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ie | An Expert Study a the Work Done in Perfecting Installa- tions on the 3000-Ton Vessels--Tooth Design Was Changed - been circulated during the past few months, it might be con- cluded that geared turbine machinery, for the propulsion of ships, has been 'by no means an unqualified success and that there has been much diffi- culty not only in getting this ma- chinery to operate properly but also from the necessity of laying up ships for repairs. While some _ troubles have been encountered in actual serv- ice, these have not been more than are to be expected with any other types of machinery; particular con- sideration being given to the fact that the operating engineers' generally have not been familiar with what would otherwise be more reliable and economical apparatus. ' Publicity has been given to some troubles incidental to the getting into operation of the 5000-ton dead- weight cargo ships being built by the Submarine Boat Corp., Port New- ark, N. J. These troubles occurred while the machinery was in the hands of the builder, and in no case were they breakdowns which occurred after the vessels had put to sea. The trou- bles, it is to be conceded, were of a serious character inasmuch as they apparently embarrassed the shipbuild- ers seriously. They were the result of a combination of circumstances, _ mot least of which was the production of machinery in a new establishment with a new organization and with all the difficulties incidental to. wartime conditions. Nothing inherently new in the principles of design was em- ployed, in fact, every element had been in successful commercial opera- tion for many years. One of the troubles which bears _no relation whatsoever to workman- ship was the particular form of in- volute tooth employed, which had been found eminently satisfactory on a large number of land and marine installations, including cases where as much as 6000 horsepower was transmitted over a single pinion during a period of six years. It appeared, however, that for 'these slow-speed cargo ships, where a speed as low as 90 revolutions per minute was in- volved, this particular form of tooth did not lend itself to maintaining an Fi: various reports that have The author is chief engineer of the Westingh Machine Works, ae East Pittsburgh, Pa. was carried out. oil film between the tooth surfaces as effectively as other forms of in- volute teeth. While this was a sim- ple matter, readily corrected, it un- fortunately was not in evidence at the commencement of the trouble be- cause so many other things which 'were the result of bad workmanship, were discovered, one after the other. These matters would probably all have been eliminated, however, had proper tests been carried out in the 'builder's works, which under ordinary circumstances, would have been done. In this instance, however, the build- ers felt) that all that. could' be done toward accelerating the production of 'the machinery during the urgency of war needs was of more paramount im- port, or that instead of carrying out full speed trials, they were content to operate the gears by means of electric motors, imposing upon them the full-load tooth pressures but at approximately 5 per cent of the full load revolutions. This. served to de- termine that the tooth contacts oc- curred throughout the whole axial length of the gears. Gear Teeth Cause Trouble The first of the vessels to be built was the Acawam, which was ready for dock trial about the middle 'of September, 1918. Difficulties were at once encountered in getting the .con- denser auxiliaries in operation .on- ac- count of the faulty pipe fitting in the vessel. The tooth surfaces of the gears became injured as soon as any mate- rial load was imposed on them. It was immediately concluded that the lubrica- tion was inadequate and some changes were made to the lubricating system, which as subsequent events proved, had nothing to do with the trouble. How- ever, after the tooth surfaces were smoothed up, the gears operated in a satisfactory manner, although, of course, since the vessel was light, full power could not be imposed on her machin- ery. The vessel proceeded to New York in order to be loaded for her first voy- age. The loading, however, could not be carried out on account of certain of the holds becoming filled with fuel oil, and on this account the vessel lay in the harbor for a considerable period, during which time a river trial On this trial machin- 348 By Francis Hodgkinson ery operated in an entirely satisfac- tory manner. The vessel then proceeded on a loaded sea trial toward the last of October, and after steaming for two hours, with everything apparently operating well, heating of the machinery indicated trou- ble and there occurred further abrasion of the tooth surfaces. At the conclu- sion of the trial, a careful examination of the machinery was made and while subsequent events proved conclusively that the scoring of the surfaces gave the necessary relief to the tooth form, and that the gears would have operated perfectly well, provided no other de- fects were present,, yet on account of the many apprehensions concerning the machinery held by people other than the builders, it was considered expedi- ent to remove the gears completely and replace them with others. Examination at that time showed that the pinion bearing was badly scored, which was the result of improper fitting of the bearings, and this was considered by some to have been the cause of scoring of the teeth. Occurrences of 'this charcter led to careful examination as _ to probable causes, and, as_ stated before, many things were discovered, particularly faulty workmanship, which concealed the prin- cipal defect, the form of _ tooth. In these examinations, the oiling sys- tem was subjected to careful considera- tion, and with the installation of new gears unquestionable improvements were 'made in the arrangement for supply- ing oil to the teeth. While it is now evident that lack of oil had nothing to do with the scoring, improvements were made to the machinery by altering the oiling system. The new gear was one of many. intended for other ships, and was placed in service without any detailed examination of its parts. The installation of the new gear re- quired an inordinate amount of time, the work having been carried out par- tially at a dock and partially while the ship was moored in the river with days of delay while in need of a crane. It was not until the end of November that the vessel was again ready for trial. In 'setting these gears, the position of the turbine had to be entirely changed, which indicated at once that the align- ment of the original gears had been wrong. This in itself would account for the cutting of the tooth surfaces.