Removable track belt with removable keeper bar

A removable track belt for installation around the outer surface of a tire carcass has on its inner surface a plurality of circumferential lands and grooves that interlock with lands and grooves on the tire carcass. The inner surface of the track belt also has a plurality of spaced axial grooves for receiving removable rigid keeper bars, to which grousers are attached. The underside of each keeper bar contains lands and grooves that also mate with those of the tire carcass.

BACKGROUND OF THE INVENTION 
This invention relates generally to tires having removable track belts, and 
more particularly to such tires for use on heavy off-road equipment. 
Removable belts containing tire treads have been developed to some extent 
for use on light-duty tires, such as for automobile and trucks. Little 
development has been done, however, with the use of this concept with 
heavy tires such as those used in off-road service. Such heavy tires are 
subjected to a great deal of abuse. Great weights are carried at 
relatively high speeds. Grouser bars are installed to provide the 
necessary traction. All elements of the tire are subject to damage and 
failure. While the prior art may have considered the possibility of 
utilizing replaceable tread or track belts on off-road tires, the 
requirements of such a tire are clearly not provided in the prior art. 
SUMMARY OF THE INVENTION 
It is the principal object of this invention to overcome the deficiencies 
present in prior art devices of this general type. 
Another object of this invention is to provide a removable track belt with 
removable keeper bars. 
Another object of this invention is to provide removable keeper bars that 
are easily installed in a removable track belt and that are themselves 
interlocked with the tire carcass. 
A further object of this invention is to provide removable keeper bars that 
have a large amount of clearance from the tire carcass sidewalls. 
The removable track belt keeper bars to be described are adaptable for use 
with tire carcasses of any construction; bias, bias-belted, or radial. The 
tire carcass can be of open or closed design. The tire carcass can also be 
of virtually any aspect ratio, up to a maximum of 0.70. However, the 
aspect ratio preferably is between 0.40 and 0.55. The term aspect ratio 
means the ratio of radial height of the tire carcass to the maximum width, 
the radial height being measured from a tangent to the radially innermost 
surface of the smallest diameter bead cores to a tangent to the radially 
outermost point on the carcass plies, the width being measured between 
opposite points of the cord reinforcing structure that extends from bead 
to bead. 
The orientation of all elements in the following description is referenced 
to the axis about which the tire rotates. 
A tire constructed in accordance with the teachings of this invention 
comprises a tire carcass, a removable track belt, a plurality of removable 
keepers, and a plurality of removable tread lugs, grousers or the like. 
The tire carcass is equipped on its outer peripheral surface with a 
pattern of lands and grooves, or the like. The track belt comprises a 
rubber belt matrix having on its inner surface a complementary pattern, 
which interacts with that on the tire carcass to anchor the belt to the 
carcass. The inner surface of the track belt matrix is broken by a 
plurality of axially oriented recesses for receiving the removable keeper 
bars. Each keeper bar has a lower surface upon which is formed the same 
pattern of lands and grooves or the like that is present on the inner 
surface of the removable track belt, so that the keepers also interlock 
with the tire carcass. This pattern can be formed in the keeper itself, or 
can be formed upon a separate strip of rubber or other material, which is 
attached to the lower surface of the keeper. The ends of the keeper bars 
extend axially outwardly of the track belt, and are equipped with means 
for attaching tread lugs, grouser bars or the like, thereto. These outer 
ends equipped with an attaching portion which has an upper surface lying 
substantially flush with the outer surface of the track belt at the points 
where the grousers are mounted. The cross-sectional configuration of the 
keeper bars define a central channel in which the removable track belt is 
received. The grousers, or both keeper bars and the grousers, can extend 
axially outwardly to a distance equal to or greater than the outwardly 
extension of the sidewalls of the inflated and loaded carcass. This 
protects the sidewalls somewhat from impact with rocks or the like, and 
can be done on one or both sides of the tires. It is especially 
advantageous when a radial tire carcass is used. 
An inextensible belt of wire or the like is advantageously integrally 
formed in the belt matrix, located radially outwardly of the recesses 
within which the keeper bars are received. The track belt has an outer 
surface upon which lugs, grouser bars or the like can be positioned. The 
pressure in the inflated carcass serves to press it against the track belt 
and the keeper bars, as well as to stabilize the keeper bars. All of the 
additional virtues of such an inextensible belt are also thus present in 
the tires. 
