A Torsionmeter of a New Design and Trial Results obtained with it

Abstract

In this paper the authors represent the principle, the mechanism, data of design and the results of calibrations of a newly designed torsionmeter which applied the “torsional magnets-striction effect” under an alternating magnetic field, and the results obtained on various kinds of sea trials with the new torsionmeters attached to the intermediate shafts of some twin-screw turbine steamers. This newly designed torsionmeter has the merits as follows:-
(1) It can record accurately the working torsion and numbers of revolution of each intermediate shaft continuously for a long time in the view of the operator
(2) No usages of special amplifier,
(3) It can record torsional vibration of each shaft.
(4) It works without regard to the direction of revolution and of the torsion of each shaft,
(5) It can make clear the time correlation between the changes of the torsion and the speed of revolution and the motion of the vessel or the handling of the main engines.
Attaching the torsionmeters of the new type to the intermediate shafts of three train ferry boats-twin screw turbine steamers-between Aomori and Hakodate, the authors and collaborators made various kinds of sea trials and obtained the following results in short.
(1) Continuous records of the torsion, numbers of revolution and the speed through the water not only on the measured mile course but also before and after of it, were obtained and it was made clear how they were changed during that period.
(2) The changes of the torsion, the speed of revolution of each shaft etc, during the turning trial were made clear.
(3) The changes of the torsion, the speed of revolution of each shaft, the ship speed, the steam-pressure in the high pressure turbine etc. during a backing trial were made clear. And the presumption made by Kinoshita and Nakajima in the previous paper read at the spring meeting of 1947 was verified that three maxima would appear in the working torsion (and thrust) of a shaft during the transition period of the change from going ahead to going astern or vice versa.
(4) Torsional vibration of each shaft were recorded.
(5) The shaft bearing and the sterntube losses ware measured and percentages of these losses to the power output were obtained.
From the the above mentioned results we can learn many new experimental facts. For instance, we can determine how long a ship must run in order to settle on a constant revolution, a constant torsion and a constant speed before she enters a measured mile course.