Gearbox Input Shaft Research Articles

Development and research of the efficiency of a tractor transmission with a disc type gearbox

BACKGROUND: Modern tractors are equipped with gearboxes that are divided into three ranges, such as slow, operating and transport, for the sake of better power usage and fuel efficiency of the engine as well as getting higher performance. In addition, gearboxes must have a large number of gears, that leads to an increase in their mass and dimensions. An increasing mass of gearbox leads to additional high-quality metal consumption as well as energy costs for self-propelling of a tractor, which reduces its operational capabilities.
 AIMS: Increasing the number of gears and reducing the weight of gearboxes for agricultural tractors.
 METHODS: A disc-type gearbox (Patent RF No. 208805) has been developed to make it possible to increase the number of gears and reduce the weight of gearboxes for agricultural tractors. The feature of this gearbox is the gear disk with three gear rims on top and three on the bottom that is installed in its housing in addition to the usual gears and shafts. The implementation of the gear disk with gear rims makes it possible to reduce the number of gearwheels by more than half. The experimental gearbox is manual and interrupted-drive. It gives 18 forward gears and 18 reverse gears. Laboratory studies of a tractor with the experimental gearbox were carried out on a roller test bench. Load condition was arranged with the STEU-40 electric brake test rig in order to determine the transmission efficiency. During the testing, the torques on the gearbox input shaft and the tractor half shafts were measured. Reliability testing of the experimental gearbox, built in the LTZ-55 tractor, lasted for 2714 hours under the normal operation condition.
 RESULTS: The results of the transmission efficiency study at the 1st, 5th and 10th gears with different drive wheels torques as well as different oil temperatures revealed that the transmission efficiency is in the range of 0.75-0.96 at the transmission oil temperature of 16 to 60C, which corresponds to the numerical values of fixed-ratio transmissions of stock tractors. Operational tests of the tractor, equipped with the experimental gearbox, showed efficiency of gearbox during operation of 2714 hours.
 CONCLUSIONS: Laboratory studies of the LTZ-55 tractor, equipped with the experimental gearbox (Patent No. 208805), showed that the transmission efficiency improves with an increase in the drive wheels torque and the transmission oil temperature, and deteriorates with an increase in the gear number. The efficiency of the experimental transmission is in the range from 0.75 to 0.96, which corresponds to stock manual interrupted-drive transmissions of tractors. With an increase in oil temperature up to 60 C, the efficiency of the transmission greatens.

Effect of input shaft torque control during gear shifting processes in automatic stepped transmissions

Introduction (problem statement and relevance).Designing gear shifting algorithms is one of the major problems in development of control systems for automatic gearboxes. Structure and parameters of these algorithms govern such characteristics of shifting processes as torque transients and energy dissipation due to clutch slippage; these, in turn, affect vehicle comfort and lifespan of the gearbox components. In particular, one of the factors defining the said characteristics is engine torque control provided during gear shifts. The functionality of the torque control extends when using the gearbox as a part of a hybrid powertrain with a traction electric machine connected to the gearbox input shaft. Studying gear shifting processes in this aspect is a relevant task aimed at improving control systems of automatic transmissions.The purpose of the studyis to compare different methods of controlling torque at the gearbox input shaft regarding their effect on gear shifting dynamics, clutch energy dissipation, and vehicle comfort.Methodology and research methods.The study was conducted by means of simulations using a mathematical model describing dynamics of a vehicle equipped with an automatic gearbox with an option of having an electric machine installed at the input shaft. Considering straight-line accelerated motion of the vehicle, both upshifts and downshifts were simulated with a correcting torque introduced in inertia phases of the shifts. Analysis of the simulation results allowed calculating key parameters of vehicle dynamics and clutch energy dissipation.Scientific novelty and results.The simulation results show a significant decrease (aver. 40%) of jerks when using an electric machine to correct the input shaft torque in inertia phases of both upshifts and downshifts. It is also shown that correction of the shaft torque allows reducing energy dissipation due to clutch slippage by 16–24% in the case of engine torque control and by 28–34% in the case of torque correction by an electric machine. However, using torque correction by means of an electric machine during downshifts raises the clutch energy dissipation 1.4–2.4 times.The practical significance.The results of the study can be used in designing control systems for automatic gearboxes intended for both conventional and electrified vehicles.

