Note: Descriptions are shown in the official language in which they were submitted.
~ackground of the Invention
This invention relates generally to tractors for towing
agricultural vehicles or implements, and more particularly to
two-wheeled tractors which, when attached to vehicles, partially
support the vehicles and which in turn are partially supported by
the vehicles. An object of this invention is the provision of a
tractor which may be rigidly coupled to the front end of a
vehicle having supporting wheels at its rear end, so that the
tractor and vehicle operate as an integrated unit.
Another object of this invention is the provision of a
tractor as set forth, having a novel steering arrangement which
eliminates the scrubbing action of wheels on the ground during
steering movement.
Another object of this invention is the provision of a
tractor as set forth, and a vehicle having cooperating inter-
connecting mechanism by means of which the tractor and vehicle
are mutually supported.
Summary of the Invention
A tractor unit is provided, comprising, a frame having
opposite side portions and front and rear ends, a pair of
laterally spaced steerable wheels, means mounting said wheels
at said opposite side portions and at one end of said frame for
rotation on generally horizontal axes and for steering movements
on generally vertical axes, and including generally vertical
pivot shafts one for each of said wheels. Means are provided
for supporting the other end of said frame, as are hitch means
at one of the ends of said frame for hitching said frame to a
vehicle. Means for imparting steering movements to said wheels
comprises: a rotary fixed shaft operatively carried by said
frame on a fixed axis, toothed wheels on each of said pivot
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shafts, a pair of primary toothed wheels one operatively rotatably
carried by said frame on a fixed axis intermediate said pivot
shafts, the other one of said primary toothed wheels being fixed
on said steering shaft for rotation therewith. Shiftable means
is provided, journaling a pair of secondary toothed wheels on
axes spaced apart in a direction transversely of said frame and
movable with each other in directions generally transversely of
said frame. An endless flexible power transmission member is
entrained over all of said toothed wheels, and shifting means is
responsive to rotation of one of said toothed wheels for imparting
shifting movements to said shiftable means whereby to rotate one
of said pivot shafts to a greater angular extent than the other
thereof in a given direction of pivotal movement of said pivot
shafts.
Brief Description of the Drawings
Figure 1 is a view in top plan of the tractor of this
invention, attached to the draft tongue of a vehicle, fragmen-
tarily shown;
Figure 2 is a view in front end elevation, as seen
from the left to the right with respect to Figure l;
Figure 3 is a fragmentary view in side elevation as
seen from the right to the left of Figure 2;
Figure 4 is a fragmentary view in side elevation as
seen from the left to the right with respect to Figure 2, and
showing the tractor partially disconnected from the draft
tongue of a vehicle;
Figure 5 is an enlarged fragmentary section taken on
the line 5-5 of Figure l;
Figure ~ is an enlarged fragmentary view in top plan
of a portion of Figure 1, some parts being broken away and
some parts being shown in section;
Figures 7 and 8 are diagrammatic views in top plan
showing the tractor of this invention coupled to a wheeled
vehicle, and illustrating different positions of the steerable
driving wheels of the tractor and the relationship thereof to
the wheels of the towed vehicle;
Figure 9 is an enlarged diagrammatic view in top plan
of the steering mechanism of the tractor; and
Figure 10 is a view corresponding to Figure 9 but
showing a modified arrangement.
Detailed Description of the Preferred Embodiment
The tractor of this invention involves a generally
rectangular frame 11 comprising an upper transverse front frame
member 12, a lower rear transverse frame member 13, a pair of
opposite side frame members 14 and 15, a motor support 16, and
hitch means in the nature of an elongated support arm element
17 extending rearwardly from the rear frame member 13 generally
centrally between the opposite ends thereof. At its front end,
the frame ~ is braced by laterally spaced brace members 18
welded or otherwise rigidly secured at their opposite ends to
the upper front frame member 12 and motor support 16, and
angular brace members 19 rigidly secured at their opposite ends
to the brace members 18 and gusset portions of the frame member
12.
