The dump truck is mainly composed of a hydraulic dumping mechanism, a carriage frame and its accessories. Among them, the hydraulic dumping mechanism and carriage structure are different among various modification
manufacturers. The following describes the structure of the dump truck according to the types of carriage and lifting mechanism.
Car Type
Carriage structure types can be roughly divided into ordinary rectangular carriages and mining bucket carriages according to different uses.
Ordinary rectangular carriages are used for bulk cargo transportation. The rear panel is equipped with an automatic opening and closing mechanism to ensure smooth unloading of goods. The plate thickness of an ordinary rectangular carriage is front plate~side plate~rear plate~bottom plate~. For example, the standard plate thickness of the ordinary rectangular compartment of the Qingzhuan brand dump truck is the front side and the bottom.
The mining bucket carriage is suitable for transporting large-grained goods such as large rocks. Taking into account the impact of the cargo and the complex design shape of the mining bucket carriage, the materials used are thicker. For example, the standard plate thickness of the Qingzhuan dump truck mining bucket carriage is the front bottom, and some models have some angle steel welded to the bottom plate to increase the rigidity and impact resistance of the carriage.
Lifting mechanism type
The lifting mechanism is the core of a dump truck and the primary indicator for judging the quality of a dump truck.
Types of Lifting Mechanisms Currently, the common tripod-enlarged lifting mechanism in China is the tripod-enlarged lifting mechanism, which is double-cylinder lifting, front-top lifting and double-sided rollover, as shown in the figure below.
The tripod amplified lifting mechanism is currently the most commonly used lifting method in China. It is suitable for load capacity ~ tons and carriage length ~ meters. The advantage is that the structure is mature, the lift is stable, and the cost is low. The disadvantage is that the closed height of the carriage floor and the upper plane of the main frame is large.
The double-cylinder lifting form is mostly used on dump trucks. A multi-stage hydraulic cylinder is installed on each side in front of the second bridge. The upper fulcrum of the hydraulic cylinder acts directly on the car floor. The advantage of the double-cylinder lift is that the closed height of the carriage floor and the upper plane of the main frame is small. The disadvantage is that it is difficult for the hydraulic system to ensure that the two hydraulic cylinders are lifted simultaneously. The stability is poor and the overall stiffness of the carriage floor is required to be high.
The front roof lifting method has a simple structure. The closed height between the car floor and the upper plane of the main frame can be very small. The whole vehicle has good stability and the hydraulic system has low pressure. However, the front roof multi-stage cylinder has a large stroke and the cost is very high.
The double-sided rollover hydraulic cylinder has good force and a small stroke, which can achieve double-sided rollover. However, the hydraulic pipeline is more complicated and the incidence of rollover accidents is higher.
With the development of dump trucks and the improvement of domestic purchasing power, dump trucks are no longer universal dump trucks in the traditional sense that can do any job. From a design perspective, they are also developed differently according to different goods, different working conditions, and different regions. The product. This requires users to provide specific usage conditions to the manufacturer when purchasing a vehicle.
Chassis
When choosing a chassis, economic benefits are generally considered, such as the price of the chassis, loading quality, overload capacity, fuel consumption per 100 kilometers, road maintenance fees, etc. In addition, users must also consider the following parameters of the chassis
① The height of the upper plane of the chassis frame from the ground. Generally, the height of the upper plane of the chassis frame from the ground is ~. The larger the value, the higher the center of gravity of the vehicle and the easier it is to cause a rollover. The factors that affect this value are mainly the tire diameter, suspension arrangement and main frame section height.
② Chassis rear suspension. If this value is too high, it will affect the lifting stability of the dump truck and cause a lifting accident. This value is generally between.
③ The whole vehicle is matched and used reasonably and reliably.
Manager Sun, China National Heavy Duty Truck Sales Service Hotline
At present, there is a mixed bag of dump truck modification manufacturers. When choosing a dump truck, choosing the manufacturer is as important as choosing the product. In addition to looking at the product, you also need to understand the manufacturer's equipment capabilities, whether the design process equipment installed on the dump truck is mature, and whether the after-sales service commitment and accessories are available, etc. Cargo
Carriage Thickness
Other Options
Carriage
The choice of carriage is mainly based on the materials used, which are stronger than ordinary materials but are also more expensive. Depending on the transported goods, the local thickness should be appropriately increased to meet the requirements. Please refer to the table above for the thickness of common transported goods.
In order to reduce the weight of the carriage, some carriages can be made of aluminum alloy or high-strength materials to reduce the dead weight and increase the load capacity.
Lifting mechanism
Selection of lifting mechanism
For general-purpose dump trucks, it is recommended to choose a tripod enlarged lifting mechanism. This structure has a history of many years in our country and the technology is relatively mature. It is suitable for carriages with a length of ~ meters. Dump truck.
