National Crane Published 5-27-2018 Control # 039-06 9-15
800D INSTALLATION
EXAMPLE:
Refer to the sample truck frame cross sections in Table E.
Truck frame yield strength is 110,000 psi (758 MPa) with the
following dimensions at the front axle location: 3/8 in (9.65
mm) thick, 1.50 in (38.1 mm) top flange, 3 in (76.2 mm)
bottom flange, 10.25 in (260 mm) deep. To find the frame
section modulus:
1. Use a channel with 1.50 (38.1 mm) flanges since in
(38.1 mm) is the smaller flange width.
2. From Table E, 3/8 in (9.65 mm) thickness, W (width) =
1.50 in (38.1 mm), D (depth) = 10.0 in (254 mm) Section
Modulus = 10.2 in
3
(167 cm
3
).
3. From Table E, 3/8 in (9.65 mm) thickness, W = 1.50 in
(38.1 mm), D = 11.0 in (279 mm) Section Modulus = 11.9
in
3
(195 cm
3
).
4. Interpolate between the two values:
10 in (254 mm) deep channel
= 10.2 in
3
(167 cm
3
)
11 in (279 mm) deep channel
= 11.9 in
3
(195 cm
3
)
10.5 in (267 mm) deep channel
5. Now interpolate between a 10.0 in (254 mm) deep
channel and a 10.5 in (267 mm) deep channel to get the
section modulus of a 10.25 in (260 mm) deep channel
10.0 in (254 mm) deep channel
= 10.2 in
3
(167 cm
3
)
10.5 in (267 mm) deep channel
= 11.0 in
3
(181 cm
3
)
10.25 in (260 mm) deep channel
Frame Section Modulus at the front axle location is 10.6 in
3
(174 cm
3
). This is greater than the 7.5 in
3
(123 in
3
) required
so the truck frame is strong enough at this location.
10.2 in
3
+11.9 in
3
2
---------------------------------------------
= =11.0 in
3
167 cm
3
+195 cm
3
2
------------------------------------------------
= =181 cm
3
10.2 in
3
+11.0 in
3
2
---------------------------------------------
= =10.6 in
3
167 cm
3
+181 cm
3
2
------------------------------------------------
= =174 cm
3
10.25 in
(260 mm)
1.50 in
(38.1 mm)
0.375 in
(9.65 mm)
3.0 in
(76.2 mm)
9442
Fo
r
Reference
Only