U.S. patent number RE30,018 [Application Number 05/903,444] was granted by the patent office on 1979-06-05 for sprocket member configuration.
This patent grant is currently assigned to Caterpillar Tractor Co.. Invention is credited to Donald E. Clemens, Glenn M. Haslett.
United States Patent |
RE30,018 |
Clemens , et al. |
June 5, 1979 |
Sprocket member configuration
Abstract
An improved sprocket configuration for use in a track-type
vehicle drive. The tooth configuration and tooth pocket
configuration accommodate packing of the pocket and permit limited
displacement of the chain without excessive wear of the chain
bushings. The pocket configuration is relatively deep so as to
permit a preselected amount of packing in the pocket root to
minimize the chain bushing displacement. The improved tooth
configuration provides a rounded topping surface avoiding bushing
wear as may occur with sharp corner tooth configurations of the
prior art.
Inventors: |
Clemens; Donald E. (Tremont,
IL), Haslett; Glenn M. (Peoria, IL) |
Assignee: |
Caterpillar Tractor Co.
(Peoria, IL)
|
Family
ID: |
24465402 |
Appl.
No.: |
05/903,444 |
Filed: |
May 5, 1978 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
615446 |
Sep 22, 1975 |
04016772 |
Apr 12, 1977 |
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Current U.S.
Class: |
474/152;
474/901 |
Current CPC
Class: |
B62D
55/12 (20130101); F16H 55/30 (20130101); Y10S
474/901 (20130101) |
Current International
Class: |
B62D
55/12 (20060101); B62D 55/08 (20060101); F16H
55/30 (20060101); F16H 55/02 (20060101); F16H
055/30 (); B62D 055/08 () |
Field of
Search: |
;74/243R,229,462,465
;305/57,21,13,11 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gerin; Leonard H.
Attorney, Agent or Firm: Wegner, Stellman, McCord, Wiles
& Wood
Claims
We claim:
1. In a chain drive sprocket member having a plurality of teeth
defining a pitch circle having a .Iadd.predetermined
.Iaddend.radius .[.of approximately 20 inches.]., an improved
pocket configuration between said teeth having opposite flank
surfaces at opposite sides of the pocket radial centerline each
defined by a pocket radius centered on a point spaced radially
inwardly of said pitch circle and spaced circumferentially from
said pocket radial centerline, and an arcuate root surface defined
by a radius centered on a point on said pocket radial centerline
and spaced outwardly of said pitch circle.
2. The chain drive sprocket member of claim 1 wherein said point is
spaced radially inwardly of the pitch circle approximately 0.063
inch.
3. The chain drive sprocket member of claim 1 wherein said root
surface has opposite end portions tangent to said flank
surfaces.
4. The chain drive sprocket member of claim 1 wherein the teeth are
further defined by rounded topping surfaces extending to outwardly
of said pitch circle.
5. The chain drive sprocket member of claim 1 wherein the teeth are
further defined by working surfaces extending outwardly from said
flank surfaces.
6. The chain drive sprocket member of claim 1 wherein the teeth are
further defined by working surfaces extending outwardly from said
flank surfaces and outer rounded topping surfaces extending
outwardly from said working surfaces to outwardly of said pitch
circle.
7. The chain drive sprocket member of claim 1 wherein the teeth are
further defined by planar working surfaces extending outwardly from
said flank surfaces.
8. The chain drive sprocket member of claim 1 wherein the teeth are
further defined by arcuate working surfaces extending outwardly
from said flank surfaces.
9. The chain drive sprocket member of claim 1 wherein the teeth are
further defined by successive arcuate working and topping surfaces
outwardly of said flank surfaces.
10. The chain drive sprocket member of claim 1 wherein said pocket
radius is centered on a point spaced radially inwardly of said
pitch circle at least approximately 0.05 inch and spaced
circumferentially from said pocket radial centerline approximately
0.2 inch. .Iadd.11. The chain drive sprocket member of claim 1
wherein said pitch circle has a radius of approximately 20 inches.
.Iaddend. .Iadd.12. The chain drive sprocket member of claim 1
wherein said pitch circle has a radius of approximately 20 inches
and said point is spaced radially inwardly of the pitch circle
approximately 0.063 inch.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to sprocket configurations and in particular
to chain drive sprocket configurations.