A motor 20 preferably in the nature of an internal
combustion engine is mounted on the motor support 16, a conven-
tional driver's seat 21 is suitably mounted on the rear frame
member 13 adjacent the side frame member 16, a steering wheel
22 is disposed forwardly of the operator's seat 21 and is
operatively connected to a conventional power steering control
valve 23 mounted in a bracket 24 that is secured to the front
frame member 12. The rear frame member 13 further supports a
fluid reservoir 25 as well as a fuel tank 26, below the opera-
tor's seat 21, for the engine 20.
The front end of the frame 11 is supported by a pair
of laterally spaced steerable pneumatic tire equipped wheels 27
that are journaled on generally horizontal axes in the lower ends
of pivot frames 28 which at their upper ends are provided with
normally vertically extending pivot shafts 29 that are journaled
in bearings 30 rigidly secured to opposite ends of the upper
front frame member 12. At their lower ends, the pivot frames 28
are provided with rotary fluid operated motors 31 which may be
assumed to be operatively connected to respective ones of the
drive wheels 27 for imparting rotation thereto. Fluid under
pressure is supplied to the motors 31 from a fluid pump 32 which,
together with another fluid pump 33, is operated by the motor 20.
Fluid conduits 34 and 35 operatively connect the motors 31 to the
pump 32. It may be assumed that the conduits 34 are connected to
respective conduits 35 by fluid passages, not shown, but extending
axially through the pivot shafts 29. Flow of fluid under pres-
sure to the motors 31 is controlled by a suitable reversing valve36 operated by a control handle 37, and a conventional speed
control valve 38.
The tractor frame 11 is adapted to be supported at its
rear end by a leg 39 that is mounted on a shaft 40 journaled in
bearings 41 rigidly secured to the support arm element 17. At
its lower end, the leg 39 has pivotally connected thereto a
skid-like foot 42 that is adapted to engage the ground. At its
upper end, the leg 39 is formed to provide an angularly displaced
lever arm 43 the outer end of which is pivotally secured to the
outer end of a piston rod 44 that is provided with a piston,
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not shown, but axially slidable within a fluid pressure cylinder
45. One end of the cylinder 45 is pivotally secured, as indicated
at 46, to a bracket 47 that is welded or otherwise rigidly
secured to one side of the support arm element 17, see parti-
cularly Figures 1 and 4. While not specifically shown, the
cylinder 45 may be assumed to be operatively connected to the
fluid pump 33 and controlled by a valve 48 disposed adjacent the
operator's seat 21 and operated by a handle 49. By manipulating
of the valve operating handle 49, the leg 39 may be caused to
swing upwardly or downwardly, as shown in Figures 3 and 4 whereby
to raise or lower the rear end of the tractor.
In Figures 7 and 8, and fragmentarily in Figures 1 and
3, the tractor is shown as being operatively coupled to an imple-
ment indicated generally at 50. The implement 50 is shown
diagrammatically in Figures 7 and 8 as being in the nature of a
wagon having a body 51 that is supported near its rear end by a
pair of laterally spaced wheels 52, and a draft tongue 53 rigid
with the body 51 and projecting forwardly from the front end
thereof. The front end of the vehicle 50, when disassociated
from the tractor, is supported by a bifurcated leg 54 that is
pivotally connected at its upper end to a bracket 55 depending
from the draft tongue 53. At its lower end, the bifurcated leg
54 is provided with a ground engaging skid-like shoe 56.
Intermediate its ends, the leg 54 is provided with a laterally
extending finger or shaft 57, the purpose of which will herein-
after become apparent. At its front end, the draft tongue 53
is provided with vertically spaced upper and lower guide portions
58 and 59 respectively, and a rigid locking lug 60 depends from
the draft tongue 53 in forwardly spaced relation to the bracket
55, the locking lug 60 having a transverse opening 61 there-
throuyh.