Integrated Prognostics Observer for Condition Monitoring of an Automated Manual Transmission Dry Clutch System

The closed loop feedback control system of an Automated Manual Transmission (AMT) electro-pneumatic clutch actuator is used for intelligent real time condition monitoring, enhanced diagnostics and prognostic health management of the dry clutch system, by integrating with the existing gearbox prognostics observer. The real-time sensor data of the clutch actuator piston position is analyzed for monitoring the condition of the clutch system. Original parameters of the new clutch are stored in the Electrically Erasable Programmable Read-only Memory (EEPROM) of the AMT controller and the real-time data is used by the observer for assessing the degradation/wear of the frictional clutch parts. Also, clutch slip during torque transmission is monitored, using the engine speed and the gearbox input shaft speed from Controller Area Network (CAN). Condition monitoring of clutch system provides enhanced prognostic functionality for AMT system which ensures consistent clutch performance, gear shift quality and timely warning for recalibration, repair and/or replacement of the critical wear and tear parts. Also, systematic analysis of the monitored data provides an accurate diagnosis of a developing fault. Thus, with the advanced control systems in place for AMT, a closed loop feedback based condition monitoring system is modelled for improved diagnostics and prognostics of AMT clutch system.

Development of power operated paddy seeder for dry and wet seeding

Rice is one of the most important crops in India with a total area of 44 Mha and a production of 110 million tonnes. The major constraints in manually transplanted paddy cultivation are non-availability of labour on time, especially during peak periods of sowing and need of large quantity of water. Mechanical transplanter could not be made widely popular because of higher cost, poor traction and sinkage. Direct seeded rice is becoming popular in India due to severe shortage of water and labour and almost comparable yield. There is no single machine available for direct seeding of rice in both dry and wet condition. It is a single wheel, 8-row riding type machine fitted with a 2.94 kW single cylinder, air cooled diesel engine which powers the forward movement of the driving wheel and rotary motion of metering mechanism. The drive wheel receives power through V-belt, cone clutch and gear box. Gear box for ground wheel comprises three sets of spur gear. The input shaft of gear rotates at speed of 1300 rpm and then according to shifting of gear lever it is reduces up to 185 rpm. A universal shaft from the gear box provides power to the sets of bevel and spur gear box and from then power is transmit to input shaft of gear box of metering mechanism as 468 rpm and then finally reduces up to 20.51 rpm to the cup type metering mechanism through chain sprocket assembly mounted over the float. The performance evaluation of a power operated paddy seeder was done with the pre-germinated paddy seed and dry seed under laboratory and field test.Engine of paddy seeder 2.43kW (4 hp) revolves at speed of 2600 rpm which reduces as 90 rpm to the metering shaft and 21 rpm to the driving wheel through reduction unit. The fuel consumption varied between 2.57 to 2.83 l/ha with an average of 2.68 l/ha in dry seeding condition and 2.78 to 2.98 l/ha with an average of 2.83 l/ha in wet condition. The effective field capacity of machine is 0.23-0.25 ha/h. The field efficiency of paddy seeder in dry condition was 77.67 % and in wet condition it is 71.88 %.

Fatigue Life Analysis and Experimental Study of the Input Shaft of 6-Speed Automatic Transmission

The input shaft of gearbox usually bears a cyclic variation of torque, which may lead to the risk of experiencing a fatigue fracture. To evaluate the fatigue life accurately and identify the weak parts, the ANSYS is used to simulate the torsional fatigue of the input shaft for the gearbox, and the fatigue life of the weak part is obtained, which is then tested and verified by the torsional fatigue testing in the MTS torsional fatigue test rig. The test results show that the maximum difference is 14% between the calculated life and the testing results, indicating that the simulation value can reflect the actual fatigue life accurately. Notably, the cracks appear in the large oil holes, and its life is mainly concentrated in the crack initiation stage, accounting for 99.2% of the total life. The analysis results show that the fatigue life of the software simulation has the guiding significance for the life evaluation. The fatigue life of the shaft can be quickly calculated by the simulation to reduce the number of fatigue tests and achieve cost-effectiveness.

