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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <language>en-us</language>
    <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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      <title>Vehicle Deceleration Residual Energy Generation Isolated Energy Supply System for High-Speed Toll Station: Energy-Saving Deceleration Belt Coupled with “Piezo-Magnetic Fluid” Power Generation</title>
      <link>https://trid.trb.org/View/2613125</link>
      <description><![CDATA[Against the background of energy conservation and emissions reduction, the recycling and utilization of surplus energy has become a hot topic studied by scholars at home and abroad. As a mandatory speed-regulating traffic facility, speed bump has designed a variety of residual energy recovery forms, like mechanical vibration energy recovery speed belt, electromagnetic vibration energy recovery speed belt, hydraulic vibration energy recovery speed belt, and piezoelectric vibration energy recovery speed belt. However, at present, the research on the above residual energy recovery speed bump is mainly focused on the structural design, for the electromagnetic vibration energy recovery speed bump and piezoelectric vibration energy recovery speed bump how to comprehensive utilization and its system power generation mechanism is rarely studied. In this paper, an isolated power supply system (IPSS) of vehicle deceleration residual energy for a high-speed toll station is designed. The IPSS takes the toll station as a relatively independent power supply system to collect, transform, and utilize the electric energy of a specific place and solves the problems of energy waste, power shortage, and environmental pollution caused by thermal power generation in daily life through energy-saving speed bumps. It can also realize self-sufficiency in power consumption of highway toll stations and can provide a theoretical basis and reference value for the future development of low-carbon emissions causes and the design of advanced high-speed reducers.]]></description>
      <pubDate>Fri, 20 Feb 2026 15:28:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/2613125</guid>
    </item>
    <item>
      <title>Investigation of Fatigue Failure Mechanisms in High-Pressure Hydraulic Pipes of Power Steering Systems</title>
      <link>https://trid.trb.org/View/2663464</link>
      <description><![CDATA[The high-pressure steering hose in a hydraulic steering system carries pressurized hydraulic fluid from the power steering pump to the steering gear (or steering rack). Its main function is to transmit the force generated by the pump so that the hydraulic pressure assists the driver in turning the wheels more easily. The high-pressure hydraulic pipeline in the power steering system is a vital component for ensuring optimal performance. During warranty analysis, leakage incidents were observed at the customer end within the warranty period. The primary factors contributing to these failures include pipe material thickness, material composition, mechanical properties, and engine-induced vibrations. This study investigates fatigue-related failures through detailed material characterization and Computer-Aided Engineering (CAE) based on real world usage road load data collected. The objective is to identify the root causes by examining the influence of varying pipe thickness on fatigue life.The investigation discovered that crack initiation predominantly occurred on the concave side of bent pipe sections, specifically on the engine-side high-pressure steering line, which is connected to the power steering pump mounted on the engine. Fracture surfaces exhibited characteristics consistent with fatigue failure, with crack propagation primarily oriented longitudinally along the pipe. The highest tangential stresses were observed on the out word, resulting from the combined effects of internal hydraulic pressure and vibrational loads. Fatigue cracks originated from the inner surface and propagated outward under cyclic stresses induced by pressure fluctuations and engine vibrations during vehicle operation on the road.Computer-Aided Engineering (CAE) simulations indicated that the failure mechanism was primarily attributable to an incorrect material thickness selection during the development phase. Modifications to the pipe design, including increased material thickness, were implemented, leading to improved performance in subsequent testing. The high-pressure hydraulic pipeline exhibits decreased failure rates and improved reliability and durability following the implementation of the revised design.]]></description>
      <pubDate>Mon, 02 Feb 2026 16:36:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2663464</guid>
    </item>
    <item>
      <title>Low-Speed Steering Returnability Analysis and Improvements through Mathematical Modeling and CAE Simulation for SUV</title>
      <link>https://trid.trb.org/View/2663437</link>
