3
1. INTRODUCTION
Model CGEO-CR Vibrating Wire Crackmeters are designed to measure movement across joints
such as the construction joints in buildings, bridges, pipelines, dams, etc.;coordinating with other
different accessories, and also tension cracks in soils and joints in rock and concrete. The gauge is
often adopted surface-mounting manner.
The instrument consists of a vibrating wire sensing element in series with a heat treated, stress
relieved spring which is connected to the wire at one end and a connecting rod at the other. The
unit is fully sealed and operates at pressures of up to 1 Mpa
（
special requirements can be
customized
）
. As the connecting rod is pulled out from the gage body, the spring is elongated
causing an increase in tension which is sensed by the vibrating wire element. The tension in the
wire is directly proportional to the extension, hence, the opening of the joint can be determined very
accurately by measuring the strain change with the vibrating wire readout box.
Ball Elbow Joint
Coil & thermistor Housing
Instrument Cable
Transducer Housing
Aligment Slot
Transducer Shaft
Ball Elbow Joint
Threaded Stud
Aligment Pin
Threaded Stud
Anhoring Rod
Figure 1 - Model CGEO-CR Vibrating Wire Crackmeter
CAUTION: Do not rotate the shaft of the Crackmeter. This may cause irreparable damage to
the instrument. The alignment pin on the transducer shaft and slot on the body serve as a guide
for alignment.
2. INSTALLATION
2.1. Preliminary Tests
Upon receipt of the instrument, the gage should be checked for proper operation (including the
thermistor). The Crackmeter normally arrives with it's shaft secured at approximately 50% of it's
range (see Figure 1). This holds the instrument in tension thereby helping protect it during shipping.
