STRUCTURE, FUNCTION, & MAINTENANCE STANDARD REVERSE PREVENTION VALVE 12 Outline This valve reduces the swing back generation in the swing body by the inertia of the swing body, the backlash and rigidity of the machinery system, and the compression of the hydraulic oil when the swing is stopped. This is effective in preventing spillage of the load and reducing the cycle time when stopping the swing (the positioning ability is good and it is possible to move swiftly to the next job.
Operation 1) When brake pressure is being generated at port MB Pressure MB passes through the notch and goes to chamber d , spool (5) pushes spring (6) according to the difference in area D1 > D2 , moves to the left, and MB is connected to e . When this happens, pressure MA is below the set pressure of spring (3), so spool (2) does not move. For this reason, the pressure oil is closed by spool (2), and the braking force is ensured. 2) After motor stops The motor is reversed by the closing pressure gen- erated at port MB . (1st reversal) When this happens, reversal pressure is generated at port MA .
Pressure MA goes to chamber a , so spool (2) pushes spring (3) and moves to the right, and MA is connected to B . At the same time, b is connected to f through the drill hole in spool (5), so the reversal pressure at port MA is bypassed to port T to prevent the 2nd reversal. 10-98 PC210/240-7K