Manitowoc National Crane NBT30H-2 Service Manual

4
10
National Crane 03-20-2019 Control # 613-06 4-1
NBT30H-2 SERVICE MANUAL BOOM MAINTENANCE
SECTION 4
BOOM MAINTENANCE
SECTION CONTENTS
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Boom Removal from Truck . . . . . . . . . . . . . . . . . . 4-4
Lift Cylinder Removal . . . . . . . . . . . . . . . . . . . . . . 4-4
Boom Disassembly. . . . . . . . . . . . . . . . . . . . . . . . . 4-5
2
nd
, 3
rd
, 4
th
Boom Section Removal . . . . . . . . . . . 4-5
Disassembly of 2
nd
, 3
rd
, 4
th
Boom Sections . . . . . 4-5
Additional Maintenance, Disassembled Boom . . . 4-6
Boom Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
Extend/Retract Cable Installation . . . . . . . . . . . . . 4-8
Telescope Cylinder Installation . . . . . . . . . . . . . . . 4-9
2
nd
/3
rd
/4
th
Boom Section Installation . . . . . . . . . 4-10
Boom Cable Tensioning . . . . . . . . . . . . . . . . . . . . 4-11
Cable Tensioning. . . . . . . . . . . . . . . . . . . . . . . . . 4-11
Cable Tension Sequence . . . . . . . . . . . . . . . . . . 4-12
4- Section Boom w/ 2 Stage Cylinder Cable
Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13
4- Section Boom w/ 1 Stage Cylinder Cable
Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14
3- Section Boom w/ 1 Stage Cylinder Cable
Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15
Cable Retention . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16
Boom Installation on the Truck . . . . . . . . . . . . . . 4-17
Lift Cylinder Installation . . . . . . . . . . . . . . . . . . . . 4-17
THEORY OF OPERATION
The boom is a four section boom that uses a hydraulic
telescope cylinder and internal cables to extend and retract
the boom. A lift cylinder located under the boom is used to
raise and lower the boom.
The telescope cylinder is two-stage, double acting, and
attached to and extends the 1
st
, 2
nd
, and 3
rd
boom sections.
Extend cables are used to extend the 4
th
boom section
(Figure 4-1).
The telescope cylinder retracts the 1
st
and 2
nd
boom
sections. Retract cables are used to retract the 3
rd
and 4
th
boom sections.
The extend cables for the 4
th
section are attached to the rear
of the 2
nd
boom section, reeved around sheaves on the front
of the telescope cylinder and attached to the rear of the 4
th
boom section.
The retract cables for the 4
th
boom section are attached to
the front of the 2
nd
boom section, reeved around sheaves on
the rear of the 3
rd
boom section, and attached to the rear of
the 4
th
boom section.
The retract cables for the 3
rd
boom section are attached to
the front of the 1
st
boom section, reeved around sheaves at
the rear of the 2
nd
boom section, and attached to the rear of
the 3
rd
boom section.
A proportioning cable is attached to the rear of the 1
st
boom
section, reeved around a sheave at the front of the 2
nd
section, and attached to the rear of the 3
rd
section. This
cable maintains proper telescope cylinder proportion and
equal boom section extension.

Manitowoc National Crane NBT30H-2 Specifications

General

Brand	Manitowoc
Model	National Crane NBT30H-2
Category	Construction Equipment
Language	English