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    <title>Transport Research International Documentation (TRID)</title>
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    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>State of the Art in High-Load Multi-Rotational Disc Bearings: Design, Practice, and Future Needs</title>
      <link>https://trid.trb.org/View/2767309</link>
      <description><![CDATA[High-load multi-rotational (HLMR) disc bearings have been available domestically since the 1970s. In the decades since, they have become an increasingly attractive option for use when bridges require higher rotations or loads than typical elastomeric bearings can transfer. These bearings can be designed for rotations higher than 0.1 rad, translate more than 36 in., transfer vertical loads in excess of 15,000 kips, and horizontal loads in excess of 1,000 kips. Moreover, unlike pot bearings, a common alternative to disc bearings, they have no seals that can leak. Although the system was initially patent-protected, about ten domestic manufacturers have developed product lines since the patent expired in the mid-1990s. Nevertheless, research on these systems has largely taken place outside the public domain. This review paper examines past work on disc bearings, existing research, US standards, state departments of transportation (DOTs) design manual language, and DOT inspection procedures; identifies research gaps; and proposes future research needs on disc-bearing behavior, design, and inspection. Altogether, DOT requirements vary greatly from state to state, and the American Association of State Highway and Transportation Officials Load and Resistance Factor Design provisions are brief in comparison to other HLMR systems. This leaves the design of disc bearings in the hands of manufacturers and limits the resources of state DOT personnel for design validation or assessment. Although this system has many advantages, additional research is necessary to better understand the behavior and design of these bearings and standardize system reliability.]]></description>
      <pubDate>Wed, 26 Aug 2026 09:21:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/2767309</guid>
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    <item>
      <title>Vibration reduction and energy harvesting on the ship thrust bearing unit excited by a measured shaft longitudinal vibration using NES-GMM</title>
      <link>https://trid.trb.org/View/2330329</link>
      <description><![CDATA[Considering the longitudinal vibration of the ship shaft system, there are disadvantages such as small damping bandwidth of passive control and complicated design of active control. An NES-GMM is proposed by the combination of nonlinear energy sink (NES) and giant magnetostrictive material (GMM) for the vibration reduction and energy harvesting of the ship thrust bearing unit. The vibration reduction effect and energy harvesting of the proposed NES-GMM device are analyzed based on actual measured longitudinal excitation as input signals. The vibration behavior including the transient and harmonic response of the thrust bearing and NES device are calculated. Meanwhile, the kinetic, potential, and damping energies of the primary system and the electrical and magnetic energy harvested by the NES-GMM are obtained. Moreover, the effects of mass, damping, and stiffness of the NES structure are also discussed over a range of rotational speeds. The research demonstrates that energy is irreversibly transferred from the primary system to the NES system. Additionally, more energy absorption and better vibration reduction of the NES-GMM device will be achieved with larger mass and damping of the NES.]]></description>
      <pubDate>Tue, 20 Feb 2024 09:25:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/2330329</guid>
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    <item>
      <title>Use of impedance mismatch in the control of coupled acoustic radiation of the submarine induced by propeller-shaft system</title>
      <link>https://trid.trb.org/View/1585740</link>
      <description><![CDATA[The three-dimensional sono-elasticity method recently developed by Zou et al. [1,2] is employed to model the coupled acoustic radiation of the submarine induced by the propeller-shaft system. Vibration isolators are widely used to control the vibration and acoustic radiation induced by machines. Nevertheless, they are not seen in the control of propeller-shaft-hull coupled vibration and acoustic radiation induced by the propeller-shaft system. The relationship between the stiffness of isolator for shaft and the characteristic frequency of coupled acoustic radiation is clearly identified. The mechanism of how the stiffness of isolator for shaft affects the coupled acoustic radiation is discussed. Furthermore, the influence of the input impedance of the base for thrust bearing upon the coupled acoustic radiation is investigated. A new vertically symmetrical base with high input impedance for thrust bearing is proposed. To realize impedance mismatch, the isolator with low stiffness and the new base for thrust bearing are applied to the propeller-shaft-hull system. The coupled acoustic radiation of the submarine induced by the propeller-shaft system is effectively reduced.]]></description>
