Background Of The invention
Field Of The Invention
The subject invention generally pertains to swap body containers,
and more specifically, to a device that restrains a parked swap body container.
Description Of Related Art
A swap body is typically a large freight container having four retractable
legs. The legs are usually retracted while the swap body is in transit on the bed
of a truck or trailer, ship or rail car. When parked at a truck loading dock, the
legs are typically extended to support the container upon a driveway with the floor
of the container generally aligned flush to the floor of the loading dock platform.
This allows a forklift to drive into the container for loading or unloading, yet
allows the truck that delivered the container to leave.
While the legs provide a vertical/columnar support for the weight
of the container and its contents (and material handling equipment), the legs are
not designed to resist substantial horizontal forces. Substantial horizontal forces,
however, can be exerted on the legs. For example, if the forklift inside the container
were to suddenly stop, by applying the brakes or striking cargo, the reaction force
would be transmitted to the container's legs. Since a forklift can weigh thousands
of pounds, and given the relative instability of the legs to resist horizontal
movement, it is possible that an abrupt stop or collision could cause the container
to move horizontally away from the dock, opening up a potentially hazardous gap
between the container and the dock. Further, such horizontal movement could place
a torque or bending force on one or all of the legs, causing them to buckle, or
fold up, or (in a worst-case scenario) to collapse altogether. Such an accident
might seriously harm the forklift operator, others nearby, the cargo or surrounding
Summary Of The Invention
In order to minimize horizontal movement of a swap body away from
the dock, there is provided a swap body leg brace that remains in the vicinity
of a loading dock area. According to preferred embodiments, the brace is selectively
repositioned from a retracted position to an engaged position on a leg of the swap
body. In the engaged position, one end of the brace is preferably anchored to the
driveway adjacent the loading dock, while an opposite end engages at least one
leg of the swap body to minimize horizontal movement of the swap body away from
the loading dock, and thus undesirable forces on the legs themselves that could
lead to their failure.
In some embodiments, the brace assembly incorporates a firm landing
pad on which the container legs may rest to provide a consistent, level height
at which the swap body is parked.
In some embodiments, the brace is at least partially fixed relative
to the loading dock when in the engaged position, yet somewhat free to be laterally
or longitudinally positioned when in the retracted position. The positioning feature
accommodates swap bodies whose legs are at various positions relative to the loading
Brief Description Of The Drawings
Figure 1 is a front-end view of a swap body container.
Figure 2 is a side view of one embodiment,
Figure 3 is a rear view of Figure 2
Figure 4 is a side view of a brace in a retracted position.
Figure 5 is a side view of a brace in an engaged position,
Figure 6 is a view taken along line 6-6 of Figure 5
Figure 7 is a view taken along line 7-7 of Figure 4.
Figure 8 is a side view of another embodiment.
Figure 9 is an end view of another brace in the engaged position.
Figure 10 is end view of the embodiment of Figure 9, but in the retracted
Figure 11 is a side view of the embodiment shown in Figure 9.
Figure 12 is a view taken along line 12-12 of Figure 10,
Figure 13 is a top view of the track of Figures 9, 10, 11, and 12.
Figure 14 is a side view of another embodiment with an encircled
portion enlarged and shown in perspective.
Figure 15 is a side view of another embodiment.
Figure 16 is a side view of another embodiment.
Figure 17 is a side view of the embodiment of Figure 16, but with
the brace engaging the leg of another swap body.
Figure 18 is a side view of another embodiment.
Figure 19 is a side view of the embodiment of Figure 18, but with
the brace in an engaged position,
Figure 20 is a side view of another embodiment.
Figure 21 is a top view taken along line 21-21 of Figure 20.
