Patent Application
20200324987
This disclosure relates generally to sealing devices for loading docks and, more specifically, to an actuated head pad.
Most warehouses, manufacturing facilities and large retail stores include loading docks that provide a location for loading and unloading trucks and trailers. Loading docks typically include an opening in the dock wall sufficiently large to accommodate the interior region of all types of trucks and trailers. A raised loading platform positioned below the opening is roughly even with the loading dock floor. A truck or trailer backs up toward the loading dock until the rear of the cargo compartment engages the dock. The cargo compartment of the truck is thus roughly aligned with the opening of the loading dock. The truck or trailer may have an overhead door or, more commonly, hinged panel doors that swing open and are stowed against the side of the trailer.
The loading platform may include a dock leveler that provides a ramp to compensate for height differences between the loading platform and the floor of the trailer cargo area. The leveler pivots between downwardly inclined, upwardly inclined, or horizontal positions to permit forklift trucks and personnel to readily move in and out of the trailer cargo area during loading and unloading operations.
In some loading dock operations, there is a large temperature difference between the inside of the truck cargo area and the outside environment, or between the interior of the loading bay and the outside environment, or both. For example, a refrigerated trailer may dock to a refrigerated loading bay, and there may be a large temperature difference between the vehicle cargo area/loading bay and the outside environment. The cargo may include perishable items or items required to be kept cold to comply with government regulations. Both the trailer's refrigerated cargo area and the refrigerated loading bay may be controlled to approximately the same temperature, but the outside environment may be significantly warmer. In another example, the loading bay may be part of a building situated in a cold climate. The loading bay may be heated to a comfortable temperature for employees, while the outside temperature may be well below freezing. In yet another example, the loading bay may be in a building located in a hot climate. The loading bay may be air-conditioned to a comfortable temperature for employees, while the outside temperature may be hot and humid.
In each of the above examples, if the cargo area of the truck is not properly sealed against the loading dock door, gaps will form and permit leakage between the ambient air and the temperature-controlled environment. Sealing the cargo area of the vehicle from outdoor environmental conditions can be an important requirement of a loading dock structure, particularly when the cargo and the receiving dock are refrigerated. To address this need, dock seals and dock shelters have been designed to prevent the ingress of outdoor environmental conditions or contaminants (e.g., rain, snow, wind, hot/cold temperatures, insects, animals, etc.) into the interior of the dock area and cargo area of the vehicle during the loading or unloading of the vehicle. Dock shelters and dock seals also address the need to prevent the egress of refrigerated air from within the loading bay and/or vehicle cargo area to the outdoor environment.
Typically, dock seals and dock shelters include vertical members along opposing sides of the loading bay door and a horizontal head pad extending across the top of the door opening. The pads are commonly made from a wear-resistant fabric (e.g., urethane-coated fabric) surrounding a resilient material such as foam that is compressed when the back of the truck or trailer is positioned against the loading dock. However, the head pad often experiences much more wear than the side pads, and can become dislodged from its mounting structure, resulting in loss of seal and eventually expensive and time-consuming replacement.
In one aspect of the invention, a head pad assembly for a loading dock includes a frame structure secured to a loading dock wall and a head pad portion coupled to the frame structure. The head pad portion is positioned above and extends across an opening to the loading dock, and is moveable between an upper position and a lower position. The head pad portion includes a compressible pad. The upper position of the head pad is not configured to provide a sealing function against a truck or trailer, and the lower position is configured to engage and seal the compressible pad against a roof surface of the truck or trailer.
In another aspect of the invention, a loading dock sealing apparatus includes first and second vertical seal members positioned on either side of an opening to the loading dock. The loading dock sealing apparatus further includes a head pad assembly positioned above and extending across the opening. The head pad assembly includes a head pad portion moveable between an upper position and a lower position. The head pad portion includes a compressible pad configured to provide an environmental seal against a trailer roof when in the lower position.
The features described herein can be better understood with reference to the drawings described below. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views.
Conventional dock seal structures include two vertical seal members on either side of the door opening and a horizontal head pad over the door opening. Typically, a trailer backs into the pliant dock seal structure to compress it and form a face seal along the vertical and horizontal edges of the trailer frame. One noted difficulty with loading dock operations is that a trailer will move downwards or upwards as much as four inches as the weight of the cargo increases or decreases during loading or unloading. As a result, the trailer's vertical displacement may unseat the face seal formed between the top edge of the trailer frame and the head pad structure. In addition, during loading and unloading operations a forklift moving in and out of the trailer often causes the trailer to ‘bounce’ which can disrupt the face seal and chafe the head pad material.
Another noted problem arises from differing trailer heights and door openings. In particular, some taller trailers may squash the bottom of the head pad into the door opening, such that it may obstruct loading and unloading operations. The exposed, obstructing portion of the head pad may be subject to repeated hits by pallets and the like, resulting in damage to the head pad, such as ripping and tearing.
