Komatsu PC88MR-10 Shop Manual page 196

10 Structure and function
Swing motor
Operation
(PC88MR-J6B2-044-K-00-A)
When port (MB) brake pressure is generated
Pressure (MB) is transmitted to chamber (d) through notch (g).
The circle area difference of spool (5) ( D1
Port (MB) and chamber (e) are interconnected.
Spool (2) does not move since the pressure (MA) is the set pressure of spring (3) or lower. The
pressurized oil is closed and the brake pressure is secured.
When the motor stops once
The motor rotates in reverse by the closed pressure generated in port (MB). (First round reversal)
The reverse pressure is generated in port (MA) side. Pressure (MA) transmitted to chamber (a).
The circle area difference of spool (2) ( D3
Port (MA) and chamber (b) are interconnected.
The oil flows through drilled hole (h) of spool (5) and ports (b) and (f) are interconnected. The reverse
pressure of port (MA) is bypassed to port (T) to prevent the second reverse rotation.
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D2) compresses spool (6) and moves spool (5) to the left.
D4) compresses spool (3) and moves spool (2) to the right.
PC88MR-10