US3127615A

US3127615A - Removable rigging for helmet

Info

Publication number: US3127615A
Application number: US141866A
Authority: US
Inventors: Jackston A Aileo
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-09-29
Filing date: 1961-09-29
Publication date: 1964-04-07
Anticipated expiration: 1981-04-07

Description

April 7, 1964 J. A. AILEO 3,127,615 REMOVABLE RIGGING FOR HELMET Filed Sept. 29. 1961 BY ire/(90ml 4/450 L/w/LWM United States Patent 3,127,615 REMOVABLE RIGGING FDR HELMET .lacksen A. Aileo, Carhcndale, Pa, assigaor to Leonard P. Frieder, Great Neck, Nfi. Filed Sept. 29, 1961, der. No. 141,366 8 Claims. (Cl. 23)

This invention relates to safety helmets and more especially to such helmets having a light rigid shell sulficiently strong to resist bumps or similar impacts which might injure the head and provided with a rigging for supporting the shell upon the head of a wearer. The invention particularly relates to the rigging and the means for supporting'the rigging within the rigid shell.

In the patent to Jackson A. Aileo 2,983,923, issued May 16, 1961 is disclosed a helmet of this type in which the rigging is provided by a head strap of stillly resilient flexible material, preferably a plastic, this head strap extending in arcuate form over the crown portion of the helmet at the inner surface thereof and carrying at its ends head band elements of arcuate form adapted to extend about the forehead and rear portion of the wearers head. The head band elements also are of stifiiy resilient flexible material and the head strap in its unstressed arcuate form disposes these head bands more closely together than the positions thereof in which the head bands engage the head of the wearer. The head strap is secured to the inner surface of the crown portion of the shell of the helmet and carries at the side thereof toward the head a resilient pad to cushion the crown of the head of the wearer. The fastening means of the helmet of the patent includes screws which are disposed in holes extending through the wall of the shell adjacent the crown portion thereof and engaging nuts which must be removed in order to remove the rigging from the shell.

It is an object of the invention to provide an improved rigging of this type.

It is another object of the invention to provide improved fastening means which is not required to be removed from the shell in order to remove the rigging therefrom.

It is a further object of the invention to provide means for securing the head strap and the head bands supported thereby in place within the shell without utilizing holes through the wall of the shell.

It is a still further object of the invention to provide a rigging in which the resiliently deformable characteristic of the head strap is utilized to effect removal of the rigging from the shell.

It is an additional object of the invention to provide a resiliently deformable head strap capable of cooperating with fastening means permanently secured to the shell for effecting easy removal of the head strap from the shell and reinsertion thereof in the shell.

It is a feature of the invention in a helmet provided with a rigging of the general type above described and shown in the Patent No. 2,983,923 to provide keyhole openings in the head strap that are designed to engage fasteners secured to the inner surface of the shell. Preferably these keyhole openings are disposed in the portion of the head strap which extends over the inner surface of the crown portion of the shell of the helmet. The keyhole openings are disposed in spaced relation to each other along the head strap with the slots thereof extending along the head strap. Preferably the slots of the keyhole openings extend toward each other with respect to the enlargements or enlarged portions of the keyhole openings. The keyhole openings, however, may be disposed with the slots thereof extending in the same direction along the head strap, that is, either toward the rear head band element or toward the front head band element respectively supported by and adjacent the ends of the head strap.

In place of the screws extending through the wall of the shell as provided in the helmet of the Patent 2,983,923, in accordance with the present invention fastening elements are provided which are disposed in spaced relation to each other and are secured to the wall of the shell and extend inwardly with respect to the inner surface thereof. In a hehnet in which the shell is made of a plastic or similar material capable of thermal softening or fusion, these fastening elements preferably are provided by stud ike elements which are of material capable of cohesively engaging or fusing with the wall of the shell at the inner surface thereof. These studs have a shank portion extending transversely of and inwardly from the inner surface of the shell and carry at their inwardly projecting ends head portions of somewhat larger diametral dimension than the diametral dimension of the shank portions. The essential diametral dimension of the shank portion referred to is that which, when the head strap is in place, normally with its length extending in the forward and rearward direction over the crown portion of the shell, and bearing against the inner surface thereof, extends transversely of the lengthwise dimension of the head strap. This diametral dimension of the shank is such that the shank of each stud may enter the slot of the adjacent keyhole opening of the head strap.

