I Working Principle
The pump is designed to transfer mechanical energy into hydraulic energy. When the prime mover drives the main shaft for rotation, the shaft will rotate the cylinder block with help of the connecting rod and plunger. Due to an angle is formed between the axial line of the cylinder block and the axial line of main shaft, the plunger makes a reciprocating movement in the cylinder block, meanwhile, the volume of the plunger hole in the cvlinder block will be changed. When the volume is becoming larger, the medium will be pumped in from the suction inlet of the pump and flow into the plunger hole through the LP window of the distribution disk; when the volume is becoming smaller, the medium is discharged from the discharge outlet of the pump through the HP window of the distribution disk. Therefore, along with a rotation of the main shaft, each plunger hole will finish a process of suction and discharge.

II Application
1. Application conditions
a. Temperature of oil：The normal working temperature of A2VK series pump is between -25℃ to 80℃, with a maximum temperature of 90℃. When the temperature is lower than 10℃, the medium should be heated.
b. Viscosity of medium：The viscosity of working medium shall be within 16-43mm2/s. For the medium with high viscosity that is adopted by the A2VK series pump, it shall be diluted to this scope by heating, and thereafter, during operation, fill in heated medium from the shaft seal cover of the pump, to maintain the normal work of the shaft seal.
c. Precision of oil filtration：The optimum precision for oil filtration is 5-10 um, and the limit is no less than 25 um.

2. The common work pressure and rotation speed of the pump shall not exceed the ratings and the transient values shall not exceed the allowed maximum value. The pump is normally capable of 1 minute continuous operation at maximum value, and the total time of it shall be no more than 10% of a shift.

3. Allowed pressure for leakage oil inside the enclosure.

4. Requirements for installation
a. A flexible coupler is adopted to connect the pump and the prime mover, with coaxiality no more than 0.1 mm.
b. During the installation of the coupler, care must be taken for no use of hammering and a coupling shall be selected reliably.
c. The support of the pump shall be with a certain rigidity, to prevent from vibration.
d. The leakage oil port shall be located on the highest place during installation, and the leakage oil tube shall be higher than the highest point of the pump to ensure the pump is filled with oil.
e. For self-priming pump, the location of the pump shall be lower than the lowest level of the oil tank.
f. Pipes and fittings that are connected to the pump must be strictly cleaned, and no debris, rust, etc. is allowed to be left in the pipes.

III Test Run
1. Inspection prior to test run
a. Check the pump for completeness and the main shaft of the pump for even rotation. If the pump is stored for long time, it shall be dismantled and cleaned at first.
b. Check various pipes, oil tanks and elements for cleaning.
c. Check the installation of pump and the connection of system for correctness and reliability; check the supports of the pump for enough rigidity.
d. Check whether the rotation direction of the pump is same with that of the prime mover; check the inlet and outlet of the pump for correctness in accordance with the rotation direction.
e. Check the viscosity of the medium and the precision of the oil filter according to requirements.
f. Check whether the pump is filled with medium; check whether the leakage pipes meet the requirements.

2. Test run
a. Unscrew the pressure control valve and let the pump start up under no-load.
b. The pump starts up under no-load and at low rotation speed. When the pump starts up, pay attention to its operation for any abnormal conditions in the system.
c. Exhaust the air in the system. The closed system can be exhausted directly and the open system can be exhausted via operation for a certain time under no load.
d. After the pump and the system come to normal run, keep running continuously for 30 minutes under no load (10% of rated pressure), then gradually increase the pressure and the speed, till the rated conditions.
e. Check the pump and the system for any abnormal conditions, such as external leakage, noise, vibration, temperature rising, etc. If there is any abnormal, stop the pump for inspection and only return to test run till the fault is solved.
f. After test run is finished, the medium shall be changed and the oil filter shall be cleaned, then the pump could be put into normal operation.

IV Maintenance and Service
1. The objective is to get the optimum efficiency and the longest service life of the pump. During the normal operation of the pump, the user shall make a reasonable schedule to check the quality of the medium, change the medium, clean the oil filter and oil tank according to the working conditions of the pump, in order to ensure the quality and cleanness of the medium. For the period of medium replacement and oil filter and oil tank cleaning, 3-6 months is recommended. During the change of the medium, care must be taken to no mixing up the new medium with the old one.

2. For the examination and repair of mainframe, the user is not allowed to dismantle and inspect the pump. When necessary, a professional shall be asked for the dismantling and maintenance.