Reasonably arrange the components so that the force will not exceed the bearing capacity of the components. The system oil pressure is small to ensure the service life of each seal.
Choose high-quality hydraulic cylinders. The hydraulic cylinder is the power component of the dump truck lifting. Try to choose products with guaranteed quality. For example, the Qingzhuan brand hydraulic cylinder manufacturer promises a lifetime warranty.
Dump trucks with carriage lengths greater than one meter generally adopt a multi-stage cylinder front-top lifting structure.
The double-cylinder lifting structure is generally used for dump trucks with a wheelbase of ~ meters.
Issues to note when selecting a model
A bucket carriage must be used to transport large items.
When the length of the carriage is greater than one meter, special attention must be paid to the height of the center of gravity and lifting stability of the carriage.
Special coal trucks cannot be used to transport earth and stone. Generally, the height of the carriage of a special vehicle for transporting coal is about ~ meters in length. This type of vehicle is designed with light cargo in mind. When used to transport earth and stone, there may be problems with poor lifting stability. In severe cases, lifting and rollover accidents may occur. Sinotruk Sales Service Hotline Manager Sun
Do not use the bucket carriage to transport viscous goods such as silt and clay. The structure of the bucket carriage makes it more difficult to unload sticky goods.
When selecting a dump truck for transporting iron ore powder, you must declare to the manufacturer that it is best to choose a transport truck for iron ore powder.
When used for transporting paving asphalt, the lifting mechanism requires a slow-down device.
Use and maintenance of dump trucks
Several common erroneous operating methods
When the engine is running, the power take-off is in the position of turning on the lifting handle and in the lifting position, the clutch is suddenly lifted. Due to the sudden engagement, the power take-off oil pump drive shaft and oil pump will cause a large impact load and easily cause early damage. It is more prominent when the engine is running at high speed and the carriage is fully loaded and the viscosity of the hydraulic oil is high in cold winter.
When the lifting handle is suddenly pushed to the lowering position during full-load lifting, the carriage will not land slowly but rush down suddenly, which will bring a great impact to the frame and even cause an accident. Although the single-acting piston hydraulic cylinder is equipped with a throttling device to ensure that the throttling effect is generated before the carriage is lowered and the falling speed of the carriage is automatically slowed down, the effect is no longer obvious for a fully loaded carriage. Therefore, the above operations should be avoided as much as possible if necessary in special circumstances. You must also operate carefully and slow down the landing speed as much as possible, and be careful not to suddenly drop the car to the bottom.
After unloading, do not disengage the power take-off or forget to disengage the power take-off before driving. In this way, when the car is driving, because the power take-off is in the engaged position, the lifting oil pump will run at high speed and for a long time without load in a small circulation state. . The so-called small circulation means that when the oil pump is running, the hydraulic oil only circulates between the high and low pressure circuits of the oil pump. In this case, the temperature of the hydraulic oil rises quickly, which can easily cause damage to the oil pump oil seal or even burn the oil pump. In addition, when driving at high speed, the oil pump drive shaft will also cause early damage under the action of excessive centrifugal force. What's more serious is that the operation of the oil pump means that the hydraulic system has a power source, which may cause the car to automatically rise due to various reasons during driving. Therefore, when unloading the goods and driving, it is necessary to disengage it in time and confirm that the power take-off has been disengaged before driving the vehicle.
Use the truck to brake hard to unload. Due to the large inertial force of the violent lifting of the vehicle, it is easy to cause permanent deformation of the vehicle frame, open welding of the compartment and sub-frame, burn the oil pump, damage the sealing ring and damage the hydraulic cylinder, etc., which will damage the service life of the vehicle, reduce the service life of the vehicle, and even cause a rollover accident in severe cases. Therefore, it is generally forbidden for dump trucks to drive when lifted.
If the power take-off is in the on position while driving, the oil pump will continue to rotate and the hydraulic system will have a power source. This will cause the car to automatically lift due to misoperation on the pneumatic control valve. Even if the air-controlled distribution valve is in the lowered position, oil will enter the oil pump, which will cause the oil pump to burn out.
When driving, place the lifting handle in the neutral position. At this time, the hydraulic system is in a closed state. When driving, the impact of the ground can be transmitted to the car through the lifting mechanism, which can easily damage some connecting parts. Therefore, the lifting handle must be placed in the lowered position when driving.
When unloading and lifting at a site with a large transverse slope
When the carriage is tilted, the turning axis of the carriage may be permanently deformed. In more severe cases, a rollover may occur.
Using safety struts when the cargo is not completely unloaded may lead to an accident. Safety struts are only used for truck inspection and maintenance.
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