WÖHWA Gyroscopic Load Cell High-accuracy weighing of heavy loads
The WÖHWA gyroscopic scale
for high-precision weighing of
heavy loads from approx. 500 kg
upwards with an accuracy of
1,000,000 d.
High-precision weighing of heavy loads with
the gyroscopic measuring cell.
• High-resolution up to 1,000,000 divisions
• Optimally suited for high tare preloads by use of hybrid technology
• Highest accuracy ensured by frictionless and hysteresis-free weighing principle
• Extremely resistant to wear and tear by displacement-free and hysteresis-free measurement
• High measurement accuracy by comparison measurements
WÖHWA is the only supplier in the world of gyroscopic scales, which utilizes the principle of
the gyroscopic measuring cell to permit highly accurate weighing of large masses from approx.
500 kg upwards. For this unique position WÖHWA can thank its founder, Josef Wöhrl, who
developed the gyroscopic measuring cell in 1968. His invention has been further developed to
achieve even higher accuracies.
Josef Wöhrl
Advantages
• High preload compensation (tare)
• Precision
• Frictionless
• Hysteresis-free
• Overload protection
• No creepage
• No delays
• Economical
• Secure
• Quality
• Reliability
The inventive spirit of the founder
of our company, Josef Wöhrl, who
died in 2000, still permeates the
business today. Together with his
brother Willi Wöhrl, he built up
WÖHWA to its present greatness.
The company has sparkled with
innovative developments right
from the beginning. The revolutionary invention of the gyroscopic
measuring cell was Josef Wöhrl’s
greatest personal success. In 1975,
his invention was even granted
a place of honour in the German
Museum in Munich. A continuously
improved model of the gyroscopic
measuring cell is still used today in
modern WÖHWA gyroscopic scales
in order to determine the weight
of heavy loads with an accuracy of
one part in 106.
1st generation of gyroscopic load cell
2nd generation of gyroscopic load cell
3rd generation of gyroscopic load cell
start/stop
markers for pulse
measurement
4
Torque Control
3

8
1
5
9
Basic Principles
Pivoted Lever
6
Gyroscope Principle
A gyroscope reacts to an applied force
with a precession movement around
its vertical axis. The precession speed
is directly proportional to the applied
force .
7
Time measurement
2F
Using the gyroscopic principle, the
force measurement is turned into a
time measurement.
Nothing can be more precisely
measured than time. Therefore, time
measurement is by far the most precise
and most reliable method for determining weight forces.
Displacement Transducer
F

oscillation curve
t
The dynamic measurement principle of the
gyroscopic load cell is the solution to the
uncountable problems of static weighing
If a vertical force 2 is applied to a gyroscope
hinged in gimbals (see figure), the gyroscope
reacts with a precession movement about
its vertical axis 3. The precession speed
is proportional to the applied force, if the
rotational speed of the gyroscope remains
constant. Changes of the rotational speed are
measured and processed.
For measurement, the number of pulses 
that the gyroscope requires for one revolution, which are captured by a photo sensor,
is added. Thus, the gyroscopic load cell uses
time measurement to determine the weight
of the applied load. The quartz used has a
reproducible accuracy of 10-7
offering near-perfect linearity.
The so-called auxiliary motor 4 compensates all frictional forces, which prevents
any incipient fall of the rotor axis 5. The
auxiliary motor does not interfere with the
measurement of the precession movement
in any way, i.e. there is absence of friction
during the measurement, no extension of
recovery times, and therefore absence of
hysteresis. This measurement method also
ensures absence of displacement and creepage, and is virtually free from malfunctions.
In order to ascertain the
accuracy of the measurements, the measured value
is continually being replaced
by the next value. The measured value will only be acknowledged after
two successive values have been detected
to be identical.
