Fault analysis of the lifting hydraulic system for mining dump trucks with TEREX spare parts

Mining dump trucks have advantages such as flexibility, strong adaptability to working conditions, high labor productivity, large loading capacity, short loading and unloading time, low labor intensity, low cost and energy consumption, and good profitability. They can achieve full loading and unloading mechanization and are widely used in construction projects such as mines, hydropower projects, urbanization, roads, bridges, and pipeline networks. Due to the harsh working environment, complex and variable working conditions, rugged and difficult driving roads, frequent high-speed and heavy loading, and high frequency of use, the normal operation, maintenance, and adjustment of the lifting hydraulic system of dump trucks are particularly important, which will directly affect the safety and reliability, loading efficiency, maneuverability, and cost and energy consumption of vehicles. Therefore, it is of practical significance to conduct fault analysis and maintenance technology research on the lifting hydraulic system of mining dump trucks for TEREX spare parts.


1、 Structural principle of hydraulic lifting system

Dump trucks, commonly known as engineering trucks or dump trucks, refer to vehicles that unload goods on their own through hydraulic or mechanical lifting. The working principle of its hydraulic lifting system is to use engine power to drive the hydraulic mechanism, that is, the engine power is output by the transmission, and the hydraulic oil pump is driven by the power take-off. The TEREX spare part hydraulic oil of the Terex accessory is pumped to the distribution valve and pressed into the hydraulic cylinder, thereby pushing the piston to lift the carriage, tilt the carriage at a certain angle, and automatically unload the cargo, and reset it based on the weight of the cargo carriage.

At present, the hydraulic lifting mechanism widely used in large tonnage dump trucks is mainly composed of lifting cylinders, control valves, lifting manual control valves, limit valves, and lifting oil pump assemblies. The lifting mechanism relies on the lifting of the lifting cylinder to complete the lifting process. The lifting cylinder is controlled by a control valve, which is operated by the driver. In order to limit the maximum inclination of the bucket and ensure that the bucket can be stabilized at a certain tilt position as needed, a limit valve is installed in the hydraulic system.

The hydraulic dumping mechanism is the core of dump trucks, and its performance and quality are the primary indicators for judging the quality of mining dump trucks. The vehicle model positioning and market positioning of the lifting and dumping mechanism are also different. When designing the lifting hydraulic system, it is necessary to comprehensively consider the power, smoothness, compactness, unloading performance, and maintenance free performance of the lifting.

2、 Classification and selection analysis of lifting mechanisms for dump trucks

1. Main classification of lifting mechanisms for dump trucks

Usually, according to the different directions of cargo dumping, dump trucks can be divided into rear tilting, side tilting, three sided tilting, and bottom dumping types. They are mainly composed of hydraulic lifting mechanisms, car buckets, frames, and accessories. Each manufacturing and modification manufacturer has different design concepts, and their hydraulic lifting mechanisms and car bucket structures are also different. The structural types of car buckets can be divided into ordinary rectangular car buckets and mining bucket cars according to their different purposes. The ordinary rectangular hopper is used for the transportation of bulk goods, and its rear plate is equipped with an automatic opening and closing mechanism to ensure smooth unloading of the goods. The thickness of the ordinary rectangular hopper plate is 4-6 mm for the front plate, 4-8mm for the side plate, 5-8mm for the rear plate, and 6-12mm for the bottom plate; The mining bucket carriage is suitable for the transportation of large stones and other goods with larger particle sizes. Considering the impact and collision of the goods, the design shape of the mining bucket carriage is complex and the materials used are thick. For example, a certain brand of mining bucket carriage has a standard plate thickness of 6mm in the front, 6mm on the sides, and 10mm at the bottom. However, some models add angle steel to the bottom plate, which can greatly improve the rigidity and impact resistance of the carriage.

2. Analysis of commonly used dump truck selection

At present, foreign dump trucks are developing towards large tonnage, lightweight, diversified, and serialized Terex spare parts. They are more utilizing high-tech research and development to develop new models, thereby shortening the design and production cycle, improving product quality, and reducing costs. With the rapid development of automotive technology and the improvement of domestic purchasing power, dump trucks are not traditional universal vehicles. In order to fully meet the strict requirements of safe, efficient, fast, convenient, and cost-effective transportation of dump trucks, various manufacturing and modification manufacturers can develop according to different goods, different working conditions, and different regions


2. The car bucket cannot stop in the middle after lifting

Fault phenomenon: The main manifestation of this fault is that the car hopper cannot stop at any position.