The advantages of the above described structure are many. Since the keeper 
bars are easily removed, a broken keeper bar can be replaced without 
discarding the entire removable track belt. Replacement of a keeper bar is 
uncomplicated, and can be quickly accomplished, even without removing the 
tire from the vehicle. The manufacture of the removable track belt is 
simplified, because the keeper bars are not a part of the belt, and thus 
there is no requirement for setting the keeper bars in a belt mold. The 
completed track belts are more easily packaged and shipped. The keeper bar 
is in intimate interlocking contact with the tire carcass, and thus it is 
held in position directly, rather than by means of the track belt. The 
system also allows keeper bars of different design characteristics to be 
used with the same tread belt, to accommodate various types of traction 
improving devices or attachment means therefor. When a keeper bar is used 
that has S-shaped upwardly curved end portions, a large clearance is 
provided between the keeper bars and the tire carcass sidewall. This 
minimizes the chances of contact between the two under situations of 
extreme distortion of the tire carcass. It is especially valuable when the 
tire carcass is of radial construction, which has very flexible sidewalls.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The overall arrangement of components is shown in FIG. 1, and comprises a 
tire carcass 10, a plurality of keeper bars 12, a removable track belt 14, 
and a plurality of grousers 16. 
Tire carcass 10 can be of many known designs and constructions. Shown is an 
open tire design having an aspect ratio of about forty percent. The tire 
could also be of closed design. The outer circumferential surface of tire 
carcass 10 is provided with a plurality of circumferential lands 20 and 
grooves 22, culminating on each side in a carcass shoulder 24. 
Track belt 14 is removable from the tire carcass. As best shown in FIG. 6, 
the underside, or inner circumferential surface of track belt 14 comprises 
a plurality of annular lands 30 and grooves 32 that mate with lands 20 and 
grooves 22 of tire carcass 10 to restrain belt 14 from lateral movement 
with respect to the carcass. The inner surface of track belt 14 also 
contains a plurality of axial recesses 34, which will accommodate the 
keeper bars 12. An inextensible belt of wires 38 is installed within the 
matrix of track belt 14, spaced radially outwardly of recesses 34. The 
axial width of track belt 14 is no less than that of the outer 
circumferential surface of the tire carcass. 
Each keeper bar 12 has a center portion 40 flanked by S-shaped end portions 
42. Each end portion 42 is provided with an attachment surface 43 and 
means for attaching a grouser or other traction device, which may consist 
of a pair of threaded holes 44 for receiving bolts. The under or inside 
surface of center portion 40 of the keeper bar is provided with lands 48 
and grooves 50 which are identical to lands 30 and grooves 32 of track 
belt 14. The circumferential dimension of center portion 40 is equal to 
that of recesses 34 in track belt 14, so that when keeper bars 12 are 
installed in recesses 34, a continuous pattern of lands and grooves is 
presented, as shown in FIG. 6 Lands 48 and/or the entire lower portion of 
lands 48 and grooves 50, can be integral with keeper bar 12, or they can 
be separate elements attached to the underside of keeper bar 12 by bonding 
or by interlocking means. FIG. 5 shows an arrangement wherein lands 52 and 
grooves 54 are part of an annular strip 56, which is attached to the 
underside of keeper 12 by bonding or the like. In the case of lands and/or 
lands and grooves being formed on a separate strip, they can be of 
dissimilar material, such as rubber. The axial width of center portion 40 
is the same as that of track belt 14. Belt 14 is not contoured at its 
edges to closely fit the S-shaped portion of the keeper. A space 41 
remains open, to accommodate the belt if the belt distends when a 
compression load is placed upon it. 
As an alternative the end portion of keeper bars 12 can be straight, and 
not curved, as illustrated in FIGS. 7 and 8. In such case, a spacer 70 is 
interposed between bar 12 and grouser 16. Spacer 70 does not contact the 
edge of belt 14, but a space 72 is allowed for expansion of the belt when 
compressive load is placed upon it. 
Grousers 16 can be of any desirable construction or material, and comprise 
a flat inner surface 58 which is seated on the outer surface of track belt 
14, and a pair of upstanding flanges 60 on the outside surface. Openings 
62 are provided for attaching the end of grouser 16 to keeper bars 12 by 
means of bolts 64. 
The edges of keeper bar 12 and grouser 16 extend axially outwardly at least 
as far as the outermost point of sidewall 45, when the tire is inflated 
and loaded. This protects the sidewall to a great extent from damage by 
contact with rocks or the like. Such axial width also maximizes the size 
of the footprint of the tire, improving traction. Grouser 16 can extend 
outwardly beyond the ends of keeper bars 12, if desired, in which case the 
end of the keeper bars can extend outwardly a lesser distance than 
sidewall 43. Although the outward extension of keeper bars and grousers is 
shown on both sides of the tire, such can be done on one side only, if 
desired, or if required by restricted clearance between the inside of the 
tire and the vehicle. 
The operation of the invention should be obvious from the above 
description. Keeper bars 12 are installed in recesses 34 of track belt 14. 
To hold keeper bars 12 in place during installation, grousers 16 are 
attached to the keeper bars as each is installed upon track belt 14. Then 
the track belt with keepers and grousers installed is placed in position 
around a deflated tire carcass. Inflating the carcass seats the tread belt 
and causes it to be held firmly in place. 
Variations and modifications of the above described embodiments may become 
evident of those skilled in the art, and it should be understood that the 
breadth of the invention is limited only by the scope of the appended 
claims.