A steering rack forms part of the commonly used rack and pinion steering system.  A rack and pinion is a type of linear actuator that consists of a coupling of gears which combine to translate rotational motion into linear motion. The pinion is a circular gear that works in conjunction with a set of teeth on the rack, which is a linear gear. When the pinion is caused to rotate by the movement of the steering wheel this forces the rack to move relative to the pinion, which has the effect of converting the rotational movement of the pinion into linear movement that results in changing the angle of the wheels.

It is important that the mechanism of the steering rack is kept clean, dry and effectively lubricated. This is achieved by encasing the end of the rack in steering rack boots. Also known as steering rack gaiters, steering rack boots are made from rubber and are flexible and waterproof. They are designed to keep out water and dirt and keep the essential lubricant in. If water or dirt is allowed to infiltrate the steering rack boots or lubricant is allowed to escape it will result in wear and, ultimately, the need to replace the entire rack. It is important, therefore, if there is any sign of a problem with a vehicle’s steering rack boots, that replacements are fitted without delay.