Post by on 2017-01-11 17:46:02
Speed ??Limitation of Concrete Mixer Truck
The maximum vehicle speed is one of the three main indicators of the vehicle's power. Car manufacturers attach great importance to this indicator will be listed as an important performance indicators.
In fact, all car speed tests are subject to conditions. The minimum speed test is to carry out the "minimum stable vehicle speed test method" (GB / T 12547)). The "maximum speed of vehicle test method" (GB / T 12544). However, the site requirements for these two speed determinations are in accordance with the "Motor Road Test Methods" (GB / T 12534) requirements, that is, "Unless otherwise specified in the test road, the performance test should be clean, dry , Flat, asphalt or concrete laying on a straight road on the road length of 2 ~ 3km, width of not less than 8m, longitudinal slope within 0.1% during this period. It can be seen, the vehicle's highest (low) speed data test are specified in the straight road on the.
Transport vehicles belonging to urban transport type vehicles, most of its transit time to be turned to avoid pedestrians and vehicles and other driving movements, is unlikely to do the maximum speed. More importantly, the truck is converted from the chassis, and its vehicle center of gravity than the chassis before the modified chassis has a significant increase in the center of gravity; at the same time in the transport of mixing drum drive the concrete to flip, so that the center of gravity toward The agitator barrel is rotated in such a way that its center of gravity deviates from the vertical plane of the axis of the agitator tube so as to affect the stability of the running of the vehicle and to easily roll over during cornering, especially at high speeds, resulting in a higher Rollover accident rate. Jicha sudden turn, and often caused by the main reason for the transport vehicle overturned.
Based on the above understanding, the high center of gravity of the truck itself, the road traffic is complex, as the urban transport vehicles that exist objectively, in its use should pay close attention to driving stability, to prevent rollover. Manufacturers should not highlight its highest speed, not the possible rollover accidents caused by the actual warning. But can not be in the instructions within the chassis maximum speed marked as the vehicle maximum speed, does not indicate the actual driving should comply with the "technical conditions" provisions: "agitation, the maximum speed shall not be higher than 50km / h". Therefore, in the instructions should be fully express high-speed driving will have a high risk of rollover accidents.
The minimum stable speed is a measure of whether the transporter is able to move smoothly into the ready-mix concrete mixing station, and make its feed port accurate to the ready-mixed concrete mixing station discharge port of an indicator. ["Concrete Mixer Trucks" (JG / T5094-1997)] in 5.1.15c states: (transport vehicles) should be able to not more than 50km / h speed stable driving. "Technical conditions" in a type test in accordance with the "Special Purpose Vehicle Type Test Regulations" (QC / T252) provides the minimum stable speed test items.
Turn the car when the rollover phenomenon is more prone to transport problems. This problem is related to the fact that the mixing drum is rotated when the truck is agitated and the concrete inside the cylinder is driven to shift the center of mass of the vehicle in a certain direction, and also to the traveling state of the vehicle (turning radius, traveling speed, Total offset, etc.) factors. The safety speed described in this article mainly refers to the speed that can ensure that the vehicle does not roll when it is running. The safety of the side slope when traveling in straight line is related to the side slope angle, which is not discussed here.
The direction of the rotation of the mixing drum of the national transport vehicle is generally determined according to the stipulation of its road vehicle to a certain side. According to China's road vehicles on the right driving travel regulations, the majority of domestic transport vehicles in the stirring operation, the mixing tube rotation direction for the right hand (for the rear look forward, clockwise rotation), the corresponding mixing tube spiral blade rotation Levorotatory. This arrangement adapts to the fact that the road cross section left and right is low at the right-hand side. Mixing cylinder design of the right-hand truck in the stirring condition of the vehicle under the gravity of the vertical axis of the mixing cylinder axis, deviated from the centerline 50 ~ 100mm vehicle, making the transporter stability slightly better. Due to historical reasons, some of China's transport vehicles to stir the driving operation, the mixing tube rotation direction for the L (facing the rear forward, counter-clockwise rotation), the corresponding mixing tube spiral blade rotation to the right hand. This arrangement makes the left-hand drum of the mixing drum in the stirring condition of the vehicle's center of gravity to the left deviation, not suitable for right-hand driving the road cross-section high left and right low actual situation, has increased lateral inertia force generated by the roll The negative impact of torque, resulting in vehicle lateral stability is relatively poor. However, only by the design of the mixing tube bias can not put an end to the car rollover.
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