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In recent years due to significant increased cost of raw material, fuel and energy, vehicle cost is increased. As vehicle cost is one of the major factors that attracts prospective buyers, it has created specific demand for low weight and low-cost components than traditional components with better performance to meet customer expectations. Suspension is one of the critical aggregates where lot of material is used and reduction in weight tends to give lot of cost benefit. As suspension system derives vehicle’s handling performance, it has to be ensured that handling performance of vehicle is maintained the same or made better while reducing weight of the suspension. Advancements in simulation capabilities coupled with manufacturing technology has enabled development non-traditional leaf springs. One of such springs is mono-leaf spring without shackle. This type of leaf spring provides advantages such as low weight and nonlinear stiffness.

Electric vehicles are fast expanding in market size, and there are increasing customer expectations on all aspects of the vehicle, including its noise and vibrational characteristics. Irritable noise from traction motors account for around 15% of the overall noise in an electric vehicle, and thus, has a need to be analysed and studied. This study focuses on identifying the critical vibro - acoustic orders for an 8 pole PMSM (Permanent Magnet Synchronous Motor) for three cases - healthy, with static eccentricity and with dynamic eccentricity. PMSM motors are widely used for traction and other applications due to their higher power density along with compact size. A coupled approach between electromagnetic and vibro - acoustic simulation is deployed to characterise the NVH behaviour of the motor.

Nowadays, E- commerce and logistics business model is booming in India with road transport as a major mode of delivery system using containers. As competition in such business are on rise, different ways of improving profit margins are being continuously evolved. One such scenario is to look at reducing transportation cost while reducing fuel consumption. Traditionally, aero dynamics of commercial vehicles have never been in focus during their product development although literature shows major part of total fuel energy is consumed in overcoming aerodynamic drag at and above 60 kmph in case of large commercial vehicle. Hence improving vehicle exterior aerodynamic performance gives opportunity to reduce fuel consumption and thereby business profitability. Also byproduct of this improvement is reduced emissions and meeting regulatory requirements.

In regions like Indian Subcontinent, Gulf or Saharan & Sub-Saharan Africa, where the sunshine is abundant almost all year round, air-conditioning is an important aspect of vehicles (passenger cars, buses etc.). Higher heat means higher cooling demand which in turn means bigger AC system. Like other auxiliaries, AC compressor is a parasitic load on the engine. The best way to beat heat and reduce cabin heat load is to stop heat build-up itself. The present paper explores one such means of reducing cabin heat build-up by leveraging latent heat properties of phase change materials and thus improving the air condition performance. With the help of a case study this paper aims at detailing comprehensive effect of phase change material (PCM) and its application on the heat build-up inside the cabin of a vehicle, the air conditioning cooling performance, the time required to achieve comfort temperature, work of compression performed by AC compressor and COP.

The future of bus transit in new millennium is promising. This optimism is based on an anticipated long-term slowdown in growth of suburbs and revitalization of central cities. It reflects and escalates the public concern with traffic congestion, sprawl and pollution. This calls for double the use of public transport to address above issues. It calls for changing the mind-set of society towards public transports like buses, coaches etc. This could happen if bus design ensures right comfort, safety and TCO by ensuring refined bus transport. Hence, it is responsibility of OEMs to provide the new generation buses and coaches, which will ensure the public demands of comforts in terms of NVH refinement. This paper covers the unique approach used to convert the existing bus NVH refinement to next level as a short-term solution and with the intention of articulating NVH strategies for new generation bus development.

Designing a cabin tilting system for Light Commercial Vehicles using a single torsion bar becomes challenging considering the operator safety and stringent design weight targets. Performance of a good tilting system entirely depends on cabin mass and location of centre of gravity with respect to (w.r.t) to tilting pivot point. Cabin Mass and COG location are very difficult to estimate while designing a new cabin as it is dependent on the maturation of all other cabin aggregates and also the accessories added by the customer. Incorporation design parameter changes like increasing cab tilting angle and increasing torsion bar length, in the later stages of product development, becomes expensive. The objective of this paper is to come up with an optimum design of a single torsion bar tilting employing “Taguchi optimization” for deciding the optimum levels of control factors, which ensures desired performance (i.e tilting effort vs.

