Komatsu PC600LC-7 Manual page 123

STRUCTURE, FUNCTION AND MAINTENANCE STANDARD
1. Function
When the swing is stopped, this valve reduces
the rocking motion of the swing body due to the
inertia of the swing body, backlash of the
machinery system, the compressibility of the
hydraulic oil, etc.
This valve is effective to prevent the cargo from
being spilled when the swing is stopped as well
as to shorten recycle time (excellent in the posi-
tioning accuracy and the next operation can be
started quickly).
2. Operation
1) When the braking pressure is present at
the port MB
MB pressure is introduced to chamber d via
the notch and spool (5) makes a stroke
motion to the left, pressing spring (6) due to
the difference in area (D1>D2) and the inter-
connection of MB to e is established.
On this occasion, MA pressure is less than
the set pressure of spring (3), so that spool
(2) does not make a stoke motion and the
pressure oil is closed by spool (2), and the
braking force is secured.
2) When the motor stopped temporarily
The motor is reversed by the shutoff pres-
sure that occurred at port MB. (First rever-
sal)
On this occasion, the reverse pressure is
generated at port MA side. This pressure at
port MA is introduced to chamber a, and
spool (2) makes a stroke motion to the right,
pressing spring (3), and the interconnection
of MA to b is established.
Also, the interconnection of b to f is estab-
lished through the drill hole and the reverse
pressure at port MA is bypassed to port T,
thereby preventing the second reversal.
PC600, 600LC-7
SWING MOTOR
10-91