Abstract
Pushing-up and torque slip tests were performed using model propeller boss (AlBC3), tiller boss of steering gear (SC410) and shaft (SF440A) to investigate friction behavior of the keyless tapered surfaces and to find out a clue of countermeasures of torque slip problem. As the results of experiments, (1) The coefficients of friction of propeller including pushing-up and torque slip tests are 0.15-0.20 under dry condition. On the other hand, the coefficients of steering gear in dry fit shows higher than 0.20 due to strong adhesion of similar metals. (2) MoS2 lubricant and anti-rust agent NP-19at the contact surfaces predominantly decrease friction and easily cause torque slip. (3) The coefficients of friction in elastoplastic deformation of boss is slightly higher than those in elastic one. From the practical aspect, it is proposed that boss is pushed up into shaft nearly to the upper limit of an allowable pushing-up distance in order to prevent an accident of torque slip.
