Grips Employing Deflection (Capstan Grips)

A load reduction curve is used for this specimen grip. The force in the specimen is reduces over the course of the load reduction curve. The required gripping forces can be reduced in the pneumatic control unit. Maximum test load ranges from 500 N to 20 kN.
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.
1x1-04-pn-5kn-defl-belt-fo

Grips with 180° Deflection

  • Specimen material:
    Metals, paper, textiles, elastomers, insulating material, and similar materials
  • Specimen shape:
    Round and flat specimens, thread, twine, belts, bands
  • Type of loading:
    Tensile

Advantages and features (180° deflection)

  • Secure holding of the specimen ensures reliable test results, even with specimens prone to shrinkage.
  • High specimen throughput thanks to quick specimen insertion and centering via guide groove.
  • Fast, easy two-handed specimen change - grips operated via foot control unit.
  • The load-reduction curve ensures gentle gripping with no jaw breaks.
  • Interchangeable load reduction curves enable optimum adaptation of the specimen grips to accommodate different specimen materials.
  • The jaws can be changed quickly and easily for different applications - no tools required. The jaws are centered automatically.

The pneumatic grips can also be used without the load-reduction curve.

Technical data, Fmax 5 kN

Type

8388

Item No.

315008

Test load Fmax

5

kN

Operating pressure

1 to 10

bar

Closing force at 6 bar

5

kN

Dimensions

Height

182

mm

Width

218

mm

Depth

130

mm

Depth with connection unit

168

mm

Maximum clamping travel

5

mm

Opening width, max.

5

mm

Connection, stud

Ø 20

mm

Weight per grip unit, approx.

6.6

kg

Ambient temperature

+10 to +35

°C

Scope of delivery

2

pieces

Image-Article_PH-Umlenkung-90

Grips with 90° Deflection

  • Specimen material:
    textiles, plastics, metals
  • Specimen shape:
    yarn, tape up to 5mm wide, wire, low-count filament and staple yarns
  • Type of loading: tensile

Advantages and features (90° deflection)

  • Secure holding of the specimen ensures reliable test results, even with specimens prone to shrinkage.
  • High specimen throughput thanks to quick specimen insertion and centering via guide groove.
  • The load-reduction curve ensures gentle gripping with no jaw breaks.
  • The jaws can be changed easily for different applications.
  • Interchangeable load reduction curves enable optimum adaptation of the specimen grips to accommodate different specimen materials.

Function description

90-Umlenk_Tab_KNA_Image-Article

The load-reduction curve with 90° deflection gently reduces the tensile force before the clamping point. Pneumatic clamping ensures constant gripping force with easy, reproducible adjustment. The specimen is held securely and jaw breaks are avoided.

Technical data, Fmax 1 kN

Type

8190

8190

Item No.

344647

014771

Test load Fmax

1

1

kN

Maximum closing force at 6 bar operating pressure

4.2

4.2

kN

Pressure, min.

1

1

bar

Pressure, max.

6

6

bar

Dimensions

Height

105

105

mm

Width

115

115

mm

Depth, upper grips

74.5

74.5

mm

Depth, lower grips

76.5

76.5

mm

Depth with connection unit

91

91

mm

Clamping stroke

5

5

mm

Opening width, max.

5

5

mm

Connection, stud

Ø 8

Ø 20

mm

Weight per grip unit, approx.

1.4

1.4

kg

Ambient temperature

+10 to +35

+10 to +35

°C

Scope of delivery

2

2

pieces

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
Grips employing deflection (capstan grips)

Specimen Grip for Tire Cords

  • Specimen material:
    textiles, plastics
  • Specimen shape:
    single and ply yarn, twine, multifilaments
  • Type of loading:
    tensile
  • Standard:
    tire cord to ASTM D885, single and ply yarn to ISO 2062

Advantages and features (tire cords)

  • Secure holding of the specimen ensures reliable test results, even with specimens prone to shrinkage.
  • High specimen throughput thanks to quick specimen insertion and centering via guide groove.
  • Fast, easy two-handed specimen change - grips operated via foot control unit.
  • The load-reduction curve ensures gentle gripping with no jaw breaks.
  • Interchangeable load reduction curves enable optimum adaptation of the specimen grips to accommodate different specimen materials.
  • The jaws can be changed quickly and easily for different applications - no tools required. The jaws are centered automatically.

Technical data, Fmax 2.5 kN

Type

8297

Item No.

326020

Operating principle/identification

pneumatic, single-actuator

Test load Fmax

2.5

kN

Closing force at 6 bar

5.8

kN

Pressure, min.

3

bar

Pressure, max.

10

bar

Dimensions

Height

183

mm

Width

215

mm

Depth

72

mm

Depth with insertion aid

109

mm

Depth with insertion aid and connection unit

134

mm

Opening width, max.

4

mm

Weight per grip unit, approx.