Figure 22 is a side view of the embodiment of Figure 20, but in an
Figure 23 is a view taken along line 23-23 of Figure 22,
Figure 24 is a perspective view of an embodiment similar to that of
Description Of The Preferred Embodiment
Figures 1, 2 and 3, respectively, show a front, side, and rear view
of a swap body 10. Swap body 10 is primarily a relatively large freight container
12 with dimensions that may exceed an 8-foot width 14, an 8-foot height 16, and
a 23-foot length 18. While in transit on a bed of a truck or trailer, ship, or
rail car, the swap body's four legs 21, 22, 23 and 24 are typically folded up into
a stowed position as shown in Figure 1. When parked at a truck loading dock area
26, the legs 21-24 are unfolded to a downwardly extended position upon a driveway
28, as shown in Figure 2. This allows a truck that delivered swap body 10 to leave,
while container 12 may be loaded or unloaded by a forklift truck 30.
Movement of lift truck 30 inside the container, particularly quick
stops and quick starts, results in forces F (Figure 2) being exerted on the container.
As legs 21 - 24 support container 10 in place, these forces F are transmitted to
the legs, and can lead to torques and stresses within the legs that could lead
to their failure. Use of one or more braces, as disclosed herein, helps reinforce
and support the legs to minimize movement of the container away from the dock,
and thus harmful stresses on the legs.
For example, opposing braces 32 and 34 can each engage and help support
opposite sides of one of legs 21-24, such as forward leg 23, as shown in Figures
2 and 3. Details of braces 32 and 34 are shown in Figures 4, 5, 6 and 7, In this
embodiment, braces 32 and 34 are coupled by a link 37, pivotally connected to both
braces at points 38 and 40 respectively, to form a clamping arrangement on leg
23. To move the clamping arrangement between retracted (Figure 4) and engaged (Figure
5) positions, a piston/cylinder 36 is coupled to braces 32 and 34. Extension of
piston/cylinder 36 causes each brace 32 and 34 to pivot relative to link 37, and
move to a generally upright engaged position, as shown in Figures 2, 3, 5, and
6. Conversely, cylinder 36 is retracted to selectively lower the braces to a retracted
position where braces 32 and 34 are disposed parallel to the driveway, as shown
in Figures 4 and 7. The retracted position of braces 32 and 34 is chosen so that
the braces present little or no impediment to a vehicle approaching the dock.
As used herein, the term "engaged position" is not limited to positions
where a brace or braces actually makes physical contact with a swap body leg,
Rather, "engaged position" denotes a range of positions in which a brace (or a portion
thereof) is either in contact with the leg, or in such close proximity thereto
that small movement of the leg would cause it to contact the brace.
While the swap body restraint according to this design could be fixed
in place on the driveway relative to the dock, containers 10 can be inconsistently
placed on the driveway relative to the dock. Also, different containers have different
leg positions. It may thus be advantageous to have the leg restraint be capable
of movement relative to the driveway and to the dock to adjust to different leg
positions, Of course, it is also desirable to lock the restraint in place once
Toward that end, a restraint incorporating clamping-type braces 32
and 34 may include a locking arrangement that allows the braces to move relative
to the dock when retracted, but that locks them in place once moved to a raised,
engaged position relative to the legs. In one example of such a locking arrangement,
an elongated toothed member 44 is fixed relative to the driveway, such as by being
fixed to the upper flange of an I-beam 43 disposed within a recess 45 in the driveway.
Each brace 32 and 34 includes a member 42 that is disposed on brace 32 and 34 so
as to engage member 44 when the brace is in its upright, engaged position relative
to a leg 23 of the container. At the same time, members 42 are disposed to move
out of engagement with member 44 as the braces 32 and 34 move toward the retracted
position. This locking arrangement thus takes advantage of the approximately 90
degrees rotation of braces 32 and 34 between their engaged and retracted positions
to move members from a locking engagement with member 44 to a spaced position
When braces 32 and 34 are in the retracted position, they are thus
free to move relative to the loading dock. Illustratively, such movement may be
facilitated by one or more rollers 48, which roll over the top surface of I-beam
43. In operation, then, the clamping-style restraint can be first properly positioned
relative to leg 23, and then actuated into its engaged position relative thereto.
