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Bogie-type suspensions for trucks are comprised of two axles and a central spring pack on each side of the truck chassis. Bogie suspensions have a good load distribution between the axles and are used for severe applications in trucks, in off-road conditions thereby subjecting them to extreme stain and load. In today’s competitive market scenario, it of utmost importance to minimize down time in commercial vehicles as it directly corresponds to loss in business which leads to customer dissatisfaction. It is therefore essential to optimize and select the right material for each component in the bogie suspension system. This paper deals with the material selection and testing of one such component - Bogie Wear Pad. The bogie wear pad undergoes sliding friction throughout its lifetime during loading and unloading of bogie suspension. Three different materials are selected and their wear is measured under the same conditions of loading.

The suspension system in a vehicle isolates the frame and body from road shocks and vibrations which would otherwise be transferred to the passengers and goods. Heavier goods vehicles use tandem axles at the rear for load carrying. Both the axles should be inter-connected to eliminate overloading of any one axle when this goes over a bump or a ditch. One of the inter-connecting mechanism used is leaf spring with tie rod, bell crank & linkages, when the first rear axle moves over a bump, the linkages equalize the loading on the second rear axle. This paper details about the failure analysis methodology to simulate the tie rod field failure using a six poster road simulator and to identify the root cause of the failure and further corrective actions.

In the emerging commercial vehicle sector, it is very essential to give a product to customer, which is very reliable and less prone to the failures to make the product successful in the market. In order to make it possible, the product is to be validated to replicate the exact field conditions, where it is going to be operated. Lab testing plays a vital role in reproducing the field conditions in order to reduce the lead time in overall product life cycle development process. This paper deals with the design and fabrication of the steering column slip endurance test rig. This rig is capable of generating wear on the steering column splines coating which predominantly leads to failure of steering column. The data acquired from Proving Ground (PG) was analyzed and block cycles were generated with help of data analyzing tools.

In heavy commercial vehicle segment in India, driver comfort and feel was largely ignored. Fierce competition in the recent years and buyer’s market trend is compelling the designers of heavy truck to focus more on the finer aspects of attribute refinements. Steering is one driver-Vehicle interface which the driver is engaged throughout. Comfort and feel in steering wheel is defined by parameters like steering effort, manoeuvrability, on-center feel & response, cornering feel & response, Torque dead band, return-ability etc. and is influenced by a long list of components and systems in the truck. This study focuses on the influences of jacking torque and steering system friction on the on-center driving performance. Experiments to measure the Jacking torque and steering system friction were conducted in the lab and subjective and objective assessments of on-center driving performance were later conducted at test track in two similar 12 Ton truck to correlate their effects.

In today competitive world, gaining customer delight is the most vital part of an automotive business. Customers’ expectations are high which need to be satisfied limitless, to stay in the business. The major expectation of a commercial vehicle customer is a vehicle without failures which involves lower spares cost and downtime. The significance of a suspension system in the new age automobiles is getting advanced. There have been many improvements in the suspension system especially in leaf springs to provide a better ride comfort, and one such modern era implementation is the Parabolic Spring which comprises of fewer leaves with varying thickness from the center to the ends without inter-leaf friction. Study reveals that parabolic spring exhibits better ride comfort, but less life compared to a conventional leaf spring which leads to the increase in downtime of the vehicle.

Steering gear box function is one of the important requirements in heavy vehicles in order to reduce driver fatigue. Improper functioning of steering gear box not only increases the driver fatigue, also concerns the safety of the vehicle. In this present investigation, the engine oil mixing up with steering oil has been identified and steering gear box failure has been observed in the customer vehicle. The root cause of failure has been analyzed. Based on the investigations, in particular design of steering pump has been failed at customer end. The same design of steering pump were segregated and analyzed. Initial pressure mapping study has been conducted. The pressure mapping results revealed that the cavity pressure obstructs the flow of suction pressure. It indicates that obstacle at suction port due to the existence of internal leakage that causes back pressure in the internal cavity of steering pump which sucks engine oil.

Steering wheel being the most used tactile point in a vehicle, its feel and response is an important factor based on which the vehicle quality is judged. Engineering the right feel and response into the system requires knowledge of the objective parameters that relate to the driver perception. Extensive correlation work has been done in the past pertaining to passenger cars, but the driver requirements for commercial vehicles vary significantly. Often it becomes difficult to match the right parameters to the steering feel experienced by the drivers, since most of the standard ISO weave test units used to describe them are of zero or first order parameters. Analyzing the second order parameters gave a better method to reason driver related feel. Also, each subjective attribute was fragmented into sub-attributes to identify the reason for such a rating resulting in the identification of the major subjective parameters affecting driver ratings.

