Gear Set Research Articles

The Bressesque Surface: Distribution of Screw Pitch

Abstract Presented is an overview of the T-N interpretation of the famous planar Euler–Savary formula. The T-N spatial analog interpretation consists of two components: the established axial component along with a new transverse component. The axial component entails the spatial Euler–Savary relation involving the Disteli axis and motion parallel to the instantaneous screw axis (ISA). The transverse component emulates the classical planar Euler–Savary relation involving motion perpendicular to the ISA. Within the T-N interpretation is an inflection surface together with a family of Bressesque surfaces. Traditionally, a Bresse circle is a planar motion concept defined by points with zero tangential acceleration. Here, the Bressesque surfaces do not consider accelerations akin to the planar scenario. Instead, the Bressesque surfaces are defined as a linear combination of two axes of the inflection surface. These two axes are used to establish a skew axis gear set where the axodes are tangent along a generator of the Bressesque surface. This tangency is the ISA for the gear set. What is new is the screw pitch for each generator of the hyperboloidal Bressesque surface. Two graphs are shown: the first graph is the variation in screw pitch in terms of the ray angle and the second graph is the variation in speed ratio of the skew axes gear set in terms of the ray angle.

Investigations on Spin Power Losses Generated in a Planetary Gear Set Using Thermal Network Method

Investigations on Spin Power Losses Generated in a Planetary Gear Set Using Thermal Network Method

Perceptions of Cancer Risk and Gear Decontamination Among Aircraft Rescue and Firefighting Firefighters: Insights from a Mixed Methods Study.

Characterize Aircraft Rescue and Firefighting (ARFF) firefighters' perceptions of occupational exposure, health impacts, and decontamination practices, and describe barriers to effective gear cleaning. A convergent parallel mixed methods design was employed, collecting and analyzing quantitative survey data (n = 81) and qualitative focus group data (n = 52) from ARFF firefighters at three Florida airports. ARFF firefighters expressed concerns about chronic exposure to hazardous materials and perceived a heightened cancer risk. Despite acknowledging the importance of gear decontamination, they reported infrequent cleaning behaviors due to persistent contamination and barriers, including lack of a second set of gear. Firefighters' perceived norms emerged as the primary predictor of gear-cleaning behavior. Targeted interventions and policies are needed to address the unique challenges faced by ARFF firefighters in reducing occupational exposure risks and improving gear decontamination practices.

Numerical investigation of vibratory response of planetary gear sets and modulation effects induced by carrier rotation

In geared system, the main source of excitation is generated by the mesh process itself. Depending on the dynamic conditions involved, the system may present a variety of problems, ranging from acoustic nuisance to system failure. Predicting and controlling the mesh process at an early design stage is a key point to avoid such issues. The problem is complex, mainly due to its multi-scale nature. Indeed, the vibroacoustic behavior of geared systems (on the scale of a meter) depend on the local micro-geometry of the teeth (of the scale of a micron), associated with the transmission error. Moreover, the problem is parametric in nature, due to the periodic fluctuation of the mesh stiffness. These parametric internal excitations generate dynamic mesh forces which are transmitted to the housing through wheel bodies, shafts and bearings. In the case of planetary gear sets, the numerical prediction presents a complementary challenge as, in many application, the carrier rotation modulates the housing vibration response, at its rotational frequency. This paper present an original simulation process to deal with modulation effects in planetary gear systems.

Instrumentation in Tractor for Evaluating Performance of a Tractor Drawn Rotavator