As a further advantage of this design, support structure or I-beam 43 can also
serve as a landing pad for receiving leg 23, making up for inconsistency or unevenness
in the driveway surface.
It should be understood that a clamping-type restraint, as shown in
Figures 2 - 7 could be implemented using structures besides these shown. For example,
other extendible/retractable actuators could be used in place of the piston/cylinder
36. Moreover, such an actuator could be used and, if properly oriented relative
to braces 32 and 34, could retract (shorten) to move the braces from the retracted
to the stored position, instead of the opposite as in the disclosed embodiment.
Other elements could also be used to form the locking arrangement or mechanism,
as the toothed members represent only a presently preferred arrangement. Other
support structures are also possible.
For example, a brace 52 of Figures 8 - 13 is a support structure whose
location on driveway 28 is readily adjustable to align to the various positions
at which container legs 21 may rest upon driveway 28. Containers of various lengths
and a truck/trailer failing to set a container down at a precise location, may
call for a brace having two degrees of positional adjustment; longitudinally (to
and from the dock) as well as some lateral adjustment. Also, a support structure
establishing a firm vertical datum for the container might help in vertically aligning
the inside floor of the container to an upper platform 29 of the dock. In some
installation sites, electrical service, hydraulics, pneumatics and other power
may not be available or economical to provide, so a manually or mechanically operated
support structure may be preferred.
To this end, brace 52 is a manually operated leg support structure
whose position is adjustable both laterally and longitudinally along driveway 28.
A carriage assembly 53 manually slid along a track 68 provides brace 52 with longitudinal
adjustment (reference numeral 80 of Figure 12). An anchor pin 70 pivotally couples
track 68 to driveway 28 to render the position of brace 52 laterally adjustable
(reference numeral 72 of Figure 13) by way of rotating track 68 about pin 70. Track
68 also provides a firm landing pad upon which a container leg 21 can rest.
To restrain leg 21, carriage 53 includes a hinge 58 having a longitudinal
axis 56 about which a U-shaped channel 54 swings from a released horizontal position
(Figures 10 and 12) to a generally upright engaged position (Figures 9 and 11).
In the engaged position, channel 54 at least partially surrounds one of the container's
legs to help maintain the leg in its normally upright position and help prevent
the leg from slipping horizontally. As channel 54 swings upward to its engaged
position, it may also be advantageously locked in place. Toward that end, a locking
member 60 coupled to channel 54, by way of a support 81 and a channel 83, protrudes
through opening 64 (Figure 12) to engage an elongated toothed member 62 (e.g.,
a gear rack) that is fixed relative to track 68. Locking member 60 engaging rack
62 prevents further longitudinal movement/adjustment of carriage 53 once leg 21
is engaged by brace 52. With leg 21 restrained, a latch 74 engages support 81 to
prevent channel 54 from falling back down to its release position. Manually actuating
latch 74 allows channel 54 to be manually lowered to its release position. Once
released, carriage 53 can be moved along track 68 while assisted by a roller 76
extending from support 81 and assisted by a bearing pad 78 that slidingly couples
channel 66 and an angle 67 to track 68.
In operation, a truck delivers a swap body container to the driveway
of the parking or loading dock area, and the initial lowering of the container's
legs serves to point out the general location at which track 68 and carriage 53
should be positioned. Once brace 52 is properly positioned, the truck lowers the
container until it is self-supported by its legs resting upon track 68 and driveway
28. Support 81 is then raised to the generally upright engaged/locked position
where it partially surrounds leg 21. This helps prevent leg 21 from sliding longitudinally
away from the dock or leaning too far away from the dock. When the loading or unloading
of the container is complete, actuating latch 74 releases support 81, so that support
81 may be lowered back down to allow a truck to remove the container from the area.
It should be noted that a brace that approaches a container leg from
the side, as in the embodiment of Figures 8 - 13, could be implemented using structures
besides these shown. Tilting the channel brace 54 can be powered by hydraulics,
pneumatics or even by the weight of the container being lowered onto the track.
Further, the actuator itself could incorporate the holding function of latch 74.
