As a maintenance engineer or equipment manager, you are well aware of the core value of the self-loading concrete mixer at the construction site – it integrates the five functions of loading, weighing, mixing, transportation and unloading, and can independently complete the whole operation process of the small concrete mixing station, which replaces the traditional “loader + stirring High-efficiency equipment combined with mixing station + mixing transport truck. One device undertakes the workload of multiple devices, which means that its maintenance logic must cover the operating risks of the whole process. The failure of any link may lead to the interruption of the entire concrete supply chain.
As an industry brand specializing in the manufacture and export of self-upply mixers, EPDAS’s products cover a full range of models from integrated to hinged, from 2.5 square to 5.5 square, and can fully adapt to all kinds of engineering needs from rural road maintenance, small township projects to urban narrow construction scenarios. The built-in maintenance convenience characteristics in its design provide a native basis for equipment managers to reduce concrete mixer maintenance costs, but no matter how reliable the equipment is, it cannot be separated from a systematic professional maintenance plan.
The continuity of concrete construction determines that the self-loading concrete mixer must always be in the peak operation state. This kind of equipment is mostly operated under complex conditions of heavy load, high strength and high corrosion. Sometimes it is on the edge of the muddy foundation pit, sometimes it is a narrow urban village construction site, and sometimes it is a rural road for long-distance transportation. The reliability of its operation directly determines the efficiency of the construction progress. Once the equipment is shut down, it will not only cause the interruption of concrete pouring and waste of materials, but also lead to a chain delay in the subsequent construction period, resulting in additional economic costs.
For maintenance engineers and equipment managers, the self‑loading concrete mixer maintenance work must not stay at the passive level of “repair after failure”. Passive maintenance often means that it has caused the loss of on-site shutdown, concrete scrapping, and additional emergency repair costs. Truly professional equipment management is to eliminate potential failure hazards in the bud through forward-looking preventive maintenance.
Structural parts inspection; check whether there are obvious cracks, deformation or loosening traces in the core structural parts such as the chassis, traction frame, mixing cylinder, unloading tank, etc.
Safety protection device inspection; confirm that all safety protection devices, such as the protective cover of the transmission part of the mixer, the safety baffle of the unloading tank, etc., are in good condition, without missing, loose or deformed. If you find that the safety device is damaged or fails, it must be repaired immediately, and you must not force the power-on operation.
Check the contact status of the tire with the ground; check whether the tire pressure of all tires is normal, and whether there are cuts, inlays, abnormal wear or exposed tire curtain lines on the tire surface. If the tire pressure does not meet the standard, it will increase the load of the driving system, resulting in a decrease in vehicle power, an increase in fuel consumption, and even a flat tire and other safety accidents.
Brake system inspection; Check whether the free stroke of the brake pedal meets the standard. Generally speaking, the free stroke of the brake pedal should be in the range of 10-15mm, and there should be no high, low or obviously loose. For models with gas-top oil braking system, it is also necessary to focus on checking whether the pressure of the brake energy storage is within the safe range and whether there are leakage marks at the joint of the brake pipeline; for models with hydraulic braking, it is necessary to check whether the oil level of the brake master pump is within the standard range.
Control mechanism inspection; check whether all control mechanisms, such as the control handle of the hydraulic control distribution valve, the variable speed rod, the unloading operation rod and other free stroke and control gap are normal. If the operation gap is too large, it will affect the accuracy of loading and unloading; if the gap is too small, it may lead to operation lag and inability to accurately control the operation.
Appearance and leakage inspection; first check the surface condition of the hydraulic oil pipe. If there are obvious bulges, local cracks, aging and hardening or traces of serious scratches on the surface of the hose, it should be replaced in time to avoid bursting and leakage during high-pressure operation. Then, start the engine, control the loading, stirring and unloading actions respectively, and check whether all hydraulic oil pipe joints and welding parts are leaking, and whether the oil pipe will collide with other parts of the equipment during operation.
Hydraulic oil quality inspection; observe the appearance of the hydraulic oil. If the color of the hydraulic oil is milky white or obviously black, or there are obvious metal particle impurities in the oil, it means that the hydraulic oil has been contaminated or over-aged. It needs to be sampled and tested immediately and replaced according to the test results.
