Mahindra JINMA-200 Operation Manual page 45

With the rotation of the engine, the oil in the cavity will continuously flow into the lifter
through gear pump.
During working, there is pressure difference between the suck oil cavity and pressure oil
cavity of the gear pump, the high pressure oil of pressure oil cavity will leak and return to the
suck oil cavity along the clearance of the end faces of the gear and sleeve, gear tip and pump
body and the clearance formed by bad gear mesh; which will cause pump volume loss and the
heat of the hydraulic system. Too much volume loss will not make the gear pump form
normal working pressure; if seriously, the gear pump can't lift the implements.
In order to reduce the volume loss of the gear pump, complete floating sleeve is adopted
in the pump, which has hydraulic automatic compensation and axial balance construction.
During working, the sleeve can float in the pump body; the position of the sleeve is decided by
the force applied on the sleeve. The width of the pump body is 0.09-0.18mm bigger than the
width sum of gear and sleeve. After mounting, the front and rear cover are pressed tightly on
the pump body, the seal ring between the covers are compressed and the sleeve is pressed
tightly on the two end faces of the gear, thus not big clearance forms between sleeve and
covers. When the oil pressure in the gear rises, the oil pressure apply on the back of the sleeve
through the clearance (Fig.4-17), which ensures the good cooperation of the sleeve and gear
stick end faces. This action is called hydraulic automatic compensation.
2) Lifter
A. Working principle of valve (simple direction exchange valve)
The structure and working principle of the simple direction exchange valve is as Fig.4-
19.
Main control valve (1) can be respectively put on lifting, neutral and lowering positions
throughpulling operation handle (5). When main control valve (1) is on neutral position (Fig-4
-19b), the oil from the oil pump into the direction exchange valve flows back into oil tank
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