Glossary D

Differential gear is defined as a bevel gear that permits rotation of two shafts at different speeds.

Demand is a term to denote the amount of goods people are willing and able to buy at a given price; often coupled with supply.

Dyes are characterized as a synthetic or natural organic chemicals that are soluble in most common solvents. Characterized by good transparency, high tinctorial strength, and low specific gravity.

Diethylamine refers to a fabric dye that is harmful to aquatic organisms.

Die-cutting refers to the use of a sharp, formed piece of metal to cut out specific shapes in a piece of paper.

Drawing is a term used for a variety of forming operations, such as deep drawing a sheet metal blank ; redrawing a tubular part; and drawing rod, wire, and tube.

Drive system refers to the means by which power is delivered to the chair's wheels. Standard drive systems include gear drive, direct drive, and belt drive. The type of drive system affects the power available to propel the chair and the amount and type of maintenance the chair requires.

Derail is a verb that is described as "to leave the rails"; as a noun however, derail concerns a safety device placed on the track, usually on a siding, to prevent cars from rolling onto the main line. It may have a cast steel frog that diverts one Wheel up and over the rail to stop a car well short of the clearance point. Some derails consist of a single switch point that is normally left open to stop any moving car clear of the main track.