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Claims  |
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What I claim is:
1. A mounting assembly for a caster wheel of an implement, said assembly
comprising:
a wheel mounting arm having attachment means for connecting said arm to a
frame member of the implement,
a king pin bushing housing affixed to said arm at a location spaced from
said attachment means,
a king pin member including a wheel spindle mounting portion and a king pin
shaft received in said king pin housing for rotation about a longitudinal
axis thereof,
a wheel spindle projecting from one side of said mounting portion and
defining a wheel axis of rotation extending substantially horizontally,
said rotation of said king pin shaft about said longitudinal axis providing
a castering turn away from a straight ahead travel position of said wheel
and toward a caster turn position of said wheel, said castering turn being
in a direction toward said one side of said mounting portion,
said axis rotation of the king pin shaft being tilted upwardly and
rearwardly from a vertical reference line,
said axis of rotation of said king pin shaft also having a sideways tilt
upwardly and outwardly from said vertical reference line in a direction
opposite to said one side of said mounting portion from which said wheel
spindle projects,
whereby during said castering turn away from said straight ahead travel
position in the direction of the projection of said wheel spindle, said
wheel axis of said wheel spindle swings from a transverse and
substantially horizontal orientation towards a rearwardly and downwardly
inclined orientation.
2. A mounting assembly as defined in claim 1, and further including spring
means engaging said king pin member and providing a biasing force on said
king pin shaft to rotate in a direction from said caster turn position
toward said straight ahead travel position.
3. A mounting assembly as defined in claim 2, and further including a first
stop means for limiting rotation of said king pin shaft from said caster
turn position to thereby establish said straight ahead travel position.
4. A mounting assembly as defined in claim 3 further including a second
stop means for limiting said castering turn of said king pin shaft to said
caster turn position of a preselected maximum.
5. A mounting assembly as defined in claim 4, wherein said first stop means
includes a member fixed relative to said arm and engagable with said king
pin member to limit the rotation of said king pin shaft from said caster
turn position for positioning said wheel spindle substantially in said
straight ahead travel position.
6. A mounting assembly as defined in claim 5, wherein said castering turn
between said straight ahead travel position and said caster turn position
determined by said first and second stop means is about 55 degrees.
7. A mounting assembly as defined in claim 3, wherein said first stop means
limits said turn of said king pin shaft to a position in which said axis
of said wheel spindle projects substantially normal to a straight ahead
travel direction of said implement.
8. A mounting assembly as defined in claim 7, wherein first stop means is
adjustable to permit variation of said straight ahead travel position of
said king pin member relative to said king pin bushing housing.
9. A mounting assembly as defined in claim 1, wherein said upward and
rearward tilt of said axis of said king pin shaft relative to said
vertical reference line is in the range from about 7 degrees to about 27
degrees.
10. A mounting assembly as defined in claim 9, wherein said upward and
rearward tilt of said axis of said king pin shaft relative to said
vertical reference line is about 17 degrees.
11. A mounting assembly as defined in claim 1, wherein said sideways tilt
of said axis of said king pin relative to said vertical reference line is
in the range of from about 20 degrees to about 40 degrees.
12. A mounting assembly as defined in claim 11, wherein said sideways tilt
of said axis of said king pin shaft relative to said vertical reference
line is about 30 degrees.
13. A mounting assembly as defined in claim 2, wherein,
said king pin shaft extends through said king pin bushing housing and
includes an upper portion of said king pin shaft above said king pin
bushing housing,
said king pin member further includes a cap means affixed to a top end of
said upper portion, and
said spring means includes a torsional spring encircling said upper portion
of said king pin shaft,
said cap means engaging an upper end of said spring and said king pin
bushing housing engaging a lower end of said spring,
whereby a rotation of said king pin shaft relative to said king pin bushing
housing during said castering turn further winds said spring to increase
said biasing force for returning said king pin member toward said straight
ahead travel position.
14. A mounting assembly as defined in claim 1, wherein said attachment
means of said arm includes a pivot connection, said arm extending
rearwardly from said frame member, said arm having an affixing bracket for
rigidly securing said king pin bushing housing to a rear portion of said
arm.
