Comparison of Applied Forces on Selective Joints and Muscles of Drivers During Clutching of MF285 and MF399 Tractors

In this research, the imposed forces on three muscles including: Gastrocnemius muscle, Trapezius muscle and Quadratus lumborum of the tractor drivers during clutching have been studied. The sample included 30 persons and the research was conducted on two domestic tractors including: MF285 and MF399 models. The clutching forces for these tractors were measured as 340 N and 290 N, respectively. The difference between drivers’ knee angle of the two tractors was proved significant at the one percent level. The decrease of pain threshold after 30 seconds and 60 seconds clutching and 60 seconds rest after clutching in MF285 tractor in all three muscles were more than that of MF399 tractor. The impact of clutching on the average decrease of pain threshold, among all the drivers, and for all time intervals, during and after clutching in the Quadratus lumborum muscle for both tractors was more than the other two muscles. In order to reduce the imposed force of clutching for MF285 tractor, some modifications is suggested. In this regard the force transfer joint between the pedal and the disc in the mechanism of clutching can be replaced with one made of cast iron.