Several sub-systems in a vehicle contribute to vehicle crashworthiness. One such system is the door latch and locking system. Correct functioning of this system is critical for facilitating occupant evacuation and preventing occupant ejection during crashes. Special care needs to be taken during vehicle safety development to achieve the desired intent. In crashes, it is observed that door opening or locking mainly occurs on account of inertial loads and deformation of the door structure. This paper studies the possible failure modes and their causes. Some likely solutions have also been discussed with a case study.

Powertrain mounts locations and stiffness in vehicle plays very important role in improving vehicle noise and vibration, which is caused by engine firing forces and road disturbances. Once locations are finalized, based on initial calculation and packaging then it is very much critical to play with mount stiffness to achieve required NVH level in vehicle. This paper describes the effect of mount stiffness on the bolted joint integrity. Stiffness fine tuning is done to improve vehicle level NVH and various iteration are done with change in stiffness values of A, B and C mounts. When stiffness specifications are finalized, it is recommended to acquire road load data on the finalized stiffness mount and check for bolted joint integrity since load signature is varying significantly on mount w.r.t stiffness change. If we change mount stiffness value from 128N/mm to 98N/mm, then loads on particular mount is getting increased from 4.5KN to 6.5KN in one of the track testing.

Reduction in the drivetrain losses of a vehicle is one of the important contributing factors to amplify the fuel economy of vehicle, particularly in heavy commercial vehicle. The conversion of 6 × 4 drive vehicle into 6 × 2 drive has a benefit of improving the fuel economy of a vehicle by reducing the drivetrain losses occurring in the second rear axle. It was cultured by calculation that in 6 × 2 drive the tractive force available at the wheels, of heavy commercial vehicle with GVW of 44 tons and above, will be much higher than the frictional force transmission capacity of tires, when the engine is producing peak torque on the driving duty cycle like going on steep gradient road. In such situations the tires will start to slip and may result in deteriorating the fuel economy and excessive tire wear. On the other side the flat road driving duty cycle in 6 × 2 drive will give better fuel economy than 6 × 4 drive.

This paper highlights the transition of multi-axis suspension test rig from fixed reacted type to semi-inertial type and the benefits derived thereof in simulation accuracies. The critical influence of ‘Mx’ and ‘Mz’ controls on simulation accuracies has been highlighted. The vital role of ‘Mz’ control in the resonance of wheel pan along ‘Z’ axis and thereof arresting unwanted failures modes in spindle has been duly emphasized. Finally, the role of constraints and boundary conditions on simulation accuracies has been demonstrated by replacing the reaction frame with vehicle body.

With the advent of new technologies and rigorous research and development work going on vehicle engines, cars are becoming quieter and more refined than ever before. This has led to the observance of subjective noises being audible to passenger compartment which were earlier masked behind engine noise. The vehicle HVAC system has several moving parts and transient flow of refrigerant which can cause certain types of irritant noise. Thus having a refinement in of air-conditioning (AC) system would aid us in cutting down on this parasitic noise source. Thus noise refinement should be one of the important parameters during the design and development of the Heating, Ventilation and Air-Conditioning (HVAC) system for a vehicle program.

In an automotive air conditioning system, evaporator is well designed for effective heat transfer between refrigerant and air flowing over the evaporator. This cold and dehumidified air obtained at evaporator is then supplied to passenger cabin. There are various parameters like air flow over evaporator, ambient temperature, humidity condition and condensate drain mechanism which can cause frost formation over the evaporator core. This study presents the probable causes of frost formation and their effects on the performance of evaporator and thus affecting overall performances of the automotive air conditioning system. In this study effect of variation in four major independent factors such as poor response of thermistor, undercharged refrigerant system and overcharged refrigerant system, drop in air flow by blower due to clogged air-filter, and also the effect of type of compressor has been studied.

Steering system is responsible for providing a precise directional control to the vehicle. The Hydraulic Power Assisted Steering (HPAS) system is commonly used in passenger cars and commercial vehicles due to low cost. Power steering pump develops and delivers required pressure to provide assistance while steering. It reduces the effort required to steer the vehicle. Steering pump (generally vane type) is a critical part providing hydraulic pressure assistance to rack and pinion or gear box. Basically the hydraulic pump noise can be classified as ‘Moan Noise’ and ‘Whine Noise’. The noise generated by power steering pump pressure pulsation is termed as ‘Moan’ and ‘Whine’ based on operational induce frequency. As power train becomes quieter, it becomes more perceivable at typical engine operating speed range and gives impression of poor refinement and quality.