15. A mounting assembly as defined in claim 5, and including an affixing
bracket for securing said king pin bushing housing to said arm, and
wherein said second stop means includes
a stop member projecting from said king pin member, and
a stop engaging member affixed to said bracket and located for engagement
by said stop member on rotation of said king pin member to limit said
castering turn.
16. A mounting assembly as defined in claim 5, wherein said first stop
means includes a lug fixed relative to said arm in a position for
engagement by said king pin member on rotation of said king pin member
from said caster turn position.
17. A mounting assembly as defined in claim 16 wherein said first stop
means includes an adjustable bolt means carried by said lug for varying
the limit of rotation of said king pin shaft from said caster turn
position.
18. A mounting assembly for a caster wheel of an implement, said assembly
comprising:
a wheel mounting arm having attachment means for connecting said arm to a
frame member of the implement,
a king pin bushing housing affixed to said arm at a location spaced from
said attachment means,
a king pin member including a wheel spindle mounting portion and a king pin
shaft,
a wheel spindle projecting from one side of said mounting portion and
defining a wheel axis of rotation extending substantially horizontally and
in a direction substantially normal to a straight ahead direction of
travel of the implement,
said king pin shaft being received in said king pin bushing housing for
rotation about a longitudinal axis thereof during a castering turning of
said king pin member away from a straight ahead travel position to a
caster turn position,
spring means engaging said king pin member and biasing said king pin member
to rotate in a direction from said caster turn position to said straight
ahead travel position,
a first stop means for limiting rotation of said king pin shaft in a
direction of turn opposite to the direction of said caster turning, and
a second stop means for limiting the caster turn of said king pin shaft to
a preselected maximum,
said first stop means includes a member fixed relative to said arm and
engagable with said king pin member to limit the rotation of said king pin
shaft to a counter caster turn direction for positioning said king pin
member in substantially a straight ahead travel position of said king pin.
19. A mounting assembly as defined in claim 18, wherein said castering turn
between the positions determined by said first and second stop means is
about 55 degrees. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field Of The Invention
This invention relates to a mount assembly for a caster wheel of the type
provided for supporting an agricultural implement, or at least a part
thereof, as the implement travels over the terrain.
2. Description Of The Prior Art
Numerous types of agricultural implements are provided with support wheels
for supporting a part of an implement such as a swather or combine header
which is mounted on a hydraulic lift system at the front of a tractor or
combine unit. The headers have considerable width transverse to the
direction of travel relative to the width of the propelling unit, and
supporting wheels, commonly called gauge wheels, are provided adjacent the
outer ends of the header. The gauge wheels have commonly been mounted on
an arm which is connected at a front end to a frame member of the header,
the arm having a wheel spindle at its rear end, the spindle projecting in
a direction transverse to the direction of travel. The gauge wheel is
mounted for rotation on the spindle. With this simpler form of mounting
for the gauge wheel, it is apparent that there is an excessive amount of
side scuffing of the wheel with the ground when the implement is being
manoeuvered through a turn. This is particularly true in relation to the
tire of the gauge wheel at the inside of a turn where it is not unusual
during a short turn for the tire of the inside wheel in the turn to
actually gouge the field. Even during a short turn, the tire of the gauge
wheel on the outside of the turn usually does not present a problem
because its radius of turn is much larger. Thus, it is not necessary for
the outside gauge wheel to caster in a turn. In any event, because of the
difficulty experienced by the wheel on the inside, there is not only
excessive wear and potential damage to the tire and wheel, but
considerable strain is also put on the mounting arm and its pivot
connection to the frame. Another problem which is present is some caster
wheel designs is that in straight ahead travel the wheel is affected by
the surface of the ground to the extent it does not track truly.
