Vibration and maintenance of hydraulic system of vibratory roller

The high-frequency strong vibration force when the vibratory roller is working is an important factor to achieve high productivity, but it is also the main reason that affects the structure, reliability and machine failure rate of the machine.

1,No vibration or abnormal vibration frequency

1) Causes and troubleshooting of abnormal vibration frequency

(1) The hydraulic pump has low efficiency and cannot meet the requirements.

Generally, the hydraulic pump should reach the rated working pressure during normal operation, and the displacement should reach the rated value. If the required value is not reached, the vibration efficiency will decrease. The reasons for the reduced efficiency of the hydraulic pump are: wear of the seal ring of the pump, wear of components or excessive bearing clearance. In the event of a fault, check each seal on the pump or adjust the bearing clearance and replace the seal if necessary.

(2) Starting valve failure

If the starting valve is not in place, the hydraulic oil circuit cannot be cut or turned on, causing the oil passage to be unreachable or the pressure to reach the rated pressure value, resulting in no vibration or low frequency. The reasons are:

The lever is not properly adjusted; the plunger spring is disabled; the foreign matter is stuck or worn at the hydraulic valve. Troubleshoot by adjusting, replacing, and cleaning the parts after a fault.

(3) The hydraulic motor is leaking, the efficiency is low, and the displacement is not up to the requirement.

The internal leakage of the hydraulic motor due to wear or damage to the seal is severe, and the vibration frequency is also changed. In addition, the hydraulic motor should reach the minimum required pressure range during normal operation, and the displacement should also reach the required value. When the pressure is too low, the vibration frequency will decrease.

The reasons are: oil seal damage (can cause hydraulic oil to enter the vibrating eccentric rotor oil chamber to raise the oil level); component wear; spline shaft or spline sleeve wear.

(4) Hydraulic oil line blockage

When there is no vibration or abnormal vibration frequency, it is often caused by blockage of the oil circuit. The blockage is usually at the hydraulic hose or joint, inside the filter and hydraulic oil cooler. The root cause is that the hydraulic oil passes through the cavity. The solution is to clean the blockage and the filter. In addition, the vibration frequency is abnormal when the inlet pipe is sucked or leaked.

(5) Engine speed is unstable

When the engine speed is unstable (generally called a cruiser), the vibration frequency also varies with the abnormality. The main reasons are: governor parts damage, speed control spring wear, connecting rod bonding, oil control rack or oil quantity control valve block. In this case, check the governor, adjust, replace and clean the corresponding parts, and the fault can be eliminated. In addition, the oil supply pump is not uniform in oil supply or some of its moving parts are subjected to abnormal resistance, which may cause instability of the engine speed.

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

Practice has proved that the excessive or too low lubricating oil surface in the vibrating wheel has a direct impact on the vibration frequency. If the oil level is too high, it will hinder the movement of the eccentric block; if the oil level is too low, the lubrication will be poor. If the lubricating oil is too small, check whether the bolts on both sides of the vibrating wheel are loose; whether the flange is skewed; whether the vibrating wheel oil seal is worn or damaged; whether the sealant is invalid or not. Once the oil leak is found and repaired, add the oil to the specified oil level. If the lubricating oil surface is too high, check if the vibration hydraulic motor oil seal has been damaged, causing the hydraulic oil to enter the vibrating wheel.


2)The cause of the engine working normally, but the vibration system is not working

(1) The elastic drive plate between the engine flywheel and the input shaft of the hydraulic pump is detached or damaged, so that the power cannot be input to the vibration pump.

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

(3) The oil tank lacks oil or the oil suction filter is seriously blocked, which causes the main circuit of the hydraulic system to fail to replenish oil in time, resulting in suction and power transmission.

(4) The hydraulic pump's displacement control system is faulty, making it inoperable.

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


3)Control measures

(1) In operation, the machine should be operated correctly and smoothly in accordance with the procedures. According to the requirements of engineering construction specifications, the static line pressure, vibration amplitude and frequency and rolling speed of the road roller should be correctly selected. The engine tachometer and vibration frequency meter should be checked frequently. For stepless variable amplitude and variable frequency road rollers, reasonable vibration amplitude and frequency should be selected according to different compacting materials and thicknesses, without frequent changes. Do not modify the machine or change the machine weight at will to ensure the static pressure and working condition of the roller.

(2) Check whether the hydraulic system leaks, whether the working conditions of each component are normal, and whether the amount of lubricating oil is normal, etc., before and after each shift. Always check the working condition of the engine. Formulate a strict warranty system, regularly maintain the hydraulic system and the vibrating wheel system, and timely add various oils such as hydraulic oil and lubricating oil to the specified height to ensure the clean and quality of the hydraulic oil and clean the filters according to the time. Net, tighten loose pipe joints and fastening bolts for key parts. Timely update of failed seals, consumables and damping components, often lubricating the vibrating components. In order to ensure the smooth flow of the hydraulic system, the vibrating wheel works reliably.


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. The hydraulic oil temperature must be between 55 °C and 65 °C during the measurement. If the oil temperature is too low, the viscosity of the oil will be too high, which will lead to inaccurate determination. Now, a certain type of roller is used as an example to introduce the detection method of the driving system pressure:

1) Start the roller and vibrate for a period of time to raise the hydraulic oil temperature to 55 ° C ~ 65 ° C:

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

3) Hold the front part of the roller against a fixed object (a large stone, a wall or other object can be used for fixing), and the fixed object should be able to block the roller from moving forward;

4) Actuate the roller and place the speed control handle in the forward gear position. The roller is blocked by the fixed object and cannot drive. At this time, the pressure value of the pressure gauge is the highest driving pressure of the drive system (the design value is 350kg/cm2). If the pressure is greater than 300 kg/cm2, the drive hydraulic system is good; if the pressure is 100 kg/cm2 to 200 kg/cm2, the drive hydraulic system has leaked;

5) When detecting the highest pressure, note that the front and rear wheels cannot be idling.


3,Hydraulic steering system determination

1) Start the roller and vibrate for a period of time to raise the hydraulic oil temperature to 55 ° C ~ 65 ° C:

2) Make the engine speed reach 1 500 r/min;

3) Connect the pressure gauge to the steering pump steering pressure joint;

4) Turn the roller to the 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 good. If the pressure is lower than 120 kg/cm2, it must be checked.