Action coordination inspection; in the no-load state, test the stability of all hydraulic operation actions, including loading, stirring cylinder rotation, unloading tank lifting and other actions, and confirm that the action of each operation actuator is consistent with the direction of the control indication, and there are no obvious abnormal phenomena such as action lag, crawling or weak operation.
Internal inspection of the mixing cylinder; under the condition that the power source has been cut off, enter the inside of the mixing cylinder to check whether the stirring blades on the wall of the cylinder are obviously worn, deformed or loose, and whether there is excessive material accumulation on the wall of the cylinder. If the blade is deformed, cracked or worn seriously, it will seriously affect the uniformity of stirring, and even cause the blade to break during stirring, causing equipment accidents.
Check the driving mechanism of the mixing cylinder; check whether the working state of the driving mechanism of the mixing cylinder, including the hydraulic motor, reducer, drive gear, etc., is normal, whether there is abnormal vibration or noise during the operation process, and confirm that the mixing cylinder runs smoothly within the standard speed range, and there is no radial beating or abnormal movement.
Check the loading system; check whether there is deformation or crack in the structure of the loading hopper, as well as the wear of the roller, guide rail and wire rope of the loading hopper. If it is a hydraulically driven loading mechanism, it is necessary to check whether the oil pipe joint part of the hydraulic cylinder is leaking; if it is a steel wire rope lifting structure, the condition of the steel wire rope should be checked. If the wire rope is broken, loose, twisted or worn, it must be replaced immediately.
Unloading system inspection; check the wear of the unloading channel to confirm that its support structure is firm, the operating mechanism is flexible, and there is no obvious deformation or leakage. Then, test the rotation function of the unloading system to confirm that the unloading groove can be rotated normally to the angle required for the operation.
Calibration verification; according to the standard operation process of the equipment, lift the hopper to a certain height, and then slowly put it down. By observing the display value of the weighing system, confirm whether the response of the sensor is sensitive and whether the numerical display is stable and zero. If there are conditions, another calibration can be carried out with standard weights to ensure that the error of the weighing system is always within the allowable range.
Appearance inspection; check whether the sensor in the weighing system is deformed or damaged, and whether there are material accumulation or other stuck objects around the sensor that affect its accuracy. It is also necessary to check whether the unloading door of the hopper is tightly closed and whether the door lock mechanism is flexible and effective to avoid material leakage during lifting or transportation.
Pre-cleaning operation; park the vehicle in the designated cleaning area, start the engine, operate the hydraulic control handle, aim the feed port of the mixing cylinder at the cleaning station, and use a high-pressure water gun to initially clean the surface of the feed port, the unloading tank and the hopper, and remove most of the unsolidified concrete residue.
Cleaning operation in the cylinder; inject a sufficient volume of water into the mixing cylinder, adjust the speed of the mixing cylinder to the highest speed, and let it rotate continuously for 5-10 minutes. During the rotation process, you can use a high-pressure water gun to rinse the blade part of the cylinder mouth to completely clean the residual mortar on the cylinder wall and blade. It should be noted that when cleaning the inside of the mixing cylinder, it is strictly forbidden to put your hands or other parts into the cylinder to avoid safety accidents.
Sewage discharge operation; After cleaning, the sewage inside the mixing cylinder is completely discharged to confirm that there is no residual water or residue in the cylinder. The discharged sewage must be precipitated in the sedimentation tank before it can be discharged into the special sewage pipe network to avoid polluting the environment.
Detailed cleaning operation; use a high-pressure water gun to clean the internal and external guide rails and roller parts of the hopper to remove the accumulated material. At the same time, the outer surface of the mixer, the suspension parts of the walking system, the front and rear axles of the chassis and other parts that are not easy to clean are washed to remove the residual concrete residue and dirt on the surface. Special attention should be paid to the fact that when using high-pressure water gun cleaning equipment, you should avoid rinsing directly on the joint part of the hydraulic oil pipe, the plug-in part of the electrical line and the seal part of the cab, so as not to damage the seal, resulting in hydraulic oil leakage or short circuit of the electrical system.
For short-term parking, park the equipment on a hard flat ground with high terrain, good ventilation and smooth drainage, and try to avoid parking in areas with stagnant water, mud or depressions and potholes. If you must temporarily park on the ramp, you must place an anti-skid pad under the tire to prevent the equipment from slipping unexpectedly. When parking, be sure to completely lower the hopper to the lowest position and lock it with a special safety pin; completely retract the unloading trough to a special position and fix it with a safety pin; turn the mixing cylinder to the appropriate position to ensure that all operating hydraulic cylinders are completely retracted, and use a dust cover to Protect the table. Finally, turn off all operating power supplies, and completely close and lock the doors and windows of the cab.
