Tadano TT-800XXL1, Service Manual

Page: 112 / 267

G-1. G-1.
Telescoping System
3
WG02-026 1 E
4. After the 3rd through top boom sections are fully
extended, press the next section extension switch
while keeping the boom telescoping lever
operated. The hydraulic valve will be energized,
the pressurized oil will be sent to the No.
1
telescoping cylinder and the 2nd boom section will
extend.
5. In this case, you need not keep pressing the next
section extension switch when the No. 1
telescoping cylinder extends slightly because the
boom full retraction switch is shifted and the
solenoid self-holding circuit for the hydraulic valve
is set up.
2.2 Retraction circuit
Telescoping mode I
(The 2nd boom section extends first.)
1 . Pressurized oil for boom retraction is delivered
from the hydraulic pilot control valve to the No. 1
and No. 2 telescoping cylinder directly.
2. While the No. 2 telescoping cylinder is extended,
the solenoid of the selector valve is energized due
to the boom full retraction detector switch.
Consequently the return circuit of the No.
1
telescoping cylinder is closed and only the No. 2
telescoping cylinder retracts, resulting in retraction
of the 3rd boom section.
3. At the same time, the 4th and top boom sections
retract by the wire-rope mechanism.
4. When the No. 2 telescoping cylinder is almost fully
retracted, the boom full retraction detector switch
is activated and disestablishes the solenoid
self-holding circuit for the hydraulic valve.
Consequently the selector valve automatically
shifts, the No.
1 telescoping cylinder retracts and
the 2nd boom section retracts.
Telescoping mode II
(The 3rd through top boom sections extend first.)
1 . Pressurized oil for boom retraction is delivered
from the hydraulic pilot control valve to the No. 1
and No. 2 telescoping cylinder directly.
2. While the No. 1 telescoping cylinder is extended,
the solenoid of the selector valve is energized due
to the boom full retraction detector switch.
Consequently the return circuit of the No. 2
telescoping cylinder is closed and only the No.
1
telescoping cylinder retracts, resulting in retraction
of the 2nd boom section.
3. When the No. 1 telescoping cylinder is almost fully
retracted, the boom full retraction detector switch
is activated and disestablishes the solenoid
self-holding circuit for the hydraulic valve.
Consequently the selector valve automatically
shifts, the No. 2 telescoping cylinder retracts and
the 3rd boom section retracts.
4. When the 3rd boom section retracts, the 4th and
top boom sections retract simultaneously by
means of the wire rope mechanism.