      <pubDate>Fri, 22 Mar 2019 10:04:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1585740</guid>
    </item>
    <item>
      <title>Axial Thrust Bearing Influence on the Dynamic Behaviour of an Elastic Shaft</title>
      <link>https://trid.trb.org/View/1105485</link>
      <description><![CDATA[This paper presents the nonlinear dynamic behavior of a flexible shaft. The shaft is mounted in two journal bearings and the axial load is supported by a hydrodynamic thrust bearing. The coupling between the axial thrust bearing behavior and the bending vibrations of the shaft is studied in particular. The shaft is modeled with typical beam finite elements. The dynamic behaviors of the fluid supports are considered as nonlinear. The dynamic behavior is analyzed using an unsteady time integration procedure. The paper shows the coupling between the axial dynamic behavior and the bending vibrations of the shaft.]]></description>
      <pubDate>Wed, 20 Jul 2011 07:26:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/1105485</guid>
    </item>
    <item>
      <title>MARINE ADVANCED PLANETARY TRANSMISSION PROGRAM DESIGN, MANUFACTURE AND TEST OF SYSTEM "A" AND "F", FINAL REPORT</title>
      <link>https://trid.trb.org/View/400054</link>
      <description><![CDATA[This report covers engineering design, procurement and testing of large marine planetary transmissions at the Curtiss-Wright Wood- Ridge Facility.  This contract resulted from earlier studies conducted by Curtiss-Wright which indicated that such designs could result in significant savings in the area of manufacture, installation, maintenance and operations when embodying the principles of modular construction and hardened and ground gearing. The units selected for development represent the final reduction stages for a total ship system and include the propeller thrust bearings as an integral part of the output shafts. The two units, System "A" of 40,000 SHP @ 105 RPM single shaft output and System "F" of 60,000 SHP @ 105 RPM contrarotating shafts output, were successfully tested for 450 hours up to 44,000 SHP, and proved satisfactory for ship installation.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/400054</guid>
    </item>
    <item>
      <title>CENTENARY YEAR CONFERENCE</title>
      <link>https://trid.trb.org/View/407067</link>
      <description><![CDATA[Marine thrust bearings have been developed for naval use from the earliest days of screw propulsion, through multicollar thrust blocks, to the present generations of tilting pad bearings. Following the introduction of the Michell thrust bearing to marine applications in the years around the First World War, there was a long period of relative stability in bearing technology. During this time, there were few design changes of major interest. In the past 20 years, however, a much wider range of choices have become available. Bearing casings, although retaining similar internal arrangements, are now designed to suit different shipboard machinery layouts. The increasing requirements for submersible vessels to operate continuously at great depth and at very slow speeds, have led to methods for enhancing the load-carrying capacity of bearings to a maximum level that still allows for effective hydrodynamic lubrication. Lubrication systems themselves have been developed, with self-contained thrust bearings becoming a realistic choice in some cases. Possible future bearing developments include the use of active magnetic bearings to absorb at least part of normal thrust loadings.]]></description>
      <pubDate>Thu, 21 Jul 1994 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/407067</guid>
    </item>
    <item>
      <title>MARINE GEARING</title>
      <link>https://trid.trb.org/View/151657</link>
      <description><![CDATA[This book outlines the many advances which have taken place in the development of modern marine gearing and updates gear design, construction, installation and operation. Comprehensive treatment is given to gear hobbing and gear grinding machines; tooth loading and distribution corrections; results of tests and experience with material combinations; single and double-helical gears; gearing configurations; types of epicyclic gears; applications to single and multiple diesel engines; reversing with steam turbines, diesel engines and gas turbines; reversing with epicyclic gearing; SSS clutches; MAAG synchronous clutch coupling; gear couplings; lubrication systems; adjustable bearing housings; journal, main wheel and thrust bearings; vibration; kinematics of tooth meshing; oil/material combinations; pitting and tooth breakage; gear damage; noise.]]></description>
      <pubDate>Wed, 08 Oct 1980 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/151657</guid>
    </item>
    <item>