Performance measurement of agricultural machinery is essential for enhancing their efficiency for which they are operated. The performance related data helps the operator to select optimum operating parameters which reduce fuel consumption and increase field productivity. This study was aimed to develop various sensing units and install them on the tractor for evaluating performance of a tractor drawn rotavator. A microcontroller based embedded system was developed for continuous recording of wheel slip, actual forward speed, throttle opening, engine speed, velocity ratio, draft and power take-off (PTO) torque related data while carrying out tillage operation with rotavator. The wheel slip (from 1.5% to 35%) and actual forward speed of the tractor (up to 6 km h-1) was measured using inductive proximity sensors. For measuring throttle opening (0 to 100%), engine speed (750 to 2500 rpm), draft (65 to 350 kg) and PTO torque (up to 420 N-m) values, a potentiometer, magnetic pickup sensor, S-type loadcell and PTO torque transducer, respectively, were used. For computing velocity ratio, peripheral speed of rotavator was measured using PTO speed data received from PTO torque transducer, and actual forward speed of tractor was measured using inductive proximity sensor. The developed sensing units were calibrated under both dynamic and static conditions, and were also verified in laboratory and field conditions. Results showed that output signals received from the sensing units varied linearly with applied load. The mean absolute percentage error (MAPE) between measured and actual values was found to be below 5%. From the measured parameters, specific energy requirement and total power required for carrying out tillage operation could be computed. The power requirement was found to increase with increase in both gear and throttle settings. The specific energy requirement was minimum when rotavator was operated in L2 gear of the tractor. The minimum specific energy of 21 Wh m-3 was found at L2 gear and 75% throttle opening.

Full-Scale Gear Tooth Bending Fatigue Tests Obtained Early in the Development of a Rotorcraft Transmission

A new gear testing method is introduced to reduce development cost and time. It allows component-level testing of individual gear meshes and new gear designs. Instrumented gear sets are tested at full load while the rest of gearbox components are still being built. Since the fatigue strength of the gears is determined earlier in the development cycle, design deficiencies are identified and understood earlier. In this new method, an individual gear mesh installed in a stiff facility housing is used to mimic the contact pattern and bending stress demonstrated by the same mesh in an actual aircraft housing. Analytical gear models are used to identify the displacement difference between the stiff test facility and the aircraft housing. The test stand is designed so it can be adjusted accurately to provide gear and pinion positions that are representative of the deflected positions under load in the aircraft housing. A spiral bevel mesh and a split torque double helical reduction stage with multiple meshes are evaluated using the developed method. The contact pattern and strain survey results of the gear meshes are correlated with predicted results.

Effect of Planetary Gear Set Designs on Thrust Bearing Power Loss in Automatic Transmission

Effect of Planetary Gear Set Designs on Thrust Bearing Power Loss in Automatic Transmission

Nonlinear damage dynamics modeling and characteristics simulation of bevel gear set

Abstract As a key core device for power transmission in the main reducer of a helicopter, the bevel gear set affects the flight performance of the helicopter directly. A nonlinear damage dynamic model of bevel gear set was constructed using the centralized parameter method. The inherent characteristics and nonlinear behavior characteristics of bevel gear sets were studied, and the time-frequency domain characteristics under different health states were simulated. The fault response transmission law and fault mechanism of the system were deeply revealed, which provides guidance and support for the optimization design of helicopter transmission system and the diagnosis algorithms development.

Analytical investigation on load sharing characteristics and speed difference of coaxial reverse closed differential herringbone gear transmission system with floating gear and errors

To investigate the influence of gear floating on the load sharing characteristics of the Coaxial Reverse Closed Differential Herringbone Gear Transmission System (CRCDHGTS) and the rotational speed difference between the upper and lower rotors, a dynamic Bending-Torsional-Axial-Pendular (BTAP) model of the CRCDHGTS was established using the centralized parameter method, which considers various excitation factors such as gear floating, errors, Time Varying Meshing Stiffness (TVMS), gyroscopic effect, and tooth friction. It considers the interaction between the closed-stage gear set and the differential-stage gear set, treating the herringbone gear as a symmetric helical gear connected through a receding slot. The dynamic model was solved using the Runge-Kutta method to obtain the dynamic meshing forces for each gear pair under single and combined floating modes. The Dynamic Load Sharing Coefficient (DLSC) of the system, which characterizes the Load Sharing Performance (LSP), was deduced. The load sharing characteristics of different floating modes were analyzed, as well as the influence of different floating displacement on the DLSC. The motion path of the gear floating was also determined. Additionally, the impact of manufacturing error and assembly error of each component on the DLSC under combined floating mode was analyzed. Finally, the influence of gear floating on the output rotation speeds of the upper and lower rotors of the system was investigated. The results indicate that both free-floating of the center gear and combined floating can effectively improve the LSP of the system. When the system adopts combined floating mode, the DLSC of inner and outer meshing changes between 0.91 and 1.09, demonstrating a significant improvement in the LSP. The DLSC of the system increases with the increase in error, with the eccentricity error having a greater impact on the DLSC compared to the assembly error. The optimal floating value for the sun gear is between 0.6 mm and 0.8 mm, while for the planetary gear, it is between 0.4 mm and 0.6 mm. The rotational speed difference between the upper and lower rotors can be controlled within 1r/min. These research findings provide a theoretical basis for further analysis of the dynamic stability and reliability of the system.

