Friday, December 14, 2018     •  Login


by Angannas


This is an overview of the components used in (mainly) MKII helmets. Most of the changes made to components were made in the interests of economy - less rubber and less metal being used with each change, although some changes were to improve performance etc.


Liner Bolts

The 3 types of bolt comprise two parts as far as versioning is concerned - the Nut and the Bolt.

Lining Securing Bolt MKI.

This was the bolt used on the MK1* and MKII helmets. Sometimes they can be seen on MKIII and RAC MKI helmets as well, as stocks were used up.

Introduced in January 1938 with the MKI* helmet (refurbished WW1 MKIs with the new MKI liner). This bolt had a broad flat disc bolt head and a broad flat disc nut:

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Reports from the field indicated that the bolt became lose easily and was difficult to keep tight - the liner and helmet used to swivel around. This led to a new bolt being designed:

Lining Securing Bolt MKII.

This uses a redesigned MKI Bolt - with a longer screw thread (9.37mm compared to 7.8mm) and a new nut. This nut was an existing proprietary model called the "Simmonds Elastic Stop Nut", manufactured bt Messers Nevilles (Liverpool) Ltd. The nut was made of brass and contained a rubber washer which stopped the bolt from becoming lose.

The MKII bolt was introduced alongside the new MKII liner (see below) in March 1940 and the MKI bolt was then declared obsolete. Technically the MKII bolt should only be seen on helmets with MKII liners, but often MKI lined helmets were 'upgraded' with the new MKII bolt.

(I have not included a picture of the MKII bolt itself because it is identical to the MKI bolt other than length)

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Lining Securing Bolt MKIII.

In 1942 a new bolt was introoduced to save on non-ferrous metals - it comprised of the existing "Simmonds Elastic Stop Nut", but with a new bolt - a much smaller one compared to the big flat disc of the MKI and MKII - only 10mm in diameter compared to 16.25mm.

These do seem to come in a variety of styles, the most common one being the first picture below:

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Its quite common to see field modifications to bolts - extra washers being added or new nuts etc - whatever was to hand.


Chinstrap, Helmet, MKI

This chinstrap is only seen on the MKI* helmet and it was designed in May/June 1936. Production did not start until 1937. The springs were a unique idea, designed to prevent the wearers neck from breaking in the event of the helmet being suddenly jerked back. This idea of sprung chinstraps goes all the way through every other british chinstrap in various forms.

The main recognition feature is the large wire loops to attach the chinstrap to the helmet:

It may be possible to see a MKI chinstrap on a MKII helmet, but I haven't yet.

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Chinstrap, Helmet, MKII

It was found that the large wire loops of the "Chinstrap, Helmet, MKI", made it possible for the helmet to slip off, so in June 1937 the MKII chinstrap was designed with smaller wire loops. Production started in 1938 alongside the MKII chinstrap lug (see below). It is normally seen on just MKII helmets and is the most common British chinstrap in WW2.

There seem to be several distinct versions of the "Chinstrap, Helmet, MKII", using different materials:

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And its quite common to see field repairs:



Chinstrap, Helmet, MKIIA

In September 1940 it was realised that there were serious shortages of non-magnetic steel springs used in the "Chinstrap, Helmet, MKII". It was decided to use magnetic springs for the MKII Type 2 helmets - the ones with the holes in the brim that were only used by the ARP and Civil Defence services.

This resulted in a new designation - "Chinstrap, Helmet, MKIIA" These chinstraps should only be found on Civil MKII Type 2 helmets - other than using a magnet, the only way to tell them apart from the "Chinstrap, Helmet, MKII" is to spot the two types of markings that were put on in the factory to denote them being only issued to Civil forces, an 'M' (for Magnetic) or a star:



Chinstrap, Helmet, MKIII

The same shortages of non-magnetic steel springs in September 1940 led the Ministry of Supply to design a new chinstrap that did not not need springs at all. In order to still give the same elasticated protection elasticated webbing was used instead - this also made the manufacturing much simpler and cheaper. A brass loop at one end attached the chinstrap to the helmet and a friction type buckle at the other end allowed for size adjustment. Any extra length hanging down after personal adjustment was meant to tuck in bewteen the liner and the helmet shell.