Other elements could also be used to form the locking arrangement or mechanism,
as the toothed members 60 and 62 represent only a presently preferred arrangement.
Another example of a manually adjustable leg support is provided by
a brace 82 that extends between an upper portion of leg 21 and driveway 28, as
shown in Figure 14. In this embodiment, brace 82 includes an upper member 84 and
a lower member 86 with upper member 84 having a bracket 85 that is U-shaped to
effectively engage the upper portion of leg 21. From its enlarged perspective view,
bracket 85 is shown to include two protrusions 87 that help hold bracket in place
by straddling leg 21. Lower member 82 is attached to a base 88. Base 88 can be
coupled to driveway 28 by relying simply on friction alone between the two or by
permanently or removably pinning base 88 to driveway 28 to provide a more solid
connection. Providing brace 82 with an adjustable length 90 accommodates variations
in leg position. In one embodiment, the adjustable length is accomplished by having
one member 82 or 84 telescope within the other, while a removable pin 92 selectively
locks and releases the two.
In another embodiment, the adjustable length is provided by a brace
94 that incorporates a manually operated hydraulic jack 96, as shown in Figure
15. As with the brace of Figure 14, brace 96 includes an upper member 85 that is
shaped to effectively engage leg 21, while a lower member of jack 96 is pivotally
attached to a base 98. However, greater variations in leg position are accommodated
in this embodiment by having the position of base 98 be adjustable in a longitudinal
direction 102 along a track 100 that is anchored to driveway 28. Once properly
positioned, base 98 is clamped or otherwise fixed to track 100 by any conventional
holding or positioning mechanism including, but not limited to, a pin and socket,
mechanical clamp, lead screw and nut, piston/cylinder, rodless cylinder or some
other type of actuator. With container 12 parked, base 98 is moved along track
100 to a position where jack 96 can reach to place upper member 85 into engagement
with the upper portion of leg 21. Base 98 is then fixed to track 100 and jack 96
is extended to have upper member 85 firmly engage leg 21, thereby restraining container
Other embodiments of a pivoting leg restraint accommodate for various
leg positions by varying the extent to which the restraining member pivots. In
Figures 16 and 17, for example, a brace 108 with a laterally extending arm 116 is
pivotally coupled to a base 110, which in turn is anchored to driveway 28, An
actuator, e.g., piston/cylinder 104, acts between a stationary surface such as driveway
28 or dock 26 and brace 108. The actuator retracts to move brace 108, about a lateral
axis 112, from a retracted position 114 (shown in phantom) to an engaged position.
After moving to the engaged position, cylinder 104 is adapted to hold it there.
In the engaged position, laterally extending arm 116 engages a forward side 118
of leg 21 at an elevation above where leg 21 connects to its corresponding leg
brace 23. This allows brace 108 to urge leg 21 towards dock platform 27, while
avoiding bending stresses in the leg that might otherwise exist if arm 116 were
to engage leg 21 below leg brace 23. In this embodiment, the closer the leg is
to dock platform 27, the more brace 108 pivots, and the higher arm 116 engages
the leg. For example, leg 21 of Figure 16 is closer to dock platform 27 than is
leg 21' of Figures 17. Accordingly, arm 116 engages leg 21 higher than it does
Cylinder 104 extending lowers brace 108 to release swap body 10.
Although in this embodiment, the movement of brace 108 is carried out by a cylinder
acting upon a lug 106 that extends from brace 108, various other actuators and
connections that could couple the actuator to the leg restraint are well within
the scope of the invention. For example, actuator 104 could be coupled directly
to brace 108 rather than through lug 106, and actuator 104 could act upon the opposite
side of brace 108 rather than as shown, which would cause the extension of cylinder
104 to lift the brace up instead of lower it. And the actuator itself does not
necessarily have to be a piston/cylinder. Examples of other actuators that would
also work would include, but not be limited to, a lead screw and nut, a motor driven
linear actuator, and a winch.