4

kg

Connection, stud

Ø 20

mm

Ambient temperature

+15 to +35

°C

Scope of delivery

2

pieces

Jaws supplied

steel, ground

Gripping area (H x W)

60 x 32

mm

Image-Article_PH-Kunststoffgarne

Grips for High-Strength Plastic Yarn

  • Specimen material:
    textiles, plastics
  • Specimen shape:
    high-strength yarn, multifilaments, cord
  • Type of loading:
    tensile

Advantages and features (plastic yarns)

  • The symmetrical weight distribution allows the center of gravity of the grips to be near the tensile axis. No transverse forces are transmitted to the load cell via the specimen grip.
  • A guide mandrel and a depth stop allow fast and convenient specimen feeding.
  • A guide groove is integrated into the load reduction roller for thread feeding, thereby positioning the specimen automatically and precisely in the tensile axis.
  • The ends are clamped pneumatically, ensuring that the gripping force remains constant even with diminishing specimen diameter.
  • Force reduction curve employing 180° deflection reduces the tensile force on the end-clamping position. The closing force is progressively loaded at end clamping, thereby securely holding the specimen and preventing jaw breaks during the test.
  • Easy and convenient opening and closing via pneumatic control unit allowing high specimen throughput.

Technical data, Fmax 2.5 kN

Type

8297

Item No.

070255

Operating principle/identification

Pneumatic, single-side closing

Test load Fmax

2.5

kN

Closing force at 6 bar

16

kN

Pressure, min.

3

bar

Pressure, max.

10

bar

Gripping area

Opening width, max.

4

mm

Dimensions

Height

183

mm

Width

232

mm

Width with pneumatic connection

267

mm

Depth

100

mm

Depth with insertion aid

116

mm

Depth with insertion aid and connection unit

126

mm

Connection, stud

Ø 20

mm

Weight per specimen grip, approx.

6.1

kg

Ambient temperature

+15 to +35

°C

Scope of delivery

2

pieces

Grips employing deflection (capstan grips)

Grips for Yarn

  • Specimen material:
    textiles, plastics, metals, glass fiber
  • Specimen shape:
    high-strength yarns, multifilaments, cord, metal strand, wire
  • Type of loading:
    tensile

Advantages and features (yarn)

  • Secure holding of the specimen ensures reliable test results, even with specimens prone to shrinkage.
  • High specimen throughput thanks to quick specimen insertion and centering via guide groove.
  • Fast, easy two-handed specimen change - grips operated via foot control unit.
  • The load-reduction curve ensures gentle gripping with no jaw breaks.
  • Interchangeable load reduction curves enable optimum adaptation of the specimen grips to accommodate different specimen materials.
  • The jaws can be changed quickly and easily for different applications - no tools required. The jaws are centered automatically.

Technical data, Fmax 2.5 kN

Type

8297

Item No.

353413

Test load Fmax

2.5

kN

Operating principle/identification

pneumatic, single-actuator

Closing force, max. at 6 bar

16

kN

Closing force, max. at 10 bar

27

kN

Pressure, min.

1.5

bar

Pressure, max.

10

bar

Dimensions

Height

254

mm

Width

358

mm

Depth

100

mm

Opening width, max.

10

mm

Connection, stud

Ø 20

mm

Weight per grip unit, approx.

7.5

kg

Ambient temperature

+10 to +35

°C

Scope of delivery

2

pieces

Image-Article_Stahlstreifencorde

Specimen grip for steel strip cord

  • Specimen material:
    metals, plastics, textiles
  • Specimen shape:
    yarn, cord, multifilaments, rovings
  • Type of loading:
    tensile
  • Standard:
    to BISFA 2002

Advantages and features (steel strip cord)

  • The symmetrical weight distribution allows the center of gravity of the grips in the tensile axis. No transverse forces are transmitted to the load cell via the specimen grips.
  • A guide groove is integrated into the load reduction roller and basic unit for thread feeding, allowing fast and convenient specimen feeding and automatic and precise positioning in the tensile axis.
  • Force reduction curve employing 270° deflection reduces the tensile force on the end-clamping position. Thus the required closing force can be reduced at end clamping for specimens that are sensitive to clamping. The closing force is progressively loaded at end clamping, thereby securely holding the specimen and preventing jaw breaks during the test.
  • The load reduction radius is reduced seamlessly via the involute form of the load reduction roller.
  • The ends are clamped pneumatically, ensuring that the gripping force remains constant even with diminishing specimen diameter.
  • Easy and convenient opening and closing via pneumatic control unit allowing high specimen throughput.

Technical data, Fmax 10 kN

Type

8397

Item No.

012415

Operating principle/identification

pneumatic, single-actuator

Test load Fmax

10

kN

Closing force at 6 bar

30

kN

Closing force at 10 bar

50

kN

Pressure, min.

1

bar

Pressure, max.

10

bar

Dimensions

Height

220

mm

Width

369

mm

Depth

113

mm

Depth with connection unit

157

mm

Opening width, max.

5

mm

Connection, stud

Ø 20

mm

Weight per grip unit, approx.

12.5

kg

Ambient temperature

+10 to +35

°C

Scope of delivery

2

pieces

Load-reduction curve supplied

Length per curve, approx.

330

mm

Deflection angle

270

°

Jaws supplied

Surface

steel, smooth, hardened

Clamping length, max.

60

mm

Hardness

58 HRC

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