The head portion of each stud is of such diametral dimension, larger than the diametral dimension of the shank, that this head portion extends over upon the parts of the head strap extending along and at either side of the slot when the shank is disposed in the slot. The length of the shank is such that the surface of the head portion thereof which is disposed toward the inner surface of the shell is spaced from this inner shell surface sufficiently to provide for the disposition of these parts of the head strap along a slot of the keyhole opening between and engaged by the head portion of the stud and the inner surface of the shell, thereby to retain the head strap and the head band elements supported there by in position within the helmet when the shanks of the spaced studs are disposed within the respective slots.

The diameter of the enlarged portion or enlargement of the keyhole opening is such that the head portion of the stud will pass through this enlargement when in register therewith. In the aspect of the invention in which the slots of the keyhole openings extend in the same direction along the head strap with respect to the enlargements, the spacing along the head strap of these enlargements is substantially the same as that of the spacing of the studs over the inner surface of the shell, ordinarily along the central arcuate contour of the shell in the forward and rearward direction. In this aspect the rigging comprising the head strap and the head band supported thereby may be placed within the shell so as to bring the studs and their heads in register with the enlargements of the respective keyhole opening. Then the head strap may be moved in engagement with and over the inner surface of the shell to bring the shanks of the studs within the slots of the keyhole openings.

In another aspect of the invention constituting the preferred embodiment thereof the slots of the keyhole ope-nings extend toward each other along the head strap with respect to the enlargements of the keyhole openings. With this disposition of the slots the portion of the head strap between the keyhole openings may be deformed so -as to space the central part of this portion away from the inner surface of the shell, thereby to draw the enlargements of the keyhole openings toward each other until these enlargements are in register with the studs and their respective head portions. When such position of register is reached the rigging may be moved away from the shell concomitantly with passing the head portions of the studs through the respective enlargements of the keyhole openings of the head strap.

The resiliency of the head strap will result in bringing it back to the form, ordinarily arcuate, conforming to the inner surface of the shell, after such removal. When it is desired again to insert the rigging within the shell the head strap may be deformed again so as to bring the enlargements of the keyhole openings to a spaced relation corresponding to the spacing of the studs and these enlargements then may be passed over the heads of the studs to bring the head strap into engagement with the inner surface of the shell. The resiliency of the head strap then results in the flattening thereof from the deformed shape and return to the arcuate form conforming to the inner surface of the shell of the helmet.

In another feature of the invention a method is provided of making a rigging for a safety helmet utilizing a stiffiy resilient flexible plastic to produce from a fiat member of I shape the head strap and head band elements which will have the characteristics above described and which will be provided with keyhole openings to enable this rigging to be inserted in and removed from the helmet.

The objects and features of the invention above generally described will be understood further from the description to follow of the drawing in which:

FIG. 1 shows a view of the helmet from the under or open side thereof;

FIG. 2 is a perspective view of the rigging including the novel head strap supporting head bands;

FIG. 3 is a fragmentary section on line 3-3 of FIG. 1 in which is shown the deformed shape of the head strap;

FIG. 4 is a vertical median section of a helmet in which the rigging is secured by fastening elements engaging the keyhole slots of the head strap; and

FIG. 5 shows in perspective 'a fragmentary view of a modified head strap utilizing keyhole openings with the slots extending in the same direction along the head strap.

In FIGS. 1 and 4 of the drawing the shell 1 of the helmet is provided by a rigid wall 3 which may be of suitable material so as to withstand a blow or impact in the nature of a bump of greater or less severity This shell may be of light weight so as not to be uncomfortable and inconvenient where the wearer is not subject to heavy impact or extra-hazardous conditions. The shell is generally ellipsoidal and of arcuate section in the vertical median plane extending forwardly and rearwardly and may be provided with a conventional peak 5.

Within the shell is disposed a rigging comprising a head strap 7 extending in arcuate form forwardly and rearwardly between and connected to a front head band 9 and 'a rear head band 11. These head bands are disposed adjacent the opening of the shell and spaced from the wall thereof so as to engage the forehead and rear portion of the head of the wearer. The head bands are of arcuate form generally in the horizontal plane and are resiliently flexible so as to bear gently against the head of the wearer. They are connected by elastic elements 13 at each side of the helmet, the ends of these elastic elements being threaded through the openings 15 formed in the end portions of the

head bands

9 and 11. The

head bands

9, 11 may be made of a stifiiy resilient flexible plastic.