2. Description of the Prior Art
In vehicle chain drives, sprockets are utilized over which the
chain is trained for guiding the chain in the driving operation.
The sprocket defines a plurality of teeth which are engaged by the
respective bushings being received in the pockets between the teeth
as the chain passes in engagement with the sprocket.
In the conventional sprocket configuration, wear may occur both in
the sprocket and the bushing because of accumulation of foreign
matter in the pockets tending to urge the chain outwardly from the
bottom of the pocket and thereby cause an elongation of the chain
in the driving operation.
The outward movement of the chain relative to the pocket causes the
bushings to make contact with the outer portions of the sprocket
teeth. Heretofore, the sprocket teeth have had relatively sharp
corners and the engagement of the bushings therewith has heretofore
caused severe wear of the bushings as a result of the tooth pocket
packing and resultant outward displacement of the chain.
A number of attempts have been made to solve this vexatious
problem. Thus, in U.S. Pat. No. 2,667,792 of Wilfrid H. Bendall, an
improved pivoted link chain drive is disclosed having a plurality
of spring members engaging the link members of the chain for
holding the pivot center of each link and its following drive
strand on a centerline substantially tangent to the sprocket pitch
circle during all phases of pivotal engagement of the link with the
tooth of the sprocket. This structure is taught as reducing the
sprocket engagement impact of pivoted link chains for providing
improved operation over a wide speed range.
In U.S. Pat. No. 3,194,609 of Lloyd Thurlow, a tractor is shown as
provided with a chain drive having a sprocket and roller-type
chain. The effective sprocket pitch is taught to be less than that
of the chain with the pocket radii being on the pitch line. Thus,
the configuration of the Thurlow patent is directed to permitting
the chain drive to operate satisfactorily as long as the pitch
diameter of the chain is in the range of the pitch diameter of the
sprocket to an imaginary sprocket having the same effective pitch
as that of the chain.
SUMMARY OF THE INVENTION
The present invention comprehends an improved sprocket
configuration for minimizing wear of the chain in normal use
notwithstanding the deposition of foreign matter in the sprocket
pockets tending to stretch the chain causing engagement thereof
with outer portions of the sprocket teeth.
The sprocket defines an improved, relatively deep pocket
configuration between the sprocket teeth to accommodate such
foreign matter without affecting the chain disposition engaging the
teeth in the normal operation of the chain drive.
More specifically, each pocket configuration includes opposite
flank surfaces at opposite sides of the pocket radial centerline
each defined by a pocket radius centered on a point spaced radially
inwardly of the pitch circle at least approximately 0.05 inch and
spaced circumferentially from the pocket radial centerline
approximately 0.2 inch.
The pocket radius center point is spaced radially inwardly to
provide a substantially deeper pocket than previously utilized in
the prior art structures to effect the desired improved chain drive
operation. In the specific illustrated embodiment, this point is
spaced inwardly of the pitch circle approximately 0.063 inch where
the pitch circle radius is approximately 20 inches.
To provide further improved chain drive operation, the sprocket
teeth are provided with rounded topping surfaces. Thus, in the
event the chain is displaced outwardly into engagement therewith,
wear of the bushings thereof is effectively minimized.
The working surfaces between the flank surfaces and the topping
surfaces may be rectilinear or arcuate, as desired, and the
invention further defines an improved arrangement of the working
surfaces with relationship to the flanking and topping
surfaces.
The inner end of the pocket may be defined by an arcuate root
surface. The root surface may be defined by a radius centered on a
point above the pitch line and on the centerline of the pocket with
the radius being tangent to the two pocket radii defining the flank
surfaces
Thus, the present invention comprehends an improved chain drive
sprocket which is extremely simple and economical of construction
while yet providing the highly desirable features discussed
above.