Globalization has intensively driven focus of car manufacturers on comfort and ergonomics. Luxuries are becoming essential features of product mix. Customer’s expectations and desires are changing because of cut throat competition and increasing variety of options. In order to sustain in marketplace, OEM has to be competitive while providing features and options with appropriate quality. Vigorously changing dimensions and definitions of comfort level, luxury and aesthetics has driven the intense focus of OEM’s on customer touch points, customer touch points are those components of vehicle which customer accesses while driving the vehicle and they play vital role in generating drive feel of vehicle. Customer’s drive feel about the vehicle is most complex and critical factor and is of subjective nature. Now days drive feel is an important aspect of product differentiation. Gear shift feel is very crucial touch point in overall drive feel of vehicle.

Indian automotive market has grown extremely competitive in the recent past. In order to meet the ever growing expectations of the customers, automobile manufacturers are compelled to offer their products under superior quality with supreme comfort. Customers wish of high levels of tactile comfort in the cabin compartment and effortless operation of peripherals will result in negligible fatigue and a pleasant drive, needs to be duly fulfilled. One has to focus more on Gear shift lever and Steering wheel, which are being the most sensitive tactile points in an automobile. The gear shift lever knob is frequently used and significantly influences the perception of the shift comfort for a driver during actual vehicle application.

The steering system of commercial vehicle is asymmetrical to left side and rightside, this causes vehicle pull during braking application. This directly affects the safety of the driver and vehicle ride & handling performance. In a similar way, the asymmetrical suspension parameter unintentionally set during vehicle assembly arealso major contributors for creating a vehicle pull. After application of brake force, the tire contact patch creates a moment about the kingpin axis. However, this moment generated is different on left and right-side due to asymmetrical design parameters resulting in vehicle deviation from its intended path. A large deviation may lead to on road accidents. Some of the major factors which are responsible for the vehicle pulling phenomenon are the asymmetrical steering system compliance, asymmetrical suspension geometry, tire, braking system, road camber etc.

Small commercial vehicles (SCVs) are the drivers of a major part of India’s indirect economy, providing the most efficient means of transport. With the introduction of BS-VI norms, some major overhauls have been done to the SCV models to meet BS VI norms in challenging timeline for early market entry. This forced to automotive designers towards challenge of cost competitiveness as well as refinement level to survive in this competitive market. This paper explains the systematic approach used to overcome challenges of higher tactile vibrations, higher in-cab noise because of BS VI requirement in 2 cycle engine required for small commercial vehicle. The solutions were need to be worked out without compromising the other performance attributes like total cost of ownership, fuel economy, ease of servicing and cost effectiveness.

The automotive sector is going through a phase of stiff competition among various Original Equipment Manufacturers for increasing their profitability while ensuring highest levels of customer satisfaction. The biggest challenge for such companies lies in minimizing their overall cost involving investments in Research and Development, manufacturing, after sales service and warranty costs. Higher warranty costs not only affect the net profit but in turn it also affects the brand image of the company to a large extent in the long run. An effort is made here to target such warranty costs due to frequent tail pinion and hub seal leakages on single reduction/hub reduction axles of Heavy Commercial Vehicles in the field. A preliminary study involving the severity analysis of such failures is followed by a step by step investigation of these failures.

The basic function of steering system is to control the direction of the vehicle. The driver applies effort on the steering wheel and receives feedback through the steering system as a result of tire to road interaction. This feedback consists of a haptic (force) feedback which is directly felt by the driver and it is termed as steering feel. Precise steering feel gives better driving experience and is decisive factor for customer to buy a vehicle as well as for OEMs in building brand image. Along with steering parameters, suspension and tire parameters also has significant impact on steering feel. In past, modelling of the steering system was done at component level or with simplified vehicle system. Such approaches had not given accurate results of steering feel metric and resulted in incorrect steering design parameter selection. In order to replicate actual vehicle characteristics, complex and detailed modelling of steering, tire and suspension subsystems is necessary.

This paper discusses the test setup and methodology required to validate complete lift axle assembly for simulating the real time test track data. The correlation of rig vs track is discussed. The approach for reduction of validation time by eliminating few of the non-damaging tracks/events, its correlation with real life condition is discussed, and details are presented. With increased competition, vehicle development time has reduced drastically in recent past. Bench test procedure using accelerated test cycle discussed in this paper will help to reduce development time and cost. Process briefed in this paper can also be used for similar test specification for other structural parts or complete suspension system of heavy commercial vehicles.