Note: Descriptions are shown in the official language in which they were submitted.
CA 02289278 2003-10-O1
ROTATING PAWL TOOL LATCH
Background of the Invention
1. Field of the Invention
The present invention relates to attachment apparatus and more particularly to
apparatus for attaching implements to a work vehicle such as a skid steer
loader.
2. Description of Related Art
Working vehicles such as skid-steer loaders frequently have tool carriers
supported
at the ends of their lift arms. These carriers are adapted to be attached to a
variety of tools,
such as a bucket. To simplify and expedite the mounting and removal of various
tools, the
carriers are typically equipped with quick-attach devices. These devices
typically include
positioning structures to position one part of the carrier relative to the
tool as well as a
latching structure to secure the tool to the carrier. The structures used to
position the carrier
with respect to the tool often take the form of a pair of spaced apart
mounting supports on
the upper portion of the tool designed to receive a compatibly spaced apart
pair of carrier
wedges on the tool carriers which are configured to be received by the
mounting supports.
Commonly, the mounting support includes an outwardly extending lip beneath
which the
carrier wedges are received. Generally the supports and wedges are widely
spaced on the
tool and carrier to provide a stable mounting connection. To lock the tool to
the carrier,
movable latch pins are provided below the positioning structure, and usually
on the carrier,
for being received in openings provided on the tool. The latch pins are
typically inserted into
and removed from the tool openings by swinging movement of a handle coupled
with axial
movement of the pin.
One known latching device has a handle-actuated latching pin structure with a
detent
to retain the pin in its latched or unlatched positions to prevent inadvertent
unlatching which
could result in the tool and carrier coming apart during operation.
These conventional latching devices typically use a pin sliding through some
type of
guide to secure the tool to the carrier. After operation in dirt or mud, which
is the design of
these machines, this pin becomes very difficult to move so that a different
attachment may
be connected to the machine.
Summary of the Invention
In the present invention, a latch is provided having a rotating pawl which is
used to
CA 02289278 2003-10-O1
latch a tool to a carrier mounted on a working vehicle. The pawl is forgiving
to debris and
trash and thus provides easier and more reliable operation in dirty or
otherwise
contaminated conditions as compared to conventional latching devices.
In an exemplary embodiment of the present invention, a latching device is
provided
which includes a handle-actuated pawl which swings about a pin on a carrier
frame main
mounting plate. A connector link from a handle provides the rotating motion.
There are two
links on the mechanism which both have springs to allow for over-center travel
in the
linkage. One over-center spring is used to lock the pawl in the down position
to insure that
attachments do not come loose from the base machine. The other is used to hold
the
handle in the up position making it possible to change attachments with only
one person.
The pawl pivots laterally (about a pivot axis extending generally parallel to
the major axis of
the vehicle), so that the entire mechanism and thus the entire attachment
weight can be held
closer to the front wheels, resulting in a more stable vehicle. In the
preferred embodiment,
two spaced-apart latching devices are provided at spaced apart positions on
the carrier to
ensure a stable attachment of the tool to the carrier.
Brief Description of the Drawings
Figure 1 is an elevated left rear perspective view illustrating the latching
device
according to the present invention utilized on a skid-steer loader and a
bucket.
Figure 2 is a left side elevational schematic view of the latching device in
its latched
position engaged with the bucket of Figure 1.
Figure 3 is a left rear worm's eye view of a pair of the latching devices in
their latched
positions.
Figure 4 is a rear elevational view of the latching devices in their unlatched
position
wherein the illustration of the housing surrounding the right hand latching
device is
fragmented to illustrate the components of the latching device.
Figure 5 is a rear elevational view of a latching device according to the
present
invention shown in its latched position.
Figure 6 is a rear elevational view of a latching device according to the
present
invention shown in its unlatched position
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CA 02289278 2003-10-O1
Detailed Description of Exemplary Embodiment
Looking first to Figure 1, there is shown in perspective a skid-steer loader
10,
including a frame 12 which supports an operator enclosure 14 and to which
wheels 16 are
mounted. The loader 10 includes booms 18 and lift arms 20 which are used to
manipulate a
work tool mounted at the front of the loader 10. The lift arms 20 terminate at
their distal end
at a tool carrier 22 which is adapted for being readily connected to a tool 24
such as the
bucket illustrated. The carrier 22 shown in FIGS. 1-4 is adapted to carry
support structures
for readily connecting and disconnecting the working tool or bucket 24 from
the loader 10.