      <description><![CDATA[In driving, steering serves as the input mechanism to control the vehicle's direction. The driver adjusts the steering input to guide the vehicle along the desired path. During manoeuvres such as parking or U-turns, the steering wheel is often turned fully from lock to lock and then released. It is expected that the steering wheel quickly returns to its original position. Steering returnability is defined as the ratio of the difference between the steering wheel position at lock to lock and the steering wheel angle after 3 seconds of release, to the steering wheel angle at the lock position, under steady-state cornering conditions at 10 km/h. Industry standards dictate that the steering system should achieve 75% returnability under these conditions within 3 seconds.Achieving proper steering returnability characteristics is a critical aspect of vehicle design. Vehicles equipped with Electric Power-Assisted Steering (EPS) systems can more easily meet returnability targets since the electric motor in EPS can apply torque in the opposite direction, helping the steering wheel return to its neutral position after the driver releases it. However, SUVs, due to their higher axle weights and greater steering effort requirements, necessitate a high assist force. Meeting these demands with EPS often requires a larger motor, which poses packaging challenges. Consequently, most large SUVs utilize hydraulic-assisted power steering systems, which employ a hydraulic pump and fluid lines to assist the steering mechanism. However, hydraulic systems can only deliver torque in one direction, and they are generally more complex and less efficient compared to EPS.In this paper, we present a novel methodology to analyse and improve steering returnability performance. This approach includes mathematical modelling, Computer-Aided Engineering (CAE) simulations, friction analysis, and targeted design modifications. The proposed methodology is validated through physical testing at the vehicle level to ensure compliance with returnability targets]]></description>
      <pubDate>Mon, 02 Feb 2026 16:36:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/2663437</guid>
    </item>
    <item>
      <title>Adaptive event-triggered robust front wheel steering angle control strategy for a novel electro-hydraulic composite steer-by-wire</title>
      <link>https://trid.trb.org/View/2625536</link>
      <description><![CDATA[The steer-by-wire (SBW) system is an important foundation for the realisation of self-driving trucks. However, the traditional SBW cannot meet the steering performance requirements of self-driving trucks due to power limitation. Therefore, this paper proposes a novel electro-hydraulic composite steer-by-wire (EH-SBW) system. The linear time-varying model and energy-saving characteristics of the new steering system are analysed. In order to improve the angle tracking accuracy and reduce the energy consumption of the novel steering system, an adaptive event-triggered robust front wheel steering angle control strategy is proposed in this paper. This strategy consists of two parts: the interval type-2 (IT2) fuzzy observer and the event triggered tube model predictive control (ET-TMPC). Fuzzy rules and primary membership functions based on the air dissolution characteristics in the hydraulic cylinder are designed. IT2 fuzzy observer estimates the nominal bulk modulus and bulk modulus perturbation bounds of the hydraulic fluid based on the fuzzy rules. ET-TMPC calculates the control volume and execution step size based on the event triggering mechanism and IT2 fuzzy observer to improve the angle tracking accuracy and reduce the computational cost. The EH-SBW test bench is built to verify the feasibility of the proposed strategy. The experiments show that compared with the existing control strategies, the proposed method not only improves the angle tracking accuracy and energy consumption performance of the EH-SBW, but also saves the computational resources of the controller.]]></description>
      <pubDate>Tue, 02 Dec 2025 09:58:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2625536</guid>
    </item>
    <item>
      <title>Study of Power Optimization Using Electrical Driven Fan in Off-Highway Diesel Engine Cooling System</title>
      <link>https://trid.trb.org/View/2623832</link>
      <description><![CDATA[Internal combustion (IC) engines experience several parasitic losses at the vehicle level, including those from cooling fans, hydraulic pumps, air compressors, and alternators. These losses limit the available output power for various applications. By replacing a conventional mechanical or hydraulic fan—typically driven by the engine crankshaft or hydraulic motor—with an electrically operated fan, engine frictional losses (fan drag) can be reduced, resulting in a gain in power. The fuel conserved due to the absence of fan drag contributes to usable power for applications. Mechanical fans operate at a fixed drive ratio that is directly proportional to engine speed, while hydraulic fans rely on a hydraulic motor, drawing power from the engine's alternator. In contrast, electric fans can run at constant speeds, independent of engine RPM, providing higher airflow at maximum torque speeds, which mechanical fans cannot achieve. The cooling performance