【正文】 with an integrated oil volume, thus providing vibration isolation through flexibility and viscous damping. More refined cab suspensions also exist where the cab is mounted on a suspended subframe [4]. Highend driver seats are monly designed with hydraulic or pneumatic dampers to cushion the driver from vibrations and shocks. The main imitation of seat and cab suspensions is the small amount of suspension stroke available. Because of these lim itations, the stiffness coefficien t of the flexible elements needs to be high enough to avoid impacts with suspension ends at large transient loads, and therefore the eigenfrequency of the cab or seat suspension is generally too high to provide vibration isolation in the lower frequency range. Furthermore, cab and seat suspensions mainly reduce vibrations in the vertical direction. This could possibly be alleviated by active systems [5], although the potential of advanced seat technology is Vehicle dynamic analysis of wheel loaders with suspended axles still unclear. It should also be noted that the vibration isolation of the seat is often reduced by inadequate operator posture . In addition to cab and seat suspensions,larger wheel loaders are monly fitted with a lifting arm suspension system to decouple the mass and inertia of the lifting arms from the vehicle body. The bucket and lifting arms are isolated from the vehicle by means of gas springs incorporated in the lifting hydraulics and thereby pitching and vertical oscillations to some extent, mainly for a loaded vehicle. Considerably greater vibration isolation can be provided by designing the wheel loader with full wheel suspension. This would mean flexibly attaching the wheels to the vehicle body by means of springs and dampers, as on virtually all road vehicles and on most offroad vehicles. Axle suspensions have greater potential for improved ride fort as the available suspension travel is larger, and also have the potential to alleviate vibrations in the lateral and longitudinal directions in ways not possible by cab and seat suspensions. Apart from reducing driver exposure to vibrations, axle suspensions could also improve the task performance of the loader. As the efficiency of an earth mover is usually defined by the volume of material that can be transported in a specified time, the working performance is directly related to the maximum practical velocity of the vehicle. This velocity is currently limited to a large extent by the operator’ s ability to withstand vibrations and therefore shielding the operator from vibrations will in practice increase the attainable vehicle speed. An axle suspension also functions to reduce wheel load fluctuations, thus improving handling quality and manoeuvring stability at high speeds. Therefore suspended axles are not only beneficial for driver fort but also for the performance of the vehicle.. With the inclusion of suspended wheel axles, a large part of the vehicle mass will be oscillating on the axle suspension rather than simply the tyre flexibility. This will clearly have an impact on the driving dynamics of the vehicle. Naturally, the increased plexity of the vehicle will also add to overall cost and maintenance needs, which is not an unimportant consideration. Suspended axles have been used on certain engineering vehicles for some time, mainly offhighway dump trucks which utilise rubber springs or hydropneumatic struts as suspension elements. On agricultural tractors, suspended front axles are being increasingly mon and some models feature rear axle suspension as well [6]. Applications to loader vehicles are less mon and have mainly been limited to military models that are equipped with suspended axles to enable high speed road travel, thereby allowing rapid deployment and increased bat survivability [7, 8]. Since previous information regarding wheel loader suspension design is limited, a review of the applicability of current design methods, as well as the development of new methodology, is required to provide the necessary knowledge for wheel loader suspension design. In construction areas loaders are also used to transport building materials such as bricks, pipe, metal bars, and digging tools over short are also used for snow removal, using their bucket or a snowbasket, but usually using a snowplow attachment. They clear snow from streets, highways and parking lots. They sometimes load snow into dump trucks for transport. Front loaders gained popularity during the last two decades, especially in urban engineering projects and small earthmoving works. Many engineering vehicle manufacturers offer a wide range of loaders, the most notable are those of John Deere,Caterpillar, Case, Volvo, Komatsu and following we will introduce Carter 938G Series II Wheel Loader. Engine The 938G II provides more power, excellent fuel economy, and reduced maintenance. Turbocharged, ATAAC. Turbocharging packs dense air into the cylinders for more plete bustion and lower emissions. Airtoair aftercooling (ATAAC) provides a separate cooling system for intake manifold air. The ATAAC system reduces smoke and emissions by providing cooler inlet air for more efficient bustion. Constant Net Horsepower. The 938G II’ s electronic engine is integrated with an ondemand cooling fan. The engine pensates for varying fan loads and provides constant horsepower, regardless of operating conditions. A consistent level of “ working” horsepower is provided and fuel consumption is reduced. Oil Change Intervals. The engine oil change interval is increased to 500 hours (with CH4 oil), reducing costs and downtime Powerful Performance. The 3126B ATAAC engine delivers power of 119 kW (160 hp), and meets EPA Tier 2 emissions standards. Its advanced system keeps fuel at low pressure in the fuel lines until