The support structures include laterally spaced-apart positioning structures
on each of the
tool 24 and carrier 22 for orienting the carrier 22 for attachment to the tool
24 and a latching
device 26 for securing the tool 24 to the carrier 22.
Referring now also to Figure 2, the positioning structures on the tool 24
include
upwardly extending ramp plates 28 at the lower portion of the tool 24 and a
downwardly
extending upper lip 30 at the top of the tool 24. Hydraulic cylinders 32 are
provided between
the lift arms 20 and carrier 22 to tilt the carrier 22 and orient it with
respect to the tool 24 so
that an upwardly extending front plate 34 on the carrier 22 can be slidably
positioned
beneath the downwardly extending upper lip 30 of the tool 24. As the cylinders
32 are
activated to position the front plate 34 beneath the tool's upper lip 30, a
bottom ramp plate
36 of the carrier 22 will slidably move along the bottom ramp 28 of the tool
24 to guide a
wedge portion 38 at the top of the carrier's front plate 34 up and into a
recess 40 beneath
the upper lip 30 of the tool 24.
Once the carrier 22 has been positioned, it must be attached to the tool 24.
For this
purpose, the latching device 26 is provided on each lateral side of the
carrier 22 (as shown
in Figure 3) to secure that side of the carrier 22 with its respective side of
the tool 24. Each
latching device 26 utilizes a pawl 42 that is secured to the carrier 22 by and
supported for
swinging movement on a pivot 44 extending generally parallel to the major
(longitudinal) axis
of the loader 10. The pawl is rotated by a latch handle 46 to insert it into
or remove it from
an opening 48 provided in the bottom ramp plate 36 of the carrier 22 and an
aligned opening
50 in the ramp plate 28 of the tool 24 to secure the carrier 22 with the tool
24.
Looking now to Figures 3 and 4, the carrier 22 is shown with laterally spaced
latching
devices 26 connected by a support member 51. The carrier is provided with
inboard pivot
supports 52 which serve as an attachment point of the carrier 22 to the lift
arms 20 so that
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CA 02289278 2003-10-O1
the carrier may pivot with respect to the lift arms. The carrier 22 is also
provided with
cylinder mounting brackets 54, which provide points of attachment for the
hydraulic cylinders
32. The handles 46 are shown in their generally horizontal, latched positions
and the pawls
are shown in their corresponding latched positions wherein a tip of the pawl
42 extends
through the opening 48.
The assembly connecting the pawl 42 to the handle 46 is shown in the right-
hand
latching device 26 of Figure 4, wherein a rear cover plate 56 has been removed
to better
show the components of the latching device 26. The handle 46 is pivotally
mounted to the
carrier 22 on a pivot 58. A handle-pawl link 60 is pinned at one end to an
outboard
extension 62 of the handle 46 for relative swinging movement by a pin 69
passed through
the link 60 and the extension 62 of the handle 46 and sandwiched between the
front plate 34
and the rear plate 56 of the carrier 22. At its other end, the link 60 is
similarly pinned to the
pawl 42. Between the handle 46 and the pawl 42, the link 60 is encompassed by
a spring 64
that is sandwiched between washers 66 abutting the handle 46 and the pawl 42.
A second
link 68 is rotatably pinned to the pawl 42 at one end, also by a pin 69 passed
through the link
68 and the pawl 42 and sandwiched between the front and rear plates 34, 56 of
the carrier
22. At its other end the link 68 abuts a bracket 70 welded to the faceplate 34
of the carrier
22. A spring 72 is positioned over the second link 68 and sandwiched between a
collar 74
on the link and a washer 76 which abuts the pawl 42. In their respective
latched positions
shown in Figure 4, the handle 46 is in an abutting relationship with a handle
stop 78 in the
form of a roll pin press-fit in the carrier 22, and the pawl 42 abuts a pawl
down stop in the
form of an end of a slot 80 provided in a carrier reinforcement gusset 82. In
the exemplary
embodiment, the openings in the links 60, 68 through which the pins 69 are
inserted at their
ends of attachment with the pawl 42 are shown as elongated slots. Although a
lost motion
connection is not necessary for the links 60, 68 to achieve their over-center
positions, the
openings are elongated to allow for tolerances and the use of pawls of varying
sizes.
