A hydraulic dock lift is an example of material handling equipment in use at the loading dock area that receives a static load.
In a truck loading application the dock lift is in the lowered position and a load is slowly driven/pushed onto the dock lift platform and stopped. The dock lift then raises the static nonmoving load to the truck bed height and the product then slowly transitions off the platform onto the truck bed.
A dock leveler is an example of materials handling equipment at a loading dock area receives a dynamic load.
In a truck loading application the dock attendant activates the dock leveler, the deck raises, the hinged lip assembly extends and the deck with the lip extended is lowered to the truck bed.
A moving loaded lift truck now approaches and crosses the dock leveler deck and lip at speed. This dynamic or moving load force creates an instant load impact to the dock leveler structure primarily to the rear deck hinges, the deck itself and the hinged lip assembly. The dynamic load in motion increases the load force that the dock leveler receives.
The faster the lift truck crosses the dock leveler or the steeper the incline of the dock leveler deck assembly as the lift truck crosses further magnifies the impact forces to the dock leveler structure.
Due to the differences between static and dynamic loading at the loading dock area it is possible to have both a dock lift and a dock leveler in operation loading the same load weight but with different load capacity ratings on the equipment.
For example a 12,000 lb. load slowly moving onto a dock lift platform, then raised and slowly moved off the dock lift platform could be accommodated by a 12,000 lb. capacity rated dock lift.
To accommodate the same 12,000 lb. load now moving at up to 5 mph across an inclined dock leveler deck assembly requires a completely different (higher) load rating to accommodate the moving load (dynamic) impact forces.
In simplistic terms to calculate the required dock leveler capacity first determine the actual total load weight crossing the deck assembly. In this case its 12,000 lbs., multiply this weight by a factor of 2.5. to determine the minimum dock leveler capacity rating, using this weight as an example the dock leveler should be rated at a minimum of 30,000 lbs. capacity.
At a busy loading dock area, multi shift loading dock area or if there is a noticeable height differential between the truck bed and floor height the capacity rating should be further increased based on site conditions. For more details relative to dock leveler capacity refer to dock leveler webpage: https://www.pentalift.com/solutions/dock-leveler-capacity-understanding-loading-dock-capacity/
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