FED-STD-228A
Method 3016.1
18 APRIL 2014
CALIBRATION, TENSION TESTING MACHINE
1. SCOPE
1.1 This method is intended for use in calibrating the testing machine described in method 3021.
2. SPECIMEN
2.1 The specimen should be a dumbbell specimen of a tread compound.
3. APPARATUS
3.1 The apparatus shall be as follows:
3.1.1 Testing machine described in method 3021.
3.1.2 A suitable hook which can be attached to the power-actuated grip of the testing machine for holding
weights.
3.1.3 Weights, equal to 10, 20, and 50 percent of the capacity of the machine.
4. PROCEDURE
4.1 One end of the dumbbell specimen shall be placed in the upper clamp of the testing machine. The
lower clamp shall be removed and there shall be attached to it a hook suitable for holding weights. The
lower clamp shall be attached to the lower end of the dumbbell specimen. A weight shall be suspended
from the hook on the lower clamp in such a way as to permit the weight assembly to rest on the clamp
holder. If the machine has a dynamometer head of the compensating type, it shall be calibrated at two or
more settings of the compensator.
4.2 The motor shall be started, with the pawls or other maximum load-indicating device engaged as in
normal testing, and the weight applied until the weight assembly is freely suspended by the specimen. If
the dial or scale (whichever is normally used in testing) does not indicate the weight applied (or its
equivalent in stress for compensating type of testers) within ± 1 percent, the machine shall be thoroughly
checked for excess friction in the bearings and all other moving parts.
4.3 After eliminating as nearly as possible all the excess friction, the machine shall be re-calibrated in the
aforementioned way until the machine does indicate correctly. The machine shall be calibrated at a
minimum of three points, using accurately known weight assemblies covering the range of forces to be
measured. The weight of the clamp and hook shall be included as part of the calibration weight. If pawls
or ratchets are used during test, they shall also be used during the calibration. Friction in the head may
be checked by calibrating with the pawls up.
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