~84~7
As shown particularly in Figures 1, 3 and 4, the
support arm element 17 is adapted to be moved into underlying
engagement with the draft tongue 53 and forwardly of its rear
end is provided with a pair of rearwardly diverging guide walls
62 that are adapted to receive the lower guide portlon 59 of the
draft tongue 53, the upper guide portion 58 being adapted to
rest on the upper edges of the guide walls 62, as shown in
Figure 3. A retaining pin 63 extends transversely between the
guide walls 62 and is disposed between the gui.de portions 58 and
59 when the draft tongue 53 is fully engaged by the support arm
elements 17, as shown in Figure 3, to limit relative vertical
movement between the front end of the draft tongue 53 and the
adjacent portion of the support arm element 17. At its rear end,
the support arm element 17 is bifurcated to provide a pair of
laterally spaced side walls 64 and 65 having downwardly con-
verging longitudinally extended guide portions 66 adjacent their
front ends, and connected adjacent their rear ends by a forwardly
and downwardly sloping rear wall 67, the side walls 64 and 65,
guide portions 66 and rear wall 67 cooperating to define an
upwardly opening socket 68 for reception of the locking lug 60.
The upper edge portions of the side walls 64 and 65 are provided
with wear strips 69 that engage the bottom surface of the draft
tongue 53, as does a wear strip 70 on the top surface of the
support arm element 1.7 forwardly of the socket 68.
As shown in Figure 4, when it is desired to couple the
tractor to the vehicle 50, the leg 39 is moved so as to lower
the support arm element 17 below the level of the draft tongue
53. The tractor is then moved rearwardly and into underlying
alignment with the draft tongue 53 so that the guide portions
58 and 59 operatively engage the guide walls 62 of the support
t7
arm element 17. The rear end of the support arm element 17 is
provided with a rearwardly extending blade-like finger 71 that
moves into underlying relationship to the stud or shaft 57 on
the leg 54. And, as the leg 39 is moved to raise the rear end
portion of the tractor and the support arm element 17, the finger
71 engages the shaft 57 and moves the leg 54 into an inoperative
storage position as shown in Figure 3. When the vehicle sup-
porting leg 54 is thus raised, the shoe 56 thereof is disposed
within an opening 72 in the draft tongue 53. During raising of
the support arm element 17, the guide portions 66 and rear wall
67 guide the locking lug 60 into a predetermined position in the
socket 68.
The side walls 64 and 65 are formed with bosses that
define aligned transverse openings 73 and 74 respectively that
are aligned with the opening 61 in the locking lug 60 when the
locking lug 60 is contained in the socket 68. An elongated
locking pin 75 has an inner end portion that is axially slidable
in the opening 74 toward and away from reception in the aligned
opening 73. Laterally outwardly of the support arm element 17,
the locking pin 75 is slidably supported by the base portion of
a U-shaped support member 76, the legs of which are welded or
otherwise rigidly secured to the side wall 65. Intermediate its
ends, the locking pin 75 has a collar 77 rigidl~ secured thereto,
the collar abuttingly engaging one end of a coil compression
spring 78. An elongated latch member 79 is disposed generally
within the U-shaped support member 76 and has an inturned outer
end 80 that loosely encompasses the locking pin 75 in abutting
engagement with the base end of the U-shaped support member 76 t
see Figures 5 and 6. It will be noted that the spring 78 has
its outer end in abutting engagement with the inturned end 80
of the latch member 79, to yieldingly urge the locking pin 75
toward reception in the locking lug opening 61 and the opposite
side wall opening 73. Intermediate its ends, the latch member
79 is formed to provide a collar engaging catch member or hook
81, and at its inner end is provided with a pair of laterally
spaced release members 82 that extend upwardly on either side
of the support member 76 for engagement with the bottom surface
of the draft tongue element 53 when the locking lug 60 is moved
downwardly into the socket 68 and the opening 61 in the locking
lug 60 is aligned with the openings 73 and 74. When the openings
61, 73 and 74 are thus aligned, the locking pin 75 is released
for movement into the openings 61 and 73 to securely lock the
support arm element 17 and draft tongue element 53 in operatively
coupled engagement.
