In which of the following locking nuts, is a slot cut halfway across the nut?

Explanation:

• Nuts are used along with bolts in an assembly which may loosen due to vibration.
• Different types of nut-locking devices are used depending on the severity of the condition in which the fastener is used.
• The following are the most commonly used types:

Swan nut (Wiles nut)

• A slot is cut halfway across the nut.
• A screw is fitted with a clearance hole on the top part and matching thread on the lower part of the nut.

Penn, ring or grooved nut:

• It has an upper portion hexagonal and a lower part cylindrical.
• It is largely used where the bolt passes through connected pieces.
• The bottom portion is cylindrical and is recessed to receive the tip of the locking set screw.
• The bolt hole requires counterboring to receive the cylindrical portion of the nut.
• In order to prevent bruising of the latter bu the case-hardened tip of the set screw, it is recessed.

Slotted/Castle nut:

• It consists of a hexagonal portion with a cylindrical upper part which is a slotted inline with the center of each face.
• The split pin passes through two slots in the nut and a hole in the bolt so that a positive lock is obtained unless the pin shears.
• It is extensively used on jobs subjected to sudden shocks and considerable vibrations.