Positive drive rubber belted track system

Prestressed compressible drive blocks are positioned on an endless belt of a track machine. The blocks are mateable with openings in drive wheel and function for driving the track and for guiding the track. Drive bars are associated with the drive wheel openings for exerting pressure on the drive/guide bars while maintaining the drive/guide bars against excessive wear.

TECHNICAL FIELD 
The present invention relates to a positive drive rubber belted track 
system for a track machine such as a tractor, for example. 
BACKGROUND ART 
Various systems have been developed for providing an endless track system 
which includes the endless track belt and the drive wheel for contacting a 
portion of the track and moving the track for propulsion of a machine or 
vehicle, such as a tractor. 
One of the latest innovative constructions has been the development of a 
cable reinforced rubber belt which has an extended life. However, it is 
desirable to further improve these rubber belts and the drive wheel and 
provide a system that has improved manufacturing capabilities and avoids 
the waste of time, labor, equipment and natural resources. 
The present invention is directed to overcome one or more problems of 
heretofore utilized systems. 
DISCLOSURE OF THE INVENTION 
A rubber belt track system of a track machine has an endless, cable 
reinforced, rubber belt and outwardly extending driver/guide blocks 
associated with a drive wheel. The driver/guide blocks are formed of 
rubber and compressed to a preselected magnitude in a direction toward the 
rubber belt in the installed position on the belt. The drive wheel has a 
plurality of openings mateable with the driver/guide blocks. A drive bar 
is connected to the drive wheel and extends along the wheel axis and along 
a rearward end of a respective opening of the drive wheel. The drive bar 
is contactable with a respective drive/guide block in the mateable 
operable condition of the system. At least one fastening element extends 
through the belt and into each respective driver/guide block and urges the 
respective driver/guide block toward the belt in the installed condition.

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring to FIGS. -3, a positive drive rubber belt track system 2 has a 
rubber belt 4 that is reinforced with cable 6. The belt 4 has a plurality 
of spaced apart, outwardly extending driver/guide blocks 8,8',8",8"' etc. 
associated with the drive wheel 10. Such a cable reinforced rubber belt 4 
and driver/guide blocks 8,8',8",8"' are well known in the art. 
In the system 2 of this invention, the driver/guide blocks (hereafter 
referred to in the written description by a single numeral 8 for purposes 
of brevity) are formed of rubber and are compressed to a preselected 
magnitude in a direction toward the rubber belt 4 in the installed 
position on the belt 4. Referring to FIG. 4, the drive wheel 10 has a 
plurality of openings 12,12',12",12"' etc. (hereafter referred to in the 
written description by a single numeral 12 for purposes of brevity). The 
openings 12 are mateable with the driver/guide blocks 8 of the belt 4. 
A drive bar 14 is connected to the drive wheel 10 and extends along the 
wheel axis 16 and along a rearward end 18 of each respective opening 12 of 
the drive wheel 10. The drive bar 14 is contactable with a respective 
drive/guide block 8 in the mateable operable condition of the system 2. 
Referring to FIG. 3, at least one fastening element 20, and preferably two 
elements 20,20' extend through the belt and into each driver/guide block. 
Fastening elements 20 urge the respective driver/guide block toward the 
belt and into compression in the installed condition of the system 2. 
Referring to FIGS. 2 and 3, each driver/guide block has first and second 
end portions 22,24 and a load distributing element 26 positioned at the 
block first end portion 22 and associated with the respective fastening 
element 20 of the system 2. The fastening element 20 preferably is a bolt 
and nut system 28 passing through openings in the block 8 and the 
fastening element 20. Preferably, the fastening element 20 is positioned 
within the respective driver/guide block 8 and is molded within the block 
20. The load distributing element 26 preferably is elongated and extends 
in a direction of the largest dimension of an outer end of the respective 
driver/guide block 8. Preferably this direction is along the endless 
longitudinal axis 30 of the belt 4. 
The rubber driver/guide block 8 is compressed a preselected magnitude 
sufficient to exert a pressure desirably greater than about 10 psi and 
preferably greater than about 20 psi against the belt 4. If the pressure 
is less than this amount, the driver/guide block 8 will undesirably be 
subjected to forces tending to separate the driver/guide block 8 from the 
belt 4. 
The drive wheel openings 12 have dimensions not larger than about 20 mm 
greater than the dimensions of the associated driver/guide block portion 
immediately adjacent the driver wheel opening 12. If the differential 
between the dimensions of the drive wheel opening 12 and the associated 
driver/guide block 8 is greater than 20 mm, the guide blocks 8 will 
undesirably wear. 
In the preferred embodiment of this invention, referring to FIGS. 6 and 7, 
the drive wheel 10 has a slot 32 extending outwardly from each wheel 
opening 12. Each drive bar 14 has first and second flattened end portions 
34,36 each being within the slot 32 and each drive bar end portion 34,36 
being positioned within a slot 32,32 ' and welded or otherwise connected 
to the drive wheel along the drive wheel slot 32. The drive bars 14 are 
preferably of tubular configuration having a chamber 38. However, without 
departing from this invention, the drive bars 14 can be solid and free of 
a chamber 38. 
It is also preferred for balance that the driver/guide blocks and 
associated guide bars be centered generally along the endless 
longitudinally extending centered axis of the belt (FIG. 4). However, in 
another embodiment shown in FIG. 5, the drive wheel 10 can have first and 
second spaced apart rows 40,42 of drive wheel openings 12 and associated 
drive bars 14, and the belt 4 can have first and second rows 44,46 rows of 
driver/guide blocks spaced one from the other and mateable with respective 
row openings of the drive wheel 10. 
As shown in FIGS. 4 and 5, the drive wheel 10 can be formed by the 
combination of first and second circumferentially extending wheel portions 
48, 50 connected one to the other by any operable means known in the art, 
for example welding, or preferably being of unitary construction, as shown 
in FIG. 4. If a relatively large load is expected to be carried by the 
machine when the machine is traveling in the reverse direction, drive bars 
14,14' can each be positioned on a respective forward and rearward side of 
each respective opening 12 of the drive wheel 10. 
INDUSTRIAL APPLICABILITY 
In the construction of this invention, the load from the drive wheel 10 
acts on the block 8 in the circumferential direction enabling it to 
function as both a guide block and a drive block. The block connection to 
the belt becomes a cantilevered beam and the drive wheel load generate a 
shear force and a bending moment. The bending moment result in a tensile 
stress on the leading end of the block causing the block to become torn in 
tension from the belt to which its base or second end portion is bonded 
The fastening element pre-stresses the block in compression. When the 
driver wheel load is applied, it only reduces the compression on the 
leading side, not allowing it to go into tension and further increases the 
compression on the trailing side. The compressive force also provide a 
frictional force across the block and reduces the likelihood of failure in 
shear. The system of this invention also provides substantial protection 
against wear from side-loading of the belt. 
Other aspects, objects and advantages of this invention can be obtained 
from a study of the drawings, the disclosure and the appended claims.