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Патент USA US2121955

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'June2s,.193s.
E565‘;
PNEUMATIC TIRE TREAD
' Filed June 15, 1956
'
4
2,121,955
‘
I
'
Patented June 28, 1938
UNITEb’IS-TATES PATENT OFFICE
' ensues
Ernst EgerrGrosse’l'ointe
mm ms'raasn
Michsarslgnor
"
‘ to United States Rubberv Products,’ Inc.I New '
York, N. 1., a corporation of Delaware
Application June 18.1838, Serial No. we
' s can».
(oi. use-zoo). '
tread is particularly improved after. ‘subjection
This invention relates to pneumatic tires, and
to the present method'of tread treatment.
Experiments have indicated that the width of
v , and to the structural formation of the antiskid 1
formation to increasethe eiliciency of such tires . the ribs should not'be less than ‘3 ‘percent of the
' I in operation. ‘ Inv general, the invention refers normal width of vthe tire in crosssection, and s
to a pneumatic tire having a tread comprising a that the maximum'wldth' of the‘ rib " should not
plurality of relatively narrow. circumferential exceed 8 percent of ' the normal width of the tire
‘ribs divided circumferentially by a pluralltycf in cross section. . In other words, the dimension
transverse incisions such as slits or narrow slots x as shown in' Fig. lshould be‘equai to from 3
10’
’ '1. having their bases terminating in openings which to 8 percent of the dimensional character Y.
Subsequent to the vulcanization of the tire, the
I extend parallel with the slits. '
I
. In tires having treads with transverse slits or tire tread is subjected to a vslitting operation for
narrow slots for improving skid qualities there producing narrow cuts or incisions 'l in the tread
in particular it relates to pneumatic tire treads
transversely of the ribs. The bases of these slits -
7 I " is a tendency for the bases to continue to extend
l6 deeper in the form of cracks. To overcome this
conditionit has been the practice to slit the tire
to a relatively shallow depth, less, than the depth
of the tread rubber, and to space the slits a sub
stantial distance apart.
Y
'
terminate ‘insmall apertures 8 which extend 15
parallel with the slits. Fig. 2 illustrates a side
view of the tire i and shows the proportionate
size of the apertures 8. The vrib formation t
is de?ned by a plurality of grooves 9, having
20
bases Ill.
1
‘
'
An object of my invention is to prevent crack
ing of slit or slotted tread tires; another object 1 As shown in Fig. 2, the apertures 8 are posi
tioned slightly above the bases ll of the grooves
is to permit the tread‘to be slit to a depth sub
stantially equal to the‘ wearing portion of they so that the apertures 8 which lie between the '
tread; and a further object is to permit the slits grooves s will be free from the curvatures at
' ll to be spaced a less distance apart. As a result the bases it. While the apertures 8 are shown 35
of these objects a tire of improved antiskid and in the form of circular openings, it is to be un
derstood that they may be of various shapes
wearing qualities is obtained.
,
‘
'
These and other objects and advantages will
appear more fully in‘the following detailed de
80 scription -when considered in connection with
‘
the accompanying drawing, in which:-,-
_
such as that indicated in Fig. 3, wherein a tire I
ii is provided with apertures I! in the form ' ~
0! triangular-‘openings which communicate with 3°
slits ll. Any form of opening at the bases of
. Fig. 1 is a transverse view, in section and in - the‘ slits‘is su?lcient to accomplish the advan
perspective, of a portion of a pneumatic, tire
tages of the present invention, provided the bases
embodying my invention; ‘
of the apertures are ?at or substantially ?at, or
vcurved as in the lower portion of a circular ap-v 35
erture, as such shapes being free from sharp
“BEE-‘tend to prevent crack propagation toward ,
‘- ll ' Fig. 2'is aside elevational view of a portion
of the tire shown‘ in Fig. 1; and
>
Fig. 3 is a similar view illustrating a modified
form. of the invention.
' the carcass 2.‘
,
Referring to the drawing, and in particular to
40 Fig. 1, I showapneumatic tire I having a car
' case I of strain resisting'elements, inextensibie
' bead elements 3 and l. and a wear resistant tread
, I of rubber composition.
-
'
In formation the tread 5 isillustratedin the
45 form of a plurality of "circumferentially extend' Iin‘g ribs tin-While the features of ‘my invention
~
The size of the apertures disposed at the base“ I
of
10118theasslits
they
is not
do' of
notparticular
materially
importanc
impair ' c"
.
-
v
strength of the ribs. , I'?nd, however; that god it
'
results are obtained from a tire having " apér-f
tures which measure from about 1/54 inch to ‘1/8
45
inch in general diameter. The size of the aper- .
ture is somewhat determined by the method
are applicable to treads having designs of vari used to provide such apertures in ‘the tread.
ous. con?gurations, I prefer its application to a For example, a hot wire may be forced into the “
.tread design of plain, circumferential rlbs.- ‘It , slit of . the tread and permitted to lodge at the 56
.- ‘so h'asbeen demonstrated that a tread comprising base of the slit for a short period. In such case
circumferential ribs of a width within deilnite the resulting aperturel will be relatively small.
‘limitations shows a substantial improvement in The apertures may also be produced by a knife
antiskid qualities,‘ particularly on wet road sur
3 faces. ' It is well known that a tread of rib for
as mation is relatively quiet in operation.- Such a
having the combined shape of the-“slit and the
opening at the base of the slit.
