Mechanical device consisting of a bar of rectangular cross section (the rack), having teeth on one side that mesh with teeth on a small gear (the pinion). If the pinion rotates about a fixed axis, the rack will move in a straight path. Some automobile steering mechanisms have rack-and-pinion drives that use this principle. If the rack is fixed and the pinion is carried in bearings on a table guided on tracks parallel to the rack, rotation of the pinion shaft will move the table parallel to the rack. On machine tools, this principle is used to obtain rapid movements of worktables.

Learn more about rack and pinion with a free trial on Britannica.com.

Rack may refer to:

People

• Rack (Buffyverse)
• Reinhard Rack, an Austrian politician

Kinds of racks

• Rack (torture device)
• Rack (billiards)
• 19-inch rack, a system for mounting electronic modules
• Amp rack, short for amplifier rack, a piece of furniture in which amplifiers are mounted
• Bicycle rack
• Bustle rack, a type of storage bin mounted on armored fighting vehicles
• Drying rack, a device intended for hanging clothing to dry
• Magazine rack, a device intended for holding and displaying magazines
• Crowned rack of lamb, a culinary dish
• Roof rack, a system used to carry items on top of a car
• Toast rack, a serving piece

Other uses

• Rack and pinion, a gear arrangement commonly used in vehicle steering
• RACK protein, an acronym for Receptor for Activated C Kinase
• Rack lift, a type of elevator
• Rack railway
• Racking, the transfer of a liquid (such as wine) from one container to another
• Racking focus, a photography technique
• Racks and quandles, concepts in abstract algebra
• Risk-aware consensual kink, a BDSM term
• A term in climbing
• A slang term for breasts
• Navy jargon for bed
• Pertaining to movement, a type of horse gait