It is a feature typical of counterweight trucks that they are capable of lifting and transferring a load whose weight is far above one half, usually about 65%, of the tare weight of the truck. When the truck is not lifting a load, the weight of the truck is almost evenly divided between the two axles of the truck. However, for a truck lifting a full load, most of the total weight of the truck rests on the front axle of the truck, which is normally the driving axle. Thus, the axle loads of the truck vary quite extensively depending on the load.
Owing to the high variations in the axle load, nowadays the trucks are generally constructed without a spring suspension. The axles are rigidly fixed directly to the truck frame, or, in particular in the case of the steering axle, the axle may be mounted pivotally on the frame. Spring suspension has usually not been used in trucks because the variations in the axle load would be excessively large if a spring suspension were operative under all circumstances of operation of the truck.
Furthermore, a truck without a spring suspension has a substantial drawback in that the truck usually becomes uncontrollable at speeds higher than about 30 km per hour because it has no shock absorption system. Thus, the truck without a spring suspension is unable to operate at speeds higher than about 30 km/hour even when unloaded, or otherwise during a transfer operation or equivalent. At present, this is a significant drawback, because it is desired that the equipment be used as efficiently as possible, whereby any unproductive operation would be carried out as quickly as possible.
In addition, when the truck is transferred from one place to another, it has often been necessary to employ specialized transportation equipment which has constituted quite an important cost factor. Thus, the transfer of the truck with specialized equipment is, for example, an unproductive operation of the truck.
USPTO Backgrounds
USPTO Backgrounds