Marine Ram-Type Steering Gear Details Load Transfer Features

Abstract

he article deals with steering gears, used on marine and river ships, namely with ram-type steering gears. Article topicality due to the fact that ship controllability and sailing safety depends of steering gears reliability. Reliability could be increased through the refinement of processes, which took place during the perception and transfer of load. Process of lateral force perception by plungers and guide beams is studied theoretically. It is shown that perception depends of gap size between plunger and sleeve and could pass in one, two or three stages. Those stages are characterized changing in the loading process plungers fixing conditions, and respectively plunger lateral load proposed to determinate by three design schemes. Received expressions for calculation ultimate gaps of «plunger-sleeve» pare landing, that gives the limits of application each of three design schemes. Ratios for determination load of plunger and guide beam are received trough consideration their joint deformation for each design schemes. On the example of YOOWON-MITSUBISHI YDFT-335-2 ram-type steering gear is shown that in new gear, where landing gap is minimal and conditioned by tolerances of plunger and sleeve diameters, guide beam can take only 2.0…6.5% of lateral force, which applied to it and plunger from tiller. In steering gear with partially worn out plunger and sleeve in time of rudder feather shifting from diametric plane to board (when α = 5…35º), guide beam could take 4.7…6.8% of lateral force. The source of origin significant loads on plungers in ram-type steering gears is application of sinus-type mechanism for transformation progressive plunger motion to rotating tiller motion. Decreasing lateral loads on plunger through using unloading guide beams, with considering low unloading percent is ineffective. Guide beams availability complicates steering gear construction, increasing number of friction surfaces and trough this complicates steering gear maintenance.

Marine Ram-Type Steering Gears Maintainability Increasing

“…Redundant constraints excluding and mechanisms improving concerning metallurgical, lifting, transport machines, diesels and its elements considered in plenty of papers [1, 6, 9-11, 13, 14], but improvement steering gears mechanisms dedicated less number of researches [7,8]. In mentioned works it is determined that guide beams presence in widely used steering gears constructions, which entered as rams unloading and around its own axis rotation excluding element is inexpedient because on its load capacity great influence makes gap between beam and ram footing connection.…”