The majority of loading docks that are equipped with dock seals have a level approach. Compression style dock seals perform best with 4” – 6” of foam compression with the truck backed into position tight to the face of the dock bumpers. With less compression the seal is not as effective. With over compression the seal may be damaged.
With a declining loading dock approach the truck backs down a ramp towards the loading dock therefore the dock seals must be designed to accommodate for this non level vehicle approach.
In a declining approach it is very important that the dock seal be specified correctly to provide an effective seal by eliminating any gaps between the dock seal and the back of the truck.
Uneven pressure on the building wall due to over compression of the dock seal can lead to more stress and friction on the dock seal covering material resulting in product damage as well as increase the risk of damaging the buildings wall.
This link leads to the description of a declining dock approach.
https://www.pentalift.com/wp-content/uploads/2020/11/Projected-Pit-Dock-leveler-Benefits-1.pdf
If the decline is calculated to be 4% there will already be a 4” foundation build out for the dock bumpers to be installed on.
The dock seal side pads should project 4” more at the bottom of the side pads than the top of the side pads to provide an effective, even compression seal as the truck backs down the 4 percent decline. With a 6 percent loading dock decline the dock seal side pads should project 6” more at the bottom of the side pads than the top to provide an effective compression seal, etc.
A declining approach can make it challenging for dock seals to create a tight seal between the back of the truck and the building wall.
Providing a dock seal with 1” of extra projection per percentage of decline on the bottom of the side pad in comparison to the top of the side pad will provide an even compression seal throughout the height of the side pads.
A future blog will provide information on declined approaches relative to the dock leveler and vehicle restraint.
For additional information on Pentalift loading dock products please contact the Pentalift Sales Department