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Failure And Maintenance Of Hydraulic System Of Vibratory Roller

Summary: The high frequency and strong vibration power of vibratory roller is an important factor to achieve high productivity, but also the main reason to affect the structure, reliability and failure rate of the machine.

The high frequency and strong vibration power of vibratory roller is an important factor to achieve high productivity, but also the main reason to affect the structure, reliability and failure rate of the machine.

1 no vibration or abnormal vibration frequency

1) The cause of abnormal vibration frequency and its troubleshooting

  (1) The efficiency of hydraulic pump is low, which can not meet the requirements

In normal operation, the general hydraulic pump shall reach the rated working pressure and the displacement shall be above the rated value. If the required value is not reached, the vibration efficiency will be reduced. The reasons for the decrease of the efficiency of the hydraulic pump are: the seal ring of the pump is worn, the components are worn or the bearing clearance is too large. In case of failure, check each sealing ring on the pump or adjust the bearing clearance, and replace the seal if necessary.

  (2) Failure of starting valve

If the starting valve is not lifted in place, the hydraulic oil circuit cannot be cut off or connected, resulting in blocked oil circuit, or the pressure cannot reach the rated pressure, resulting in no vibration or low frequency. The reasons are as follows:

Improper adjustment of the control rod; failure of the plunger spring; foreign matters stuck or worn at the hydraulic valve, etc. After malfunction, adjust, replace and clean the corresponding parts, then the trouble can be eliminated.

  (3) Due to leakage and low efficiency, the displacement of hydraulic motor fails to meet the requirements

The internal leakage of hydraulic motor is serious due to wear or seal damage, which will also cause the change of vibration frequency. In addition, when the hydraulic motor works normally, it should reach the minimum required pressure range, and the displacement should also reach the required value. When the pressure is too low, the vibration frequency will decrease.

The reasons are: the oil seal is damaged (which may cause the hydraulic oil to enter the vibration eccentric rotor oil cavity to raise the oil level); the components are worn; the spline shaft or spline sleeve are worn, etc.

  (4) Blocked hydraulic oil circuit

When the vibration cannot be started or the vibration frequency is abnormal, it is often caused by the blockage of the oil circuit. Generally, the blocked parts are at the hydraulic hose or joint, the filter screen and the inside of the hydraulic oil cooler. The root cause is the hydraulic oil passing through the cavity. The solution is to clean the blockage and the strainer. In addition, when the oil inlet pipe is flat or leaking, the vibration frequency will be abnormal.

  (5) Unstable engine speed

When the engine speed is not stable (generally known as traveling block), the vibration frequency is also abnormal. The main reasons are: the governor parts are damaged, the speed regulating spring is worn, the connecting rod is bonded, the oil control gear rod or the oil regulating valve is blocked, etc. At this time, check the governor, adjust, replace and clean the corresponding parts, and the fault can be eliminated. In addition, the speed of the engine is unstable because of the uneven oil supply of the oil supply pump or the abnormal resistance of some of its moving parts, resulting in the delayed response of the governor.

  (6) Too much or too little lubricating oil in the vibration wheel

It has been proved that too high or too low lubricating oil level has a direct impact on the vibration frequency. If the oil level is too high, the movement of eccentric block will be hindered; if the oil level is too low, the lubrication will be poor. If the lubricating oil is too little, check whether the bolts on both sides of the vibrating wheel are loose; whether the flange is skewed; whether the oil seal of the vibrating wheel is worn or damaged; whether the sealant is invalid, etc. After finding and repairing the oil leakage, add the oil to the specified oil level. If the lubricating oil level is too high, check whether the oil seal of the vibration hydraulic motor has been damaged, causing the hydraulic oil to enter the vibration wheel.

2) The reason why the engine works normally, but the vibration system does not work

  (1) The elastic drive plate between the engine flywheel and the input shaft of the hydraulic pump falls off or is damaged, resulting in the failure of power input to the vibrating pump.

  (2) The coupling between the vibration hydraulic motor and the vibration shaft is damaged, so that the power of the hydraulic motor cannot be output.

  (3) The lack of oil in the hydraulic oil tank or the serious blockage of the oil suction filter results in the failure of the main circuit of the hydraulic system to replenish oil in time, resulting in air suction and power transmission failure.

  (4) The displacement control system of the hydraulic pump has failed to work.

  (5) The hydraulic pump or motor is worn and has serious internal leakage, so the system pressure cannot be established.

3) Prevention and control measures

  (1) During operation, the machine shall be operated correctly and smoothly in accordance with the regulations. The static line pressure, vibration amplitude, frequency and rolling speed of the roller shall be selected correctly according to the requirements of the engineering construction specifications, and the engine tachometer and vibration frequency meter shall be checked frequently. For the roller with stepless amplitude change and frequency conversion, the reasonable vibration amplitude and frequency shall be selected according to different compaction materials and thickness, without frequent change. Do not modify the machine or change the machine weight at will to ensure the static line pressure and working state of the roller.

  (2) Before and after each shift and during the operation, check whether there is leakage in the hydraulic system, whether the working condition of each component is normal, whether the lubricating oil quantity is normal, etc. Check the working condition of the engine frequently. Establish strict warranty system, regularly maintain the hydraulic system and vibration wheel system, add various kinds of oil such as hydraulic oil and lubricating oil to the specified height in time, ensure the cleanness and quality of the hydraulic oil, clean the filter screen on time, and tighten the loose pipe joints and the fastening bolts of key parts. Timely update the failed seals, vulnerable parts and damping elements, and regularly lubricate the vibrating parts. In order to ensure the smooth flow of hydraulic system oil and reliable operation of vibrating wheel.

2. Determination of technical status of hydraulic drive system

The technical status of the hydraulic drive system can be determined by measuring the pressure of the hydraulic drive system. When measuring, the oil temperature of the hydraulic oil must be between 55 ℃ ~ 65 ℃. If the oil temperature is too low, the viscosity of the oil is too high, which often leads to the inaccuracy of judgment. Taking a certain type of roller as an example, this paper introduces the detection method of the driving system pressure

1) Start the roller and vibrate it for a period of time to make the hydraulic oil temperature rise to 55 ℃ ~ 65 ℃:

2) Connect the pressure gauge to the pressure tap of the rear drive motor;

3) Hold the front of the roller against a fixed object (the fixed object can be a big stone, a wall or other objects), which can prevent the roller from moving forward;

4) Start the roller and put the speed control handle in the forward position. The roller is blocked by the fixed object and cannot drive. At this time, the pressure value of the pressure gauge is the maximum driving pressure of the driving system (its design value is 350kg / cm2). If the pressure is greater than 300kg / cm2, the driving hydraulic system is in good condition; if the pressure is 100kg / cm2 ~ 200kg / cm2, the driving hydraulic system has leakage;

5) During the detection of the highest pressure, the front and rear wheels shall not idle.

3 Determination of hydraulic steering system

1) Start the roller and vibrate it for a period of time to make the hydraulic oil temperature rise to 55 ℃ ~ 65 ℃:

2) Make the engine speed reach 1500 R / min;

3) Connect the pressure gauge to the steering pressure connector of the steering pump;

4) Turn the roller left or right to the maximum position, and measure the steering system pressure. At this time, the pressure reaches 140 kg / cm, indicating that the steering system is in good condition. If the pressure is lower than 120 kg / cm2, check it.