The head strap 7 also may be made of a stifily resilient flexible plastic and in such arcuate form as to dispose the head bands toward each other with respect to their positions when engaging the head of the wearer, as shown in FIGS. 2 and 4, when the head strap is unstressed. The

head bands

9 and 11, however, may be separated concomitantly with a degree of stretching of the elastic elements 13 in order to fit to the front and rear portions of the head of the wearer. This separation is accompanied by flexure of the head strap 7 to an arcuate form of somewhat less curvature. As shown in FIG. 2, however, the rigging comprising the head strap 7 and the

head bands

9 and 11 has sufiicient stiffness to retain the form thereof 4 when the rigging is removed as a Whole from the helmet and the head strap and head bands are unstressed. The steps of removal of and of reinsertion of the rigging in the helmet now will be described.

As shown in the several figures of the drawing, in the head strap 7 are formed

keyhole openings

21, 23, the keyhole opening 21 being disposed adjacent the crown portion of the head strap but toward the end of the head strap connected to the front head band 9, the keyhole opening 23 being disposed adjacent the crown portion but toward the end of the head strap 7 connected to the rear head band 11. The

slot portions

25, 27 of the

respective keyhole openings

21, 23 extend toward each other, as shown in FIGS. 1 and 2. In these

slots

25, 27 of the respective keyhole openings are disposed the

shank portions

29, 31 of

studs

33, 35 which are secured to the inner surface of the shell Wall 3. These studs respectively are provided with

head portions

37, 39 of larger diameter than the

shank portions

29, 31 so as to extend over upon the exposed inner surface of the head strap 7 along the

respective slots

25, 27.

The

studs

33, 35 in the embodiment being described are made of plastic and the inner ends of the

shank portions

29, 31 thereof are cohesively secured to the wall 3 of the shell as shown in FIGS. 3 and 4. These studs may be molded with the

head portions

37, 39 thereof integral with the shank portions and so as to be in the spaced relation to the inner surface of the shell above mentioned.

Having regard to the stifliy resilient flexible character of the material of the head strap 7 it now will be understood that the portion 41 of the head strap which extends between the

keyhole openings

21, 23 may be deformed to the arched form shown in FIG. 3. Thus, by inserting an instrument or the finger of the hand between the shell 3 and the portion 41 of the head strap in the position shown in FIG. 4, this portion 41 may be moved away from the inner surface of the shell concomitantly with drawing the parts of the head strap respectively adjacent the

studs

33, 35 toward each other. In this movement the

respective shank portions

29, 31 of the studs are moved out of the

slots

25, 27 of the keyhole openings and the studs and their

head portions

37, 39 respectively come into register with the

enlargements

43, 45 of the keyhole openings. Thereupon, while maintaining the arched form of the portion 41, the parts of the head strap adjacent the respective keyhole openings may be moved from the shell, the

respective head portions

37, 39 of the studs passing through the

enlargements

43, 45. The rigging thus may be moved as a whole away from the shell and, because of the resiliency of the head strap, will return to the form shown in FIG. 2.

When it is desired to reinsert the rigging in the shell the central part of the portion 41 extending between the keyholes of the head strap may be bent to the arched form generally shown in FIG. 3, so that the

enlargements

43, 45 of the keyhole openings become spaced substantially the same as the spacing of the

studs

33, 35 projecting from the inner surface of the shell. These enlargements then may be passed over the

respective heads

37, 39 of the studs and, upon releasing the portion 41 from its arched form, this portion 41 will move toward the inner surface of the shell and, with slight pressure thereon, will engage the inner surface of the arcuate form as shown in FIG. 4. In this return to the arcuate form the

shank portions

29, 31 of the studs enter the

respective slots

25, 27 of the keyhole openings, the

head portions

37, 39 then extending upon and engaging the head strap along the

slots

25, 27 to hold the head strap securely in position within the shell and supporting the head bands as shown in FIG. 4.

As shown in FIGS. 1, 3 and 4, at the face of the head strap, specifically the face of the portion 41 thereof between the keyhole openings in the embodiment being described, a resilient pad or cushion 47 is secured by adhesive or other suitable means. This pad serves to cushion the crown portion of the head of the wearer with respect to the head strap. It will be understood that in the deformation of the head strap from the arcuate form of FIGS. 2 and 4 to the arched form of FIG. 3, the pad 47 also may be deformed but is carried with the head strap 7 and is removable from the shell therewith.

