National Crane 600H, Service Manual

Page: 191 / 232

NATIONAL CRANE
08-19-2022 Control # 092-13
9-9
600H SERVICE CRANE INSTALLATION
9
TRUCK FRAME STRENGTH
In order for a truck frame to be suitable for accepting a Series
600H size crane, the truck frame must have a requirement
for rigidity so as not to allow excessive boom movement due
to truck frame deflection, and it must be strong enough to
resist the loading induced by the crane so as not to
permanently bend or deform. Section Modulus (S.M.) is a
measurement of the area of the truck frame and determines
the rigidity of the frame. Resistance to bending moment
(RBM) is a measurement of strength and is determined by
multiplying the section modulus of each frame rail by the
yield strength of the rail material.
For a standard, behind-the-cab mount, 180° stability, the
Series 600H crane requires a minimum of 1,749,000 in-lb
(197,610 N-m) RBM and 15.9 in
3
(261 cm
3
) S.M. under the
crane frame between the front and rear springs with
1,430,000 in-lb (161,590 N-m) RBM and 13 in
3
(213 cm3)
S.M. through suspension to rear jacks on each truck frame
rail. For 360° stability, the truck frame must have a 15.9 in
3
(261 cm
3
) section modulus [1,749,000 in-lb (197,610 N-m)
RBM] minimum at the crane frame between the front and
rear springs with 1,430,000 in-lb (161,590 N-m) RBM and 13
in.
3
(213 cm
3
) S.M. through suspension to rear jacks on each
truck frame rail. Listed below is a table showing the
commonly used truck frame and reinforcing materials and
the section modulus required for each material to ensure
adequate strength and rigidity. In all cases, the minimum
requirements for section modulus and RBM must be met.
SECTION MODULUS TABLES
The following tables will determine the section modulus of
the truck frame. Always measure the truck frame and check
the tables to be sure that any truck factory listed section
modulus is correct.
Channel (Table A)
Table A provides the section modulus of channel frames in
thicknesses of 3/16 in (4.76 mm), 1/4 in (6.35 mm), 5/16 in
(7.94 mm), and 3/8 in (9.52 mm) with each grouping a flange
width and web depth column. When the depth of frame
channel and flange width is known, the point at which these
two lines intersect is the section modulus from that particular
channel.
If the section modulus of the channel does not meet the
requirements, the channel should be reinforced in the most
applicable method following.
Channel Reinforcement (Table A)
In order to provide more strength, a channel of suitable
thickness can be added to the existing frame. The depth and
flange width of this channel should be chosen so it fits over
the existing frame. The section modulus of the needed
channel is obtained from Table A and should be added to the
section modulus obtained from the truck frame.
Angle Reinforcement (Table B)
If the truck is reinforced with an angle, refer to Table B for the
data on the added strength provided by the angle.
Add this to the section modulus of the channel obtained from
Table A.
Fish Plate Reinforcement (Table C)
The frame can be strengthened by adding a fish plate of
suitable thickness and depth equal to the frame. The section
modulus of the fish plate can be obtained from Table C and
this must be added to the section modulus of the frame to
obtain the total section modulus.
Angle Under Reinforcement (Table D)
This table lists the section modulus of an angle with the
flange under the truck frame that is added to a frame with an
angle reinforcement already added. Add the section
modulus from Table D to the section modulus obtained from
tables A and B to determine total section modulus.
REQUIRED FRAME STRENGTH
Truck Frame or
Reinforcing
Material
Minimum
Section Modulus
Under Crane
Minimum Section
Modulus
Through Rear
Suspension
RBM Under
Crane
RBM Through
Suspension
360° Stability
110,000 PSI
(758 MPa)
20 in
3
328 cm
3
) 13 in
3
(213 cm
3
)
2,200,000 in-lb
(248,624 Nm)
1,430,000 in-lb
(161,570 Nm)
180° Stability
110,000 PSI
(758 MPa)
15.9 in
3
(261 cm
3
) 13 in
3
(213cm
3
)
1,749,000 in-lb
(197,637 Nm)
1,430,000 in-lb
(161,570 Nm)
50,000 PSI
(345 MPa)
33.0 in
3
(541 cm
3
) 17.0 in
3
(279 cm
3
)
1,650,000 in-lb
(186,425 Nm)
850,000 in-lb
(96,050 N-m)
REFERENCE ONLY