Rice Lake Weigh Modules/Mount Assemblies - Manual (Page 45)

WEIGH MODULES
2-16
Compression Canisters
Compression Canister Load Cell Modules
Introduction
When mounts are needed in capacities over 100,000 lb, canister
load cell mounts may be the only choice. These cells are good in
severe conditions and have provided proven performance for
decades in truck, railroad, and heavy-capacity tank applications.
Available in capacities to 500,000 lb per mount assembly, most
canister mounting assemblies require more complex components
than mounts using beam load cells, especially if the mounts are
designed to accommodate expansion.
The load is transferred to the cell through a hardened, convex load
button which mates with a hardened flat loading plate. The rounded
load button and flat plate tend to promote point loading, minimiz-
ing extraneous forces.
General Mounting Principles
• A compression canister should be mounted on a flat plate of
sufficient thickness to prevent deflection. The foundation
must be rigid.
• The load should be introduced through a spherically-radiused
load button which is hardened.
• The load must be introduced vertically along the center line
of the cell.
• The top plate which contacts the load button must be hard-
ened to prevent peening of the contact point.
• Some external method of both horizontal and vertical check-
ing may be required.
Rice Lake Weighing Systems
Weigh Modules
RLC Weigh Modules
The RLC self-aligning silo mount, together with the RLC load cell
family, is an ideal solution for medium capacity process control,
batch weighing, silo/hopper and belt scale applications.
The RLC mount incorporates a removable rocker pin design that
uses hardened stainless steel components on all load bearing
surfaces. The full stainless steel construction guarantees long
term reliability, even in the most harsh environments.
Allowable Movement
The RLC mount shown in Figure 2-31 tolerates controlled
movement in all directions. The silo or hopper is held captive,
eliminating the need for additional check rods, unless major load
movement is anticipated. The unique design allows the load cell
to be easily removed for replacement.
Construction and Features
1) The RLC load cell consists of three concentric rings machined
from a single piece of stainless steel. The outer ring rests on the
base plate. The middle ring contains four circular strain
gauges. The inner ring accepts the load and deflects vertically,
activating the strain gauges in the middle ring.
2) A separate loading pin fits into the load cell’s inner ring and into
a hardened bearing cup on the top plate of the mount. The
inner ring vertical travel is limited by the base plate, providing
positive overload protection at 150% of capacity.
3) The RLC ring load cell is held captive in the mount by three pins
at the cell’s outer circumference. To install or replace the load
cell, the mount’s top plate need only be raised with the integral
jacking screws a fraction beyond the height of the pins.
4) The jacking screws provide lift-off protection as well as lateral
self-checking capabilities to eliminate the need for check rods.
Figure 2-30
Figure 2-31