The applied forces are transmitted from the
static parts to the dynamic parts by means
of a ball bearing tie rod 6, which, in the
vertical axis, is linked directly to the cross
flexures of the rotating lever by means
of separable bearings 7. One end of the
rotating lever is attached to the outer frame
8 and the other end to the inner frame 9
by means of cross flexures. Based on the
gyroscope laws, the lever rotates directly
proportional to the applied load around its
vertical axis. The rotational speed of the
gyroscopic system depends upon the load
to be measured.
The dynamic measurement method returns
an integral throughout the measurement
period, therefore allowing the computation
of an average. This guarantees highest
accuracy.
grinding of knives
milling of knives
balancing of main gyroscope motor
The WÖHWA gyroscopic scale – unmatched
handcrafted precision “Made in Germany”.
The scale system works on the principle of
the gyroscopic load cell. It has the design of
a hybrid scale. The load is received by the
weighing platform and transmitted to the load
levers via so-called ball support bearings.
The ball support bearing transmits the load
vertically.
By means of a transverse lever and additional
levers, the load is transmitted vertically to
the gyroscopic load cell. To improve the load
reception, the load levers are provided with
two double-plate lever heads. This design
guarantees a high bending and torsional
stiffness. Pairs of knives and bearings are
used for the load transmission between the
levers. The perfect seating of the knives
allows a precise load transmission.
A durable and perfect seating of the knives
over their entire contact area is achieved by
using welded levers. Knives and bearings
are manufactured by WÖHWA from casehardened tool steel. Special manufacturing
processes and test procedures guarantee
a long service life and a high availability of
these highly accurate platform scales.
The weighing platform is welded and has a
stable and rigid design. The platform can be
adapted to each customer‘s special requirements. For example, the high-accuracy scale
can be equipped with a saddle for receiving
cylinders or containers of various sizes. Such
a saddle design allows the safe loading and
weighing of different vessels.
The scale system is supplied with a mounting frame that allows perfect fixing of the
corner bearings and traverse lever plates on
the floor. The scale is assembled, adjusted
and calibrated on site by an experienced
WÖHWA engineer, who will also prepare the
scale for the initial verification.
milling of grooves in knives
hardness testing of bearings
Measurement of concentricity
quenching of hardened knives and bearings
weighing platform
ball bearing
bearings (inside)
load lever
knives
transverse
lever
transmission lever
support for gyroscopic
load cell
mounting and
installation frame
bearing supports for
transverse lever /
transmission lever
WÖHWA is worldwide
“the measure of all things”
if the reproducibility of
accuracy is required for
heavy loads.
Mass Comparator
Applications:
• calibration and verification of
standard weights in measurement
offices
• weighing of precious products, for
example gold, uranium, etc.
• batching of mixtures, for example
in the pharmaceutical, chemical, paint,
rubber and photo industries
Technical data
Rated capacity:
3,000 kg
Operating capacity: 1,000 kg
Scale interval: 1g
Resolution: 1,000,000 d
Scale system for
calibrating flow
meters for
gas pipelines
Applications:
• calibrating flow meters for
gas pipelines
• high preload compensation (tare)
Technical data
Rated capacity: 20,000 kg
Tare:
12.000 kg
Operating capacity: Scale interval: Resolution: 600 kg
50 g
240,000 d
Uranium Scale
System
Application:
• weighing uranium hexafluorid
cylinders for production and inventory
purposes
Technical data
Rated capacity
25.000 kg
Operating capacity: 20.000 kg
Scale interval: Selectable: Resolution: 1 kg
100 g
200,000 d
Scale system for calibrating flow meters for
use with liquids
Application:
• calibrating flow meters for use
with liquids
• high preload compensation (tare)
Technical data
Rated capacity:
40.000 kg
Operating capacity: 30.000 kg
Scale interval: Resolution: 100 g
300,000 d
WÖHWA Waagenbau GmbH
Öhringer Strasse 6
74629 Pfedelbach
Germany
Phone +49 7941 9131-0
Fax +49 7941 9131-28
[email protected]
www.woehwa.com
The physical laws specific to the gyroscope are the same all
around the world. World-wide there is only one supplier who
uses these principles for the purpose of high-accuracy weighing.