Yet another noted problem with conventional head pad structures arises when the trailer is positioned with a trailer jockey (or yard jockey). The trailer jockey raises the front of the trailer higher than the back end, and when the back end is pushed into the pliant dock seal structure, the trailer is actually pivoted and the contact force is concentrated along the upper edge of the trailer frame, rather than equally distributed over the entire face of the frame. In a worst case scenario, the pivot angle is large enough to cause the top of the trailer to hit the building before bottom of the trailer contacts the loading dock bumpers. When the jockey lowers the trailer, the pivot angle decreases but the rotation of the top edge of the trailer frame, which is jammed into the head pad, can cause large shearing forces that may result in damage to the head pad, such as ripping and tearing. If the jockey is not removed prior to loading or unloading operations, as is sometimes the case, large shearing forces in the head pad can still occur as the trailer moves up or down due to the weight of the cargo increasing or decreasing.
Embodiments of the present invention solve these problems by providing a head pad assembly that lowers down onto the roof of the trailer. The head pad assembly includes a stationary portion that may be fixed to the building, and an actuated head pad portion that is moveable between an upper position and a lower position. The head pad remains in the upper position above the loading dock opening until the trailer engages the vertical seals and bumper. Then, the resilient head pad is lowered to engage the trailer roof. A sufficient pressure or force is applied to hold the head pad against the trailer roof, thereby effecting a seal from the outside environment. Any jarring movement (vertical or otherwise) by the trailer during loading or unloading operations is absorbed by the resiliency of the head pad material. Damage to the head pad caused by shearing forces is eliminated since the head pad engages the trailer roof, and not the face of the trailer frame. Additionally, since the head pad lowers from above the trailer, it will not obstruct the opening when moved to the lower position.
For purposes of illustration and to further explain orientation of certain features of the invention, a lateral axis is defined as substantially parallel to the loading dock wall and is denoted as the x-axis; a longitudinal axis is defined as substantially in the direction of vehicle motion when backing into the loading dock and is denoted as they-axis; and the vertical axis is denoted as the z-axis.
Referring to
Referring to
While the drawings have illustrated the vertical seals 22, 24 as roughly rectangular or trapezoidal in cross section, it is contemplated that other seal configurations, both conventional and otherwise, may be utilized without departing from the scope of the invention. For example, the vertical seals may have a U-shaped cross section, such as the U-Seal Non-Compression Dock Seal available from DL Manufacturing, North Syracuse, N.Y.
The loading dock sealing apparatus 10 further includes a mechanically actuated head pad assembly 32 that includes a moveable head pad portion 34. The head pad portion 34 is moveable between an upper, non-sealing position and a lower, sealing position. Stated another way, the head pad traverses vertically in a downward motion to compress and seal against the roof of the docked trailer, then raises away from the roof when loading operations are complete and trailer is ready to be moved. The moveable head pad portion 34 can include a compressible pad 36 that is configured to provide an environmental seal against the trailer roof to seal off the dock opening 12 from outside conditions. The pad 36 may be formed of polyurethane foam, for example. The moveable head pad portion 34 can further include a rigid backbone 38 to provide strength and dimensional stability to the head pad assembly 32. The backbone 38 may be formed of any suitable strong material that will withstand the weather elements, such as stainless steel. In the illustrated example, the backbone 38 is formed from 2×8 lumber. The pad 36 may be glued to the backbone 38, for example, or secured with fasteners. The pad 36 and backbone 38 can be overwrapped with a heavy gauge vinyl skin, similar to the vinyl overwrap used on the vertical seals 22, 24.
In the illustrated embodiment of the invention, the moveable head pad portion 34 includes two separate structures fastened together with one or more brackets 40. Each structure may include a compressible pad portion 36A, 36B (hidden) and a rigid backbone portion 38A, 38B. Together, the pad 36A and backbone 38A may be roughly rectangular in cross section. In one example, the head pad 36A and backbone 38A may be 8 inches to 16 inches thick (in the z-direction), and 18 inches to 24 inches deep (in the y-direction). In one embodiment, the head pad 36 may be formed of variable density foam to better control the compression characteristics. In one example, the upper portion of the foam body may be more dense than the bottom, so as to provide more weight pushing down to effect a seal.
In one embodiment of the invention, an auxiliary seal 42 can be used to provide an extra measure of sealing capability. In one example, the auxiliary seal 42 can be formed from closed cell sponge rubber, such as EPDM per ASTM D1056-2A5, it can have a tubular or partially tubular cross section, and can adhere to the front and underside surface of the head pad 36A.
Turning now to
In one embodiment of the invention, the vinyl overwrap can include a flap of material 44 that abuts the seal member 22 and remains in contact with it as the head pad portion 34 traverses upwards and downwards. The head pad portion 34 may include a flap 44 extending laterally (i.e., in the x-direction) to contact the front surface 26 of the vertical seal members. In other embodiments, the head pad portion 34 may further include another flap 44 extending longitudinally (i.e., in the y-direction) to contact an inside surface 46 of the vertical seal member (shown best in
The moveable portion of the head pad 34 may be unguided as it traverses up and down to engage with the top of a truck trailer. That is, a lifting mechanism could simply lower the head pad 34 onto the trailer, then lift it back up when the truck is ready to depart. In this configuration, there would be no lateral (i.e., side-to-side) or longitudinal (i.e., forward-and-backward) alignment of the head pad 34. In many scenarios this configuration is adequate.
