Double Deflect Grips

The double capstan grips can be used to grip filamentary,high-extension tensile specimens.
Grips employing deflection (capstan grips)

Key Advantages and Features

  • With pneumatic end clamping the gripping force remains constant, allowing high specimen throughput.
  • Automatic centering of specimens via guide grooves in the load reduction curve.
  • No transverse forces are transmitted to the load cell via the specimen grips.
  • The symmetrical weight distribution allows the center of gravity of the grips to be near the tensile axis.
Grips employing deflection (capstan grips)

Double Deflect Grips

  • Specimen material:
    Rubber, elastomer, textile
  • Specimen shape:
    High strain, filamentary materials, e.g. rubber threads and elastic fibers
  • Type of loading:
    Tensile

Advantages and features (double deflection)

  • Wrapping the specimen around the load reduction rollers ensures gentle gripping without jaw breaks.
  • These specimen grips ensure exact strain measurement on high-extension threads.
  • Preventing jaw breaks allows for efficient testing.

Function description

The double capstan grips can be used to grip filamentary, high-extension tensile specimens.

With this deflection principle a force differential occurs over two stages, allowing specimen failure within the gauge length with no jaw breaks.

After the deflection of the double thread, a prestress weight (not included in scope of delivery) is attached. During this phase all three rollers can be moved to compensate for the change in length caused by the attachment of the pre-tension weight. The three lengths are adjusted to the material being tested.

Finally, the double thread is also gripped in height adjustable specimen grips.

After closing the specimen grips, the deflection rollers are locked into place. This results in frictional forces between the rollers and the specimen, which gently reduce the tensile force prior to end clamping (specimen grip), ensuring that the specimen is gripped securely and prevents the jaws from breaking.

A specimen grip with constant gripping force is used to clamp the double thread because the specimen to be tested can frequently slip out from between the gripping areas.

Technical data, Fmax 0.5 kN

Item No.

317800

Type

8170

Test load Fmax

0.5

kN

Usable load cells, type 1

0.1 ... 1

kN

Minimum gauge length

50

mm

Specimen diameter, max.

5

mm

Deflection rollers radius

10

mm

Upper specimen grip

Height

159

mm

Width

119

mm

Depth

72

mm

Width with clamping lever

153

mm

Connection

Ø 8

mm

Weight

0.7

kg

Lower specimen grip

Height

180

mm

Width

93

mm

Depth

62

mm

Depth with clamping lever

94

mm

Connection diameter

20

mm

Weight (with wedge screw grip), approx.

1.3

kg

Connection, stud

Ø 8 / Ø 20[1]

mm

Ambient temperature

-20 ... +60

°C

Scope of delivery

Set[2]

  1. The upper specimen grip has a connecting diameter of 8 mm and the lower one of 20 mm
  1. Upper and lower specimen grip, one wedge screw grip type 8106, Fmax 500 N
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