Another example of an actuator would include manual actuation with
a counter balance, as shown in the embodiment of Figures 18 and 19. A brace 122
is similar to brace 108, but with cylinder 104 replaced by a tension spring 124
co-acting with a ratchet-type locking device 126. Spring 124 reduces the force
needed to manually lift brace 122 from a retracted position of Figure 18 to an
engaged position of Figure 19. Once in the engaged position, ratchet 126 helps
hold brace 122 in place. Ratchet 122 is schematically illustrated to represent
any one of a variety of locking devices including, but not limited to, a Rite-Hite
Model Releasable Hold-Down. Assembly, which is disclosed in US Patent No. 3,699,601
and specifically incorporated by reference herein.
Another variation of the leg restraint of Figures 16 and 17 is to
make laterally extending arm 116 retractable to allow the wheels of the truck more
room on the driveway as the truck delivers or removes a swap body, This can be
done in variety of ways, but in one exemplary embodiment (shown in Figures 20 -
23) a leg restraining arm 130 retracts and extends automatically in reaction to
a brace 132 moving between its release position (Figures 20 and 21) and its engaged
position (Figures 22 and 23). In this example, brace 132 pivots about an axis or
pin 134 supported between two side members 136, which in turn extend upward from
a base 137 that is anchored to driveway 28. An angular support 138 pivotally couples
brace 132 to a carriage 140 (138 and 140 are not shown in Figure 23 for clarity).
Carriage 140 moves (e.g., slides or rolls) along a track 144 as brace 132 pivots
about 134. With a brace powered up and/or down, carriage 140 and track 144 schematically
represent an actuator such as a lead screw and nut, piston/cylinder, or some other
conventional actuator or drive unit that moves brace 132 up and/or down. Conversely,
with a manually operated brace (depicted in Figure 24, and bearing the same reference
numerals as Figures 20-23, but supplemented with a prime, as in 140'), carriage
140' simply follows the motion of brace 132' as brace 132' is lifted or lowered
manually. With the manual brace, carriage 140' includes a manually releasable
locking element that selectively locks onto and releases track 144' in a manner
well known to those skilled in the art or similar to those already explained (e.g.,
releasably engaging an elongated tooth member, such as a gear rack). Regardless
of the how brace 132 is moved, a connecting rod 146 forces leg restraining arm
130 to pivotally extend (Figure 23) and pivotally retract (Figure 21) about a pin
148 that couples arm 130 to brace 132. An angularly compliant coupling, such a
rod bearing 150, is at each end of rod 146 to couple a pin 152 of side member 136
to another pin 154 that extends from arm 130. As brace 132 pivots upward about
pin 134, pin 148 moves farther away from pin 152, while pin 154 does not due to
the fixed length of rod 146. Consequently, arm 130 extends. The reverse happens
as brace 132 pivots back down, It should be noted that the mechanism to extend
and retract arm 130 in reaction to moving brace 132 represents just one many possible
ways in which this can be carried out, or example, arm 130 could retract linearly
or pivot in other directions, such as 180 degrees from the its position shown in
Further, the extension of arm 130' is slightly different in the manual
embodiment of Figure 24. A tab 160' is fixed for rotation with pin 148'. As brace
132' is raised, pin 148' moves further from pin 152' than does the end of tab 160'
coupled to rod 146' at angularly compliant coupling 154'. This exerts a torque
on pin 148' causing arm 130' to rotate and extend. Note that rod 146' may be adjustable
in length, yet includes a stop to limit its extension to ensure rod 130' is properly
extended and retracted.
Further still, each restraint shown herein could be provided with
a means for sensing when the restraint is in an engaged and/or locked position.
Appropriate visual signals (red lights, green lights, etc.) or audio signals could
be connected to this sensing means to give dock personnel, drivers and the like
appropriate indications that the swap body either is or is not properly restrained
Although the invention is described with respect to a preferred embodiment,
modifications thereto will be apparent to those skilled in the art. Therefore,
the scope of the invention is to be determined by reference to the claims, which