In such case a
I
2
2,121,955
the slit and the aperture may be cut into the
tread in the same operation.
It 'is also possible to produce the transverse
apertures in the tread by providing removable
pins in the mold, and forming the apertures in
the rubber during vulcanization of v the tire. m
such case the tire would be subsequently slit in
such manner that the cuts would extend into
the previously formed apertures.
While I prefer to make slits in the limited
openings extending relatively transversely of the
ribs and located between the outer free face
of each rib and its base, and an incision extend
ing from each of said openings outwardly vto the
outer free face of the rib in‘which the opening
is provided.
4. A pneumatic tire ‘comprising a carcass of.
strain resisting elements and a tread of rubber
composition de?ning antiskid elements which are
interrupted by spaced incisions of a widthsuch 10
sense of the. word, that is by making. incisions ' that when under load their side walls engage for
without the removal of substantiallyany of the appreciable distances for mutual support and
tread rubber; yet the invention is- applicable to terminating in enlarged openings for the pre- '
narrow slots or incisions whose side walls are
vention of crack propagation into the underlying
15 normally out of engagement, such as would be
rubber composition.
. I.
produced by a saw cut, but which engage for
5. A pneumatic tire comprising a carcass of 15
cooperative support when a load‘l's applied, and strain resisting elements and a tread of rubber
such slots are included in the term “incisions" as composition de?ning antiskid elements which are 1
herein used.
,
.
interrupted by spaced slits whose walls are sub- '
While I have shown the slits and communicat
stantially parallel and normally in engagement
ing apertures extending transversely of all of 7 for a considerable distance and which terminate 20
the circurnferentially extending ribs, it is to be well within the tread rubber composition in en
understood that the slits and their accompany
larged openings for the prevention of crack prop
ing‘ base apertures may extend in a wide variety agation into the underlying rubber composition.
of patterns, such as diagonally of the circumfer
6. A pneumatic tire comprising a carcass of
ential ribs, or they may extend only into certain strain resisting elements and a tread of rubber 25
of the ribs or combinations thereof, depending composition de?ning circumferential, functionally
upon the particular slit formation desired.
continuous ribs and intervening grooves, said ribs
While I have shown and described certain pre
having spaced ‘incisions of a width such that
80
l0 .
ferred embodiments of my invention, it will be
understood that modifications may be made
therein without departing from the spirit of the
invention or the scope of the appended claims.
Having thus described my invention, what I
35 claim and desire to protect by Letters Patent is:—
1. A pneumatic tire having a carcass of strain
resisting elements and an outlying tread of vul
canized and wear resistant rubber composition,
said tread having an antiskid con?guration and
being provided with a plurality of relatively small
openings extending more transversely than cir
cumferentially located between the ground-con
tacting surface of the' tread and the underlying
carcass, said tread being provided with slits ex
45 tending from said openings outward to the ground
contacting surface of the tread,,the'walls de?n
ing said slits being substantially parallel and
spaced apart a substantially less distance than
the width of said openings.
. .
2. A pneumatic tire having acarcass of'strain
resisting elements and an outlying tread of vul
canized and wear resistant rubber composition,
said tread ‘being provided with anantiskid con
?guration de?ned by grooves -molded into the
55 tread, and said tread being provided with a"
multiplicity of small openings extending more
transversely than circumferentially located be-i
tween the ground contacting surface. of the tread
and the bottoms of said grooves,‘said tread being
provided with incisions substantially narrower
than said openings and extendin'g'from said open
when under load their side walls engage for ap
preciable distances for mutual support and ter
minating in enlarged openings for the ‘prevention
of crack propagation into the underlying'rubber
composition.
‘‘
‘7-. A pneumatic tire comprising a carcass of '
strain resisting elements and a tread of rubber
composition de?ning circumferential, function
ally continuous ribs and intervening grooves, said
ribs having spaced slits whose walls are substan
tially parallel and normally in engagement for 40
a considerable distance and which terminate well
within the tread rubber composition in enlarged
openings for the prevention of crack propagation
into the underlying rubber composition.
8. A pneumatic tire comprising a carcass of
strain resisting elements and a tread of rubber
'ally continuous ribs of a width of the order of
from 3 to 8 percent of the maximum width of i
the tire and intervening grooves, said ribs having 50
spaced incisions of a width such that when under
load their side walls engage for appreciabledis+
tances for mutual‘ support and terminating in
enlarged openings for ‘the prevention of crack
propagation into the underlying rubber compo 55
sition.'
'
-
-~
.
-9. A pneumatic tire comprising a carcass of
strain resisting elements and a tread of rubber
composition de?ning circumferential, function
ally continuous ribs of a width of the order of
-from_ '3' to 8 percent of the maximum width of
ings' to the ground contacti-ngsurface ‘of the, the tireand' intervening grooves, said ribs having
tread.
_
.
.
>
.
_
3. A pneumatic tire having a carcass'of ‘strain
elements and an outlying" tread of vul
as. resisting
caniz‘ed and wear resistant rubber. composition;
" said tread’ being providedwith a plurality of cir-'
’ vcumt'erentially extending ribs, each of‘ said ribs
beingprovided with a plurality of relatively small
45
composition de?ning circumferential, function
spaced slits whose walls are substantially parallel
and normallyin engagement for a considerable
distance and which terminate well within the
tread rubber composition in enlarged openings
forthe prevention of crack propagation into the .
underlying rubber composition.
v
ERNST EGER.
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