While caster type wheels which are mounted to allow free 360 degree
revolving of the wheel about a substantially vertical axis are used on
some implements, such an arrangement is not particularly feasible in
implements such as headers as the mounting position for such a caster
wheel would have to be a considerable distance behind the header for
clearance during its revolving action. Another alternative which is known
involves a wheel mounted on an assembly which turns about a substantially
vertical axis, and wherein the steer is controlled by a powered steering
mechanism, such as one using a hydraulically operated cylinder. Such an
arrangement and any associated automatic control adds considerably to the
cost of the implement as well as to its maintenance costs. An apparatus of
a type including a mechanism for locking a castor wheel other than when
cornering is shown in Canadian Patent No. 1,331,842, Jeannotte, Sep. 6,
1994.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an effective implement
caster wheel mounting assembly which can be conveniently mounted close to
a frame member of an implement, such as a swather or combine header, and
which allows appropriate turning of the gauge wheel at the inside of a
turn to avoid scuffing during a turn. A feature of the invention also
automatically achieves straight travel of the wheel during normal forward
movement of the implement.
According to the present invention there is provided a mounting assembly
for a caster wheel of an implement, the mounting including a wheel
mounting arm having an attachment means for connecting the arm to a frame
member and a king pin mounting housing attached to the arms at a location
spaced from the attachment means. A king pin member includes a wheel
spindle mounting portion and a king pin shaft received in the king pin
mounting housing for rotation about a longitudinal axis of said king pin
shaft. A wheel spindle projects from one side of the spindle mounting
portion and defines a wheel axis extending substantially horizontally. The
axis of the king pin shaft is tilted upwardly and rearwardly from the
vertical and is tilted outwardly from the vertical in a direction opposite
to the side of the projecting wheel spindle. Thus, in a caster turn away
from a straight ahead travel condition and in the same direction as the
projection of the wheel spindle, the axis of the wheel spindle swings from
a transverse and substantially horizontal orientation towards a more
rearwardly and downwardly inclined position.
In an embodiment of the invention, there is provided a spring means
engaging said king pin member and biasing the king pin shaft to rotate in
a direction opposite the caster turn.
According to a specific embodiment of the invention, there is also provided
in the mounting assembly of the present invention a first stop for
limiting rotation of the king pin shaft in the direct opposite the caster
turn. Preferably there is provided a second stop means for limiting the
caster turn of the king pin shaft to a predetermined maximum.
More specifically the caster turn between the positions determined by the
first and second stop means is about 55 degrees.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, which show an embodiment of the invention, as
an example,
FIG. 1 is a top view showing outer opposite ends of a combine header
supported by a pair of caster wheels each carried in a mount assembly of
the present invention;
FIG. 2 is an enlarged cross sectional view as seen from the line 2--2 of
FIG. 1;
FIG. 3 is a still further enlarged top view of the caster wheel and mount
assembly as shown at the left hand end of FIG. 1;
FIG. 4 is a rear view of the caster wheel and mount assembly of FIG. 3.
FIG. 5 is a cross sectional view as seen from the line 5--5 of FIG. 4;
FIG. 6 is a cross sectional view as seen from the line 6--6 of FIG. 4;
FIG. 7 is a top view similar to FIG. 3, on a small scale and showing only
the king pin member in its relationship to the king pin bushing housing;
FIG. 8 is a side view of the king pin member as shown in FIG. 7;
FIG. 9 is a rear view of the king pin member as shown in FIG. 7, and
FIGS. 10A, 10B and 10C are top views of the caster wheel mount assembly of
the present invention illustrating the position of the wheel as it
progresses into a full caster turn at FIG. 10C from its normal straight
ahead position of FIG. 10A, and
FIGS 11A, 11B and 11C are rear views of the assembly of FIGS. 10A, 10B and
10C showing the wheel position as it progresses into the caster turn from
the normal straight ahead position.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to FIG. 1 and 2 which shows opposite ends of a header 10, caster
wheel mount assemblies 11 of the present invention are provided adjacent
the outer ends of the header 10. Briefly the header 10 includes an upper
transverse main frame member 12 from which is suspended a deck 13. A
sickle bar 14 extends across the front of the deck 13 for cutting a crop
as the header is moved forwardly in the direction of the arrow B by a
tractor or combine unit (not shown). The header 10 is mounted on the front
of the tractor or combine unit by way of a hydraulic lift system so that
the entire head can be lifted to an inoperative position or lowered to its
cutting position. The outer ends of the header are at least partially
supported in the lowered position by the gauge wheels 15 which are
attached to the header by the wheel mount assemblies 11 of the present
invention. As previously indicated, it has been known to mount gauge
wheels which rotate about a horizontal axis but have no provisions for
turning about a vertical axis. Thus, in such a mount design, the wheel
does not track the radius of turn of the header as the tractor or combine
steers to the right or left, such as in a turn at the end of a field
having finished a swath along the field. As can be seen in comparing
arrows C' and C" of FIG. 1, the gauge wheel 15 at the inside of the turn
experiences a much sharper turn than the outside wheel, and without the
ability to in effect turn, there is experienced considerable sideways
scuffing.