If the equipment needs to be parked for a long time, in addition to complying with the above-mentioned requirements for short-term parking, the following special maintenance operations need to be carried out;
5.Park the equipment in a closed dry garage and cover the whole vehicle with a waterproof cover. During the parking period, start the engine at least once a month and idle for 10-15 minutes, so that each friction surface can re-form a lubricating film to prevent the cylinder liner, piston and other parts from rusting due to long-term rest.
When lubricating the equipment, wipe all the lubricating nozzle parts clean, and then point the lubrication gun vertically at the lubrication nozzle, and then press the handle of the lubrication gun to evenly inject the grease into the lubrication point. The amount of grease injected at each lubrication point should be between 0.5-1L, not too much or too little. After the lubrication is completed, the overflowing excess grease should be wiped clean to avoid adsorption of dust or impurities, causing wear of parts.
For the core lubrication points such as the supporting bearing part of the stirring cylinder, the input and output shaft hole part of the rotary reducer, and the mesing part of the rotary support turntable, when injecting grease, the mixing cylinder should be rotated while filling to ensure that the grease can be evenly distributed on the entire friction surface. When supplementing grease to the lubricating part of the equipment, all the old grease should be discharged until the new grease overflows from the gap of the lubricating part, so as to avoid the mixing of the old and new grease, resulting in a decrease in lubrication performance.
The hydraulic system is the “power nerve center” of the equipment. The quality of its working state directly determines the smoothness of the core operations of the equipment such as loading, stirring and unloading. 80% of the failure of the hydraulic system is caused by the pollution of hydraulic oil. Therefore, the core of the maintenance of the hydraulic system is to ensure the cleanliness of the hydraulic oil.
When the new equipment is used for 500 working hours for the first time, all hydraulic oil must be discharged and replaced with new hydraulic oil. The hydraulic oil needs to be replaced for every 1,500 working hours or every other year (whichever comes first). When replacing the hydraulic oil, the filter element of the hydraulic oil should be replaced at the same time, and the inside of the hydraulic oil tank, the heat dissipation pipe of the hydraulic oil and the oil line of the entire hydraulic system should be thoroughly cleaned.
The mixing and loading system is the core working mechanism that directly contacts building materials, and it is also the area with the most concentrated load and the most wear. In addition to the cleaning and lubrication of each shift, it also needs to be comprehensively checked and maintained regularly. Every month, when the equipment is down, cut off the power source and lock the switch, supervised by a special person, enter the inside of the mixing cylinder, and check the wear status of the mixing blade, the tightening of the connecting bolt and the degree of wear of the inner wall of the cylinder.
Check the oil level of the lubricating oil of the mixer drive reducer every month to confirm that it is not below the off-line of the oil standard scale. Check the wear of the rollers, rails and wire ropes of the hopper every week. If it is a hydraulically driven loading mechanism, check whether the oil seal of the hydraulic cylinder is leaking, and whether the pin shaft of the hydraulic cylinder is loose or worn. Check the wear of the unloading channel every week and the firmness of its support structure to confirm that there is no abnormal wear or leakage.
The chassis and power transmission system are the installation foundation of the whole equipment. They support all the operating mechanisms on the car and bear the longitudinal, transverse and torsional load of the vehicle. Its strength and stability directly determine the operation safety of the equipment.
Maintenance of the chassis frame; weekly check whether the frame of the chassis is deformed, cracked or obviously dented, as well as whether the connecting parts of the front and rear axles and the bolts of the steel plate spring fixing part of the frame are loose or falling off.
Dynamic system maintenance; check every week whether the connecting bolt of the transmission shaft is loose, and whether the dustproof sleeve of the gidirectional transmission device is damaged or leaking.
Running system maintenance; check every week whether the tire pressure of the tire meets the standard, whether the fixing bolt of the tire is loose, and whether the tread of the tire is abnormally worn, budded or seriously cut.
Brake system maintenance; weekly check whether the oil level of the storage tank of the brake system is within the standard range, and whether there is wear, aging or leakage in the brake pipeline.
The accuracy of the weighing system directly determines the water-ash ratio and strength level of concrete. The core of its maintenance is to avoid dust and accumulated materials affecting the normal operation of the sensor.
