Pickup truck vehicles play an important role in traortation and distribution of goods and facilities within the cities, so the distribution of daily consuming goods is deeply depended on this kind of vehicles. Common pickup truck vehicles have a cargo box with a fixed bed, so the loading and unloading process usually needs to be done by auxiliary equipment or by hand. The methods used for loading and unloading are inflexible for different conditions and usually a large space is needed. In these methods the goods need to be displaced several times and so the safety risks increase. The aim of current study is to create a new design for the rear part of the pickup truck vehicle to facilitate the loading and unloading process. Our proposal includes a U-shape rear chassis which has a bed structure. This bed structure can move up and down by a hydrolic-mechanical lifting mechanism. The proposed bed can reduce its height to zero (ground surface) and then after loading the bed can move up on the vehicle. This method puts down the need for expensive auxiliary equipment’s or handy loading which has safety risks. The proposed designation includes 4 robust pins which were placed in U-shape lateral space and transfer the load from the bed to the chassis. This design was simulated in Abaqus software and the results confirm the design for U-shape chassis and pins. Moreover, in this study the rear suspension system was fully designed. The suspension system includes a leaf spring, shock absorber and a unique independent suspension mechanism. After designing the suspension system parameters including spring hardness and shock absorber damping, the appropriate leaf spring was designed. Also, a joint wheel carrier was used to design the suspension mechanism. The rear suspension system was analyzed by rear suspension pattern design in Adams/car software. The analysis results confirm the design for rear suspension system. In this analysis the maximum suspension mechanism movement without locking, camber and toe angels of the wheels, leaf spring deformation in different situations, and effect of shackle attachment presence on leaf spring have been investigated Key Words Pickup Truck vehicle, U-shape chassis, bed structure, Leaf Spring, Suspension Mechanism
