Helmet with three-point chin strap

A helmet for protecting a head according to this invention has a hard shell generally symmetrical to a longitudinal plane and having a rear edge normally juxtaposed with the nape of the neck of the wearer and a pair of front temple regions flanking the plane and normally juxtaposed with the temples of the wearer, a rear center strap having two ends and lying generally on the plane and a pair of similar side straps generally symmetrically flanking the plane and each having a rear end fixed to the other end of the center strap and a front end secured to the helmet at the respective temple region. The one end of the center strap is adjustably secured to the shell at the rear edge therefor generally on the plane. Respective fittings are slidable on the side straps between the ends thereof and a chin strap extends between the fittings and normally passes under the chin of the wearer.

FIELD OF THE INVENTION 
The instant invention relates to a helmet for protecting the head for 
occupational or sport purposes. More particularly this invention concerns 
such a helmet having a chin strap with a three-point attachment. 
BACKGROUND OF THE INVENTION 
A standard helmet is known, for example from German utility model 8,306,006 
which is secured to the wearer's head by a strap assembly comprising a 
pair of side straps each having a rear end attached in the back of the 
helmet and a front end attached at the temple region, and a chin strap 
passing from the center region of the one side strap to the center region 
of the opposite side strap. Normally fittings are provided on the side 
straps that allow attachment of the chin strap to the side straps and a 
releasable buckle or clasp is provided at one end of the chin strap to 
allow easy removal of the helmet. 
In the known system the side straps are permanently fixed at their rear 
ends on the helmet, but are fitted to any of several different attachment 
location at the front temple region of the helmet so their lengths can be 
adjusted. In addition the fittings on the side straps where the chin strap 
is attached are of the self-binding type can slide easily when no tension 
is applied to them, but that cannot slide when the chin strap pulls on 
them. 
As a result it is fairly difficult to adjust such a helmet. The ends of the 
side straps must both be set, and then the positions of both side-strap 
fittings. Finally the length of the chin strap must be set. Clearly such 
complicated adjustment is disadvantageous. 
OBJECTS OF THE INVENTION 
It is therefore an object of the present invention to provide an improved 
helmet of the above-described type. 
Another object is to provide such a helmet which is easy to adjust and 
which is particular adapted for a cyclist. 
SUMMARY OF THE INVENTION 
A helmet for protecting a head according to this invention has a hard shell 
generally symmetrical to a normally vertical longitudinal plane and having 
a rear edge normally juxtaposed with the nape of the neck of the wearer 
and a pair of front temple regions flanking the plane and normally 
juxtaposed with the temples of the wearer, a rear center strap having two 
ends and lying generally on the plane, and a pair of similar side straps 
generally symmetrically flanking the plane and each having a rear end 
fixed to the other end of the center strap and a front end secured to the 
helmet at the respective temple region. The one end of the center strap is 
adjustably secured to the shell at the rear edge thereof generally on the 
plane. Respective fittings are slidable on the side straps between the 
ends thereof and a chin strap extends between the fittings and normally 
passes under the chin of the wearer. 
With the system of this invention, therefore, it is possible to adjust the 
tightness of the strap assembly simply by shortening or lengthening the 
rear center strap. This action simultaneously adjusts both side straps 
identically and, since the wearer's head is invariably symmetrical and the 
hat is invariably worn on center, this adjustment will automatically be 
what is desired. 
According to another feature of this invention the rear ends of the side 
straps are unitary with each other. In fact the side straps can be formed 
of a common piece of strapping that is folded at and stitched to the other 
end of the center strap. Such construction is extremely simple and strong. 
The fold makes it possible to relatively easily set the angle the side 
straps form with the center strap. 
According to yet another feature of the current invention each fitting is 
formed with three throughgoing slits generally forming an equilateral 
triangle and each side strap passes through all three of the slits of the 
respective fitting. 
It is possible according to this invention for the front ends of the side 
straps to be fixed to the helmet at the respective temple regions. They 
may also be adjustably secured to the respective temple regions. 
In order to make the rear center strap adjustable the helmet is formed at 
the rear edge with three generally parallel throughgoing slits through 
which the one end of the center strap passes in a loop. These slits are 
just a little wider than the width of the strap to keep the rear strap 
centered. A similar arrangement of three slits can be used at each temple 
region if for some reason it is desired to individually adjust the side 
straps.

SPECIFIC DESCRIPTION 
As seen in FIG. 1 a standard cyclist's helmet as described in German 
utility model 8,702,777 has a main center part 3 centered on a 
longitudinal plane 1--1 (FIG. 2) flanked by a pair of side parts 2 forming 
with the center part 3 a pair of downwardly U-shaped cutouts 4. A helmet 
strap 5 runs circumferentially around the parts 2 and 3 in a plane 
perpendicular to the plane 1--1 and can be shortened to reduce the size of 
the helmet or lengthened to increase it, as is known per se. 
According to this invention the helmet parts 2, 3 are secured to the 
wearer's head by a strap assembly attached at a central rear-edge 
attachment location 6 lying on the plane 1--1 and at a pair of front 
temple locations 7 symmetrically flanking this plane 1--1. This strap 
assembly comprises a pair of identical side straps 8 and 8' that are in 
fact formed of a single piece of strapping and that each carry a 
respective side fitting 10 and a chin strap 9 secured between the fittings 
10 and normally running under the jaw or chin of the wearer. 
The side strap 8, which is fully shown in FIG. 1 and which is identical to 
the strap 8', passes through three throughgoing slits 11 in the fitting 10 
so that as seen in FIG. 3 it enters and exits this fitting 10 at a right 
angle 12. At its front end the side strap 8 has a snap or rivet 7' by 
means of which it is attached at the respective temple region 7. In 
addition the ends of the chin strap 9 are looped through one of the slits 
11. Thus it is possible for the fittings 10 to be slid along the straps 8 
and 8' although when there is some pull on the fittings 10 they do not 
slide. The chin strap 9 is provided with a cushion 20 and with a pair of 
matable fittings 13 and 13' allowing this strap 9 to be opened to remove 
the helmet. 
The strapping forming the two straps 8 and 8'; is folded at 15 to form an 
angle 16 that is roughly right and is secured by stitching 17 to the lower 
end of the rear strap 14. The upper end of this strap 14 is woven as a 
loop 19 through three throughgoing parallel slits 18 in the rear region 6 
of the helmet part 3. Thus it is relatively easy, when there is no tension 
in the strap 14, to slide it in the slits 18 and adjust its length. This 
automatically also, of course, adjusts the side straps 8 and 8'.