Cleaning and maintenance; After the completion of each shift, the weighing hopper of the symmetrical system should be thoroughly cleaned to remove the accumulated material, clumping dust and other debris in the weighing hopper.
Appearance inspection; check every day whether the sensor of the weighing system is deformed, damaged or stuck by the material, and whether the connection line insulation of the sensor is damaged, squeezed or worn.
Calibration and maintenance; the calibration verification of the symmetrical system should be carried out once a day. If a deviation in the weighing accuracy is found, the system needs to be calibrated immediately before it can be continued after the calibration is completed.
Wiring inspection; check all the terminals in the weighing system every month to confirm that they are firmly connected and not loose, and check whether the terminals are water in, oxidized rusted or contaminated by dust.
| Malfunction phenomenon | Possible reasons | Solutions |
| Walking is weak/hydraulic oil temperature is too high | The clutch piston seal fails or the oil pressure is insufficient | Check the pressure of the hydraulic system, use the air pressure to test the valve, and replace the clutch seal according to the situation; check whether the oil volume and cooling system are normal. |
| The mixing shaft is stuck. | Incomplete flushing or improper water inser position leads to concrete clumping. | Check the pressure of the hydraulic system, use the air pressure to test the valve, and replace the clutch seal according to the situation; check whether the oil volume and cooling system are normal. |
| Equipment tripping/automatic shutdown | Overfeeding leads to excessive load; slack of the triangle band; loose safety limit switch | Control the feeding volume and feeding speed; check and adjust the belt tension or replace the worn belt; fix the safety switch; check the gap between the blade and the lining plate, and replace the blade lining plate if necessary. |
| The concrete is mixed unevenly. | The mixing blade is seriously worn; the mixing measurement error | Check the degree of wear of the mixing blade and replace it when the wear exceeds 30% of the original size; calibrate the weighing system or check the scale sensor to ensure that the ratio is accurate. |
| Leakage of hydraulic system | The hydraulic pipeline is aging and the joint is loose | Check the hydraulic hose and joint, tighten the loose part; replace the aging or damaged oil pipe; check the valve body seal and rule out leakage. |
In order to ensure the continuity of equipment operation, it is recommended to always have the following key spare parts and consumables.
Two. Roller sealing ring and raceway bushing: The sealing ring and raceway bushing will leak oil or affect operation after wear. It is recommended to check it every year and update it according to the wear situation.
Six Lubricating oil and grease: equipped with engine oil, hydraulic oil, transmission oil and other lubricating oils that meet the specifications; and grease such as lithium-based grease. Prepare to consume enough oil according to the maintenance mileage.
Seven Electrical components: such as spare light bulbs, relays, sensors, etc., to cope with sudden damage.
Personnel qualification compliance; equipment operators and maintenance personnel must undergo professional safety technical training, and after passing the assessment, they must be licensed to work.
Compliance with operating procedures; the user unit shall formulate detailed safety operation procedures and maintenance procedures that meet the standard requirements according to the instruction manuals provided by the equipment manufacturer and the actual working conditions of the equipment.
The maintenance process is compliant; the user unit shall formulate a reasonable maintenance plan and program according to the instruction manual provided by the equipment manufacturer and the actual working conditions of the equipment, and the maintenance operation shall be carried out by professionals according to the plan.
Repair accessories are compliant; the repaired and replaced accessories must be original genuine accessories that meet the equipment safety technical standards, or brand accessories with the same performance parameters.
Regular inspection compliance; regular inspection requirements should be submitted to the local special equipment inspection and testing institutions one month before the expiration of the validity period of the safety inspection of the equipment. Equipment that has not been regularly inspected or failed to pass the inspection shall not continue to be used.
The self-loading concrete mixer safety and stability are directly related to the continuity of the construction progress, as well as the safety of personnel and property at the construction site. Only by truly running through the concept of “prevention-oriented and compulsory maintenance” into the whole process of equipment use, and embed the maintenance action into the whole cycle of each shift operation, daily operation, weekly operation, monthly operation, quarterly operation and annual operation of the equipment, and strictly follow the official technical standards of the equipment manufacturer. Hierarchical preventive maintenance can always maintain the highest operating efficiency of the equipment, maximize the return on investment value of the equipment, and ensure the safety and compliance of equipment operation.
