Pinion Bearing Research Articles

Maintenance and Reliability Improvement of Roller Bearings Operating at High Temperature: Thermal Stress Analysis Approach

In this paper the authors present the outcome of an experimental maintenance and reliability investigation conducted to prevent operation failure of pinion bearings caused by excessive temperature with a case study of a 1360kW ball mill driveline system in mineral processing application. Aiming to improve the overall plant performance, the lubrication regime of pinion bearings as key component within the ball mill driveline system was studied to determine possible causes of temperature increase at 80 to over 100°C with a 25 - 30°C gap over the maximum operating temperature. An analytical review of maintenance data is conducted to mitigate future operational risks by implementing a new lubrication regime and shutdown frequency for overall statutory inspection. Accelerated life test based inverse power law has been applied to identify the root causes of excessive bearings temperature to establish immediate short-term solution paths towards a guaranteed less required maintenance asset improvement practice, less operational cost, and plant availability enhancement. Furthermore, long-term solutions have been proposed based on modelling by thermal network approach of pinion bearings for thermomechanical stress prevention. A single parameter based accelerated test on pinion bearings was applied to establish operational fault tolerant factors to be considered for asset capability improvement, which remains an open question for future studies. These actions have shown significant improvement with temperature decrease between 15 and 25°C below the maximum required temperature.

Investigation of the Vibration Features and Dynamic Load Sharing Characteristics of Concentric Face Gear Torque Split Transmission

Abstract A concentric face gear torque split system used in the helicopter main transmission to transfer more power and reduce the structure weight is introduced. A mathematical model is proposed to analyze the vibration characteristics as well as load sharing performances of the torque split system. The excitations including mesh stiffness, backlash, static transmission error, and system work torque are considered in the model. The vibration property, dynamic displacement responses, and the system factors which affect the load sharing capacity of the system are studied based on the numerical analysis results. The results show that vibration forms of the system can be classified into three categories: pinion vibration mode, face gear vibration mode, and pinion coupled face gear mode. Resonance peaks and jump phenomena are detected around rotation speed 5772 rpm and 10,250 rpm, mainly related to the coupled translational–rotational–axial of face gears vibration modes. In addition, appropriate gear pair backlash and pinion distribution angle parameters are significant to improve the dynamic load sharing capacity. The increase of the pinion bearings' supporting stiffness will generate worse load sharing characteristics and a relative flexible bearing is recommended to the pinions' supporting.

Effects of bearing clearance and atmospheric temperature on performance of pinion bearings of railway vehicles

Effects of bearing clearance and atmospheric temperature on performance of pinion bearings of railway vehicles

Failure analysis of a high-speed offset bearing

Abstract There are presented the consequences of the events during the operation of two variants of sliding bearings (offset type) within two gearboxes of similar construction and way of loading. Both assemblies have suffered serious damages of the gear transmission (gear teeth breaking, active flanks scoring, etc.), accidents that occurred after a longer or shorter period of use. During operation, each gearbox was monitored and the parameters values were recorded: gas turbine speed, driving power, important temperatures (oil input, bearing surface, etc.), vibrations (proximity sensor on the input shaft, accelerometer on the gearbox housing). For each type of bearing, the geometric characteristics are presented, the antifriction material is described by its mechanical properties, and the dynamic characteristics of the bearing surface are used to estimate the critical mass which establishes the boundary between stable and unstable operation. Relying on the operating parameters, the behaviours of two HS bearings (HS Sun pinion bearings), which have been analyzed are compared mainly during instability occurrences and especially in the last period before their removal from service. The conclusion is that the stability of the undamaged fluid film bearing is proved both from the computational model and by the dynamic response of bearing to external loading.

Investigation of Seizure Factors of Pinion Bearings

Investigation of Seizure Factors of Pinion Bearings

Experimental Setup and Methodology to Carryout Fatigue Testing of Spiral Bevel Gears Used in Differential Gear Box Using NVH Approach

Currently the fatigue testing of bevel gears are being done by using non rotating type of fixtures that applies fatigue load on a single tooth, which does not resemble the actual loading condition in an automotive differential gear box. This paper discusses the experimental setup with the noise and vibration analysis approach to determine the signature of failures of spiral bevel gears. The proposed experimental setup seems promising for further research and development in the fatigue testing of spiral bevel gears. The Crown pinion and wheel assembly is used for the testing. The pinion is connected to the electric 3 phase AC motor of 75HP with a suitable coupling and the crown wheel is mounted on the half axle shaft, which in turn is connected to an electric dynamometer. The speed/torque of electric motor and the load applied by the dynamometer can be varied. The acoustic sensor is mounted near the differential gear box and the accelerometers are mounted on the Pinion bearing, Crown wheel bearing and the half axle bearing. A four channel data acquisition system is used to log data in time domain (raw data) by three accelerometers and an acoustic sensor. The variations of sound pressure(dB) v/s time, sound Pressure(FFT-(RMS)) amplitude v/s Frequency, Acceleration v/s Time, Octave analysis i.e., Band power v/s Frequency, Noise spectrum Power v/s Frequency, Histogram, Power density v/s Time can be obtained. These data are then used to plot vibration and SPP levels in frequency domain to develop the noise and vibration signature of that crown pinion for given cycles of operation. The tests on Bevel pinion and gear set were performed in the BEC, Bagalkot NVH lab facility. The gear set run successfully at double the rated torque for 30 million pinion cycles. And the signature of pinion failure was obtained. The results demonstrated the suitability of using the given bevel crown pinion and gears set for specified speed, high load application in differential gear box of an automobile.