The Design and Analysis of the Helical Gear in the Car Gear Box for the Slag Port Transfer

The design and analysis of helical gears with involutes profiles is the primary focus of this study. The most widely utilized gearing system in use today is the involutes gear profile. Power and torque are typically transmitted through them. When compared to other forms of transmission, the efficiency of power transmission via gears is extremely high. Bending and contact stress are the main causes of gear tooth failure. The current study examines helical gear, which has to do with slag transfer in the steel production sector. The most affected stress concentrated location of any set of gears in the slag port transfer car (SPTC) gear box is identified by examining the contact stresses for the current design set of gears. The high stress concentration gear set was redesigned with a constant (45mm) face width at various Helix angles (14, 15, 16, 17, 19^, 20 ̊, 25^, and 30 ̊) and a constant pressure angle (20). To calculate the contact stresses between two gears that are mating. The robust and cutting-edge solid modeling program AUTODESK FUSION 360 creates a three-dimensional solid model. The ANSYS Workbench module was utilized to do the numerical analysis. The outcomes of the workbench module for ANSYS. The current study is helpful in quantifying the previously mentioned factors, which aids in the safe and effective design of the helical gear in the SPTC Gearbox.

Image reconstruction method based on wavelet fusion in electrical capacitance tomography with rotatable electrode sensor

In this paper, an image reconstruction method based on wavelet fusion in electrical capacitance tomography with a rotatable electrode sensor is proposed. This method can weaken the effect of the relative position distribution between the electrodes and the phantom object, thus improving the quality of the reconstructed image. To investigate the reliability of the proposed image reconstruction method, a new mechanical design of a rotatable 12-electrode sensor is introduced. The rotation of the 12-electrode sensor is accomplished by stepping motor and gear sets, which can easily change the measurement position of the electrodes. Five independent datasets of 66 capacitance measurements can be obtained by rotating the electrode sensor 4 times with an angle of 6°from the initial position. Then solving the inverse problem for each of the datasets, 5 reconstructed images are obtained. Finally, the wavelet fusion algorithm is used to fuse the reconstructed images. To verify the validity of the method, this paper evaluates the error case of rotational accuracy, the error case of measurement data and the case of real experiment, respectively. The experimental results indicate that the method can reduce the artifacts in the reconstructed images and improve the quality of the reconstructed images. Meanwhile, this processing method can enhance the shape and edge contour of the measured phantom.

Theoretical and experimental investigation on gearbox vibration signal separation of planetary gear set

The gearbox vibration signal of a planetary gear set contains multiple components caused by different excitations. Separating the gearbox vibration signal to decouple its components can provide core information for operational status monitoring. In this paper, we propose an indirect gearbox vibration signal separation method based on parameter identification. A novel vibration signal model is established using the modal shape of ring gear. A parameter identification method is adopted to determine the parameters of the vibration signal model. The vibration signal components are reconstructed based on the vibration signal model and identified parameters. To evaluate the performance of the proposed method, a ring gear response calculation method derived from the elastic theory of ring gear is presented. The influences of unequal load sharing and meshing position errors on vibration signals are studied through numerical simulations using the calculation method. Experiments are conducted in a planetary gear set test rig. Comparisons between the experimental results obtained by the separation and calculation methods indicate the effectiveness of the proposed separation method.

