【正文】 would have consisted of a twowheeled cart hinged 圖3to the axle with the center of gravity, when loaded, just behind the axle. The loaded front body was hooked, and when unlatched, would dump. These carts were used in open mines and pulled by horses along a railway track.After 1900, a fourwheeled horsedrawn flatbed wagon with a rectangular body lifted with a hand hoist in the front was employed.Early Truck Mounted Dump BodiesThe earliest versions of truck mounted dump bodies relied on the principle of gravity for dumping. Some of the first trucks with dump bodies designed on this principle appeared as early as 1904 when the Mann gravity dump was built in England.Hydraulic Dump BodiesHydraulics was being incorporated into truck mounted dump bodies relatively early on. Records show that one of the first hydraulic dump bodies was the Robertson Steam Wagon with a hydraulic hoist that received power from the truck’s engine or an independent steam engine. Alley amp。 however, when speed restrictions posed a problem, the wagons were mounted on wheels to improve speed. Manufacturers of such trailers and haulers included Euclid, James Hagy, LaPlantChoate, RexWatson, and Streich and Western.Euclid Dump Trucks Euclid was a pioneer in the development of dump trucks. George Armington Jr., son of founder George Armington, was a hydraulics designer and made two significant contributions to the world of dump trucks. These included the modern heavy duty offhighway truck and the wheel tractor bottom dump wagon. In 1934 the pany introduced its 10/11ton dump truck called the Trak Truk. It was the first reardump truck that was designed for heavyduty off road service. This was followed up in 1936 with the pany’s 15ton Model IFD truck that featured a diesel engine, modern drive line, planetary final drives, leafspring suspension, and pneumatic tires. The truck replaced heavy, gasoline powered chain drive Mack trucks that had previously been used for standard work in construction and mining operations.Dump Trucks in the 1950s By the 1940s the technological development of dump trucks had reached its peak. In the ., bottom dump trucks were already dominating earthmoving sites by the 1950s. The decade continued to mark a proliferation in the manufacturing of dump trucks. In 1951, for example, Euclid produced the world’s largest dump truck when it manufactured the 1LLD. In 1954 Komatsu built the first dump truck on wheels that traveled at 26 miles (42 km) per hour and had a payload. In 1958, the 600 horsepower AP40 Auto car was the largest single engine dump truck on the market.Ralph H. Kress and the HaulpakRalph Kress is perhaps best known in the dump truck world for pioneering and bringing dump truck technology to the forefront, in particular, heavyduty, offroad dump trucks used in mining.In 1955, as a consultant for WABCO (now Komatsu), he was instrumental in configuring a dump truck that incorporated a short wheelbase and had a high angle of turn with a deep, sloped, flat body known as a Haulpak and was viewed as the “quantum advance in design” with its hydropneumatic “Hydrair” struts.The first versions of the Haulpak were made available to the market in 1957 featuring 25 to 32ton payload capacities and were eventually marketed and used as tractors to pull supplementary 75ton trailers. These earlier versions, ranging from 25 to 32ton range capacity, were too small initially to be used in open pit mines but gained acceptance from contractors. Eventually Haulpak grew in size and became the dump truck of choice in the surface mining industry. The Haulpak would exist as the standard to which other offhighway dump trucks would e to be designed.3. 現(xiàn)有機構(gòu)分析（1）專利綜述Patent ReviewThe dump truck, as one the largest special vehicles, is developing from the 5t dump truck to more tons. The core of a dump truck is the lifting mechanism, which develops from the single cylinder centrallymounted straight top type and the multistage cylinder centrallymounted straight top type to the single cylinder connecting rod bined type and the multistage cylinder lead straight top type. From the patents among the searching results from the US patent and trade mark office, we can see that most of the trucks are designed with the single cylinder connecting rod bined type such as US2849255, US3172703, US3620458 or so. US4036528 uses the single cylinder centrallymounted straight top type. US6382731 uses the multistage cylinder lead straight top type.Here are some advantages and disadvantages of the four type of the dumping mechanism:The single cylinder centrallymounted straight top type—— it is the pioneer of the lifting mechanism of the dump truck. Its structure is very simple and tight and its cost is low, but its load is very small so that it is used as the trucks below 5t. It is widely used as lightweight trucks, for example Dongfeng 3092F uses this lifting mechanism. See Patent: US4036528. 圖4The multistage cylinder centrallymounted straight top type—— it improves the disadvantages of the single cylinder centrallymounted straight top type. It improves the condition of the cylinder and the frame to extend their lifetime and redu