Bora A.J.,John Deere India Pvt. Ltd.
SAE International Journal of Commercial Vehicles | Year: 2011
Gear rattle noise is a common issue in manual gear transmissions and is often difficult to resolve. This paper discusses a methodology involving development of a simulation model for noise prediction and subsequent design of experiments (DOE) analysis to select optimal design parameters to reduce rattle noise. A one-dimensional torsional vibration simulation model for a tractor driveline was developed and was correlated with experimental measurements. This correlated model was used to calculate the torque variation between the gear pairs based on engine excitations. The standard deviation of this mesh torque was used as a metric and was correlated to noise ratings assigned by experts during experimental evaluation. Using this metric as the response variable, a DOE was conducted to determine the contributing factors and their influence on the rattle noise. Optimal design parameters were selected to achieve target value on the rattle metric. Physical prototype was built using these optimized parameters and was validated against noise ratings assigned by experts. It was found to successfully satisfy the subjective rattle criterion. © 2011 SAE International. Source
Pawar S.,John Deere India Pvt. Ltd.
SAE International Journal of Commercial Vehicles | Year: 2015
Displacement joystick controls are considered as most suitable for manual controls wherever proportional outputs are required for dynamic applications such as when variable speed sensitivity or position are required. These joysticks are being used widely in both open loop as well as in close loop controls. The operator applies force to either the joystick itself or to its proportional linear displacement thumb wheel switches. This movement is then detected by either resistive or Hall Effect sensors, placed right inside joystick, and converted into an electrical signal. These joysticks, along with proportional linear displacement thumb wheel switches, find a wide range of applications in off-road vehicles such construction and forestry vehicles, harvester machines, and etc. for applications like attachment speed controls, boom position control, rotation speed control, and etc. The higher the displacement of the joystick, or its linear displacement thumb wheel switches, the better will be the control over the control parameter. When it comes to open loop attachment control systems, where joystick displacement is directly linked with speed, most times the displacement provided by joystick or linear displacement thumb wheel switches is just not enough to fine tune the control parameter. In such cases, a small variation in displacement results in a large change in output parameter. The operator needs to move the joystick very slowly and cautiously to ensure fine adjustments in the control parameters. It takes a good amount of time to learn to achieve these fine adjustments using a joystick. In a shaky environment it becomes even more difficult to precisely control the parameters using a joystick. In these conditions, a small variation in joystick displacement, or linear displacement thumb wheel displacement, leads to either over or under adjustment of the control parameter. When working in tight places, where there is not much space available to move the vehicle or attachment, it is necessary to control the joystick displacement or linear displacement thumb wheel displacement precisely to ensure objects around vehicle or attachment are not damaged. Due to an operator's mistake, or due to jerks and vibrations to joystick or linear displacement thumb wheel switches, a large amount of change can occur in the control parameter, erroneously leading to accidents or damage to the environment around the machine. For accident and worry free operation, with better efficiency, an operator controlling such attachments or vehicles requires a means to adjust the sensitivity of the joystick or linear displacement thumb wheel switches. There are many ways to achieve this. For example, a switch can be provided to set & lock the upper limit of the control parameter to a level lower than its usual maximum. Reducing the upper limit reduces the effective range. In this way, normal displacement of the joystick or linear displacement thumb wheel switch will be converted to a relatively lower range of the control parameter. This gives the effect of reduced sensitivity. Copyright © 2015 SAE International. Source
Umbare V.G.,John Deere India Pvt. Ltd.
SAE Technical Papers | Year: 2013
The design and analysis plays a major role for determining the root cause for the problem. Once the problem and its root cause were well defined, the solution for addressing the problem would be made clear. The engine excitation frequency and the chassis natural frequency were coming closer and it leads chassis to resonate. The resonance increases vibration levels at the Tractor footrest which was reducing comfort level of the operator. The vibration reduction methodologies like stiffening the structure, isolating the source from excitation and dampening techniques were studied to reduce vibration levels at footrest. The benchmarking evaluation was done with selected tractor models qualitatively to assess the difference in vibration level perception for customers. The test methodology and data acquisition methodology was formulated and used for better analysis and discussions. In this paper, the author demonstrated the systematic approach to reduce tractor footrest vibrations by 20%-25% through concept design, virtual analysis and experimental validation. Copyright © 2013 SAE International and Copyright © 2013 SIAT, India. Source
Pawar S.,John Deere India Pvt. Ltd.
