Unic URW295CR, Maintenance Manual

Page: 68 / 125

(5) When T eles coping C ylinder3 extends
P iston
Apply "Lock Tight#638".
S lide pipe
P ressure Oil
S elector valve ass’y
C heck valve 2
C heck valve 2
S lide pipe
S elector valve ass’y
P iston
P iston
R od
R od
To tank
R od
C heck
valve
B olt
Tele3
C heck valve 1
S pool
C heck valve 1
B olt
Tele2
Tele1
Tele2
Tele3
P ipe for cord reel
C ounter balance
valve
After the set-screw is tightened with Lock Tight #2701
applied
、 hit with a punch at 2 places on the
circumference and leave it as it is for 1 hour.
How oil flows when tele3 is extended
P ressure oil opens the check valve in the counter-balance valve to
enter the cylinder rod of tele1 and flows through the slide pipe to reach
the check valve 2 of selector valve ass’y.
S ince the slide pipe of tele1 is pulled by piston immediately before the
tele1 is fully extended which in turn opens the check valve 2 of selector valve
ass’y to lead the pressure oil to the extension side of tele2.
P ressure oil entered the extension side of tele2 flows through the
slide pipe to reach the check valve 2 of selector valve ass’y.
S ince the slide pipe of tele2 is pulled by piston immediately before the
tele2 is fully extended which in turn opens the check valve 2 of selector valve
ass’y to lead the pressure oil to the extension side of tele3.
S imultaneously, oil in the retraction side of tele3 flows through the
dual cylinder in the cylinder rod of tele3 to enter the extension side of tele2,
then it flows through the dual cylinder and further through the dual
cylinder in the cylinder rod of the tele1 to return to the tank.
This allows the tele3 to extend.
S ince the check valves 1 of selector valve ass’y of tele1 and tele2 are
closed at this stage, the passages of extension side for tele1 and tele2 are
shut off.
B oth tele1 and 2 will not be actuated because no oil is remained in
the retraction side of tele1 and 2 as the tele1 and 2 are fully extended.
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