On the see-saw, the children move either in or out from the fulcrum, relocating their
weight at distances “d” or “D” until they balance each other. The see-saw balance can
be illustrated by stating that weight “w” multiplied by distance “d” equals weight “W”
multiplied by distance “D”. This illustrates that various combinations of weight
“multiplied by distance” can create a balanced condition.
The principles of stability in a reach stacker are like a see-saw in that the weight of the
load and its distance from the fulcrum determine counterbalance requirements.
Remember that the reach stacker is different because the weight rearward of the drive
axle centerline (fulcrum) multiplied by the distance to the “CG” (center of gravity) of
that weight must always be greater by a wide margin than the weight forward of the
drive axle multiplied by the distance to its “CG.” If a balanced condition is approached,
dynamic forces involved in stopping, traveling, or tilting can cause a dangerous vehicle
upset.
The weight of the reach stacker located rearward of the fulcrum and the “CG” of this
weight does not change; therefore, counterbalance is always a fixed value. The weight
of the boom and attachment is also a fixed weight; but, the distance to the “CG”
forward of the fulcrum is variable depending on the angle and extension of the boom.