In the modification of FIG. 5 the head strap 7 and the

head bands

9 and 11 constitute a rigging of the same form and characteristics as that described in connection with FIGS. 1 to 4, inclusive. In this embodiment, however, the keyhole openings 51, 53 are disposed in the head strap 7 with their respective slots 55, 57 extending in the same direction along the head strap in relation to the

respective enlargements

59, 61 of the keyhole openings. It will be understood that the spacing of the

enlargements

59, 61 along the head strap may be substantially the same as the spacing of the

studs

33, 35 upon the inner surface of the shell 3. The rigging of FIG. 5 then may be brought into position within the shell so that the

enlargements

59, 61 are in register with the

heads

37, 39 of the studs. Without requiring the deformation thereof to the arched form as in FIG. 3, the head strap 7 then may be moved toward the inner surface of the shell, the

head portions

37, 39 moving through the

respective enlargements

59, 61. With the head strap in engagement with the inner surface of the shell this head strap may be moved along the shell in the direction of its length until the

shank portions

29, 31 of the studs become disposed in the respective slots 55, 57 of the keyhole openings 51, 53. The

heads

37, 39 then will overlap upon and engage the parts of the head strap along the slots and the head strap and head bands supported thereby will be held in position within the shell.

By forming the head strap in an arc such that, due to the resiliency of the plastic of the head strap, this head strap tends to assume the form of FIG. 2, it will be understood that pressure will be exerted by the head strap at the surfaces of the head portions of the

studs

33, 35 that are disposed toward the inner surface of the shell. Thus frictional engagement of the head strap 7 with these inner surfaces of the

head portions

37, 39 of the studs as well as frictional engagement of the head strap with the inner surface of the shell 3, will be secured which serve to hold the head strap against lengthwise movement thereof with respect to the shell. When the helmet is in place on the head of the wearer, the head bands being moved apart somewhat, the friction against the inner surface of the shell is increased to aid in holding the head strap in position in the shell.

While the invention has been described in connection with a helmet having a shell which may be made of a plastic and having studs also made of a plastic fused or otherwise eohesively secured to the shell, the head strap also being formed of a plastic, these parts and members may be made of other materials while embodying the features of the invention including the keyhole openings in the head strap. The studs, for example, may be formed as separate parts which are secured to the shell at the inner surface thereof by any suitable means. For example, they may be made of metal and threaded in blind holes at the inner surface of the shell. The head strap may be made of any material, for example, of metal of suitable thickness, providing the stiflly resilient flexible characteristic, especially in the portion thereof extending between the keyhole openings. In the embodiment of the invention described in connection with FIG. 5 it will be understood that a material other than a stiiily resilient flexible material may be utilized for the head strap. By suitably dimensioning the width of the slots with respect to the diametral dimension of the shank portions of the studs and the length of the shank portions with respect to the thickness of the head strap, the desired frictional engagement of these parts and the overlapping engagement of the head portions of the studs upon the parts of the head strap along the slots will be secured in both embodiments. All such variations and modifications and others within the skill of the art are intended to be covered by the appended claims.

I claim:

1. A safety helmet comprising a shell having an opening for receiving the head of a wearer and having a crown portion to be disposed adjacent the crown of the wearers head, head hand elements disposed and formed respectively to extend about and .to engage the front and rear of the Wearers head, a head strap of stifily resilient flexible material extending over the inner surface of said shell between and connected adjacent its ends to said head band elements for supporting said head band elements in spaced relation to said shell, said head strap having an intermediate portion thereof spaced from said head band elements and extending over the inner surface of the crown portion :of said shell, said head strap having keyhole shaped openings therein spaced therealong adjacent said intermediate portion thereof, said keyhole openings having the slots thereof extending toward each other along said head strap and the enlargements thereof disposed away from each other, and fastening elements rigidly secured to said shell at the inner surface of said crown portion thereof in a spaced relation to each other along said head strap corresponding substantially to the spacing of the closed ends of said slots of said keyhole openings, said fastening elements respectively providing shank portions having diametnal dimensions to enter said slots of said keyhole openings and having head portions spaced on said shank portions from said inner surface of said shell, the diametral dimension of said head portions being larger than said shank portions, the enlargernents of said keyhole openings being dimensioned to provide for passing the head portions of said fastening elements through the respective enlargements of said keyhole openings, said intermediate portion of said head strap between said keyhole openings being capable of flexure to a form curving from the parts thereof adjacent said keyhole openings to the central part thereof between said keyhole openings disposed away from said shell, thereby to draw said keyhole openings toward each other along said crown portion of said shell to positions to register said enlaugements with the respective fastening elements and to provide for passing said head portions of said fastening elements through said enlargements, the resilience of said head strap determining flattening thereof from said curved form concomitantly with movement :of said keyhole openings away from each other along said crown portion of said shell to cause said shank portions of said fastening elements to enter the respective slots and said head portions to over-lie and engage the head strap along said slots to hold said head strap and said head band elements in position in relation to said helmet.

