Theory Of Operation; Basic Description; Linkage Factor - Komatsu 930E-2 Shop Manual

THEORY OF OPERATION

Basic Description

The payload meter uses the four suspension pres-
sures and the inclinometer to determine the load in the
truck. These inputs are critical to the calculation of the
load. The other inputs to the payload meter (Body Up,
Speed, Brake Lock, Alternator R Terminal, and Engine
Oil Pressure) are used to indicate where the truck is in
the haul cycle. These inputs enable the payload meter
to make time and distance measurements for the haul
cycle.
The suspension pressures are the key ingredients in
determining the sprung weight of the truck. These
pressures are converted into forces using the formulas
shown below. These forces are combined with the
geometry of the truck to produce the load calculation.
It is critical that the suspension pressure sensors are
functioning properly.
π
Sprung Weight = Suspension Diameter
4
Sprung Weight = Axle Weight(lbs)/2000
The inclinometer gives the payload meter information
regarding the pitch angle of the truck. The front and
rear incline factors are determined by the pitch angle.
These two factors account for the load transfer that
occurs when the truck is inclined nose up or nose
down.
M20-6
2
(Psi Left + Psi Right)
Payload Meter II

Linkage Factor

The linkage factor is part of the complex calculations
performed by the payload meter to determine the load
in the truck. The linkage factor is dependent on the load
on the rear suspensions.
Figure 20-3 shows the side view of a truck. The nose
pin is marked with a star and there are three arrows
pointing to different spots of the rear tire. This figure
shows how the support under the rear tire can affect
the calculation of the load. The payload meter does not
directly measure the load transferred to the frame
through the nose pin. To account for portion of the load
carried by the nose pin, the linkage factor is multiplied
by the rear suspension force. It is assumed that the
truck is supported under the center of the tire. In this
case the payload meter uses L2 to help compute the
linkage factor. If, however, the truck is backed into a
berm and the rear tire is supported towards the back
of the tire, the actual linkage factor calculation should
use L3. Since the payload meter assumes L2 it will
overestimate the load in the truck. The opposite is true
in the case where the rear tires are supported toward
the front of the tire. The linkage factor should use L1
but the payload meter assumes L2. This change in
leverage will cause the payload meter to underesti-
mate the load.
Figure 20-3.
M20007 10/00