Although the majority of loading dock areas has a level approach to the building declining approaches is common and precautions must be taken with a declining approach at time of the building construction.
At a level approach area the truck backs into position and stops when the rear of the truck contacts the dock bumpers. From a side view perspective, the truck is basically in position square to the face of the building foundation wall and the exterior building wall.
Without taking precautionary measures and with a declining approach at the loading dock area the top of the trailer may make contact with the building wall above the overhead door before the rear of the truck made contact with the dock bumpers. This impact would cause damage both to the building wall and the top of the trailer. At a declining approach the loading dock area should be designed to stop the incoming truck in the correct position without damaging the exterior wall surface or the top of the trailer. Basically stop the truck further away from the building wall to avoid impact. The greater the decline the more likely it is impact will occur. Smaller decline approaches may not require the dock to be cantilevered.
Stopping the truck further away from the building wall is achieved by designing a projected pit, also referred to as a cantilevered pit. This following link illustrates a projected/cantilevered pit.
https://www.pentalift.com/wp-content/uploads/2020/11/Projected-Pit-Dock-leveler-Benefits-1-1.pdf
At each loading dock position a section of the buildings concrete foundation wall is projected forward. The dock bumpers are installed on the face of this projected foundation wall stopping the trucks further forward and away preventing impact damage to the building wall or the top of the trailer.
The percentage of decline towards the loading dock varies and determines the number of inches to project the pit forward beyond the face of the main concrete foundation wall. For example an 8 percent decline over 50’ would result in projecting the pit 8” beyond the face of the main foundation wall, a 6 percent decline over 50’ would result in projecting the pit 6” beyond the face of the main foundation wall etc.
Loading docks equipped with compression style dock seals at a declining approach should have tapered side pads manufactured in relation to the percent of decline to assure an even seal when the truck is in position.
For example if it’s a 6 percent decline the dock seal side pads should have 6” more projection on the bottom than on the top of the side pads. Tapered dock seal side pads provide an efficient and even seal top to bottom without putting undue stress on the building wall due to over compression at a projected pit installation.
If a vehicle restraint is to be utilized consideration and adjustments may be required to accommodate proper orientation based on the cantilevered dock.
For additional information on projected loading dock pits or any Pentalift product please contact the Pentalift Sales Department.