SAE Technical Papers | Year: 2015
Work lights with high power rating consume high current. Since the battery voltage is fixed, high currents are needed to generate the necessary power (wattage). This makes it difficult to manage the load on the Electronic Control Unit (ECU) responsible for controlling the work lights and also on the entire electrical system of the vehicle. It is possible to prevent the system from getting over loaded by employing effective means of work light control techniques. These techniques differ based on the type of work lights connected on the vehicle. There are three types of work lights available in the market. Halogen work lights, High Intensity Discharge (HID) work lights and Light Emitting Diode (LED) work lights. HIDs are not preferred by most customers due to their high warm up times & cost/unit. The other two types of lights, i.e. LED & Halogen, are comparatively less expensive. They also need negligible warm up times which are not objectionable to the vehicle operators. Due to these aspects, LEDs or Halogen work lights are provided as the default option on most of the off-road vehicles, regardless of the fact that their current consumption is relatively higher when compared to HID work lights. Sometimes, a combination of LED and Halogen work lights is provided on the vehicle. The type and rating of the work lights governs the design of the electrical system controlling the lights. For example, the gauge of the wire driving the work lights depends on the current rating of the light, the maximum duration the lights will remain on & the distance of the light from the ECU responsible for controlling these work lights. Also, the ECUs controlling high power work lights need to have components with higher current/ wattage rating. This adds to product cost as ECUs with higher ratings are expensive due to higher component costs. This cost further increases due to the complex design of the heat sink required to satisfy the heat dissipation needs of the ECU. To interface high power work lights with a relatively low power & cost effective controller, current limiting means can be employed. But sometimes, the vehicle operators replace the factory fitted lights once the default lights are worn out. In any case, control methods programmed in ECUs for controlling lights shall be compatible with the type of light installed on the vehicle, i.e. halogen or LED; else they may either damage the ECU/work lights or substantially reduce their life. This paper provides methods for controlling high power work lights with a relatively low power ECU without damaging the work lights/ECUs and at the same time ensuring that sufficient intensity of light will be available at the most critical places around the vehicle. This in turn helps to manage the load on the ECU and on the entire electrical system of the vehicle. Employing these techniques enable system architects to use low cost low power controllers for controlling high power work lights. One of the essential components in these techniques is light type detection. This paper also provides an innovative technique for automatic detection of the type of light connected on the vehicle to ensure employment of compatible control methods. Since, LED and Halogen lights are most preferred as work lights; the scope of this paper is restricted to these two types of lights. © Copyright 2015 SAE International. Source
Pawar S.,John Deere India Pvt. Ltd.
SAE Technical Papers | Year: 2014
Off-road commercial vehicles many times have to work at remote areas in poor working conditions like reduced visibility due to fog, snow, inadequate ambient lighting, dust etc. They may not have any access to emergency facilities in such places. Challenging geographical terrains and adverse weather conditions makes the situation worse. The combination of both can further degrade working conditions. The operator may need to either work or guide his vehicle through tight places or in hilly areas having such conditions. That imposes many challenges to operator in terms of efficiency & safety of both operator & vehicle. In an effort to increase productivity and efficiency operator may miss to look at safety aspects consequently, leading to accidents that can incur heavy losses due to damages to vehicle further delaying the work. It can even lead to a life threatening emergency in some cases. On the other hand, decrease in efficiency results in increased cost of operation due to unnecessary wastage of fuel & delays in getting the work done. Defense sector, due to their nature of work & high risk; have been investing a lot to invent technologies that can enable soldiers to work in adverse conditions reducing the potential hazards to their soldiers & war machines. Due to this, defense sector already has upper hand in developing such technologies for their forces to help them work in adverse conditions without compromising performance & efficiency and can save lives. These highly advanced technologies are helping modern militaries in applications such as performing covert operations, reconnaissance without getting detected, covert target illumination & detection etc. thereby reducing casualties and losses to war machines. Some of these technologies can find their applications in commercial off-road vehicles used in agriculture, construction, forestry & mining with same intent. Once closely guarded these technologies are now commercially available. As these technologies are made to order and are not being mass produced; at present, their cost is relatively higher to the technologies being used in off-road vehicles. But, once they are introduced in vehicles, with advent of mass production the cost will go down. Radar is one such example of technology which was once used in combat applications and was very costly, but now being widely used in vehicles for various applications. The intent of this paper is to identify some of these technologies and their potential applications in off-road commercial vehicles. Copyright © 2014 SAE International. Source