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1) Before reassembling or replacing the worm and worm gear, measure and adjust the engagement center of
the worm gear and the worm again until the center of worm is on the same central plane with the central
plane of worm gear gorge circle as follows: apply a thin layer of red lead on the working surface of the
worm gear, manually turn the worm gear for several times, observe its engagement point, and properly
engage the worm with the worm gear by increasing or decreasing the seal paper pads on the bearing
pedestal.
2) As the metering pump moves under alternating load, the wear of the worm gear under load in the discharge
stroke is severer than that in the suction stroke. Therefore, during pump disassembly for inspection, the
worm gear may be reassembled relative to the original assembly position according to the wear of the gear
after 180
°
rotation along the axis, thus prolonging its service life.
3) During reassembly of crosshead and crosshead oil seal, observe that the crosshead is free of scratch or
damage, otherwise this will affect the sealing performance of the transmission box and the hydraulic tank.
4) After all the components in the transmission box are reassembled in a reverse order, rotate the motor fan
and check whether it rotates freely without jamming. Turn the motor impeller and adjusting handwheel at
the same time until the pump is at the zero position, and reassemble and adjust the pointer to the zero
position.
5.2.4 Reassembly of components for hydraulic end
Before assembly, clean and check all the parts, and replace worn-out and irreparable parts. The components for
the hydraulic end shall be reassembled in a reverse order, but the following shall be noted
1) Carefully check the "three valves" (deflation safety valve, limit valve, and oil refilling valve), and make
sure that the O-rings are intact, the seal surfaces of deflation valve spool and safety valve spool of the
deflation safety valve are free from damage or rust and well-sealed; the fit clearance between limit valve
sleeve and limit valve spool are appropriate, otherwise the diaphragm will easily rupture, which is mostly
caused by excessive fit clearance; the connecting rod ball and oil refilling valve seat of the oil refilling
valve are well-sealed.
2) Sealing inspection for inlet and outlet valves of the pump. The flow accuracy of the metering pump largely
depends on the sealing accuracy of the valve ball for the inlet and outlet valves and the valve seat, and the
sealing performance of the valve ball and valve seat shall be inspected through kerosene leakage test; if no
leakage is found within 3min, it shows that they have good sealing performance and can be reassembled,