of the engine remains uncompromised, as the electric fan can be strategically positioned in the optimal airflow zone through computational fluid dynamics (CFD) analysis. Unlike mechanical fans, which operate in a single direction, both hydraulic and electric fans can rotate clockwise or counterclockwise. Electric fans have the added advantage of functioning with reverse polarity in the electrical circuit. This capability allows them to act as blowers, helping to keep heat exchange cores clear of debris during dusty applications for the construction machines on the site, which can restrict airflow when using a conventional puller-type fan. The replacement of electric fans resulted in a significant power saving which resulted in lesser load on hydraulic oil cooler in the case of hydraulic fan.]]></description>
      <pubDate>Thu, 13 Nov 2025 16:26:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2623832</guid>
    </item>
    <item>
      <title>Integration and Evaluation of Different Thermal Loops through Simulation for Improved Defrost and Range of an Electric Truck</title>
      <link>https://trid.trb.org/View/2623812</link>
      <description><![CDATA[The rapid advancement in thermal management for electric vehicles (EVs) is driven by the need to reduce battery load and enhance EV range. Unlike conventional platforms, EV thermal management is complex due to temperature sensitivity and the numerous components involved. Powertrain components, such as the motor and transmission, operate at higher temperatures, while the battery and passenger cabin require distinct thermal conditions. This necessitates a carefully modelled thermal layouts that considers the diverse thermal needs of each component.The primary objective of this study is to improve the existing thermal layout of EVs, aiming for a more efficient design and evaluating its benefits through simulation. Utilizing the 1D commercial software GT-SUITE, the research integrates different layouts of EV’s and study the hydraulic and thermal feasibility. Integrations are based on operating temperatures, flow, and pressure requirements, while ensuring thermal comfort in the cabin and preventing deration. Design optimizations through thermal simulations demonstrate benefits in terms of battery power consumption under various environmental conditions. While integrating energy-saving loops is not new, their impact varies across different vehicles. Quantifying these benefits is vital for assessing the risk and potential advantages for end-users. Computational Fluid Dynamics (CFD) helps in identifying crucial design changes and provides quantifiable numbers in power consumption without the need for actual testing, saving time and cost during the initial design phase.]]></description>
      <pubDate>Thu, 13 Nov 2025 16:26:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2623812</guid>
    </item>
    <item>
      <title>Fuel cell air compressor concepts to enhance the efficiency of FCEV</title>
      <link>https://trid.trb.org/View/2612941</link>
      <description><![CDATA[The thermal management system and the balance-of-plant (BoP) in fuel cell electric vehicles (FCEV) are characterized by a particularly high level of complexity and a number of interfaces. Optimizing the efficiency of the overall vehicle is of special importance to maximize the range and increase the attractiveness of this technology to customers. This paper focuses on the optimization potential of the air supply system in the BoP, whereby the charging concepts of the electric supercharger (ESC) and the electrically assisted turbocharger (EAT) as well as the integration of water spray injection (WSI) at the compressor inlet are investigated in the framework of an FCEV complete vehicle co-simulation. As a benchmark for the integration of these optimization measures, the complete vehicle co-simulation is designed for a fuel cell electric passenger car of the current generation. Here, thermo-hydraulic fluid circuits in the thermal management software KULI are coupled with mathematical-physical models in MATLAB/Simulink. Applying advanced simulation methodologies for the components of fuel cell, powertrain and vehicle cabin enables the mapping of the effects of realistic operating conditions on the FCEV characteristics. The EAT offers the advantage over the ESC that, due to the arrangement of an exhaust gas turbine, a part of the exhaust gas enthalpy flow downstream of the fuel cell stack can be recovered, which reduces the electrical compressor drive power. Moreover, an additional reduction of this power consumption can be achieved by WSI, as the effect of evaporative cooling lowers the initial compression temperature. For analysis and comparison, these concepts are again modeled with high degree of detail and integrated into the benchmark overall vehicle simulation. The results indicate considerable reductions in the electric compressor drive power of the EAT compared to the ESC, with noteworthy potential for reducing the vehicle’s hydrogen consumption. At an operating point in Worldwide harmonized Light Duty Test Cycle (WLTC) under 35 degrees C ambient temperature and 25 % relative humidity, the electrical compressor drive power shows a reduction potential of −40 %, which corresponds to a vehicle-level hydrogen consumption reduction of up to −3 %. In addition, the results also highlight the effect of the WSI in both charging concepts, whereby its potential to reduce the hydrogen consumption on the overall vehicle level is relatively small. In WLTC, at 35 degrees C ambient temperature and 25 % relative humidity, the compressor drive power reduction potential for ESC and EAT averages −5 %, while the effect on hydrogen consumption is only around −0.25 %.]]></description>
