Construction vehicles.
After the 1930s, the capacity of excavator buckets in mining and engineering construction has become larger and larger, which requires supporting trucks. It has a load capacity of 14 tons and can be used with a steam shovel to transport muck or ore. This can be said to be the prototype of a mining dump truck.
After the 1950s, the load-carrying tonnage of trucks has become larger and larger. In 1951, Euclid launched the Euclid-1LLD dump truck, the largest in the world at that time, with a load capacity of 50 tons. The car uses a three-axle 10-wheel chassis and is equipped with two Cummins diesel engines with a total power of 375 horsepower. Load-carrying dump trucks have greatly improved the mining efficiency of open-pit mines. However, open-pit mines mostly have switchback ramps, and the operating costs of diesel trucks are relatively high. In order to improve the economy of ramp transportation of heavy-duty vehicles, electric-wheel trucks came into being. American engineering machinery legend R.G. LeTourneau proposed the idea of ??diesel-electric multi-wheel drive: each wheel is driven by an independent electric motor to improve its traction capacity by distributing the engine's power to each wheel. This was very similar to the concept of a railway locomotive at the time, except that the steel wheels were replaced with rubber tires.