, Testing and Evaluation of Pedal Operated Paddy Thresher
4.4 Pilot Study – Pedal Operated Paddy Thresher
Fig. 4.8 Pictorial representation of DHM applications in agriculture
Pedal-operated paddy thresher is locally manufactured by small scale industries. A survey related to its design parameters and physiological aspects of operation was conducted to collect relevant facts and figures (survey Proforma is given in Appendix 4).
Musculoskeletal risks of operation were obtained from the farmers of three states of NER namely, Assam, Arunachal Pradesh and Meghalaya. The questionnaires were prepared separately for each survey.
The Indian manufacturers of paddy thresher are mostly from West Bengal, together with however, also from Jharkhand, Odisha, Rajasthan, Tamil Nadu, Punjab, Maharashtra, Uttar Pradesh and Haryana; but none was found to be from the NER. A systematic survey was conducted to acquire technical design inputs pertinent to the paddy thresher from different manufacturers through website, telephonic conversation and e-mail. Twenty nine manufacturers responded willingly providing with detailed technical figures regarding design and manufacture of pedal-operated paddy thresher. Adoption of the stipulations of the Indian Standard IS: 3327 regarding the material, dimensional and other requirements for the pedal-operated paddy thresher is mandatory while manufacturing any such thresher.
The Proforma for musculoskeletal concerns of operation was sent to ICAR Research Complex of Meghalaya and Department of Agricultural Engineering, North Eastern Regional Institute of Science and Technology (NERIST), Arunachal Pradesh. The survey in Assam was carried out by personal interview. Surprisingly, most of the Assamese farmers did not have even seen any pedal operated paddy thresher prior to this survey.
Across entire Assam, only a fewer number of threshers were seen, fitted with electric motor and used on rental bases.
4.4.1 Results and Discussion
4.4.1.1 Availability of pedal operated paddy thresher
Result of the survey on pedal operated paddy thresher, shown in Fig. 4.9, revealed that about 48% manufacturers belonged to West Bengal, while no manufacture was found from the NER. Majority of the manufactures did not appoint any dealer for advertising and selling the thresher. They used to supply the equipment to the farmers directly, based on their requirement. Most of manufacturers had in-house production and assembly,
whereas some of them procured the spares / components from other states and assembled in-house. Manually powered and engine driven threshers are available. The average capacity of manufacturing threshers normally ranges between 500 – 800 units yearly, with no warranty on the product / spare. The manufacturers even do not use any pamphlets or hoardings for sales promotion. This industry thus hosts a low-yield low- profit business. The state Agro Industries Corporations also buy threshers from them, but for demonstration purposes in the farmer field only. All threshers are normally sold on cash in 100% advance payment basis.
(States of India: JH – Jharkhand, OR – Orissa, RJ – Rajasthan, UP – Uttar Pradesh, KL – Kerala, MH – Maharashtra, PB – Punjab, TN – Tamilnadu,
WB – West Bengal)
Fig. 4.9 Percentage of pedal thresher suppliers participated in survey
All the threshers operated on human power use four bar linkage mechanism. There was large variability in design dimensions of various components of threshers. The design dimensions of some main components are listed in the Table 4.1 appended below.
3.45 3.45 3.45
3.45 6.90
6.90
10.34 13.79
48.28
1 2 4 8 16 32 64
JH OR RJ UP KL MH PB TN WB
Percentage (%)
States of India
Table 4.1 Design dimensions of pedal operated threshers manufactured in India
Particulars Specification
Overall dimensions and specifications
Length, cm 60-121
Width, cm 71-145
Height, cm 72-85
Side frames Mild steel angle
Front Grain Shield Mild steel sheet
Rear Grain Shield Mild steel sheet
Weight, kg 40-90
Operating parameters
Power requirement 1-2 person minimum
Drum speed, rpm 300-550
Power mechanism Crank-follower four bar linkage
Gear ration 3:1-5:1
Material of construction for gear Cast iron Threshing drum specifications
Length, cm 48-125
Diameter, cm 30-43
Material Cost iron
Fingertip height, cm 5.5-7.5
No of fingers per meter length 18-22 Distance between the tip, cm 4.8 to 7.5
Finger type loop
Mounting method Staggered
Pedaling parameters
Minimum height above ground, cm 5-7 Maximum height above ground, cm 19-24
Pedaling strike per min 60-90
Material of construction Wooden/Mild steel 4.4.1.2 Musculoskeletal concerns with pedal operated paddy thresher
A total of 46 participants responded for the questioners related to musculoskeletal problems in operating pedal operated paddy thresher. The data received from ICAR Research Complex of Meghalaya, Department of Agricultural Engineering, North Eastern Regional Institute of Science and Technology (NERIST), Arunachal Pradesh and personal interview of Assamese farmers were analyzed. The lower legs ailment evidently dominated (95.65%) among the farmers using pedal operated paddy thresher over their
upper legs (73.91%), lower back (52.17%), foots (28.26%), upper arms (19.57%), lower arms (15.22%), shoulders (6.52%) and neck respectively (Fig. 4.10). This showed that some of the body parts like calf, thigh muscle, lower back and ankle region got highest discomfort due to continuous pedaling with greater amount of force exerted on the pedal.
The upper thigh and calf muscle soreness due to elongated application of larger force was also reported in some cases.
Fig. 4.10 Percentage of Agricultural workers reported MSD in different parts of the body during paddy threshing with existing pedal thresher
It appeared from the above result that, higher prevalence of musculoskeletal disorders reported could be associated with the higher physical demand for the pedaling operation of the paddy thresher; or might be due to the variable dimensions and capacity of thresher leading to mismatch with the body dimensions.