In addition to the transverse frame member 12, the header also includes
frame members 16, which include an upright portion 17 and a forwardly
projecting portion 18 on which the deck 13 is carried (FIG. 2). Each mount
assembly 11 includes an arm 20 which is pivotally connected at its forward
end, by way of a pivot pin 21, to the portion 18 of the frame member 16.
The pivot pin 21 allows the arms to pivot about a substantially horizontal
axis extending transversely to the direction of normal travel of the
header so that the arm 20 can swing up and down in an arc disposed in a
substantially vertical plane which is in the direction of travel of the
header. The arm normally extends rearwardly from the pivot pin and is held
in a substantially horizontal position by way of a compression strut, such
as a shock absorbing unit 22, connected between the main frame 2 and an
upright lug 23 affixed to the arm 20 near its rear end. The unit 22 is
selected to provide a downward resilient bias to transmit a portion of the
weight of the outer end of the header to the wheel 15 so that the head is
maintained level, but will allow some upper movement of the wheel 15 by
way of the arm 20 pivoting upward, when, for example, the wheel encounters
an unevenness of the ground or other obstacles. The unit 22 includes a
cylindrical member containing a compression spring (not shown), and may
include adjustment means so as to be able to control its downwardly
bearing effect.
Affixed rigidly to the side of the rear end portion of the arm 20, by way
of a mounting bracket 24, is a king pin bushing housing 25 which receives
for rotation therein a king pin member 26. The king pin member 26 is in
the form of a shaft 28 of circular cross section which has integrally
formed therewith at its lower end a spindle mounting portion in the form
of a tubular housing 27 for receiving a wheel spindle 30 on which wheel 15
is rotatably mounted. The upper end portion 31 of the king pin shaft 28
extends above the housing 25, and a biasing means in the form of a
torsional coil spring 32 encircles the upper end portion 31. A cap 33 is
affixed to the upper end portion 31 by way of a bolt 29 which passes
through the shaft 28 and the cap 33 so that the cap 33 turns with the king
pin shaft 28. The cap 33, has a downwardly projection tab 34. The tubular
housing 27 which forms the lower portion of the king pin member 26 is
affixed to the king pin shaft 28 and provides an upper shoulder 49 which
bears against a lower end surface 38 of the king pin bushing housing 25.
Affixed to the king pin shaft 28 above an upper end surface 39 of the king
pin bushing housing 25, by way of a bolt 40, is a collar 41. Thus,
vertical movement of the king pin shaft 28 is restricted, but the shaft 28
is journalled for free turning within the bearing members 42 contained
within the king pin bushing housing 25 (FIG. 5).
The spring 32 is contained between a lower end surface 43 of the cap 33 and
an upper end surface 44 of the collar 41. Opposite ends 35 and 36 of the
spring project radially from the spring, the upper end 35 engaging the tab
34 of the cap 33 and the lower end 36 engaging an upward projecting stop
member 37 which is affixed to the bushing housing 25. Thus, while the
spring 32 may be prewound to bias the king pin against rotation as the
wheel 15 turns to a caster position, the spring experiences a winding
effect which reacts in its contact with the tab 34 to bias the king pin
shaft 26 to return the wheel 15 to a straight ahead condition.
