5.1 Choice of fifth wheel
Standard Fifth wheels (as defined in 94/20/EC) have a rating of 20
Tonnes Imposed Load and a ‘D’ value of 150 kN. These ratings can
be found on the “Type label” of the Fifth wheel Equipment. Whilst
the Imposed Load is easy to determine the vertical load at the
kingpin) the ‘D’ value is more complicated and is determined using
the formula shown in Figure 1.
The Fifth wheel Coupling chosen should be rated with loads equal
to or higher than the calculated values, and under NO
CIRCUMSTANCES should a coupling be fitted where the calculated
rating is higher than the values indicated on the equipment.
5.2 Mounting bolts
Coupling Equipment is normally supplied with the correct mounting
bolts for installation purposes (unless specifically requested
otherwise).
The bolts supplied will be rated at the correct grade for the
installation. However a good general guide for normal use is to use
12 bolts size M16 grade 10.9.
These bolts should be tightened to the torque values displayed in
Table 2.
Table 2 - Most common Bolt sizes and grades as supplied with
Fontaine Fifth wheel Equipment and their relevant torque values
which should be used for tightening these bolts.
All of the torque values shown are in Nm. To convert these values
to lbs ft divide the figure shown by 1.356
3000 Fifth Wheel Instruction Manual
12
I N S T A L L A T I O N
Table 2
Metric Bolts Bolt Grade
8.8 10.9
14mm / 227
16mm 252 280
18mm 347
20mm 367 /
Figure 13 - Typical fifth wheel installation
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