      <pubDate>Thu, 30 Oct 2025 13:27:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2612941</guid>
    </item>
    <item>
      <title>The Method of Thermal Calculation of the Aircraft Hydraulic System, Taking into Account Heat Losses at the Power Unit</title>
      <link>https://trid.trb.org/View/2407949</link>
      <description><![CDATA[In this paper, the authors propose the method for thermal calculation of the hydraulic system of a combat aircraft. This method takes into account the heating of hydraulic fluid in spool valves of control system actuators, depending on external load on actuators and the control surfaces slew rate. In contrast to the existing methods, the change in pump heat rejection is determined depending on the aircraft engine rotor speed.]]></description>
      <pubDate>Mon, 14 Jul 2025 12:53:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/2407949</guid>
    </item>
    <item>
      <title>Detection of Airplane Cabin Air Quality Events from Engine Bleed Air Contaminants: Data Management Plan</title>
      <link>https://trid.trb.org/View/2550836</link>
      <description><![CDATA[The purpose of this multi-year, multi-phase airplane cabin air quality research study was to: (1) Identify and measure levels of engine and auxiliary power unit bleed air contaminants; (2) Identify sensor technologies to detect/provide warning(s) of bleed air contaminant events; (3) Identify techniques to minimize airplane diversions from smoke, odor, fume events; and (4) Assess potential health-related risks of human exposure (i.e., passengers and flight/cabin crew) to chemicals generated during contaminated air events. Phase 1 work assessed the current state of knowledge of engine bleed air/cabin air contamination events and evaluated the current state of sensor technologies that could be used to detect airplane engine bleed air/cabin air contaminants. Phase 2 work involved static aircraft engine stand tests and ground-based, on-aircraft tests. Phase 2 tests assessed the capability of current, commercial off-the-shelf sensors to detect bleed air contaminants resulting from engine oil, hydraulic fluid, and deicing fluid, and included the collection and chemical analysis of engine bleed air contaminants resulting from engine oil, hydraulic fluid, and deicing fluid. Phase 3 work resulted in the toxicological review and interpretation of the chemical sample data to examine the potential health-related risks of human exposure to engine bleed air contaminants resulting from engine oil, hydraulic fluid, and deicing fluid. The overall study produced multiple data sets and technical reports on sensor technology performance, chemical analyses of engine bleed air contaminants, and a toxicological assessment of the potential health effects of engine bleed air contaminants on passenger and flight/cabin crew.]]></description>
      <pubDate>Thu, 05 Jun 2025 11:59:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2550836</guid>
    </item>
    <item>
      <title>Indirect Blocked Force Measurement of a Hydraulic Power Pack for Structural Vibration Transmission into an Airframe</title>
      <link>https://trid.trb.org/View/2552165</link>
      <description><![CDATA[Centralization of electrically driven hydraulic power packs into the body of aircraft has increased attention on the noise and vibration characteristics of the system. A hydraulic power pack consists of a pump coupled to an electrical motor, accumulator, reservoir, and associated filter manifolds. In previous studies, the characteristics of radiated acoustic noise and fluid borne noise were studied. In this paper, we focus on the structure-borne forces generated by the hydraulic pump characterized through blocked force measurements. The blocked force of the pump was determined experimentally using an indirect measurement method. The indirect method required operation with part under test fixed to an instrumented receiver structure. Measured operational accelerations on the receiver plate were used in conjunction with transfer function measurements to predict the blocked forces. Blocked forces were validated by comparing directly measured accelerations to predicted accelerations at positions on the receiver plate that were not used for the inverse calculation. To build further confidence in the results, two receiving structures were used to calculate the blocked forces and blocked forces were compared. The determined blocked forces can be used by aircraft OEM’s for further acoustic evaluation.]]></description>