      <title>LONGITUDINAL STIFFNESS ANALYSES FOR THE PROPULSION SHAFTING SYSTEMS OF THE POLAR CLASS ICEBREAKERS</title>
      <link>https://trid.trb.org/View/154051</link>
      <description><![CDATA[During the first and second seasons of its deployment in the Antarctic region, the new United States Coast guard Icebreaker, POLAR STAR, experienced longitudinal vibration problems in the center and wing shaft systems while breaking ice.  To minimize and hopefully eliminate the vibratory responses, the USCG initiated several investigations, some of which will be treated in this paper.  One of the items under study concerned the axial stiffness of the shafting systems that is contributed by the thrust bearings, their housings and the foundations on which they rest.  Aside from model test studies, numerical assessments were made of these stiffnesses using finite element methods and other techniques.  In all, three sets of thrust bearing foundations were analyzed in great detail.  These include the original (as-built) foundations, a modified configuration that was subsequently adopted for the wing shafts of the POLAR STAR and POLAR SEA, and a reinforced configuration that represents an upper bound on the foundation stiffness that can be achieved without drastic changes in shafting system architecture.  The bulk of the paper deals with the development of the three finite element models that were exercised with the NASTRAN Computer Program to predict the stiffness of the three foundation designs. Various considerations that arise in model formulation are treated in some detail, especially the influence of chosen boundary conditions on the final answers.  A simplified procedure is next outlined and used for estimating the stiffness of the thrust bearing itself.  The estimate is based upon the use of simple structural models whose flexibilities are summed to get the net system flexibility. The results of all the calculations are reviewed in light of the broader objectives of the overall program and recommendations are given for further investigations that will aid in the understanding of the Icebreaker vibration problems.]]></description>
      <pubDate>Thu, 26 Jun 1980 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/154051</guid>
    </item>
    <item>
      <title>THE NEW HDW-SIMPLEX-HL THRUST BEARING</title>
      <link>https://trid.trb.org/View/74368</link>
      <description><![CDATA[The Howaldtswerke-Deutsche Werft Simplex-HL tilting-pad thrust-bearing, patented in Germany and other countries, is now fitted in a number of ships, mostly large tankers, and has proved itself under severe conditions in trials and in service.  The bearing is also suitable for thrust applications in other types of high-power machinery.  The Author of HDW, describes the construction and operation of this bearing in some detail, with particular reference to the improved type of tilting pad that has been developed, the method of assembly and dismantling of the bearing, and the lubrication system (which can be a part of the main-engine or other sytem, or can be integral with the bearing assembly).  Order from: BSRA as No. 48,401.]]></description>
      <pubDate>Sat, 19 Aug 1978 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/74368</guid>
    </item>
    <item>
      <title>STATIC AND DYNAMIC PERFORMANCE OF AN INFINITE STIFFNESS HYDROSTATIC THRUST BEARING</title>
      <link>https://trid.trb.org/View/53584</link>
      <description><![CDATA[A novel form of variable hydrostatic restriction is proposed which will automatically achieve a high, infinite or negative static stiffness over a substantial load range. The restrictor is formed between the bearing body and a spring mounted conical plug.  The steady state performance is analyzed and design curves presented which are valid for any cone angle from zero, i.e., fixed clearance, to 90 deg which is the normal diaphragm restrictor.  The dynamic response to forced sinusoidal vibrations is examined in conventional vibration analysis form and it is found that the restrictor system may be designed to act as a vibration absorber.]]></description>
      <pubDate>Mon, 15 Aug 1977 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/53584</guid>
    </item>
    <item>
      <title>EXPERIMENTAL INVESTIGATION OF THE EFFECT OF PROPELLER BLADE PITCH ON PROPELLER-PRODUCED UNSTEADY BEARING FORCES AND MOMENTS</title>
      <link>https://trid.trb.org/View/48960</link>
      <description><![CDATA[Experimental results are presented to show the effect of pitch-diameter ratio on propeller-produced unsteady loads. Eight three-bladed propellers with changes of equal increments of pitch resulting in pitch-diameter ratios from 0.58 to 1.75 were tested in three-cycle and four-cycle wake screens. The data indicated that, in general, for the same thrust loading coefficient C sub Th, the unsteady thrust and bending moments tend to decrease with increasing pitch whereas the torque increases and the side forces change negligibly. However, it is impracticable to reduce unsteady thrust by altering pitch.]]></description>
