Bitte wählen Sie ihr Lieferland und ihre Kundengruppe
The paper considers ship propulsion installations consisting of reciprocating engine and propeller interconnected by a line shaft and a propeller shaft which in regard to the one-noded torsional vibration characteristics may be treated as, or reduced to, an equivalent two-mass system in which the mass inertia, comprising the rotating plus half the oscillating mass inertia of the engine, is connected to the propeller mass inertia by the shafting, acting as a torsional spring. Especially when torsiographic records are evaluated, in the actual system under consideration the exciting torque is ensuing mainly from the engine, whereas the greater part of the damping torque is produced by the vibratory motion of the propeller. The assumption of proportionality with the free vibration form, therefore, is not quite true. An exact algebraic analysis leads to rather complicated formulas from which the effect of changing one or more of the variables is not easily visualized. As shown a vector analysis, however, provides a particularly clear picture of the interconnection between the physical constants of the system and the resulting movements. A vector diagram is developed from the equations in the paper. Certain characteristic points are discussed and equations for the absolute and relative reflections of the two masses are given and illustrated by curves. Finally the significance of the placing of the measuring points a torsiographic measurings are investigated.