In one embodiment of the invention, however, it may be desirable to use a guide system to align the vertical path of the head pad 34. Turning now to
The guide track 50 may comprise a U-shaped channel similar to the guide track commonly found in overhead door installations. In the illustrated embodiment, the guide track 50 is anchored to the same mounting block 56 as the vertical seals 22, 24. The mounting block 56 is anchored to the outside wall 14 of the loading dock. The mounting block 56 may be adapted to define a recess in which the guide track 50 can be flush-mounted.
In an alternate embodiment, not illustrated, the guide tracks 50 can be outside-mounted relative to the vertical seals 22, 24, rather than inside-mounted. In this configuration, the guide track 50 can still anchor to the mounting block 56, but a longitudinally-extending guide arm would be required to jut past the full depth of the vertical seals 22, 24. The width of the moveable portion of the head pad would then extend laterally past the vertical seals 22, 24 when joined to the guide arms. The rear portion of the head pad 36B previously disclosed would probably not be used.
In another embodiment of the invention, additional environmental sealing can be realized by incorporating a brush seal in addition to, or instead of, the fabric flap 44 on the moveable head pad portion 34. In one example, a first brush seal 58 can be mounted horizontally along the rear angled surface of the backbone 38B, with bristles facing the vertical seal 22, 24. The brush seal 58 can extend rearward such that it is in contact with, and therefore seals against, the guide track 50.
In a similar manner, a second brush seal 60 can be mounted to the endcap 52 in a vertical orientation and extend the entire height of the backing plate 48. The bristles can extend past the plane of the mounting block 56, such that they will contact, and therefore seal against, the inner wall of the dock door opening 12.
Returning briefly to
Turning now to
The head pad assembly 32 may further include an actuator assembly 74 configured to move the head pad 34 between the upper position and the lower position. In one embodiment of the invention, the actuator assembly 74 includes a motor 76 and a linear drive actuator, which may be mounted essentially horizontally to save space under the canopy 62. A cable and pulley system may be utilized to convert the horizontal travel of the actuator shaft 78 to a vertical motion. In one example, three lengths of 3/16″ steel cable 80 may be secured to the tip of the actuator shaft 78, passed over horizontal pulleys 82, then passed over vertically-oriented pulleys 84, then secured to the cable termination hardware 72.
When not in use, the head pad assembly 32 is stowed in its highest raised position so as to not interfere with a trailer backing up to the loading bay overhead door. Referring briefly to
Turning now to
A command signal may then be initiated to lower the head pad assembly 32. The command signal may be manual, such as by manually pressing a button or switch, or the signal may be tied to a safety interlock system, such as the Smart Chock trailer restraint system available from DL Manufacturing, North Syracuse, N.Y. The motor 76 drives the actuator shaft 78 through its range of motion, which slowly lowers the suspended head pad assembly 32 down onto the roof of the trailer, as shown by the shaded area. In one embodiment, the weight of the moveable portion is sufficient to compress the foam head pad 36 against the roof of the trailer and effect a satisfactory seal.
The head pad assembly 32 may include sensors to provide data input to a safety interlock system. In one example, a proximity sensor 86 may provide confirmation that a trailer is parked at the dock. The trailer proximity sensor 86 may be mounted to the frame of the head pad assembly 32, for example on the forward support channel 64, so the sensor remains stationary.
The head pad assembly 32 may further include a sensor to provide feedback when the head pad is seated against the trailer roof. One possible implementation is based upon the observation that the tension in the cable 80 will go slack when head pad seats against the trailer roof and the actuator assembly 74 continues to extend the shaft 78. Turning to
There are many improvements over the prior art associated with the disclosed head pad assembly. One of the improvements is that the head pad does not compress against the loading dock wall. The compressive force applied by prior art head pads can be substantial, especially when a yard jockey applies a concentrated load. The longitudinal force against the building is not only detrimental to the building, but also may result in shear forces on the pad when trailer moves up and down, which increases wear on the fabric overwrap. Embodiments of the invention disclosed herein eliminate this problem.
Another improvement is that a better seal is effected because the degree of compression is controlled and repeatable, instead of variable with each truck driver. One benefit of this improvement is that rain water is prevented from leaking onto the dock leveler or the shipping product.
Another improvement is that there is no possibility of the head pad obstructing the door opening, which may be the case with fixed-position head pads and tall trailers.
Reference is made to and this application claims priority from and the benefit of U.S. Provisional Application Ser. No. 62/343,146, filed May 31, 2016, entitled “ACTUATED DOCK SEAL”, and U.S. Provisional Application Ser. No. 62/385,157, filed Sep. 8, 2016, entitled “ACTUATED DOCK SEAL”, which applications are incorporated herein in their entirety by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2017/043439 | 7/24/2017 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62343146 | May 2016 | US | |
| 62385157 | Sep 2016 | US |
