Created on:2022-01-12 14:24

Use of axial piston pump

Use of axial piston pump

(1) The pump shall be cleaned before installation and commissioning. Before installation and commissioning, the oil tank, oil pipe and joint, actuator (such as hydraulic cylinder) and hydraulic control valve must be cleaned. The new oil filled into the oil tank must be filtered by oil filter to prevent oil pollution caused by unclean oil barrel.

(2) Hydraulic oil requirements for new pumps. After the new hydraulic pump is used for one week, all the oil in the oil tank shall be filtered once, and the oil tank and filter shall be carefully cleaned. Then, the hydraulic oil shall be replaced and the oil tank shall be cleaned once every 3 ~ 6 months according to the working environment and working load of the hydraulic system.

(3) System cooling measures. During use, it is strictly prohibited to remove the oil tank cover due to system heating. Other measures can be taken to dissipate heat, such as setting a cooler.

(4) Several problems of self suction of hydraulic pump.

1) Height requirements for pump installation. The distance from the center height of the hydraulic pump to the oil surface shall be ≤ 500mm, and the suction pressure shall be within 125mmhg, otherwise cavitation is easy to occur, resulting in parts damage, noise, vibration and other faults, as shown in Figure B.


2) Requirements for oil suction filter. 150 mesh oil suction filter shall be installed on the oil suction pipeline. Some plunger pump manufacturers stipulate that the oil filter is not allowed to be installed on the suction pipeline, but it shall have strict requirements on the cleanliness in the oil tank. Install a filter on the outlet side of the pump, with a filtering accuracy of 25 μ M pipeline oil filter.

3) The speed of the pump is specified. The speed of the pump shall not be greater than the rated speed.

4) Requirements for oil suction pipe. The diameter of the suction pipe shall not be less than the recommended value (see the product catalogue of installation dimensions), and there shall be at most one elbow joint of the suction pipe.

5) Requirements for deflection angle of oil distribution pan. If the oil distribution plate needs to reduce the deflection angle of the swashplate, self-priming cannot be guaranteed. If the user needs small flow, the variable mechanism shall be used to change the flow after the full deflection angle of the pump is started.

(5) Backflow self suction (as shown in Figure C).

1) When the minimum oil level of the oil tank is 300 mm higher than the center height of the oil inlet of the hydraulic pump, the hydraulic pump can start self-priming at a small deflection angle.

2) The diameter of suction pipe 3 shall not be less than the recommended value, and the diameter of stop valve 2 shall be twice that of suction pipe 3.

3) The length of the suction pipe of the hydraulic pump L < 2500mm, the pipe elbow shall not be more than two, the distance from the suction pipe to the oil tank wall H1 > 3D, and the distance from the inlet of the suction pipe to the bottom of the oil tank h ≥ 3D.

4) For pumps with a flow rate greater than l60l / min, it is recommended to use back filling and self-priming.

(6) Self priming of vertical mounted hydraulic pump (as shown in Figure d).

1) The distance from the oil suction port of the hydraulic pump to the lowest oil surface shall be ≤ 500mm.

2) The oil filling joint on the oil return pipe shall be higher than the bearing lubrication line of the hydraulic pump (end face of shaft end flange cover).

(7) Connection method of pressure and drain pipe in shell. In use, the shell of the hydraulic pump is sometimes required to bear a certain pressure. Due to the restriction of the oil seal (rotary seal) and the flange gasket on the variable mechanism of the pressure compensation variable pump, the pressure in the shell should not exceed 0.16 ~ 0.2MPa, and the drain pipe cannot be connected with other circuits, so it should be returned to the oil tank separately. There are several connection methods of drain pipe as shown in Figure E.

1) In the general hydraulic system, the connection method shown in Figure e (a) is adopted, and the value of the pressure gauge in front of the oil filter shall not exceed 0.16 ~ 0.2MPa.

2) When the hydraulic pump often operates under zero eccentricity or the system working pressure is lower than 8Mpa, so that the leakage of the hydraulic pump is too small and the pump body is heated, the oil circuit forced circulation cooling as shown in Figure e (b) can be used.


3) When the booster oil tank is used due to the needs of the hydraulic system, its pressure is ≤ 0.16 ~ 0.2MPa, as shown in Figure e (c).

(8) Selection of working medium.

Generally, the normal working temperature is recommended to be 10 ~ 65 ℃. When the working temperature is 5 ~ 40 ℃, l-hm32 or l-hm68 hydraulic oil is recommended; When the working temperature is 40 ~ 80 ℃, l-hm68 or L-HM100 hydraulic oil is recommended. The optimum kinematic viscosity of hydraulic oil is 16 ~ 47 (10-6) × M2 / s), the viscosity index shall be above 90, and the water, ash and acid value in the oil must comply with the provisions of relevant hydraulic oil.

(9) Start of hydraulic pump.

1) After the hydraulic pump is installed, the pump must be filled with clean hydraulic oil through the oil drain port on the pump housing before the first start. Otherwise, it cannot be started.

2) Rotate the coupling by hand to check whether the force on the pump shaft is uniform during rotation, whether the installation is firm and reliable, and whether the two couplings are concentric, etc.

3) Check whether the rotation direction of the motor driving the pump meets the requirements. For variable flow, check whether the indication direction of the dial is consistent with the specified oil inlet and outlet direction. For example, this item should be checked for servo variable pump. When the oil inlet and outlet are shown on the label on the pump, the pointer should be in the forward direction of the dial, and vice versa.

4) Before starting the pump, adjust the overflow valve on the oil drain pipe to the minimum pressure, and gradually increase it to the required pressure after the pump operates normally.

5) When starting the hydraulic pump, first start and stop the start button for several times, and then start it continuously after confirming that the oil flow direction is correct and the sound of the hydraulic pump is normal.

6) For the hydraulic pump that has been disassembled, cleaned and reinstalled, check whether the rotation direction of the shaft and the oil drain pipe are correct and reliable before use. Fill the pump body with working oil from the high oil drain port, turn it by hand for 3-4 turns and then start it to avoid burning the pump.

7) The hydraulic system shall have an empty load circulation circuit to prevent the hydraulic pump from starting or stopping at full load, otherwise it will reduce the service life of the hydraulic pump and cause motor overload. The adjustment pressure of the safety valve of the hydraulic system shall not exceed 35.mpa.

8) If the system is equipped with auxiliary hydraulic pump, start the auxiliary pump first, adjust the overflow valve controlling the pump to reach the specified oil supply pressure, and then start the main pump. In case of any abnormality, stop the main pump first, and then stop the auxiliary pump after the main pump stops stably.

(10) Load operation.

1) Low load operation: after the above preparations are completed, first run the hydraulic pump under the pressure of 1.0 ~ 2.0MPa for 10 ~ 20min.

2) Full load operation; After low load operation, gradually adjust the pressure of overflow valve and safety valve to the maximum pressure of hydraulic system for 15min, and check whether the system is normal. In case of leakage, the sound of the hydraulic pump and hydraulic system is normal, and the maximum temperature on the pump shell is generally 10 ~ 20 ℃ higher than the oil temperature at the hydraulic pump population in the oil tank, which is still normal. For example, when the oil temperature in the oil tank reaches 65 ℃, the maximum temperature on the pump casing is ≤ 70 ℃.

3) After the above load operation is completed, the hydraulic pump can enter normal operation.

4) During the operation under the maximum service pressure, the operation time shall not exceed 10% of the cycle time, which is generally completed within 6S.

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