DETERMINATION OF ROLLER BEARING INNER RACE DEFECT BASED ON VIBRATION SIGNAL

The present article’s intent is to measure and identify the roller bearing inner race defect width and its corresponding characteristic frequency based on filtered time-domain vibration signal. In case localized fault occurs in a bearing, the rolling elements encounter some slippage as the rolling elements enter and leave the bearing load zone. As a consequence, the incidence of the impacts never reproduce exactly at the same position from one cycle to another. Moreover, when the position of the defect is moving with respect to the load distribution zone of the bearing, the series of impulses are modulated in amplitude in time-domain and the conforming Bearing Characteristic Frequencies (BCFs) arise in frequency domain. In order to verify the ability of time-domain in measuring the fault of rolling bearing, an artificial fault is introduced in the vehicle gearbox bearing: an orthogonal placed groove on the inner race with the initial width of 0.6mm approximately. The faulted bearing is a roller bearing quantification of the characteristic features relevant to the inner race bearing defect. It is located on the gearbox input shaft—on the clutch side. To jettison the frequency associated with interferential vibrations, the vibration signal is filtered with a band-pass filter based on an optimal daughter Morlet wavelet function whose parameters are optimized based on maximum Kurtosis (Kurt.). The residual signal is performed for the measurement of defect width. The proposed technique is used to analyse the experimental signal of vehicle gearbox rolling bearing. The experimental test stand is equipped with two dynamometer machines; the input dynamometer serves as an internal combustion engine, the output dynamometer introduces the load on the flange of the output joint shaft. The Kurtosis and Pulse Indicator (PI) are selected as the evaluation parameters of the de-noising effect. The results show the reliability of the proposed approach for identification and quantification of the characteristic features relevant to the inner race bearing defect.

A Case Study on Fatigue Failure of a Transmission Gearbox Input Shaft

In this paper, a root cause analysis of premature failure of a gearbox input shaft, manufactured of AISI 1045-H, was performed through standard procedures for failure analysis. Shaft failed on cross oil hole through a helical fracture and therefore did not meet bogie 100,000 cycles during the verification with 10 Hz frequency cyclic testing. The fracture in the oil hole implied evidence of fatigue (i.e., beach marks on the fracture surface were clearly visible). Prior to improving the fatigue life and suggesting required remedial actions, mechanism of failure has to be understood, especially the initiating point of cracking. To this end, chemical analysis, microstructural characterization, fractography, hardness measurements, and finite element simulation were used to assess the nature of fracture in detail. The fractography analysis showed that fatigue beach marks originate from transition zone of the case on the cross oil hole. This is possibly due to the fact that torsional strength in this area is lower than torsional fatigue strength which leads to fatigue crack initiation, crack growth, and final fracture. At the end of this paper, proper remedial actions have been proposed.

Dynamic analysis of rail gearbox bearings

Track and railcar wheels can wear and develop flat spots during use that create vibration and high acceleration shock loading conditions in axle-mounted gearboxes. It is important to understand how these dynamic conditions affect gearbox bearing durability during bearing design and selection. A multistep dynamic analysis process for linking railcar vibration conditions to bearing component motions is presented. Field-relevant vibration conditions are applied to a model of a rail gearbox input shaft supported by two tapered roller bearings. Recently developed bearing load–displacement models are used to calculate the shaft and relative raceway displacements under these imposed vibration conditions. The calculated raceway displacements are then used as inputs for dynamic calculations of roller–cage impact forces within each bearing. Knowledge of the detailed dynamic conditions within the bearings leads to improved bearing designs that reduce the likelihood of cage damage.

A prognostic method for fault detection in wind turbine drivetrains

Abstract In this paper, a prognostic method is presented for fault detection in gears and bearings in wind turbine drivetrains. This method is based on angular velocity measurements from the gearbox input shaft and the output to the generator, using two additional angular velocity sensors on the intermediate shafts inside the gearbox. An angular velocity error function is defined and compared in the faulty and fault-free conditions in frequency domain. Faults can be detected from the change in the energy level of the frequency spectrum of an error function. The method is demonstrated by detecting bearing faults in three locations: the high-speed shaft stage, the planetary stage and the intermediate-speed shaft stage. Simulations of the faulty and fault-free cases are performed on a gearbox model implemented in multibody dynamic simulation software. The global loads on the gearbox are obtained from a dynamometer test bench and applied to the numerical gearbox model. The method is exemplified using a 750 kW wind turbine gearbox. The case study results show that defects in the high- and intermediate-speed bearings can be detected using this method. It is shown that this procedure is relatively simple, yet accurate enough for early fault detection in wind turbine gearboxes.

