Document No.: A5E00353789B
Page 7
1. General Conditions for Installation and Assembly
1.1 Lift-off
Protection
Lift-off protections prevent the top plates being lifted from the load cells or
permanently mounted load cells from being overloaded by tension against the
measuring direction. Lift-off protections are necessary if there is a danger of the
load platform being lifted or tipped. This is possible with light high containers or
with silos that are not affixed for example.
Lift-off protections are integrated in the
combination mounting units of the SB
series. When using the mounting units,
the lift-off protections should be
planned constructively. A suggestion for
an effective solution is shown in Fig. 1-
1. The measurement X indicates the
possible lift-path of the load platform.
The drill hole ØD must be larger than
the bolt diameter Ød. The movement of
the load platform may not be hindered.
1.2 Overload
Protection
Overload protection means protecting load cells from loads in the direction of
measurement that are too great. Forces that exceed the load limits for the load cells
can also come from the side.
Overload protection in the direction of measurement
Load cells are normally protected against vertical overloading by placing a stop-bolt
under the transmission of force. The path of measurement for the load cell is
limited in this manner. On load cells with high rated loads, the danger of accidental
overloading is not so great. Any possible excessive loading can be taken into
account while dimensioning the load cells.
Another way of protecting load cells from overloading is in over-dimensioning the
load cells.
Overload protection from the side
Transverse force are produced, for example, by wind, filling processes, acceleration
or conveyor belt friction. If these forces exceed certain values, the load cells must
be protected from them.
The weight force is transferred to the load cells via elastomer bearings or pendulum
bolts in the SB cells. These elements allow a certain amount of sideways movement
of the load platform or a change in length due to thermal expansion. They generate
a responsive force which centers the load platform position again corresponding
with the occurring movement. This freedom of movement is expressly wished and
necessary for exact weighing. If the restoring force is so high that the return force is
overcome by pendulum bolts or elastomer bearings up to the deflection limit,
appropriate safety measures must be taken. These could be oscillation limitations or
guidings (see chapter 1.3). Oscillation limitations must be constructed or set so that
Fig 1-1 Lift-off protection
solution suggestion