Exploring Tribological Behaviors of Profile-Shifted Spur Gears: An Experimental Investigation

The tribological behavior of an addendum modified altered tooth sum optimized spur gear set were experimentally compared with that of the standard spur gear under several loading conditions including the wear morphology study and wear debris analysis. The temperature, viscosity, elastohydrodynamic oil film thickness, specific film thickness, and combined surface roughness variation under increasing operating load were analyzed experimentally. Finally, the performance impact of addendum shifted altered tooth sum optimized gear was examined. Results show that the tribological improvement strongly depends on the addendum alteration and modified tooth sum condition. The modification of the addendum in gears with a negatively altered tooth sum facilitates the transition from single-tooth contact to two-tooth contact, broadening the lubrication range while preserving optimal film thickness and improving wear resistance. However, it is reverse to decrease the film thickness and increase wear for standard and profile-modified positively altered tooth sum gear. The gear tribological performance can be significantly improved by profile modification and negatively altered tooth sum approach with a lower rate of degradation of oil and damage on the tooth contacting surface.

Multi-Objective Optimization for Finding Main Design Factors of a Two-Stage Helical Gearbox with Second-Stage Double Gear Sets Using the EAMR Method

Multi-Objective Optimization for Finding Main Design Factors of a Two-Stage Helical Gearbox with Second-Stage Double Gear Sets Using the EAMR Method

A Numerical Analysis of Materials Effects on Involute Helical Gear Set Meshing

A Numerical Analysis of Materials Effects on Involute Helical Gear Set Meshing

Solving a Multi-Objective Optimization Problem of a Two-Stage Helical Gearbox with Second-Stage Double Gear Sets Using the MAIRCA Method

This paper provides a novel application of the multi-criteria decision-making (MCDM) method to the multi-objective optimization problem (MOOP) of creating a two-stage helical gearbox (TSHG) with second-stage double gear sets (SDGSs). The aim of the study is to determine the optimum major design components for enhancing the gearbox efficiency while reducing the gearbox volume. In this work, three primary design parameters are chosen to accomplish this: the gear ratio of the first stage and the coefficients of the wheel face width (CWFW) of the first and second stages. Additionally, the study is conducted with two distinct objectives in mind: the lowest gearbox volume and the maximum gearbox efficiency. Moreover, phase 1 and phase 2, respectively, are the two stages of the MOOP. Phase 2 handles the MOOP to identify the ideal primary design factors as well as the single-objective optimization problem to minimize the difference between the variable levels. Additionally, the Multi-Attributive Ideal–Real Comparative Analysis (MAIRCA) approach is selected to deal with the MOOP. The results of the study are utilized to determine the ideal values for three crucial design parameters in order to create a TSHG with SDGSs.

Przykłady Małej Architektury w oparciu o System Arm-Z

Arm-Z is a conceptual hyperredundant robotic manipulator composed on linearly joined number of identical modules. Each of them has one-degree-of-freedom (1-DOF) – the relative twist. Since modules are congruent, Arm-Z presents potential economical advantages and enhanced robustness. The modules can be mass produced and easily replaceable. The control of Arm-Z, however, is difficult and not intuitive. Therefore it most often requires the use of computational intelligence techniques. This article presents selected concepts for kinetic street furniture based on Arm-Z: a helical column of adjustable height, a sun tracking shade or solar energy harvesting device, bio-mimicing sculpture, sprinkler or fountain. All these ideas are based on low-tech approach. For this purpose, the initial unit in the chain is fixed to the solid foundation. For simplicity, the drive is applied directly to the first unit and transferred by the means of internal gears to the following modules. All of them are equipped with a set of cylindrical and bevel gears with straight teeth with involute profile (for connecting the modules).

