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

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Question

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ALP CBT 2 Fitter Previous Paper: Held on 21 Jan 2019 Shift 1

Answer 1

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.

swan 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.

F1 Satya madhu 10.06.20 D12

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.

Fitter 34 20Q Hindi - Final images q15h

Jam nut or lock nut:

The thin lock nut is first tightened down with ordinary force, and then the upper nut (thicker nut) is down upon it.
The upper nut is then held tightly while the lower nut is slackened back against it.

Fitter 34 20Q Hindi - Final images q15d