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ORIGINAL SCHNORR®

BOLT LOCKING SYSTEMS: SAFETY WASHERS

The SCHNORR® safety washers can be made from different materials and can be supplied with different surface treatments.

The original SCHNORR® safety washers were developed as a reliable and economic bolt locking device with the basic principle of a disc spring. This ingenious form combines the advantage of security through friction and mechanical locking.  Original SCHNORR® safety washers are now used worldwide where secure fastening connections to counter the effect of vibration, thermal expansion, etc are required.

Applications span many industries automotive,  machine, plant engineering, conveyors, electrical.  Anywhere where a fastener needs to be reliably secured.   SCHNORR® safety washers are used, for example, in mowing machines, textile machines, machine tools and a lot of other applications.

The original SCHNORR® safety washers are in the form of a disc spring but with a trapezoidal cross-section and serrations on both sides. The outer diameter is matched to the head diameter of the pan head and socket head cap screws.

SCHNORR® safety washers are available in two versions:

The standard safety washer type “S” is available for screws of sizes M1.6 to M36 and of the property classes up to 8.8. For screws of property classes 8.8 and 10.9, higher pretension forces might be necessary. These are covered by our reinforced washers type “VS”. Due to the conical form, optimal traction is achieved at highest positive locking due to the helical gearing.


Original SCHNORR® Safety Washers “S”

The Original SCHNORR® Safety Washer “S” is suitable for normal requirements and available for screws from M 1,6 to M 36. Other sizes as well as customized dimensions can be inquired for.

Original SCHNORR® Safety Washers “VS” with greater thickness

 

The Original SCHNORR® Safety Washer “VS” can be used with high-strength bolts of the grade 8,8 without any restrictions.

This strengthened safety washer has a greater thickness and for this reason achieves higher pre-tensioning loads.

The outside and the inside diameter as well as the toothing correspond to the type “S”. It can be delivered for screws M 5 to M 3.

Special sizes are also available upon request.

 

Original SCHNORR® safety washer type “S”

The Original SCHNORR® safety washer „S“ is suitable for normal requirements and available for bolt sizes from M 1.6 to M 36 in grades up to 8.8. Please enquire should you require an item with different dimensions, material or surface treatment.

Materials and Treatment

Artical Number:

Applies to the normal version made of spring steel, hardened, blackened; mechanically plate

H Max:

Maximum dimension as delivered

H Min:

Minimum dimension after load test

Available Material  Grade:

Spring steel acc. to DIN EN 10132-4; corrosion-resistant steel 1.4301; Phosphorus Bronze CuSn8; nickel cobalt alloy; creep-resistant steel 1.4122; Inconel

Surface Treatments:

Blackened (standard), bronzed, phosphated, zinc-coated, zinc lamellar coatings Inconel

Original SCHNORR® safety washer type “VS”

The Original SCHNORR® Safety Washer “VS“ can be used with high-strength bolts of the grade 10.9 without any restrictions. This very strong safety washer has a greater thickness for higher pre-tensioning loads. The outside and inside diameters as well and the serrations are the same as the “S“ type. It can be delivered for screws M 5 to M 30. Special sizes, materials and surfaces are also available upon request.

Materials and Treatment

Artical Number:

Applies to the normal version made of spring steel, hardened, blackened; mechanically plated

H Max:

Maximum dimension in delivery condition

H Min:

Minimum dimension after load test

Available Material  Grade:

Spring steel acc. to DIN EN 10132-4; corrosion-resistant steel 1.4301; Phosphorus Bronze CuSn8; nickel cobalt alloy, creep-resistant steel 1.4122; Inconel

Surface Treatments:

Blackened (standard), bronzed, phosphated, zinc-coated, zinc lamellar coatings Inconel

Due to the conical form, optimal traction is achieved at highest positive locking due to the helical gearing.

Vibration test according to DIN 65151

Extensive test series carried out at independent public material research laboratories prove that the original SCHNORR® safety washer brings about a clear improvement of the safety properties

 

Conclusions

  • Connections secured using a SCHNORR® safety washer maintains the pretension force also after 1,500 cycles.
  • An unsecured screw connection has lost its pretension already after less than 500 cycles.

Product Comparison

Die Original SCHNORR® Safety Washers offer the following advantages:

 

  1. High resistance to vibration due to positive locking of the serrations.
  2. Concentrical force transmission and uniform axial load eliminate bending torques and deformation of the bolt stem.
  3. The design of the serrations prevents friction and damage to components when tightening.
  4. Extremely high safety against loss of pretension force and loosening.
  5. Wide variety for materials and different finishes.
  6. The closed ring form results in high degree of pretensioning, while avoiding burst-open effect.
  7. Development and design of the washers take place on the basis of the screw geometrics, tightening torque as well as the constructive circumstances.

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