      <pubDate>Tue, 13 May 2025 10:11:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/2552165</guid>
    </item>
    <item>
      <title>Modeling and Evaluation of Fluid Flow Resistance Characteristics of the Cooling Channel in the Aircraft Oil-Cooled Electric Machine</title>
      <link>https://trid.trb.org/View/2511799</link>
      <description><![CDATA[Oil cooling technique is one of the important ways to reduce the temperature rise and enhance the power density of aircraft electric machines (EMs). However, the high viscosity of the oil leads to high flow resistance, which may reduce the efficiency of the hydraulic system and damage the components. This article conducts research on the flow resistance characteristics of cooling channels. First, considering computational efficiency and accuracy, the influence of mesh type, size, and boundary layers on the cell count and calculation results is compared and summarized. Then, computational fluid dynamics (CFD) models for the series cooling channel and split-flow cooling channel are established. Another split-flow method is explored to optimize the cooling channel. Based on CFD and theoretical formulas, the influence mechanism of channel type and flow rate on flow resistance is revealed. Further, the heat-pressure ratio (HPr) is defined as an indicator to evaluate the heat dissipation capability of cooling structures. Finally, the pressure test models are constructed by 3-D printing. The experiments verify the correctness of analysis. The optimization methods can reduce flow resistance by 80.4% and increase heat transfer coefficient (HTC) by 44% at the same pressure. The HPr can serve as a reference for evaluating cooling structures.]]></description>
      <pubDate>Wed, 23 Apr 2025 11:54:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/2511799</guid>
    </item>
    <item>
      <title>Design and Analysis of a High-Speed Wet-Type Fault-Tolerant Permanent Magnet Motor Considering Oil Frictional Loss for Aerospace Electrohydrostatic Actuator Application</title>
      <link>https://trid.trb.org/View/2511708</link>
      <description><![CDATA[This article proposes a new high-speed wet-type fault-tolerant permanent magnet synchronous motor (WFTPMSM) for aerospace electrohydrostatic actuator (EHA) application, which can solve the rotating oil seal issue of the EHA via the motor stator and rotor all immersed in hydraulic oil. The topological structure of the five-phase WFTPMSM is first proposed, in which the flux-intensifying rotor is used to improve the power density. The analytic expression of the oil frictional loss is proposed, while the multiphysics model of the WFTPMSM is established to accurately calculate the electromagnetic–thermal fluid performance. The oil frictional loss and thermal behavior are systematically analyzed. Finally, a 15-kW 20 000-r/min WFTPMSM is designed and manufactured. The experimental results show that the proposed WFTPMSM has the excellent electromagnetic performance with the power density of 3.3 kW/kg.]]></description>
      <pubDate>Mon, 14 Apr 2025 09:35:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2511708</guid>
    </item>
    <item>
      <title>Aircraft Air Quality and Bleed Air Contamination Detection: Phase 2, Volume 2 [supporting dataset]</title>
      <link>https://trid.trb.org/View/2516405</link>
      <description><![CDATA[The purpose of this project was to provide a data driven process to identify sensor technologies with the potential for detecting and identifying low levels of contaminants that may occasionally be present in aircraft engine bleed air supplies. Bleed air from a ground-based aircraft propulsion engine and an auxiliary power unit (APU) were used to supply air through an ozone/volatile organic compound (VOC) converter to the environmental control system on a Boeing 747, while injecting controlled amounts of fluid contaminants (i.e., aircraft engine oil, hydraulic fluid, and deicing fluid). Measurements of contaminants were performed at the ozone/VOC converter inlet and exit, and at the air conditioning pack exit. Ultrafine particles (UFP) were found to be a sensitive marker for engine oil contamination with measurements at all three locations showing similar, highly elevated UFP concentrations with a mean diameter near 40nm and smaller when the sample stream was cooled to near room temperature. In situ measurements showed that UFPs are generated by condensation and high UFP concentrations were not detected in uncooled bleed air. Oil contamination VOC levels were very low upstream of the ozone/VOC converter at bleed air temperatures up to 220˚C and increased at bleed temperatures of around 315˚C; however, oil contamination VOC levels remained at sub-ppmv levels. Fine particle concentrations also increased with oil contamination at lower bleed air temperatures, but not with temperatures around 315 ˚C. Secondary contaminants including pentanoic acid, heptanoic acid, acetic acid, formaldehyde, and acetaldehyde formed in the ozone/VOC converter as the oil aerosol oxidized. Consideration must be given to contaminant deposition within the bleed air system and sample lines as this deposition may lead to delayed responses and contaminant release during temperature transients. Of the sensor technologies assessed, spectrometers provided the best opportunity to detect and identify contaminants. Carbon monoxide (CO) measurements confirmed that CO is not generated in sufficient quantities to be of value as a marker for engine oil or hydraulic fluid contamination of bleed air. CO may be useful as a marker for ingestion of engine exhaust in some cases. However, carbon dioxide (CO2) is a much better marker for engine exhaust ingestion.]]></description>
