The magnitude of frictional clutch moment during the start acceleration of automobile or tractor

Abstract

At the present time there are still works where it is assumed that the frictional clutch moment in dynamics is greater than in static. In reality, this is not the case. It is shown that for existing types of friction linings (based on asbestos, asbestos-free polymer or powdered sintered), working in a dry environment with cast iron, the sliding friction coefficient is 0.23 ... 0.27. In this case, its value is 60 ... 70% of the coefficient of static friction. For friction clutches operating in oil, the value of the static coefficient of friction in the contact of the closed clutch discs of the disconnected gear is 1.7 ... 2.2 larger than the dynamic friction coefficient of the friction clutch of the gear involved. These data were obtained experimentally for friction discs with sintered powdered material MK-5 on a copper basis, Shadef on an iron basis, as well as HS43 and HS09 (Hoerbiger, Austria) on a copper basis. This confirms that frictional clutch moment in the dynamics is always less than in the static. The oscillograms with the results of the process of dispersal from the place of various tractor units are given, from which it follows that in most cases of start acceleration of the vehicle the clutch ends its slipping until it is fully turned on. Consequently, in most cases start, the acceleration of the vehicle does not use the maximum friction torque of the clutch in the dynamics, which, as was shown above, is always less than the frictional clutch in static.