Looking now to Figure 5, the latching device 26 is shown in its latched
position and
the links 60, 68 are shown in their latched over-center positions. In the
latched over-center
position of the link 68, an end of the link 68 is trapped in a corner of the
bracket 70 and the
spring 72 biases the pawl 42 toward its latched position, wherein the pawl 42
engages its
down stop 80 and the tip of the pawl 42 extends through the opening 48 and
will also extend
through the opening 50 in the bottom ramp surface 28 of the tool 24 to secure
the carrier 22
with the tool 24 (see Figures 1 and 2). The link 60 is also in its latched
over-center position
wherein its associated spring 64 serves to bias the handle 46 away from the
pawl 42 and
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hold the handle 46 is its latched position, as illustrated in Figures 2-5. The
pin 78 serves as
a down stop to ensure that the handle 46 achieves a secure, generally
horizontal orientation
in its latched position. The latched over-center positions of the links 60, 68
shown assist in
assuring that the latch device 26 will remain in its latched position without
the necessity of a
constant application of force.
Referring now to Figure 6, the latching device 26 is shown in its unlatched
position
and the links 60, 68 are shown in their unlatched over-center positions. In
the unlatched
over-center position of the link 68, an end of the link 68 is trapped in a
corner of the bracket
70 and the spring 72 biases the pawl 42 toward its unlatched position, wherein
the pawl 42
engages an edge of the bracket 70 which serves as an up stop and the tip of
the pawl 42 is
withdrawn from the opening 48. The link 60 is also in its unlatched over-
center position
wherein its associated spring 64 serves to bias the handle 46 away from the
pawl 42 and
hold the handle 46 is its unlatched position. The unlatched over-center
positions of the links
60, 68 retain the latching device 26 in its unlatched position which allows a
single operator to
properly position the carrier 22 with respect to the tool 24, the tip of the
pawl 42 being
retained from opening 48 and preventing interference so that manipulation of
the handles 46
required only to place the latching device 26 in its latched position after
the tool 24 and
carrier 22 have been positioned.
Looking back to and comparing Figures 5 and 6, it can be seen that when the
operator wants to move the latching device 26 from the latched position
illustrated in Figure
to the unlatched configuration illustrated in Figure 6, he or she moves the
handle 46
clockwise to its raised, unlatched position to lift the pawl 42 out of the
opening 50 and rotate
the pawl 42 counterclockwise as viewed in Figure 6 (the handles 46 shown are
provided with
raised surfaces 86 intended to provide a better frictional grip). The pawl
swings laterally to
minimize interference with the carrier and tool structures and simplify
activation by the
operator from his seat. During this movement the link 68 will move from the
latched over-
center position illustrated in Figure 5 biasing the pawl 42 against its down
stop 80 to the
unlatched over-center position illustrated in Figure 6 biasing the pawl 42
against its up stop
(bracket 70). Further, the link 60 will also move from a latched over-center
position biasing
the handle 46 toward its full-counterclockwise, latched position, abutting the
pin 78(shown in
Figure 5) to an unlatched over-center position wherein the handle 46 has
rotated clockwise
to its unlatched position corresponding to the position of the pawl 42 when
the pawl 42
contacts the bracket 70. When rotation of the handle 46 is completed, the
respective springs
64, 72 on both links 60, 68 bias the pawl 42 and handle to their unlatched
positions and the
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pawl 42 and handle 46 will be retained in their unlatched orientation until
force is applied to
the handle to overcome the biasing force of the springs 64, 72.
Thus, a rotating pawl tool latch is provided. One skilled in the art will
appreciate that
the present invention can be practiced by other than the described
embodiments, which are
presented for purposes of illustration and not limitation, and the present
invention is limited
only be the claims that follow.
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