Means for withdrawing the locking pin 75 from engage-
ment with the locking lug 60, and for resetting the locking pin
75 in operative engagement with the catch member or hook 81,
comprises an elongated resetting shaft 83 that is journaled in
aligned bearings 84 and 85 at one side of the support arm ele-
ment 17. An operating handle 86 extends upwardly from the frontend portion of the resetting shaft 83 adjacent the operator's
seat 21. ~he shaft 83 is yieldingly urged in one direction of
its rotary movement by a coil tension spring 87 connected at
one end to the operator's seat 21 and at its other end to a
flexible member in the nature of a chain 88 that is connected
to a crank arm 89 at the lower end of the handle 86. At its
opposite or rear end, the resetting shaft 83 has rigidly secured
thereto a pair of crank arms 90. A U-shaped resetting yoke 91
has a base portion 92 that encompasses the locking pin 75 out-
wardly of the support member 76, and a pair of spaced legs 93
g _
that are pivotally connected at their ends each to a differentone of the crank arms 9Q. The spring 87 yieldingly urges the
shaft 83 in a direction to move the resetting yoke 91 into
engagement of the base portion 92 thereof with the outer closed
end of the U-shaped support member 76, as shown in Figures 5 and
6. An abutment pin 94 is mounted in the outer end portion of the
locking pin 75, and is adapted to be engaged by the base portion
92 of the resetting yoke 91 to move the locking pin 79 to its
latched inoperative position shown in Figures 5 and 6, responsive
to operator imparted movement of the resetting handle 86 in a
given direction. When the operator releases the handle 86 after
having reset the locking pin 75 in its latched position, the
spring 87 automatically rotates the resetting shaft 83 to move
the yoke 91 to its position shown in Figures 5 and 6. It will
be appreciated that the handle 86 must be manually held in its
locking pin resetting position until the support arm element is
lowered sufficiently to cause disengagement between the draft
tongue element 53 and the release members 82, so that the catch
member or hook 81 will operatively engage the collar 77 on the
locking pin 75. Thereafter, upon forward movement of the tractor,
the leg 54 will be permitted to drop to its operative vehicle
supporting position shown in Figure 4, under the action of
gravity.
For the purpose of imparting steering movements to the
steerable drive wheels 27, I provide a rotary fluid pressure
operated steering motor 95 that is mounted on the upper front
frame member 12, and which has a rotary steering shaft 96 dis-
posed on a fixed generally vertical axis and extending upwardly
from the steering motor 95. While not specifically shown, the
steering motor 95 may be assumed to be driven from one of the
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f~
fluid pumps 32 or 33 and controlled by the power steering valve
23 in the usual manner. Each of the pivot shafts 29 has fixedly
mounted thereon a different one of a pair of sprocket wheels 97.
A pair of primary sprocket wheels 98 and 99 are disposed inter-
mediate the sprocket wheels 97, the sprocket wheel 98 being fixed
on the steering shaft 96, the sprocket wheel 99 being an idler
wheel and journaled on a pivot bolt or shaft 100 extending upward-
ly from the frame member 12 on a fixed axis.
A pair of secondary sprocket wheels 101 and 102 are
each journaled on the intermediate portion of a different one
of a pair of respective levers 103 and 104 that have inner ends
pivotally connected to the frame member 12 as indicated at 105
and 106 respectively. The outer ends of the levers 103 and 104
are pivotally connected each to an opposite end of a rigid link
107, and operatively connected to one of the sprocket wheels 97
by a longitudinally adjustable pitman arm 108. An endless
link chain 109 is entrained over all of the sprocket wheels 97-
99, 101 and 102. The arrangement is such that the sprocket
wheels 101 and 102 will rotate in the same directions as the
sprocket wheels 97, whereas the primary sprocket wheels 98 and
99 will rotate in directions opposite the directions of rotation
of the sprocket wheels 97, 101 and 102.
