Wedge and wheel lock nuts

Wedge and wheel lock nuts

Wedge and wheel lock nuts offer high-quality, user-friendly, easy-to-assemble locking for screw connections in demanding situations, especially in multiple use. The fastening of the wedge lock washer and nut into a single unit makes screw connections even more simple and efficient where extreme vibrations and dynamic movement are present.

Construction of the wedge and wheel lock nut

The wedge and wheel lock nuts are supplied already pre-assembled. Consisting of a flange nut and a standard wedge lock washer, these two elements form one unit in a captive rotating connection. As with ring lock washers, this pre-assembled connection guarantees correct positioning and arrangement of the wedge lock nuts in all assembly instances and at all times. The wedge and wheel lock nut functions using the same tried-and-tested principle as the wedge lock washer.

Benefits

  • Minimisation of the risk of error during construction
  • Permanent fixing and correct positioning of the wedge lock washers
  • Reduction in assembly time and effort
  • Handling advantages especially in places difficult to access
  • Reduction in component parts
  • Simple, safe and quick installation even for unfamiliar users
  • Multiple usage without loss of quality
  • The wedge and wheel lock nut has a strength class of 10, therefore it can be used with 8.8 and 10.9 screw connections.

Materials and technical properties:

  • Steel, strength class 10
  • Surface zinc flake coating Delta Protekt KL 100 + slide coating VH302*
  • Corrosion resistance: 600 hours without Fe corrosion, salt spray mist test in accordance with ISO 9227

Fastening type

The wedge and wheel lock nuts belong to the family of fasteners designed to prevent unscrewing.

Important properties:

  • The connection does not unscrew
  • The pre-tension is maintained
  • The fastening element remains in the starting position
  • The connection remains “robust”

Note

In order to ensure the functionality of a locking element designed to prevent unscrewing, the hardness of the mating material must be lower than that of the washer.

No locking effect when used with additional countersunk washers.

Functioning principle

Difference in hardness

  • The surface hardness of lock washers is higher than conventional screws (strength class 8.8, 10.9 and 12.9).
  • Steel hardness (through-hardened) 485 ± 25 HV0.3
  • Stainless steel hardness (surface-hardened) > 520 HV0.05
  • The radial teeth on the outside of the wedge lock washers dig into the mating material. This creates a positive-fit connection when the screw connection is tightened.

Angle difference α > β

  • The locking principle is based on the angle α existing between the wedge surfaces. In the case that the screw loosens independently, a self-locking function occurs as a result of the wedge effect (α > β).
  • The angle of the wedge surfaces must be adjusted to the pitch angle of the screw (ISO thread and UNC thread) in the appropriate nominal size

Friction difference μa > μi

  • Wedge sections on the joint faces of the two halves of the washer have a considerably lower coefficiency of friction (μi) than the toothed exterior (μa) of the washers.
  • As a result of the property described above, any unscrewing movement (caused by dynamic loads) only causes movement between the two halves of the washer and not between the washer and mating material or washer and nut.

Pretensioning difference Fdyn > Fstat

  • The expansion of the thickness of the wedge lock washer caused by unscrewing movement causes the screw to elongate.
  • This results in an increase in pretensioning, causing the screw connection to self-lock.