2. A safety helmet as defined in claim 1 in which said head strap and said head band elements are formed of a plastic and are of arcuate form extending respectively along the inner surface of the crown portion of the helmet and about the front and rear of the head of the wearer and so as to dispose said head hand elements in spaced relation to the front and rear portions of the shell of the helmet.

3. A safety helmet as defined in claim 1 in which said shell and said fastening elements are formed of plastic matenial cohesively secured together at the inner surface of said shell.

4. A safety helmet as defined in claim 1 which comprises a resilient pad secured to the inwardly disposed surface of said intermediate portion of said head strap between said keyhole openings, so that upon flexing said head strap to said curved form said pad is removable with said head strap.

5. The method of making a rigging for a safety helmet which comprises forming of a stifily resilient flexible 7 plastic a flat member in -I shape, heating said l-shaped plastic member concomitantly with forming the stem of the I in arcuate form so that the crown portion of the arc thereof may conform generally to the crown portion of the helmet at the inner surface thereof, concomitantly with said heating forming the cross bars of the I respectively in arcuate form so as to extend about the front and rear of the wearers head, and cooling said plastic memher to maintain said arcuate form of said head strapand of said head band elements when unstressed while remaining stiffiy resilient and flexible in said arcuate form.

6. The method of making a rigging for a safety helmet as defined in claim which includes the step of forming keyhole openings in spaced relation to each other along said stem of the I with the slots of said keyhole openings extending along said stem.

7. A safety hehnet comprising a shell having an opening for receiving the head of a wearer, a member extending upwardly over the inner crown surface of said shell and having end parts respectively disposed adjacent to but spaced from portions of said shell that are spaced about said opening, head band elements for extending about the head of the wearer and respectively supported by said member adjacent said end parts thereof, said member having an intermediate part between said end parts thereof and provided with keyhole shaped openings spaced therealong with the slots of said keyhole openings extending longitudinally of said member and with the enlargements of said keyhole openings disposed away from each other and the closed ends of said slots disposed toward each other, and fastening elements rigidly secured to said shell at the inner surface thereof in spaced relation to each other over said surface corresponding generally to the spacing of said slots of said keyhole openings, said fastening elements respectively providing shank portions having a diametral dimension to enter said slots of said keyhole openings and having head portions spaced on said shank portions from said inner surface of said shell, the diametral dimension of said head portions being larger than said shank portions but restricted to provide for passing said head portions through the respective enlargements of said keyhole openings, said member being held in fixed relation to the inner surface of said shell when said shank portions of said fastening elements are disposed in said slots of said member and said head portions engage the surface of said member along said slots.

8. A safety helmet comprising a shell having an opening for receiving the head of a wearer, a head strap of flexible material extending upwardly over the inner crown surface of said shell and having end parts respectively dis posed adjacent to but spaced from portions of said shell that are spaced about said opening, head band elements for extending about the head of the wearer and respectively supported by said head strap adjacent said end parts thereof, said head strap having an intermediate part between said end parts thereof and provided with keyhole shaped openings therein spaced therealong with the slots of keyhole openings extending along said head strap and with the enlargements of said keyhole openings disposed away from each other and the closed ends of said slots disposed toward each other, and fastening elements rigidly secured to said shell at the inner surface thereof in spaced relation to each other over said surface corresponding generally to the spacing of said slots of said keyhole openings, said fastening elements respectively providing shank portions having a diametral dimension to enter said slots of said keyhole openings and having head portions spaced on said shank portions from said inner surface of said shell, the diametral dimension of said head portions being larger than said shank portions but restricted to provide for passing said head portions through the respective enlargements of said keyhole openings, said head strap being held in fixed relation to inner surface of said shell when said shank portions of said fastening elements are disposed in said slots of said head strap and said head portions engage the surface of said head strap along said slots, said head strap being capable of flexure of said intermediate portion to provide for drawing said enlargements of said keyhole openings toward each other into register with said head portions of said fastening elements.