      <pubDate>Fri, 07 Mar 2025 15:04:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/2516405</guid>
    </item>
    <item>
      <title>Aircraft Air Quality and Bleed Air Contamination Detection; On-Wing Tests, Sensor Technologies, and Chemical Sampling (Phase 2, Volume 2)</title>
      <link>https://trid.trb.org/View/2508899</link>
      <description><![CDATA[The purpose of this project was to provide a data driven process to identify sensor technologies with the potential for detecting and identifying low levels of contaminants that may occasionally be present in aircraft engine bleed air supplies. Bleed air from a ground-based aircraft propulsion engine and an auxiliary power unit (APU) were used to supply air through an ozone/volatile organic compound (VOC) converter to the environmental control system on a Boeing 747, while injecting controlled amounts of fluid contaminants (i.e., aircraft engine oil, hydraulic fluid, and deicing fluid). Measurements of contaminants were performed at the ozone/VOC converter inlet and exit, and at the air conditioning pack exit. Ultrafine particles (UFP) were found to be a sensitive marker for engine oil contamination with measurements at all three locations showing similar, highly elevated UFP concentrations with a mean diameter near 40nm and smaller when the sample stream was cooled to near room temperature. In situ measurements showed that UFPs are generated by condensation and high UFP concentrations were not detected in uncooled bleed air. Oil contamination VOC levels were very low upstream of the ozone/VOC converter at bleed air temperatures up to 220˚C and increased at bleed temperatures of around 315˚C; however, oil contamination VOC levels remained at sub-ppmv levels. Fine particle concentrations also increased with oil contamination at lower bleed air temperatures, but not with temperatures around 315 ˚C. Secondary contaminants including pentanoic acid, heptanoic acid, acetic acid, formaldehyde, and acetaldehyde formed in the ozone/VOC converter as the oil aerosol oxidized. Consideration must be given to contaminant deposition within the bleed air system and sample lines as this deposition may lead to delayed responses and contaminant release during temperature transients. Of the sensor technologies assessed, spectrometers provided the best opportunity to detect and identify contaminants. Carbon monoxide (CO) measurements confirmed that CO is not generated in sufficient quantities to be of value as a marker for engine oil or hydraulic fluid contamination of bleed air. CO may be useful as a marker for ingestion of engine exhaust in some cases. However, carbon dioxide (CO2) is a much better marker for engine exhaust ingestion.]]></description>
      <pubDate>Mon, 24 Feb 2025 09:11:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2508899</guid>
    </item>
    <item>
      <title>Study the Effect of Fasteners Coating Materials to Resolve the Leakage Issue in Steering Gear Assembly</title>
      <link>https://trid.trb.org/View/2511105</link>
      <description><![CDATA[In commercial vehicle, Hydraulic Power Assisted Steering (HPAS) gear plays a vital role to utilize the hydraulic force to assist the steering application. HPAS gear consists of housing, sector shaft, side cover, worm shaft, valve housing and rack piston. Side cover assembly is connected with the housing assembly through bolts which is in exposure to high pressure working hydraulic fluid. Since, some of the bolts are exposed to the fluid environment in the inner surface of the housing, during high pressure running condition, torque relaxation in the bolt is observed which leads to the loosening of bolts and tends to hydraulic fluid leakage through bolts. The current phosphate coated bolts are getting relaxed and loosened due to the bolts that exposed to the oil environment which have insufficient coefficient of friction in the bolt head and thread. To overcome the bolt failure during high pressure hydraulic application, various bolt coating analysis is experimented to withstand the sufficient coefficient of friction in the bolt. The detailed comparison study is carried out for the bolts such as failure torque, load, frictional force, bearing stress and thread profile deviation. This paper deals with the failure analysis of bolts in a high pressure HPAS gear assembly and comparison study is carried out between analytical calculations and experimental validation.]]></description>
      <pubDate>Tue, 18 Feb 2025 14:58:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2511105</guid>
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