Rice Lake Combination System - Precision Loads On-Board Weighing Systems - Manual (Page 29)

Applications 25
So the rigidity of the installation is maximized, both kingpin plate load cells should be positioned so that most of
the combined area of both load cell single-piece bearing plates is aligned directly over the truck fifth wheel plate
when the kingpin and fifth wheel are coupled. Installation rigidity requirements can also be met if the kingpin
skidplate used has a material thickness of 3/4" to one inch (19 to 25 mm). Thinner skid plates will generally require
a reasonable amount of added stiffening.
Skid Plate Inspection
Inspect the skid plate to ensure it is flat , clean and shows no signs of cracks or wear. Look for any evidence of
bending, warpage, corrosion, pitting, burns or other characteristics which can affect the strength and performance
capabilities of the installation or the correct fit of the load cell bearing plates.
Load Cell Installation to Skid Plate
The surface to which the load cell bearing plates are installed must be smooth and flat. The installer must ensure
that once the load cell bearing plates have been welded in place, and the cells mounted, the top surface of both cells
must be co-planar, with no evidence of any twisting or distortion of the skid plate. Consideration should be given to
tack welding temporary stiffening members to the skid plate to prevent the possibility of plate distortion caused by
the welding of the single piece bearing plates.
For most fifth wheel models, it is recommended to position the load cells on the kingpin skid plate at a lateral
parallel spacing of 26.50 inches to 28 inches apart (67 to 71 cm). Both load cells should be centered on the kingpin
skid plate so that load cell bearing plates are positioned directly over the location of the coupled fifth wheel plate.
5th Wheel
Kingpin Skid
Plate
Stitch Welds
(Bottom Also) Load Cell Model
PL9000-26
(2 required)
Plug Welds
1” Plate
Kingpin Skid Plate
Figure 4-21. Kingpin Inside View
Note
Locate kingpin plate load cells on the skid plate to cover as much of the coupled 5th wheel plate area as
possible.
In cases where the trailer body subframe will determine the positioning of the load cells to the skid plate, it may not
be possible to mount the cells directly over the center position of the fifth wheel plate. Rice Lake Weighing
Systems recommends that a 1 inch (25 mm) thick skid plate be used for such installations to ensure adequate
rigidity. Load cells should always be centered (fore to aft) on the kingpin skid plate.
In order to provide adequate stiffening of the kingpin skid plate in areas of the load cell bearing plates, the installer
should consider using gussets and outboard stiffeners as well as internal structural reinforcing to ensure a rigid
kingpin plate.