It was introduced in March 1941. It can be seen on MKI*, MKII, MKIII and RAC MKI helmets.

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Chinstrap, Helmet, MKIIIA

This is the rarest British chinstrap and it ws only produced in small numbers - I have never managed to find one.

It was agreed in January 1943 to reduce the amount of elastic (rubber) being used in chinstraps in the interests of wartime economy, so rather than the whole chinstrap being made of elasticated webbing, the central section was replaced with just plain webbing. This had the effect of almost recreating the original "Chinstrap, Helmet, MKII" design but having elasticated webbing sections where the springs would have been:

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Its is worth looking at the post-war version of the "Chinstrap, Helmet, MKIV", as it is a different colour and material to wartime examples:


Chinstrap Lugs

Chinstrap securing lug MKI

This chinstrap lug is only found on MKI* helmets and attachs the "Chinstrap, Helmet, MKI":


Chinstrap securing lug MKII

A new chinstrap securing lug was designed in June 1937 - designed to be more secure than the MKI. It was put into production early in 1938.

This is the first lug that has a date stamp, suggesting that they were manufactured seperately to the helmets. Also there seems to be two distinct methods of attaching the lug to the helmet - using split pins (WW1 MKI helmet style) or using roundhead rivets. I haven't been able to work out if this is specific to particular manufacturers yet:

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Chinstrap securing lug MKIII

It was found that it was very difficult to replace a damaged chinstrap - so a new lug was designed by the Home Office in February 1939 - specifically for use on the MKII helmets manufactured for the ARP services. The new design meant that a blade or screwdriver etc could be inserted and the lug prised apart to get the chinstrap off the helmet and a new one installed.

As the design was seen as superior to the "Chinstrap securing lug MKII", it was made standard for all new MKII helmets and the "Chinstrap securing lug MKII" was declared obsolete.

Sometimes they have date stamps, sometimes not:

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It is worth comparing the British Chinstrap securing lugs with an Australian MKIII helmet lug and a South African MKII helmet lug:
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The MKI liner was designed as a superior replacement to the original WW1 MKI helmet liners (these were uncomfortable, unstable and expensive) as part of the MKI* helmet upgrade programme. Helmets Ltd. designed the MKI liner in 1936, with production commencing in 1937.

The five liner tongues are made of leather cloth (sometimes called rexene) which contains linseed oil. This is then attached to a vulcanised fibre headband, which is then riveted to 4 fibre strips connecting the crown pad - this pad is sponge rubber (sorbo) covered with more leather cloth and riveted on to the 4 fibre strips using 4 rivets. Around the outside of the headband are pieces of folded sorbo that form the buffer cushions between the liner and the helmet shell.

MKI liners are only found in MKI* and early MKII helmets.




In an attempt to simplify and cheapen the construction of the MKI liner, BMB ltd. overhauled its design in April 1939. They removed the big oval crown pad and replaced it with a solid piece of x shaped rubber. This was attached using the liner attachment bolt rather than the 4 separate rivets of the MKI liner - the single bolt held the liner into the helmet and the crown pad onto the liner.

They also replaced the folded sorbo rubber buffer pads with solid moulded rubber buffer pads - these just slotted into holes in the fibre crown strips, rather than having to be riveted on like the MKI liner.

The War Office approved this new efficient liner design on the 21st June 1939 with production starting immediately in BMB. It wasn't until early 1940 that MKII liner production took off outside BMB.

MKII liners can be found in MKII, MKII type 2, MKIII and RAC MKI helmets
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The MKIII liner was designed spefically for the MKIV helmet and is known as the "Lift the Dot liner" - it is exactly the same constuction as the MKII liner apart from the crown pad. This contained a special socket that clipped over a protruding stud in the helmets dome. This system replaced the "Lining Securing Bolt MKIII", making the helmet watertight so it could be used for containing water.

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