Commercial vehicles have steering systems with one or more steering links connecting the steering gear box pitman arm and front axle steering arm. In case of twin steer vehicles, intermediate pivot arm is used to transfer the motion proportionately between the two front axles. Intermediate pivot arm is also used in some longer front over-hang vehicles to overcome their packaging constraints and to optimize the mechanical leverage. The pivot shaft is a mechanical part of the intermediate pivot arm assembly upon which pivot arm can swivel in one axis. Steering forces transferred through the drag links generates resultant forces and bending moments on the pivot shaft. In this work, study has been carried out on premature failure of the pivot shaft in city bus application model (Entry + 1 step). Metallurgical analysis of failed part indicated the failure to be due to fatigue. Pivot shaft was tested in rig with similar load conditions in order to replicate the failure.

Vehicle handling is an important attribute that is directly related to vehicle safety. The rapid development of road infrastructure has resulted in a greater focus on safety and stability. Commercial vehicle stability and safety assumes higher significance because of high center of gravity (CG) and heavier loads. A gamut of parameters influence vehicle handling directly and indirectly. However, it is quite difficult to gauge through physical testing, the extent of each parameter's influence on handling. Therefore, this paper examines vehicle handling by way of a sensitivity analysis through numerical simulation. A prototype vehicle is also instrumented and tested to confirm trends and validate the results of the simulation. An Intermediate Commercial Vehicle (ICV) with Gross Vehicle Weight (GVW) of around 13 tonnes is modeled and parameters like wheelbase and tyre stiffness are altered and the effect of these changes on handling parameters (yaw rate, lateral acceleration) is observed.

Development of split Catalytic Converter (Cat-Con)-Muffler system was done to be used in front engine low floor (FELF) Bus from perspective of cost saving, modularity and reduction in complexity. This system is developed as an alternate to an existing solution of integrated Cat-Con and muffler. The paper describes the development of a split Cat-Con and muffler exhaust system for a FELF Bus, so as to meet cost and time considerations. The development also had to achieve a feasible solution, which could be installed within the packaging volume of the existing configuration of FELF while meeting the regulatory requirements [1] for Pass by noise (PBN), and at the same time conforming to backpressure limits set for optimum engine performance. Multiple design - prototypes - test iterations were carried out to meet the PBN and back pressure target for FELF Bus. The final solution was developed which achieved both the requirements within the specified space constraints.

Automotive component light weighing is one of the major goals for original equipment manufacturers (OEM's) globally. Significant advances are being made in developing light-weight high performance components. In order to achieve weight savings in vehicles, the OEM's and component suppliers are increasingly using ultra-high-strength steel, aluminum, magnesium, plastics and composites. One way is to develop a light weight high performance component through multi material concept. In this present study, a bimetal brake drum of inner ring cast iron and outer shell of aluminum has been made in two different design configurations. In two different designs, 40 and 26% weight saving has been achieved as compared to conventional gray cast iron brake drum. The component level performance has been evaluated by dynamometer test. The heat dissipation and wear behavior has been analyzed. In both designs, the wear performance of the bimetal brake drum was similar to the gray cast iron material.

The Bogie suspensions ensure better stability at higher loads and also give the utmost reliability under extreme climatic conditions with minimum maintenance. Many vehicle manufactures have adopted for the bogie suspension at rear based on its advantages. The noises generated from the vehicle in the field includes engine noises and flow noises and hence it is very difficult to clearly discern the noise generated from suspension system of the vehicle [1]. Most suspension system noises do not come from a single part but they are caused by the coupling action between related parts, making it difficult to clearly identify the exact cases. This paper details the overall approach to identify the bogie suspension noise on a commercial vehicle and countermeasures to reduce the same.

Commercial vehicle payload depends on the client for which the vehicle fleet owner is operating. Load carriers like flatbed trailer offer the flexibility to be loaded with a large number of light payloads or a few numbers of massive payloads. Such load carriers have to be evaluated for various possibilities of loading patterns that could happen in the market. The objective of this work is to evaluate flatbed trailer for its structural strength for different customer application cases, using computer simulation. Structural load cases due to payloads like containers, steel coils and cement bags are arrived at. Static structural analysis using MSC Nastran is performed to evaluate for the worst customer loading pattern from structural stress point of view. This paper also describes a simplified method for simulating the effect of trailer suspension, tractor suspension and the fifth-wheel coupling in the analysis whose detailed modeling is not possible at the concept level.

In this paper, valve spring parameters are optimized based on an iterative logic with constraint on space availability, stress limit, stiffness and natural frequency of the system. The optimized valve spring configuration is used in the push rod type valve train and the valve train dynamics for different engine speed is studied using commercially available multi-body dynamic ADMAS software. The valve train components such as cam, tappet, push rod, rocker arm, valve retainers and valve are modelled as rigid bodies and the valve springs (inner and outer valve springs) are modelled as flexible bodies. Each coil of the springs is modelled as separate flexible body and contact between these coils are established. A comparative valve train dynamics analysis is also carried out with the existing and optimized valve spring combinations.