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Last edited 20 Jan 2020
Types of washers
Although they can vary widely, in general, washers have an outer diameter that is approximately twice the inner diameter.
There are three main categories of washer:
Types of plain washer include:
- Penny washer (or Fender washer): A flat washer with a larger outer diameter proportional to the central hole, meaning it can distribute loads more widely.
- Spherical washer: Consists of one radiused surface which, when used with a mating nut, allows for several degrees of misalignment between parts.
- C-washer: Can be slid in and out of position on a bolt or shaft.
- Countersunk washer: When secured, this type of washer creates a flush surface.
- Belleville washer: Has a slight conical shape which helps maintain tension in assemblies where there is thermal expansion and contraction.
- Curved disc spring: Is only curved in one direction and so is used to support relatively light loads with a wide deflection range.
- Wave washer: Has a ‘wave’ in the axial direction which makes it suitable for use as a cushion spring or spacer.
- Split washer: Has a ring that is split at one point and bent into a helical shape creating more friction and rotation resistance.
Types of locking washer include:
- Helical spring: Increases the pre-load on the fastener while tightening. This provides protection against loosening.
- Toothed lock washer: Has serrations around its edge that can extend inward or outward to bite into the surface material and provide maximum torsional resistance.
- Tab washer: Has a side tab that can be bent into place against a nut, preventing rotation.
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