RUBBER BUSHING CHAIN TENSIONER

TENDEUR DE CHAINE A MANCHON EN CAOUTCHOUC

English Abstract

This invention describes a compact, light weight, durable, quiet in operation, economical, chain tensioning device with means for controlling chain slack between two drive sprockets, found in all terrain vehicles or the like. The assembly comprises a chain tensioning device which is spaced between the two drive sprockets. The chain tensioning device is easy to assemble, install and adjust. The device exerts a modest pre- load tension pressure, requires infrequent adjustment and is suitable for reversed loads.

French Abstract

Tendeur de chaîne compact, léger, durable, silencieux et économique doté d'un moyen de contrôle du mou de la chaîne entre les deux roues d'entraînement des véhicules tout-terrain ou d'autres véhicules du genre. L'ensemble comprend un tendeur de chaîne placé entre les roues d'entraînement. Le tendeur de chaîne est facile à assembler, à installer et à régler. Le tendeur, qui exerce une modeste traction de précharge, ne nécessite pas de réglage fréquent et convient à la marche arrière.

Claims

I CLAIM
1. An assembly of a chain tensioning device for an all terrain vehicle or the
like
comprising an assembly of a T shaped base bracket which supports a freely
pivoted arm
pivotally fastened on one side of one end of the arm, opposite side and end of
the pivoted
arm is a freely pivoted arched toggle slider pivotally fastened to the pivoted
arm, and
adjacent and opposite the arched toggle slider, is a vertical adjustable tap-
bolt connecting
the pivoted arm and supported by a compressible rubber bushing foot.
2. An assembly as described in claim 1 wherein the chain tensioning device is
mounted
on a supporting structure and is located below a chain looped and a pair of
drive
sprockets; the said chain tensioning device is located between the drive
sprockets and on
the outer most often unloaded side of the chain loop, the angularly upwardly
extending
pivot arm, lifts the arched toggle slider to form an irregular tensioned chain
loop, a
manual adjustment to the vertical tap-bolt exerts a desired steady, even,
modest pre-load
tension pressure, and reversing chain loads further progressively compress the
rubber
bushing foot as required.
3. An assembly as described in claims 1 and 2 wherein the base of bracket of
the chain
tensioning device extends the full longitudinal length of the device.

Description

CA 02620980 2009-03-16
BACKGROUND OF THE INVENTION
Over a number of years the following types of chain tensioning devices have
been tested
on prototype all terrain vehicles. The resulting observations have led to the
development
of my invention.
Type 1
Adjustable, but fixed in place tensioning arm devices are best suited for non-
reversing
industrial applications and bear against the unloaded side of a chain.
Typically, the arm with its slider or idler sprocket is adjusted to remove
most of the chain
slack and is locked in place. The tensioning device would be adjusted to
compensate for
wear as required.
This is not suited for use in an all terrain vehicle application, in that if
the chain slack is
adjusted out to eliminate chain slap, the chain becomes excessively tight as
it warms up.
This tightness creates wear and excessive tension on chains, sprockets and
bearings. If
the chain is left slack, it suffers sudden take-up loading when exposed to
reversing loads.
The abrupt take-up further stretches chains.
Type 2
When using self-adjusting heavy-spring tensioning devices it was found that
for reversing
load applications the required heavy springs exert a high pre-load force
against the chain.
These heavy-spring tensioning devices failed when used in an all terrain
vehicle
application, as they are heavy in weight, difficult to install and service.
They have a high
pre-load force creating noise and wear on chains, sprockets and bearings.
/1

