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2-27-1
BOOM DOWN OPERATION (TYPE 2)
During the boom lowing operation, the pilot pressure from RCV is supplied to the port Pb2 of the
spring opposite side and shifts the boom 1 spool in the right direction.
The bypass passage is shut off by the movement of the boom 1 spool and the hydraulic fluid from
the pump A2 enters the parallel passage and is directed to the port B2 through the load check.
Following this, it flows into the rod side of the boom cylinder.
At the same time, the return flow from the head side of the boom cylinder returns to the port A2
and boom holding valve. And it is directed to the hydraulic oil tank through opened tank passage
by movement of the boom 1 spool.
Meanwhile some of return flow is directed to P1 parallel passage through the internal passage of
the boom 1 spool. (boom regeneration)
In this case, the holding valve is open condition, for details of the boom holding valve, see page
following page.
During the boom lowering operation, the fluid from A1 pump is not summation.
From RCV
P1 Bypass passage
Tank passage
Boom holding valve
P1 Parallel passage
A2
B2
Boom 1 spool
Load check
Pb2
140L2MC26
Summary of Contents for HX140L
Page 12: ...SECTION 1 GENERAL SECTION 1 GENERAL Group 1 Safety Hints 1 1 Group 2 Specifications 1 10...
Page 209: ...4 5 MEMORANDUM...
Page 694: ...8 68 125LCR8TM30 Turn casing 1 upside down and remove oil seal 3 using jig 29...
Page 734: ...8 108 Assemble plug 2 Plug NPT1 16 11 EA 17 21078TM68 21078TM69 21078TM70 21078TM71...
Page 756: ...8 130 Remove lock nut 22 and then boot 23 14 36078RL14 2507ARL10...