Boots – shoes – and leggings
Patent
1991-08-08
1993-10-26
Harvey, Jack B.
Boots, shoes, and leggings
3644241, 74866, 123478, B60K 4106
Patent
active
052571939
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a method for automatically changing the speed of a dump truck for use as a construction vehicle to a speed stage to be determined according to the operating condition of a power transmission or speed change gear thereof when the vehicle is running, and also relates to a method for operating the power transmission thereof.
BACKGROUND TECHNIQUE OF THE INVENTION
As for the method of automatically changing the running speed of a vehicle wherein the output side of the engine is connected to a torque converter provided with a lock-up clutch, the output side of the torque converter is connected to the input side of a hydraulically actuated power transmission or speed change gear having a plurality of speed stage clutches. The output side of the power transmission is connected through a differential gear mechanism to the left and right drive wheels. An automatic speed change method has been known wherein speed increasing points and speed decreasing points, i.e., speed change points, are set on the basis of the relationship between the tractive force at each of the speed stages of the power transmission when the engine is developing a maximum speed and the vehicle speed at that time. The vehicle speed is detected from the number of revolutions of the engine and the like. When the thus detected vehicle speed exceeds a speed change point, an automatic speed changeover to a next speed stage can be made.
For example, as shown in FIG. 1, the arrangement is made such that speed change points f.sub.1 to f.sub.6 are set from the relationship between the tractive forces when the engine is developing a maximum output at forward first to seventh speeds F.sub.1 to F.sub.7 and the running speeds of the vehicle. When the vehicle speed exceeds each of the speed stages, it is automatically changed over to a next speed stage.
That is to say, the maximum outputs of the engines mounted on dump trucks for use as construction vehicles are not so high as those outputs required for them, and the weight of such vehicles in a loaded condition varies significantly from that in an unloaded condition. Further, because the loadage and the gradient of roads on which vehicles run vary so much, the loading imposed on dump trucks for use as construction vehicles fluctuates largely. Also since it is difficult to detect the cargo on board and the gradient of roads with a high accuracy, it has been a common practice for dump trucks for use as construction vehicles to set speed change points which correspond always to the maximum output condition developed by the engine mounted on each of them, assuming cases where the loading imposed on them is high, and to run them with their engines developing maximum outputs.
In the above-mentioned conventional automatic speed change method, in case the loading on a vehicle is extremely light as, for example, in the case of an unloaded vehicle running on a flatland or in case a loading on the vehicle is comparatively light as in the case of the vehicle in a light load condition running up a slope, the output developed by the engine is not utilized fully thus consuming an extra fuel ineffectively. This is because the output required for a dump truck for use as a construction vehicle in the above-mentioned light load condition is in fact less than the maximum output developed by the engine. Further, in mining slopes and so forth, a plurality of dump trucks for use as construction vehicles having different engine outputs usually run along the same course. So, it is not allowed for only one truck to run at a higher speed than the others, at a maximum output developed by its engine. Rather, the truck must be driven at a lower speed which is adjusted to the lower speeds of other vehicles. Therefore, vehicles with higher engine outputs are required to run at a lower speed stage; that is, at a higher number of revolutions of the engine, thereof, resulting in increases in the fuel consumption rate.
Whilst, as to the engine, output, there are cases where even wh
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Kaneko Kiyoshi
Kato Takeo
Kato Yoshiaki
Kusaka Kohei
Harvey Jack B.
Kabushiki Kaisha Komatsu Seisakusho
Kananen Ronald P.
Pipala Edward
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