With reference particularly to the diagrammatic showing
in Figure 9, lt will be noted that the levers 103 and 104 are of
equal length, and that the axes of rotation of the secondary
sprocket wheels 101 and 102 are equidistant from the axes of
the pivotal connections 105 and 106 of their respective levers
103 and 104. The full line positions of the levers 103 and 104,
link 107 and pitman arm 108, in Figure 9, are the positions
assumed when the wheels 27 are in true forward or rearward
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67
driving positionsl indicated by ~he broken lines A-A. In this
position of the front wheels, the pivotal connection of the
pitman arm 108 to the lefthand sprocket wheel 97 is disposed in
substantially dead center relationship between the axis of the
lefthand sprocket wheel 97 or pivot shaft 29 and the pivotal
connection between the pitman arm 108 and the outer end of the
lever 103. As steering movement is imparted to the pivot shafts
29 in either direction away from a straightforward or reverse
direction as indicated by the lines A-A, movement of the levers
103 and 104 will cause one of the pivot shafts 29 to rotate to
a further extent than the other thereof. As shown by full and
broken lines in Figure 9, when turning the pivot shafts 29 in a
clockwise direction, so as to cause the tractor to steer to the
right, the righthand pivot shaft 29 will rotate to a greater
angular extent than the lefthand steering shaft 29, as indicated
by the broken lines B-B in Figure 9. As therein shown, when the
lefthand pivot shaft 29 is rotated 45 of circular arc, the
righthand pivot shaft 29 will rotate approximately 55 of
circular arc. In practice, this has been found to occur whether
the pivot shafts 29 are rotated in a clockwise direction as
shown in Figure 9, or in a counterclockwise direction wherein
the lefthand pivot shaft 29 will rotate to a greater angular
extent than the righthand pivot shaft 29. When the tractor is
coupled to a given vehicle 50, as shown in Figures 7 and 8, and
the tractor wheels 27 are steered in a clockwise direction to a
given extent as shown by dotted lines in Figure 7, the wheels
27 may be made to steer about an axis substantially coincident
with the vertical center line of one of the vehicle wheels 52,
such as the righthand wheel 52. In this situation, the lefthand
wheel 52 will also swing generally forwardly about the same
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axis. When the wheels 27 are swung further, as shown in
Figure 8, the wheels will swing about a common axis substantially
coincident with a vertical center line of the lefthand wheel 52,
in which condition the righthand wheel 52 will swing generally
rearwardly about the same axis. In any case, all of the wheels
27 and 52 will partake of steering movements without skidding
or scrubbing of any of the wheels, the wheels 27 in any steering
position on either side of a straightforward or reverse position
will steer about a common axis. It will be noted, with reference
to Figures 1 and 9, that the link chain 109 is provided with a
conventional spring biased coupling member or link lO9a for
maintaining the chain at a predetermined driving tension.
Modification of Figure 10
In the arrangement illustrated in Figure 10, the
sprocket wheels 97 are fixed on pivot shafts 29 that are journaled
in a frame member 12a that differs only slightly in structure
from the frame member 12. A platelike carriage 110 is provided
with a pair of elongated slots 111 for reception of mounting
bolts 112 by means of which the carriage 110 is mounted on the
frame member 12a for linear sliding movements between the
sprocket wheels 97. The carriage 110 is provided with other
slots 113 and 114 through which extend the steering shaft 96
and the pivot bolt 100 respectively on which respective ones of
the primary sprocket wheels 98 and 99 are mounted as in Figure
9. The secondary sprocket wheels 101 and 102 are mounted on the
carriage 110 for rotation with respect thereto and for common
movements therewith. The carriage 110 is connected to one of
the sprocket wheels 97 by a pitman arm 108a by means of which
the carriaye 110 is moved responsive to rotation of the
respective sprocket wheel 97 in either direction from a neutral
or straightforward position of the tractor wheels, as indicated
by the center lines C-C.
The carriage 110 operates to provide a differential
in rotation between the pivot shafts 29, in either direction
from a neutral position, in the same manner as do the levers
103 and 104. As shown in Figure 10, when the pivot shafts 29
are rotated in a counterclockwise direction, a 90 rotation of
the lefthand pivot shaft 29 will result in approximately 67 of
rotation of the righthand pivot shaft in the same direction, as
indicated by the center lines D-D in Figure 10. As is the case
with the structure of Figure 9, when the pivot shafts 29 of the
structure in Figure 10 are rotated in a clockwise direction from
a neutral position of the tractor wheels, the righthand pivot
shaft 29 will rotate to a greater extent than does the lefthand
pivot shaft 29.
While I have shown and described a preferred embodiment
and a single modified arrangement of this invention, it will be
understood that the same is capable of further modification
without departure from the spirit and scope of the invention,
as defined in the claims.
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