DEVELOPMENT OF STANDARDS FOR ASSESSING THE LEVEL OF PREPAREDNESS OF EXPLOSIVE ORDNANCE DISPOSAL TECHNICIANS FOR PUTTING ON A SET OF ARMOUR AND RADIATION PROTECTION EQUIPMENT

An urgent and unsolved part of the problem of humanitarian demining of radiation-affected areas by specially trained specialists is the scientific and methodological apparatus of substantiation of standards for assessing the level of preparedness of explosive ordnance disposal (EOD) technicians for putting on a set of armour and radiation protection equipment. According to the results of an experimental study, the authors established that the change in the time of putting on a set of armour and radiation protection equipment is exponential depending on the level of readiness of EOD technicians preparing for humanitarian demining in a radiation-contaminated area. The experiment participants put on a set of armour and radiation protection equipment consecutively for six days (one attempt each day). It is worth noting that with a significance level of a = 0.05, starting from the third attempt, the time EOD technicians put on armour and radiation protection equipment can be considered constant. Based on the experimental results obtained in the third and fourth attempts, we developed standards for assessing the level of preparedness of EOD technicians of the State Emergency Service of Ukraine for putting on a set of armour and radiation protection gear. For this, we used an adapted statistical method for substantiating the standards, which featured the use of weighted average estimates of the fractions (frequencies) of the performance time that fall within the intervals of the excellent standard, as well as between the ‘excellent’ and ‘good’ and ‘good’ and ‘satisfactory’ standards. We determined that for the case of a combination of an L-1 protective suit, armour protection such as a protective vest of the IV protection level, an armoured helmet of the III-A protection level, and a filter gas mask of the GP-5 type, the time for executing this operation could be estimated starting from the third attempt using the following standards: ‘excellent’ – 155 seconds, ‘good’ – 185 seconds, and ‘satisfactory’ – 220 seconds. Keywords: standard, armour and radiation protection equipment, demining, radioactive contamination, experiment.

Fault modulation mechanism and kinematic modeling of planetary gear with local fault

A planetary gear train involves multiple components and has more complex kinematic relationships than a parallel gear train. Consequently, the fault characteristics extraction is more complicated. To ensure safe operation, it is necessary to properly understand the fault behavior of the planetary gear train. In the previous kinematic modeling, the relationship between the faulty tooth meshing location and the fault impact response phase is not fully considered. However, the fault impact response phase variation plays an important role in accurately characterizing the fault characteristics in the planetary gear train. To solve this problem, we analyze the relationship between the faulty tooth location variation and the fault impact response phase variation and then a novel fault response model is established. Based on this model, a revised planetary damage detection scheme is formulated. Through the simulated data analysis, it is revealed that the faulty tooth location variation not only affects the fault impact response phase, but also reallocates the sideband distributions in the response spectrum. Finally, using a laboratory planetary gear set, it is validated that the proposed model is able to reflect the real damage response better. Therefore, using the proposed model, more accurate damage features are able to be extracted from the measured vibration responses.

A Novel Continuously Variable Transmission with Circumferentially Arranged Disks (CAD CVT)

This paper presents a novel Continuous Variable Transmission (CVT) design. CVT is highly beneficial for actuators with rotary output as it can improve the energy efficiency of the actuators by providing an optimum transmission ratio. This property of CVT is highly beneficial for fossil-fuel-based vehicles, electric vehicles, wind turbines, industrial robots, etc. With the exception of Spherical CVT and DH CVT, all known CVTs like push belt CVTs, toroidal CVTs, Milner CVTs, etc., require additional gear sets and clutches for direction reversal and neutral gear ratio. However, Spherical CVT and DH CVT have low torque capacity due to a single traction point constraint. Foregoing in view, a new CVT named CAD CVT has been developed. The paper presents the design conception, the operating principle, the transmission ratio, the torque capacity, frictional losses, and experimental verification of the basic functionality by manufacturing a Proof of Concept (PoC). The proposed CVT is the only CVT capable of independent direction reversal and high torque capacity as it can transmit torque through multiple traction points. The new CVT will significantly impact high-torque applications in different engineering applications, especially land transport consisting of heavy vehicles like trucks, buses, and trailers.