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Glossary

 
Data transmission The use of sensors to transmit data via pulse-modulated light beam systems typically from host stations to mobile carriers such as AGV's or stacker cranes.
 
DC In electrical terms, direct current (as opposed to AC which is alternating current).
 
Deadband An unusable area extending from the face of an ultrasonic proximity sensor to the minimum sensing distance allowing for target detection where pulses are received too quickly to be accurately evaluated.
 
Decking The material, generally made from welded wire, that is placed on shelves, rack load beams or walks to support loads of variable sizes.

The decks or flooring of a mezzanine can be made of several different types of materials depending upon the requirements, features and capacity of the mezzanine. These flooring/decking options may include bar grating, plank grating, wood planking, plywood, composite materials and cement.
 
Decking section A completely fabricated decking assembly with reinforcing members ready for installation upon supporting storage rack framing.  One or more decking sections are used to form a shelf surface.
 
Deflection The amount of deformation or bending in a pallet or pallet component under load.
 
Deflector

A stationary or moveable angled arm which deflects product flow access across a belt or roller conveyor to the desired location.
 
Demurrage

A term associated with the charge (monetary) that can be levied against a shipper or consignee who detains a container, truck, ship or railroad car beyond the allotted time for loading and unloading of that piece of transport equipment.

Such a monetary "penalty" is used to offset the loss to the carrier as a result of the delay.  "Detention" is another work used for demurrage.
 
Detachable frame pallet A pallet that features a frame or superstructure that is removable.
 
Direct thermal label A label that is printed using a direct thermal printer.  Advantage to thermal labeling/do not use ribbons.
 
Dispersion angle The degree of the angle of light.
 
Diverter A device on a conveyor sortation system used to move a case/carton/piece off the main line.
 
Dock The sorting or staging platform where shipments are loaded or unloaded.
 
Dock board A device for bridging the gap between the warehouse and/or loading dock platform and a vehicle's load bed.
 
Dock bumper Pieces of rubber located at the floor level of a dock opening to cushion the building from truck trailer impact.
 
Dock face The outside wall of the dock door area.
 
Dock leveler A manually, hydraulically, or electrically operated plate, located at the dock entrance, that can be raised and lowered to accommodate varying trailer floor heights.
 
Dock lift A lift whose travel is generally 5 feet (1524 mm) or less and which is primarily used to load/unload material from trucks and transfer it to dock or ground elevation.
 
Dock plate A moveable metal ramp that allows access to a rail car or trailer.
 
Dock seal A rubber or canvas covering that extends out from a dock face to seal the gap between the dock and the trailer's entrance.
 
Dock shelter A cover that protects the space between the door of a rail car or truck and a warehouse from inclement weather.
 
Double deck pallet A pallet constructed of both a top and bottom deck or deckboards.
 
Double deep rack

A racking system that is used where a greater storage density is required. It accommodates two pallet loads stacked back-to-back and requires special fork trucks called reach trucks.
 
Double girder crane An overhead traveling bridge crane that utilizes two bridge beams set atop the runway (end) trucks.  Generally this type of crane utilizes a top running trolley hoist which moves along the top of the two bridge beams on its own set of trucks/trolley wheels.  The hook from the hoist "falls" between the two bridge beams.  Headroom under the crane is increased by utilizing this hoist/crane configuration.
 
Double leg gantry An overhead traveling crane designed so that the bridge carrying the trolley or trolleys is rigidly supported on two or more legs moving on fixed rails embedded in the floor (via end trucks attached to the bottom of each leg) or on wheels.
 
Double row, double face shelving One generally continuous row of units joined together, back to back and side to side to be serviced from two service aisles.
 
Double wing pallet A pallet constructed in such a way as to have the top deck extending out from opposite sides.
 
Drawer storage

Storage utilizing drawers in cabinets or within shelving systems and are suitable for applications where volume of inventory turnover is low and where smaller items are being stored.
 
Drayage Transportation of materials and freight on a local basis, but intermodal freight carriage may also be referred to as drayage.
 
Drive in rack This type of rack utilizes upright frames, rails, and ties to allow a vehicle to enter a storage rack structure from one side only and pick up or deliver pallets on continuous rails.  Drive-in rack is used to address repetitive products and serves to take advantage of cubic space available for storage, when such unit loads do not lend themselves to block stacking.
 
Drive through rack

This rack is similar to drive-in rack except that the fork truck is capable of driving straight through the structure at any storage location along the aisle.
 
Drop cantilevered jib crane Similar to a full cantilevered jib crane with the exception of a column or beam connection that allows the load beam or boom to be mounted at any point on the column or mast.
 
Drum turner An attachment to a fork truck, lift table or below-the-hook on a hoist that enables that piece of equipment to turn over drums for filling and emptying.
 
Dunnage Materials or devices used in the securing and/or bracing of products during shipments.
 
Dynamic storage system

A storage system that provides varying means of either mechanically moving storage locations or loads within the systems so as to increase storage density and/or to increase storage, retrieval and order picking throughput.