Fault analysis: When there is significant internal leakage in the directional valve or oil cylinder, the location of the leakage should be investigated and the leaking components replaced; When reversing under heavy load, the valve stem is subjected to high hydraulic power, causing the reversing valve to malfunction, resulting in occasional no intermediate stop. Therefore, the reversing valve must be turned to the slow lowering position; When the directional valve is not in place or stuck, the directional valve must be replaced; When the distribution valve and return valve are not tightly sealed, the sealing components must be tightened or replaced; When the one-way valve inside the hydraulic one-way valve is not tightly controlled, the one-way valve needs to be repaired or replaced; When the oil is too dirty, it is easy to cause the check valve to not seal tightly, and the hydraulic oil needs to be replaced; When the viscosity of hydraulic oil is too low, replace it with hydraulic oil with high viscosity; When there is oil leakage in the pipeline, it is necessary to repair the pipeline; When the manual control valve joystick is not in place, the joystick should be adjusted.

3. The car bucket cannot fall after lifting

Fault phenomenon: The main manifestation of this fault is that when the car bucket is in the lifting or middle position, the manual directional valve is turned to the lowering position, and the car bucket cannot automatically fall.

Fault analysis: The main cause of the malfunction is insufficient air pressure, which prevents the distribution valve and return valve from operating, resulting in the hydraulic oil in the lower chamber of the oil cylinder not being able to smoothly return to the oil tank. This will generate a certain negative pressure and prevent the bucket from falling. The truck should be started to achieve the specified air pressure, or the manufacturing process and inspection method of the distribution valve should be improved to eliminate it by improving the design; When the manual control valve control handle is not in place, the control handle should be adjusted to make it in place; If the operation is not standardized and the lifting angle exceeds the designed maximum lifting angle, it is easy to cause jamming. It is necessary to detach the power take-off and let the vehicle start and move forward before braking, and use inertia to lower the car bucket; When dumping goods on a ramp for lifting, it is often beyond the limit of the lifting angle. At this time, it is advisable to dump on a flat road surface as much as possible; When the limit valve or safety valve malfunctions or the limit valve pipeline is damaged, immediate repair or replacement is required; When the lifting cylinder is stuck or concave, or the piston rod is bent or deformed, it is easy to get stuck on the piston rod and affect the fall of the bucket. It is necessary to straighten the piston rod or repair the cylinder body; When the lifting and dumping mechanism is not used for a long time or is contaminated by impurities, it may sometimes cause stagnation. It should be maintained, lubricated, maintained or replaced according to regulations; When there is too much hydraulic oil in the oil tank, it can also affect the bucket to fall back, so it is necessary to adjust the hydraulic oil to the normal level; When there are foreign objects blocking the hydraulic system, they should be removed, the oil tank should be cleaned, and the filter screen should be replaced.

4. Do not lift during heavy loads

Fault phenomenon: The main manifestation of this fault is that the bucket cannot be lifted when the truck is fully loaded with goods, but the bucket is lifted normally when the truck is empty.

Fault analysis: When the vehicle is severely overloaded, it is very easy to damage the oil pump and also cause deformation and damage to the transmission shaft. It must be strictly shipped according to the rated loading capacity, and overloading is strictly prohibited; When the vehicle is parked on a heavily sloping slope, it should be parked in a suitable position before being lifted; When the nut fastening the piston is loose, or when the oil cylinder piston ring is aligned, broken, or the piston is broken, it can cause the sealing rubber ring between the piston and the piston rod to be not tightly sealed and cause oil leakage. It is necessary to tighten the piston nut or replace the piston ring or piston; When the control valve stem is severely worn, hydraulic oil is prone to leakage from the valve stem, and it is necessary to replace the valve stem and re grind it; Lifting cylinder



4、 Conclusion

The lifting hydraulic system is a key working system for dump trucks, and its performance directly affects the main performance indicators of the vehicle. Its faults involve the vehicle's driving safety, transportation function, and dump function, and its working status is related to the vehicle's work efficiency and engineering progress. Terex accessories TEREX spare parts therefore conduct in-depth research on fault analysis and control technology for the lifting hydraulic system of dump trucks, which can significantly improve the operational efficiency, integrity rate, and operability of vehicles.

The company mainly sells TEREX spare parts for Terex off-road rigid dump trucks, including TR100, TR50, TR60, TR353307/3305 series products. Terex spare parts include TR100, MT3700, MT4400, MT5500, Terex spare parts, and other mining dump truck components such as Allison transmission parts, Cummins engine parts, hydraulic seals, high and low voltage harnesses, hydraulic cylinders, machined parts, gears, and chassis series.

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