Gehman Tester

Using wires of known stiffness, this instrument determines the torsional modulus of vulcanized rubber samples at low temperature, consisting of a measuring unit and a separate controller.
The top of each torsion wire is attached to a head while the bottom is fastened to a pointer and a coupling to which each sample is clamped. The deflection of the torsion wire is easily read from a protractor, marked in 1O divisions.
Three catridges are supplied with the apparatus, having torsional constants of 0.70, 2.81, and 11.24 mNm/rad of twist respectively. Each torsion wire is mounted in an easily removable stainless steel “cartridge”, attached to the torsion head by a knurled screw for finger tightening.
A revolving 10 station test piece rack is mounted on the measuring head support so that each test piece may be indexed accurately under the torsion wire.
The bath consists of a removable stainless steel container located in an insulated box to which the heater/stirrer unit is attached by thumb screws.
The controller houses the speed control for the stirrer motor and a digital temperature controller which displays the fluid temperature and the ramp rate of heater.
Cutting Tool 
For the special cutting tool, order L15/1