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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.

Leaf springs are used for vehicle suspension to support the load. These springs are made of flat sections of spring steel in single or in stack of multiple layers, held together in bracketed assembly. The key characteristics of leaf spring are defined as ability to distribute stresses along its length and transmit a load over the width of the chassis structures. The most common leaf spring steels are carbon steels alloyed with Cr and micro-alloyed with Ti, V and Nb. The specific thermomechanical process and alloying elements result in specific strength and fatigue properties for spring steels. The unique properties which facilitate use of spring steel in leaf spring suspensions are ability to withstand considerable twisting or bending forces without any distortion. The microstructure of these steel determines the performance and reflects the process of steel manufacturing. The performance is mainly determined by evaluating fatigue life durability.

Unfavorable climates, fatigue, safety & deprived sleep of driver’s leads to use of AC system for their quick thermal comfort during night with engine ON. This scenario is very critical from a human’s safety & vehicle functionality point of view. This also consumes an additional 10-15% of fuel requirements in AC running conditions. So, to address the social problems of driver’s sleep and pollution-free environment by reducing the use of fossil fuels, there is a need for alternative techniques for air cooling which work during engine OFF condition. Various alternative options for air cooling have been reviewed. Accordingly, the packaging flexibility of phase change material (PCM) technology makes it easy to implement, yet effective usage of large quantity stored PCM, needs optimization. This paper proposes a design of a hybrid air conditioning system for sleeper commercial vehicles using a combined conventional compression and phase change material.

In a current competitive automotive market, weight and cost optimization is the need of an hour. Therefore it is important to explore use of alternative material which has less weight, low manufacturing cost and better strength. This paper presents methodology to achieve cost & weight reduction through use of Austempered Ductile Iron (ADI) instead of alloy forging. ADI casting has lower density, physical properties at par with alloy forgings and lower manufacturing cost. Pivot arm is the one of the critical component of twin axle steering system which transfers the hydraulic torque from steering gearbox to second forward axle via linkage system. In order to design lightweight pivot arm, existing chromium alloy steel material is replaced with the Austempered ductile iron (ADI). Pivot arm is designed and validated digitally as well as bench test and results are found to be meeting cost and weight targets.

With India achieving the BSVI milestone, the diesel particulate filter (DPF) has become an imperative component of a modern diesel engine. A DPF system is a device designed to trap soot from exhaust gas of the diesel engine and demands periodic regeneration events to oxidize the accumulated soot particles. The regeneration event is triggered either based on the soot mass limit of the filter or the delta pressure across it. For a Heavy Duty Diesel Engine (HDDE), pressure difference across the DPF is not usually reliable as the size of the DPF is large enough compared to the DPF used ina passenger vehicle diesel engine. Also, the pressure difference across DPF is a function of exhaust mass flow and thus it makes it difficult to make an accurate call for active regeneration. This demands for a very accurate soot estimation model and it plays a vital role in a successful regeneration event.

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.

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.

In the current customer centric automotive market, NVH is one of the prime focus for the automotive industry. Almost all light commercial vehicles in the market are with hydraulic power steering system. Hydraulic power steering pump is heart of the steering system which circulates the hydraulic oil to steering gear for assisting the driver. One of the NVH problem which is inevitable with the hydraulic vane pump is humming noise and this is perceived as an irritant by end user. This paper describes a novel technique for reducing the humming noise which is perceived at driver ear level. Base vehicle level objective measurements is carried out to set the acceptance criteria. Existing design is optimized as per CAE iterations and vehicle updated with the multiple solutions and objective measurements are recorded. Driver ear level noise reduction upto 4 dB(A) perceived which meets acceptance criteria.

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.

The small commercial vehicle business is driven by demand in logistic, last mile transportation and white goods market. And to cater these businesses operational and safety needs, they require closed container on vehicle. As of now, very few OEM’s provide regulatory certified container vehicle because of constrains to meet inertia class of the vehicle. This paper focuses on design of a durable and extremely reliable container, made of the low-cost economy class glass fibre & core material. The present work provides the means to design the composite container for the N1 category of the vehicle. The weight of after-market metal container ranges between 300-350 Kg for this category of vehicle, which affects the overall fuel economy and emission of the vehicle. A detailed CAE analysis is done to design composite container suitable to meet inertia class targets and to achieve weight reduction of 30-40% as compared to metal container.

Recent infrastructural developments and emerging automotive market in India has given an impetus to the transportation industry and has led to high end research activities in synchronization with growing customer demands and competition especially in last decade. Since average speeds in India has gone up from 50 kmph in the year 2000 to almost 100 kmph in 2011, even the Light Commercial Vehicles (5 to 9.6T) are gradually experiencing a shift from low speed to high speed goods carrier. These new age vehicles are developed with a driver centric outlook towards safety and comfort. They are better optimized and equipped to the changing needs of the consumer and road conditions. Increase in vehicle speed poses many challenges in terms of occupant safety and control. In view of this, refinement of different vehicle handling parameters with respect to steering system compliance becomes far more critical.

The vehicle pull (sideways) is a complex outcome of many parameters in an automobile vehicle. This is mainly due to steering, suspension, brake, wheels and chassis parameters. The road conditions like road camber also plays an important role in vehicle pull behavior. All efforts are put in design and manufacturing processes to maintain controlled vehicle pull in normal driving condition. Even though normal vehicle pull seems to be in acceptance limit (subjectively), its intensity increases many folds at the time of harsh braking. In these kind of panic situations where driver firmly holds on the steering wheel, it is expected that the vehicle should stop without deviating too much sideways from its intended straight line path to avoid any kinds of accidents. This work is an outcome of systematic study carried out to understand the root cause of brake pull as a field complaint on current production vehicles and adopting best possible solutions to minimize the brake pull.

In this paper hydropneumatic suspension system design methodology for light military tracked vehicle is discussed in detail. A guide to locate the major impact factor & its effect on the system level design is demonstrated. Spring & damping characteristics of hydropneumatic suspension have significant bearing on the tracked vehicle mobility characteristics. A methodology has been derived to optimize the kinematics of the suspension system by optimizing the load transferring leverage ratio resulting in enhanced system life. The paper also discusses the analytical method used for prediction of spring & damping characteristics and the factors affecting them.

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.