Educational Set-Up for Vibration Measurements in Vehicle Gearboxes

In this paper we present a set-up specifically prepared for an educational application. The aim of the set-up is to build an educational tool for students of automotive engineering. The open test stand we used is equipped with two dynamometers and can accommodate various automotive gearboxes. The most common type of gearbox intended for transversal powertrain placement in small and midsize vehicles was chosen as the test gearbox. At our disposal we had two identical and completely new gearboxes provided by a car manufacturer. The differential of the gearbox was blocked. The total power is taken-off from one side only. In one gearbox two artificial faults were introduced: • An orthogonal placed groove on the inner race with the initial width of 1 mm. The damaged bearing is a roller bearing located on the gearbox input shaft – on the clutch side. • Pitting defect ground on the teeth sides of the IV th speed. The mounting base of the test stand allows easy changing of the gearboxes. During the student training, the new undamaged gearbox is first measured. After completion of signal measurement and analysing by means of FFT, Order and Envelope analysis, the gearbox is changed for the damaged one. After measurements under the same conditions, the same type of analysis of the measured signal is performed. The students have to identify the type of damage(s) present in the damaged gearbox.

Failure Analysis of a Cylindrical Roller Bearing from a Rolling Mill

Premature failure of a cylindrical roller bearing of a gear box input shaft from a hot strip mill has been investigated. The pins of the cylindrical rollers of the bearing broke from the welded joints at their ends on the cage ring. Investigations were carried out on the failed roller pin and the welded joint. The investigation consists of visual observation, chemical analysis, characterization of macro- and microstructures, measurement of hardness profile, fractography, and energy dispersive spectroscopy (EDS). The fracture surface of the roller pins exhibits beach marks. Scanning electron microscopy (SEM) of the fracture surfaces reveals striations suggesting fatigue failure. The measured hardness profile along the welded joint shows very high hardness due to the presence of untempered martensite at the fusion boundary as revealed by the microstructural examination. Analyses of the results infer that the roller pins failed by the initiation of fatigue cracks from the welded joint because of the presence of untempered martensite originated due to improper welding process.

Asynchronous input gear damage diagnosis using time averaging and wavelet filtering

Vibration signals are often used for fault diagnosis in mechanical systems because they are containing dynamic information of mechanical elements. Vibration signals from a gearbox are usually noisy and the signal-to-noise ratio (SNR) is so low that feature extraction of signal components is very difficult, especially in practical situations. One of the solutions to this problem is applying signal time-averaging techniques in time domain for signal denoising, but using this method is only possible when gearbox input shaft rotation is constant or synchronous. In this paper, a new noise canceling method, based on time-averaging method for asynchronous input, is developed, and then complex Morlet wavelet is implemented for feature extraction and diagnosis of different kind of local gear damages. The complex Morlet wavelet, used in this work, is adaptive because the parameters are not fixed. The proposed method is implemented on a simulated signal and real test rig of Yahama motorcycle gearbox. Both simulation and experimental results have proved that the method is very promising in analysis of the signal and fault diagnosis of gearbox.

ESG — electrical shift gearbox

This article presents the electric shift gearbox (ESG), which ideally combines the advantages of the twin clutch gearbox and a minimum hybrid driveline. By mounting the electrical motor to the gearbox input shaft, all hybrid functions can be achieved without needing any further components. The article describes the design and construction of the system and presents measuring results of specific driving situations.

The design and hardware-in-the-loop simulation test of a parallel hybrid transmission control system

Presented within this paper is the design and hardware-in-the-loop simulation test, HILST, of the transmission control system for the HERO vehicle. The acronym HERO refers to hybrid electric realised off-road, which constitutes a parallel hybrid derivative of a Land Rover Defender. The powertrain comprises of an electrical machine mechanically coupled to the gearbox input shaft. The transmission control system employs the electrical machine to actively assist in the gear change process. The simulated performance of the control system is compared to the results obtained when the control algorithms have been converted to a source code program and compiled to the control module operating within a HILST environment.

The Hardware Are-In-The-Loop Simulation Test of a Parallel Hybrid Transmission Control System

This paper will present the hardware-in-the-loop simulation test of the transmission control system for the HERO (Hybrid Electric Realised Off-road) vehicle. HERO is a parallel hybrid derivative of a Land Rover Defender. The powertrain consists of a diesel engine and an electrical machine mechanically coupled to the gearbox input shaft. The main function of the transmission control system is to employ the electrical machine to actively assist in gear changes. The transmission control system is a combination of feedback compensation elements and supervisory rule-bases. The simulated performance of the control system is compared to the results obtained when the control algorithms have been converted to a source code program and compiled to the control module operating within a HILST environment.