Sakthivel A.,Tractors and Farm Equipment Ltd |
Sriraman S.,Tractors and Farm Equipment Ltd |
Verma R.B.,Tractors and Farm Equipment Ltd
SAE International Journal of Commercial Vehicles | Year: 2012
Steering wheel vibration is one of the major factors in determining the operator comfort in agricultural tractors. Main sources of steering wheel vibration are engine imbalance, resonance of steering system, lesser damping, road / field induced vibration, etc. The European Council directive 2002/44/EC recommendations are taken as guidelines in this work. Steering vibration study was conducted on various tractor models (40 - 50 kW range) and one tractor was identified for improvement. Upon detailed analysis on that particular tractor, it was found that the resonance of steering system with engine excitation is the root cause for excessive vibration. Various methods to reduce vibration due to resonance were considered, such as shifting the natural frequency away from the second order engine frequency and increasing damping coefficient to reduce the vibration amplitude at resonance. Six different concepts were generated and analyzed using the design assessment matrix. Two concepts were selected, namely radial damper and axial damper concepts for further processing. These concepts were tested and a significant reduction in vibration levels was achieved. Axial damper concept offers higher vibration reduction when compared to radial damper concept. These new design concepts were modeled as a 2 degree of freedom (2-DOF) system with support motion from engine vibration as input. Expressions were derived for vibration transmissibility from engine to steering wheel and coded in MATLAB. A simulation was done in ADAMS software. It was observed that steering vibration predicted by the mathematical model matched well with the measured values. Furthermore, this model could be employed as a tool in selection of optimal suspension parameters for the steering system. © 2012 SAE International.
Range Gounder R.,Tractors and Farm Equipment Ltd |
Sriraman S.,Tractors and Farm Equipment Ltd |
Verma R.,Tractors and Farm Equipment Ltd
SAE Technical Papers | Year: 2010
Tractors along with implements are used to prepare the soil. There are two broad classification in implements attached, one is passive or trailed implements and other one is active tilling implements which will take drive from engine through Power Take Off (PTO). The drivelines for transmission and PTO should have clutches to engage / disengage them from the engine while changing gears and switching PTO On/Off respectively. In present scenario, there are independent clutches for both drivelines to operate PTO driven implements without disrupting vehicle speed. In general, IPTO is being achieved by dry clutch which is integral with engine mounted clutch operated by separate linkages or by hydraulically operated wet clutch located in PTO driveline after auxiliary pump. An attempt is made with mechanically operated wet clutch in the PTO driveline to have an IPTO. Design proposals for mechanically operated multiplate wet clutch and linkage mechanism for engagement/disengagement were generated by considering the design targets to be met and having equivalent performance as that of hydraulically operated wet clutch. A mathematical model for drag torque based on Newton's law of viscosity is developed. The drag torque increases linearly with increasing speed at low speed region. However; in actual case, drag torque decreases with increasing rotational speed at high speed range due to the lower coefficient of viscosity of interface oil. This is attributed to the air trapped between friction disc and separator disc. Hence, the law of viscosity cannot be used to explain this (high speed range i.e. greater than 1500) phenomenon. The torque response is calculated by determining the hydrodynamic torque and asperity torque as a function of oil film thickness and time by another mathematical model. Actual torque transmitted is increased to a maximum value of 390 Nm within 0.8 to 1.2 second where as the simulated torque response value is approximately 1.3 seconds. Parameters like force required to disengage the clutch, oil temperature rise were also compared with test results. Copyright © 2010 SAE International.
Ravindran V.,Tractors and Farm Equipment Ltd.
SAE Technical Papers | Year: 2013
This paper deals with the techniques of reducing noise in agricultural tractors. Noise reduction in agricultural tractors is an emerging concern and apart from meeting the noise norms it helps in increasing the productivity of farmers. Noise is also a factor affecting the health of the farmers. Two major European regulatory requirements are driver ear noise level and passer by noise level. Of the two regulatory requirement, driver ear noise is critical, since the limit is 86 dB (A) compared to 89 dB (A) of passer by noise limit which is measured at 7.5 meters from tractor. Various strategies for noise reduction are discussed in this paper including reduction at source level and passive solutions. Passive solutions are used where the timeline for development is short. Various passive solutions like acoustic foam design are discussed. Finally with the combination of active and passive solutions, driver ear noise target was met successfully. Currently domestic noise norms in India is around 94 dB(A) whereas in Europe, it is 86 dB(A). TAFE as a number one exporter of tractors from India need to reduce noise to around 60% in order to meet European regulations. Copyright © 2013 SAE International.