Aileco May 16, 1961 Bowers et al. Mar. 27, 1962

Claims

1. A SAFETY HELMET COMPRISING A SHELL HAVING AN OPENING FOR RECEIVING THE HEAD OF A WEARER AND HAVING A CROWN PORTION TO BE DISPOSED ADJACENT THE CROWN OF THE WEARER''S HEAD, HEAD BAND ELEMENTS DISPOSED AND FORMED RESPECTIVELY TO EXTEND ABOUT AND TO ENGAGE THE FRONT AND REAR OF THE WEARER''S HEAD, A HEAD STRAP OF STIFFLY RESILIENT FLEXIBLE MATERIAL EXTENDING OVER THE INNER SURFACE OF SAID SHELL BETWEEN AND CONNECTED ADJACENT ITS ENDS TO SAID HEAD BAND ELEMENTS FOR SUPPORTING SAID HEAD BAND ELEMENTS IN SPACED RELATION TO SAID SHELL, SAID HEAD STRAP HAVING AN INTERMEDIATE PORTION THEREOF SPACED FROM SAID HEAD BAND ELEMENTS AND EXTENDING OVER THE INNER SURFACE OF THE CROWN PORTION OF SAID SHELL, SAID HEAD STRAP HAVING KEYHOLE SHAPED OPENINGS THEREIN SPACED THEREALONG ADJACENT SAID INTERMEDIATE PORTION THEREOF, SAID KEYHOLE OPENINGS HAVING THE SLOTS THEREOF EXTENDING TOWARD EACH OTHER ALONG SAID HEAD STRAP AND THE ENLARGEMENTS THEREOF DISPOSED AWAY FROM EACH OTHER, AND FASTENING ELEMENTS RIGIDLY SECURED TO SAID SHELL AT THE INNER SURFACE OF SAID CROWN PORTION THEREOF IN A SPACED RELATION TO EACH OTHER ALONG SAID HEAD STRAP CORRESPONDING SUBSTANTIALLY TO THE SPACING OF THE CLOSED ENDS OF SAID SLOTS OF SAID KEYHOLE OPENINGS, SAID FASTENING ELEMENTS RESPECTIVELY PROVIDING SHANK PORTIONS HAVING DIAMETRAL DIMENSIONS TO ENTER SAID SLOTS OF SAID KEYHOLE OPENINGS AND HAVING HEAD PORTIONS SPACED ON SAID SHANK PORTIONS FROM SAID INNER SURFACE OF SAID SHELL, THE DIMETRAL DIMENSION OF SAID HEAD PORTIONS BEING LARGER THAN SAID SHANK PORTIONS, THE ENLARGEMENTS OF SAID KEYHOLE OPENINGS BEING DIMENSIONED TO PROVIDE FOR PASSING THE HEAD PORTIONS OF SAID FASTENING ELEMENTS THROUGH THE RESPECTIVE ENLARGEMENTS OF SAID KEYHOLE OPENINGS, SAID INTERMEDIATE PORTION OF SAID HEAD STRAP BETWEEN SAID KEYHOLE OPENINGS BEING CAPABLE OF FLEXURE TO A FORM CURVING FROM THE PARTS THEREOF ADJACENT SAID KEYHOLE OPENINGS TO THE CENTRAL PART THEREOF BETWEEN SAID KEYHOLE OPENINGS DISPOSED AWAY FROM SAID SHELL, THEREBY TO DRAW SAID KEYHOLE OPENINGS TOWARD EACH OTHER ALONG SAID CROWN PORTION OF SAID SHELL TO POSITIONS TO REGISTER SAID ENLARGEMENTS WITH THE RESPECTIVE FASTENING ELEMENTS AND TO PROVIDE FOR PASSING SAID HEAD PORTIONS OF SAID FASTENING ELEMENTS THROUGH SAID ENLARGEMENTS, THE RESILIENCE OF SAID HEAD STRAP DETERMINING FLATTENING THEREOF FROM SAID CURVED FORM CONCOMITANTLY WITH MOVEMENT OF SAID KEYHOLE OPENINGS AWAY FROM EACH OTHER ALONG SAID CROWN PORTION OF SAID SHELL TO CAUSE SAID SHANK PORTIONS OF SAID FASTENING ELEMENTS TO ENTER THE RESPECTIVE SLOTS AND SAID HEAD PORTIONS TO OVERLIE AND ENGAGE THE HEAD STRAP ALONG SAID SLOTS TO HOLD SAID HEAD STRAP AND SAID HEAD BAND ELEMENTS IN POSITION IN RELATION TO SAID HELMET.