In order to limit the turn of the king pin member 26 into a caster turn,
the lower portion of the king pin member 26 is provided with a radially
projecting stop member 45 affixed thereto (FIG. 4). Rigidly affixed to the
mounting bracket 24 is a lug or flange 46 which provides a stop engaging
surface 47 against which the stop member 45 engages when the wheel has
reached its maximum permissible caster turn. In order to limit the turn of
the wheel during its return to the straight ahead position, there is
provided in association with the flange, a stop means 48 which engages the
portion of the king pin member 26 formed by the tubular housing 27. The
stop means 48 includes a bolt 50 which passes through a hole 51 in the
flange 46, and a pair of nuts 52 threaded onto the bolt 41, one on either
side of the flange 46. Thus, by adjusting the position of the nuts 52, the
head of the bolt 50 can be moved toward or away from the housing 27
thereby establishing the position of the king pin member 26 when it has
returned substantially to the straight ahead position (FIG. 6). As best
illustrated in FIGS. 7 to 9, the central axis 60 of the king pin shaft 28
about which the king pin member 26 rotates in its castering action is
tilting. The tilt is in an upwardly direction, both rearwardly and away
from the side of the spindle housing from which the wheel spindle 30
projects. The angle between the horizontal H and the central axis 60 is
shown as X (FIG. 4). As indicated, the tilt of the axis 60 is away from
the side of the wheel spindle housing, and the angle X may be in the order
of about 63 degrees to about 83 degrees, and preferably about 73 degrees.
The angle between the horizontal upward and rearward tilt of the central
axis 60 as shown at Y is between about 110 degrees and about 130 degrees
and preferably about 120 degrees. Alternatively stated, the axis 60 of the
turn of the king pin member 26 is tilted upwardly and outwardly from the
vertical V at the side of the king pin member opposite to the wheel
spindle in the range of about 7 degrees to about 27 degrees, and
preferably about 17 degrees, while the tilt of the axis 60 is upwardly and
rearwardly from the vertical in the range of about 20 degrees to about 40
degrees, and preferably about 30 degrees.
The result of the above stated angles of tilt of the axis 60 of rotation of
the king pin member is that as the header enters a turn to the left, as
illustrated by arrows K, K' and K" in FIGS. 10A, 10B and 10C, the wheel 15
is free to caster into the turn due to the turn of the king pin shaft
about its axis. The caster occurs as the axis 61 swings rearwardly to a
position in which the axis 61 of the wheel spindle is normal to the plane
in the direction of the wheel travel in the turn. At the same time the
axis 61 tilts downwardly relative to the horizontal 14 as seen from the
rear views of FIGS. 11A, 11B and 11C.
The effect of the above described castering of the wheel has proven to
achieve a number of desired characteristics, particularly when also
incorporating the stop means for limiting the amount of caster and the
spring means to assist in return of the wheel to its straight ahead
travel. The wheel has been found to turn smoothly and accurately into a
turn in the direction of travel of the end of the header on which the
wheel is mounted, i.e. when the wheel is at the inside of the turn.
Additionally the wheel returns accurately to the straight ahead position
where it remains without undue wobble as frequently occurs with
conventional caster wheel designs. Because of its limited caster travel
and the angle relative to the ground surface it assumes during a turn it
can be mounted as close to the frame work as non-castering gauge wheels,
but at the same time, of course avoiding side scuff and the stresses
established by stationary gauge wheels.
As in most apparent from FIGS. 9 and 11A, the relationship between the
shaft 28 and the tubular housing 27 may be such that the axis of the wheel
spindle 30 which determines the axis 61 of the rotation of the wheel 15 in
the straight ahead travel the axis 61 is not entirely horizontal. The axis
61 may slope downwardly away from the horizontal H in the direction of the
projection of the spindle at an angle of about 5 degrees. This results, of
course, in the plane of the wheel 15 which is normal to the axis 61 of
rotation sloping slightly away from the vertical. This feature has been
found desirable to allow for distortion which can occur due to the full
weight of the header on the gauge wheel.
In relation to the amount of maximum caster turn of the wheel which is
determined between the location of engagement of stop 45 with the stop
engaging surface 47 in an extreme caster turn and the engagement of stop
means 50 with the tubular housing of the king pin member 26 on return from
the caster turn, it has been found desirable that this maximum permissible
caster turn be limited to about 55 degrees.
While a preferred embodiment of the invention has been shown as an example,
alternate features which are within the spirit of the invention as defined
in the appending claims will be obvious to those skilled in the art.
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