      <pubDate>Tue, 31 May 1977 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/48960</guid>
    </item>
    <item>
      <title>SOME CONSIDERATIONS ON SHAFT ALIGNMENT OF MARINE SHAFTINGS</title>
      <link>https://trid.trb.org/View/51964</link>
      <description><![CDATA[A review of some of the more dominant external factors that influence the shaft alignment in service is given.  The effects of draught alterations, thermal influences, eccentric propeller thrust, thrust bearing tilting and bearing flexibility are discussed.  Some further aspects of shaft alignment are also dealt with, such as the connection between requirements to alignment versus whirling vibrations, the importance of considering angular deflection between shaft and aft stern tube bearing, and alignment in dock.  It is concluded that these factors must be taken into consideration in the design analysis if one is to ensure an approach to the concept of "optimum alignment".]]></description>
      <pubDate>Wed, 27 Apr 1977 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/51964</guid>
    </item>
    <item>
      <title>ISOLATION OF PROPELLER THRUST FLUCTUATION TO SHIP STRUCTURES BY AIR SPRINGS</title>
      <link>https://trid.trb.org/View/51820</link>
      <description><![CDATA[The thrust fluctuation of a propeller is an important part of the ship's vibration exciting force.  The so-called air spring thrust block, vibration isolation equipment using air springs combined with height control valves was invented to isolate the thrust fluctuation.  An air spring thrust block, the natural frequency of which was designed to be one- sixth of the frequency of thrust fluctuation at a normal operating speed, was installed aboard a ship 30 m long to measure the transmissibility of the thrust fluctuation at sea.  As a result of the measurement, it was proven that while the transmissibility of the thrust itself was 100%, the transmissibility of thrust fluctuation was under 4%, where measured values and theoretically calculated values agreed well with each other.  Furthermore, the air spring thrust block for ships driven by the geared diesel engine was so designed as to ensure its applicability.  To avoid uncomfortable vibration, many kinds of air springs have already been applied to railway coaches and other vehicles with successful results; thus it can be expected that the air spring thrust block will also result in a more comfortable ride on ships.]]></description>
      <pubDate>Wed, 13 Apr 1977 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/51820</guid>
    </item>
    <item>
      <title>REDUCTION GEAR DAMAGES RELATED TO EXTERNAL INFLUENCES</title>
      <link>https://trid.trb.org/View/35353</link>
      <description><![CDATA[Increases in the tonnage of tankers, LNG carriers, and container vessels accompanied by increases in the powers of propulsion plants have led to incompatibility between the deflections of the hull and the line-shafting stiffness. This incompatibility is at the origin of the harmful influences exerted on main gears by external effects, including: deformability of the hull girder and double-bottom structure; flexibility of thrust foundations and rocking of thrust bearings; improper shafting and turbine alignment; and thermal expansion.  Strain-gage, displacement, and vibration measurements on the journals of shafting and gears have given evidence of the existence of these harmful external influences.  The solution adopted for different types of gearing and thrust bearing designs have produced positive results.  Previous experience together with modern finite-element calculation techniques on speedy computers have made it possible to proceed with preliminary calculations that furnish the alignment data for satisfactory installation of main gears and shafting. These modern calculation methods have served to explain some phenomena recently encountered on gears and shafting of VLCC vessels which were caused by the influence of ship's structure.]]></description>
      <pubDate>Wed, 03 Dec 1975 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/35353</guid>
    </item>
    <item>
      <title>PERFORMANCE FACTORS FOR CIRCULAR, HYDROSTATIC, GAS LUBRICATED THRUST BEARINGS. PART III, RING THRUST BEARINGS</title>
      <link>https://trid.trb.org/View/18133</link>
      <description><![CDATA[A general design procedure for ring type, hydrostatic, gas thrust bearings has been derived.  Dimensionless load and flow factors have been calculated for a wide range of bearing parameters using a conformal transformation procedure proposed by Mori and Yabe.  These factors are combined with empirical correlations for the bearing entry losses to provide a simple, convenient design procedure. The predicted performances are compared with a number of experimental studies.  The results indicate the procedure is adequate for all normal design requirements.]]></description>
      <pubDate>Tue, 07 May 1974 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/18133</guid>
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