CA 02620980 2009-03-16
Type 3
The "Rosta"TM type tensioning devices employ rubber elements which are
compressed
within a section of square metal tube surrounding their arm pivot bolts. The
bolts are
cam shaped to compress the rubber elements within the square tube as the arm
rotates
approximately 45 degrees.
These tensioning devices are not suited for moderate or heavy duty reverse
loading
applications because the force on the rubber element is leveraged by the
length of the arm
from the slider or sprocket to the rubber element. The excessive force causes
even
moderate sized rubber elements to fail. Also the Rosta TM tensioning device is
heavier,
difficult to adjust in confined space and costly.
Type 4
The technology known in hydraulic damper type tensioning devices found in
combustion
engines to control slack in timing belts and chains could be used, however,
they would be
heavier, complex and costly.
SUMMARY OF THE INVENTION
The object of my invention as described is an assembly of a chain tensioning
device for
controlling chain slack between two drive sprockets, found in all terrain
vehicles or the
like, that is compact, lightweight, durable, quiet in operation, economical,
reduces time
and effort in adjusting, installation and repairing.
DESCRIPTION OF THE DRAWINGS
Although the characteristic feature of the invention will be particularly
pointed out in the
claims, the invention itself and the manner in which it may be made and used
may be
better understood by referring to the following description and accompanying
drawings,
/2

CA 02620980 2009-03-16
where like reference numerals refer to like parts throughout the several views
of the
drawings, in which
FIG. 1 is a perspective view of the assembly for the chain tensioning device
for all terrain
vehicles, or the like,
FIG. 2 shows an exploded view of the assembly depicted in FIG.1,
FIG. 3 shows the assembly of the chain tensioning device in its environment;
FIG. 4 is a cross-sectional view taken along line X-X; and
FIG. 5 is a further embodiment of the chain tensioning device where the
longitudinal
length of the T-bracket base has been extended.
THE DESCRIPTION OF THE PREFERRED EMBODIMENT
The accompanying drawings, as described above, illustrate a preferred
embodiment of an
assembly for a chain tensioning device. The following disclosure, describes a
preferred
embodiment of a chain tensioning device comprises the following assembly of
component parts. Reference from FIG. 1 and FIG. 2 a chain tensioning device
assembly
21, a T shaped base bracket 1 supports a freely pivoted arm 2 which is
fastened by means
of a bolt 9 and a nut 10 near and on one side of one end of the arm 2. At the
opposite
side and end of the arm 2, is an arched toggle slider 3 made of urethane or of
similar
material fastened by means of a bolt 11 washers 12 and 13 and nut 16; said
arched
toggle slider 3 is free to pivot thus conforming with the chain loop. Located
adjacent bolt
11 and nut 16 and opposite the arched toggle slider 3 is a vertical adjustable
tap-bolt 5
threaded through a nut 6 a connector nut 15 welded to the arm 2, a nut 7, a
washer 8 and
a compressible rubber bushing foot 4 which is threaded part way through on the
end of
the adjustable tap-bolt 5 (shown in FIG. 4).
/3

CA 02620980 2009-03-16
Reference from FIG. 3 the assembly of chain tensioning device 21 is shown in a
functional environment. Located at either end of the chain loop 20 are two
drive
sprockets 22 and 24 between said drive sprockets and on the outer most often
unloaded
side of the chain loop, is the chain tensioning device 21, enabling easy
installation and
access. The T shaped base bracket 1 is mounted to a flat supporting structure
26. The
pivoted arm 2 extends angularly upward where the arched toggle slider 3 lifts
the chain
loop 20 to form an irregular compressed loop which creates tension on the
chain between
the two drive sprockets 22 and 24. The vertical adjustable tap-bolt 5 extends
though the
connector nut 15 welded to the arm 2 and part way through the compressible
rubber
bushing foot 4. The manual adjustment feature of the chain tensioning device
is achieved
by extending or retracting the threaded tap bolt 5 applying tension on the
chain loop 20
and the pressure on the compressed rubber bushing foot 4. The required
adjustments are
infrequent in that the chain tensioning device smoothly cushions reversing
loads, by the
pivoting toggle action of the arched toggle slider 3 in concert with the
adjustable feature
of the arm 2.vertical tap bolt 5, and the compressible rubber bushing foot 4;
all of which
exerts a steady, even, modest pre-load tension pressure, when the chain loop
20 is under
either a forward or reversed load.
A further embodiment of this invention is shown in FIG. 5 wherein the base of
bracket 1
extends the full longitudinal length of the arm 2.
This chain tensioning assembly represents a simple compact, light weight,
durable, quiet
in operation, and economical device, and enables easy installation and access.
/4

Representative Drawing