BRIEF DESCRIPTION OF THE DRAWING
Other features and advantages of the invention will be apparent
from the following description taken in connection with the
accompanying drawing wherein:
FIG. 1 is a fragmentary side elevation of a chain drive having an
improved sprocket configuration embodying the invention;
FIG. 2 is a fragmentary enlarged elevation of a portion of the
sprocket; and
FIG. 3 is a fragmentary elevation with the chain bushing shown in
transverse section illustrating the association of the bushing and
sprocket tooth where the chain has been stretched to permit the
bushing to engage the topping surface of the tooth.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the exemplary embodiment of the invention as disclosed in the
drawing, a chain drive generally designated 10 is shown to comprise
a chain generally designated 11 having a plurality of bushings
generally designated 12 and links generally designated 13 adapted
to be entrained about a sprocket generally designated 14 defining a
plurality of teeth 15 spaced apart by a corresponding plurality of
pockets 16. As best seen in FIG. 1 of the drawing, chain 11 defines
an effectively polygonal pitch line extending between the
respective bushings. This pitch line may be varied radially from
the central axis 17 of the sprocket as by the stretching of the
chain during use. The chain may be stretched undesirably by the
deposition of foreign matter in the pockets 16, tending to urge the
chain radially outwardly from the pockets. The present invention is
concerned with an improved sprocket configuration which effectively
minimizes such chain stretched by accommodating foreign matter in
the pockets without effecting undesirable outward stretching of the
chain. The invention further comprehends an improved sprocket
configuration where wear of the bushings is effectively minimized
notwithstanding a displacement of the bushings outwardly into
engagement with the outer portions of the teeth in the operation of
the chain drive.
More specifically, as seen in FIG. 2 of the drawing, the present
invention comprehends an improved configuration of sprocket 14
wherein each pocket 16 is defined by flank surfaces 18 and 19 at
opposite sides of the pocket radial centerline 20. The root surface
21 of the pocket herein comprises an arcuate surface extending into
each of flank surfaces 18 and 19.
Each tooth 15 is defined by a pair of working surfaces 22 extending
outwardly from the flank surfaces and an outer topping surface 23
extending outwardly from the working surface to the tip 24 of the
tooth. The sprocket, as shown in FIG. 1, further defines a tooth
pitch circle 25.
As shown in FIG. 2, the radii 18a and 19a defining the flank
surfaces 18 and 19, respectively, are respectively centered on the
points 18b and 19b spaced radially inwardly of the pitch circle 25
at least approximately 0.05 inch and spaced circumferentially from
the pocket radial centerline approximately 0.2 inch where the pitch
circle radius is approximately 20 inches. More specifically, in the
illustrated embodiment, the points 18b and 19b are spaced radially
inwardly of the pitch circle approximately 0.063 inch. The radius
21a defining the root surface 21 is centered on a point 21b spaced
outwardly of the pitch circle on the pocket radial centerline
20.
It has been found that, by increasing the spacing of the points 18b
and 19b inwardly from the pitch circle as disclosed herein, a
substantial improvement in the operation of the chain drive is
effected unexpectedly. The use of the same length pocket radii 18a
and 19a as in the prior art thusly provides an improved deep pocket
configuration which has been found to accommodate foreign matter
without casing stretching of the chain in the normal operation of
the chain drive, thereby providing an improved extended life and
minimization of maintenance.
The topping surfaces 23 are effectively defined by radii 23a
centered on points 23b located in the adjacent tooth so as to
define an arcuate, or rounded, topping surface 23 adapted to
provide minimum wear relative to the bushing 12 in the event the
bushing is urged outwardly to the tip portion 24 of the tooth in
the operation of the chain drive for further improved long life and
minimization of maintenance in the operation of the chain
drive.
In the illustrated embodiment, the working surfaces 22 are
rectilinear, or planar, it being understood that the surfaces may
be arcuate, as desired. Where the working surfaces 22 are
rectilinear, the topping surface radius 23a may be struck on a line
perpendicular to the working surface.
The improved sprocket configuration permits the chain to pass
freely thereabout in the normal operation of the chain drive
notwithstanding accumulation of foreign matter at the root portion
of the pockets. Should an excessive amount of foreign matter be
retained in the pockets causing the bushings to be displaced
outwardly as they pass around the sprocket, wear of the bushings is
minimized as a result of the improved rounded configuration of
topping surfaces 23.
Thus, the improved sprocket configuration of the present invention
provides a long, troublefree chain drive life while yet being
extremely simple and economical of construction.
The foregoing disclosure of specific embodiments is illustrative of
the broad inventive concepts comprehended by the invention.
* * * * *