2-15
Install Grips
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•
selecting jaw faces with a surface area large enough to cover the tab (for dumbbell-
shaped specimens) or as much surface area as possible for parallel-sided specimens.
• ensuring that the specimen is gripped by at least 75% of the available jaw face
length.
• using serrated jaw faces
Breaks at the jaw face may be caused by:
• Screw action grips - you may be using too much force when tightening the grips.
Use a torque wrench or switch to pneumatic grips for a consistent force.
• Pneumatic grips - the pressure may be too high. Drop the pressure, but not to the
point where you get slippage.
• Serrated faces - the serrations are damaging the specimen. Change to faces that have
more serrations per inch (less bite) or cover with masking tape or similar material to
soften the bite and prevent damage to the specimen.
Insert Jaw Faces into Grips
Different grips use different mechanisms for attaching jaw faces. Refer to the documentation
supplied with the grips for more information.
Install Grips
Figure 2-7 on page 2-16 shows a typical grip with clevis pin coupling.
Before you begin, check the following:
There is sufficient space between the load cell and the load frame base to install the
grips.
The crosshead is stationary and the TEST IN PROGRESS indicator light is not
illuminated.
The crosshead limit stops on the load frame are set to prevent the upper and lower grips
from colliding with each other (refer to “Set the crosshead limit stops” on page 3-10).
The mating surfaces of the grips, load cell and the base adapter are free of dirt or debris.
To install the grips:
1. For the lower grip, insert the adapter on the grip into the female clevis socket on the load
frame base adapter, as shown in Figure 2-7 on page 2-16.
2. Align the clevis holes and insert the clevis pin through the holes.
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