Gas-Expanded Lubricant Performance and Effects on Rotor Stability in Turbomachinery

Gas-expanded lubricants (GELs) are tunable mixtures of synthetic oil and carbon dioxide that enable dynamic control of lubricant viscosity during bearing operation. This control can help reduce bearing power loss and operating temperatures while also providing direct control over bearing stiffness and damping, which can enhance rotordynamic performance. In this work, the bearing and rotordynamic performance of two representative high-speed machines was evaluated when different lubricants, including GELs, were supplied to the machine bearings. The machines chosen for this analysis, an eight-stage centrifugal compressor and a steam turbine-generator system, represent a wide range of speed and loading conditions encountered in modern turbomachinery. The fluids compared for machine performance were standard petroleum-based lubricants, polyol ester (POE) synthetic oils, and POE-based GELs. The performance simulations were carried out using a thermoelastohydrodynamic bearing model, which provided bearing stiffness and damping coefficients as inputs to finite element rotordynamic models. Several bearing performance metrics were evaluated including power loss, operating temperature, film thickness, eccentricity, and stiffness and damping coefficients. The rotordynamic analysis included an evaluation of rotor critical speeds, unbalance response, and stability. Bearing performance results for the compressor showed a 40% reduction in power loss at operating speed when comparing the GEL to the petroleum-based lubricant. The GEL-lubricated compressor also exhibited lower operating temperatures with minimal effects on film thickness. GELs were also predicted to produce lower bearing stiffness when compared to standard fluids in the compressor. Rotordynamic results for the compressor showed that the fluid properties had only minor effects on the unbalance response, while GELs were found to increase the stability margin by 43% when compared with standard fluids. The results from the turbine-generator system also demonstrated increases in low-speed bearing efficiency with the use of GELs, though at higher speeds the onset of turbulent flow in the GEL case offset these efficiency gains. Rotordynamic results for this system showed a contrast with the compressor results, with the GELs producing lower stability margins for a majority of the modes predicted due to increased bearing stiffness in the high-speed turbine bearings and negative stiffness in the lightly loaded, low-speed pinion bearings. These results suggest that GELs could be beneficial in providing control over a wide range of machine designs and operating conditions and that some machines are especially well suited for the tunability that these fluids impart.

Turbo-alternator bearing problems caused by degradation products

Progressive build-up in a matter of weeks, of a brown deposit on the pinion bearings of two 8 MW geared turbo-alternators caused production problems in a sugar-beet processing plant. This case study describes the history, investigation and elimination of the problem

Effect of Lubricants on Rear Axle Pinion Bearing Break-In

The effect of lubricants on rear axle pinion bearing break-in has been studied in a motored differential carrier assembly. The pinion torques and lubricant temperatures measured with a multipurpose lubricant were higher than those observed with a lead soap-active sulfur lubricant whereas the bearing wear was lower. Preheat treatment of the multipurpose lubricant was effective in producing more rapid pinion bearing break-in and lower lubricant temperatures. A zinc dialkyldithiophosphate was found to exert a predominant effect on break-in as compared to sulfurized terpenes and chlorinated paraffins when these additives were blended with a straight mineral oil. It has been concluded that a zinc organodithiophosphate may control pinion bearing break-in with the multipurpose lubricant. Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Pittsburgh, Pennsylvania, October 16–18, 1962.

Breakdown of EP gear lubricants in pinion bearings : W. E. Ellis, R. L. Hill, E. M. Downs. Lubrication Eng., 17 (1961) 529–539; 16 figs., 4 tables, 14 ref.

Breakdown of EP gear lubricants in pinion bearings : W. E. Ellis, R. L. Hill, E. M. Downs. Lubrication Eng., 17 (1961) 529–539; 16 figs., 4 tables, 14 ref.

Some Studies on the Damages of the War-time Standard Turbines and their Reduction Gears

Many damages have been reported on moving blades, high speed pinions and wheels as well as flexible couplings of the war-time standard turbines and their reduction gears of the propulsion use.It is generally understood that these damages were caused by the use of materials of inferior quality and the poor workmanship during the war time. However, the author's careful investigations on several damaged parts has disclosed that the fault of the so called“racked train”type gearings in its mechanism is another important cause of these damages.Since the high speed pinion of the single helical“rocked train”type, having thrust collar between fore side pinion bearing and flexible coupling, has long dimension in overhang length, the pinion itself tends to be put into the unstable condition, such as the whirling motion in the journal bearings. The load fluctuation on the gear teeth caused by the whirling motion results the irregular distribution of the pitting, which is clearly observed on the gear teeth.It is noted that the frequency of this load fluctuation which is observed as the irregular distribution of the pitting on gear teeth is ten or twelve cycles per revolution of pinion, and that it coincides with the mumber of coupling teeth.From the above mentioned phenomena, the author concludes that the shock load caused by the whirling motion of the high speed pinion introduces all sorts of unusual damages above-mentioned and he also gives the follwing recommendations for the design of the reduction gear: -(1) The advantage of so called“rocked train”type gearings in which the transmitting load is reduced to half, is cancelled by the demerits that the severe shock load induced by the whirling motion is added to transmitting load and, that the adjustment of the ununiform distribution of teeth loads is very difficult. From this point of view, the employment of this type of gearings is to be avoided as practicable as possible.(2) When the employment of this type of gearings is obliged, the ball or roller bearings are to be used in high speed pinion in order to prevent the whirling motion of the pinion as small as possible.(3) As the gear coupling having insufficicient flexibility may introduce the damage on turbine blades, high speed pinions and gears as well as couplings themselves, some devices are necessary to be considered to increase the flexibility and improve the lubrication.