National Crane Published 03-18-2019 Control # 582-04 3-11
NBT30H-2 OPERATOR MANUAL CONTROLS AND OPERATING PROCEDURES
Before Making the Lift
• Set the outriggers as described in Outrigger Setup, page
4-1.
• Program the RCL as specified in the RCL Operator
Manual which is located in the document case.
• Check all controls for proper operation. If any abnormal
operations are detected, the condition must be corrected
before continuing.
• Check the work area for electric power lines.
LOAD CHART
The crane is designed to provide satisfactory service if it is
not loaded in excess of the maximum rated loads specified in
the load chart. Overloading can create safety hazards, cause
structural damage, and shorten the service life of the crane.
You must understand how to use the load charts located in
the document case. Make sure the load, the working area,
and the crane configuration are within the load limit specified
in the load chart.
NOTE: Load handling devices (hook blocks and slings) are
considered part of the load.
Using the Load Chart
The following list is a definition of terms needed when using
the load chart.
• Load Radius - The horizontal distance from the
centerline of rotation, before loading, to the center of the
vertical load line or block. This distance is slightly
greater with a loaded boom due to deflection.
• Loaded Boom Angle - The loaded boom angle is the
angle between the first section boom and the horizontal
with the load. The loaded boom angle combined with the
boom length approximates the operating radius.
• Working Area - The area measured in a circular arc
above the center line of rotation to the suspended load.
NOTE: The standard work area for the NBT30H-2-2 is
180°. With a center front stabilizer (SFO) the work
area is 360°.
• Freely Suspended Load - The load hanging free with
no direct external force applied except by the loadline.
• Side Load - Horizontal side force applied to the lifted
load either on the ground or in the air.
• Boom Length - The length from boom pivot pin to the
boom nose. Decals on either side of the boom shows
when specific boom lengths are reached.
• Range Diagram - The range diagram (Figure 3-5)
shows the operating radius and height of the unloaded
boom nose at all boom lengths and angles. It should be
used as a guide to position unloaded loadline and to
determine to approximate height to which the load can
be lifted.
The load chart contains the lifting capacities of the crane in
all allowable lifting configurations. The information is
presented in three parts, one for outriggers fully retracted,
one for outriggers at mid point, and one for the outriggers
fully extended. Each part contains the load chart, range
diagram, and hoist data sheet. In the examples shown here,
the information for the outriggers fully extended is used.
• The load chart (Figure 3-4) is used to determine the
weight limit of the load based on the load radius and
boom angle. All lifting devices must be included when
determining the weight of the load.
• The range diagram (Figure 3-5) shows the operating
radius and the height from horizontal of the unloaded
boom.
• The hoist data chart (Figure 3-6) shows hoist capacity
and multi-part line reeving. The correct reeving for all
loads listed in the load chart is also shown.
Before you can determine the crane configuration you need
to know:
• the weight of the load to be lifted.
• the lifting devices and weights needed.
• the height of the lift.
• the horizontal distance from the center of rotation (load
radius) to where the load is to be placed.
To determine the safe operating parameters you need to:
1. Get the weight of the load to be lifted.
2. Approximate the load radius. This is the horizontal
distance from crane center of rotation to where the
payload is to be placed.
3. Determine the lifting devices and hook block reeving
using the hoist data chart.
4. Calculate the combined weight of the lifting devices and
load to be lifted.
5. Determine the boom angle and length from the range
diagram using the height and load radius of the lift.
6. In the load chart, take the load radius and boom angle/
length column over to the weight column and check the
weight. If the weight is between two values, use the
lower value.
LIFTING THE LOAD
The following general guidelines outline the proper
procedure for making a lift after the crane has been properly
set up.
To Next Page
Loading...
Need help?
General
