Recirculating ball, also known as recirculating ball and nut or worm and sector, is a

steering Steering is the control of the direction of motion or the components that enable its control. Steering is achieved through various arrangements, among them ailerons for airplanes, rudders for boats, cylic tilting of rotors for helicopters, ...

mechanism commonly found in older automobiles,

off-road vehicle An off-road vehicle (ORV), also known as an off-highway vehicle (OHV), overland vehicle or adventure vehicle, is a type of transportation specifically engineered to navigate unpaved roads and surfaces. These include trails, forest roads, and ...

s, and some

truck A truck or lorry is a motor vehicle designed to transport freight, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construct ...

s. Most newer cars use the more economical rack and pinion steering instead, but some upmarket manufacturers (such as

BMW Bayerische Motoren Werke AG, trading as BMW Group (commonly abbreviated to BMW (), sometimes anglicised as Bavarian Motor Works), is a German multinational manufacturer of vehicles and motorcycles headquartered in Munich, Bavaria, Germany. Th ...

and

Mercedes-Benz Mercedes-Benz (), commonly referred to simply as Mercedes and occasionally as Benz, is a German automotive brand that was founded in 1926. Mercedes-Benz AG (a subsidiary of the Mercedes-Benz Group, established in 2019) is based in Stuttgart, ...

) held on to the design until well into the 1990s for the durability and strength inherent in the design. A few, including

Chrysler FCA US, LLC, Trade name, doing business as Stellantis North America and known historically as Chrysler ( ), is one of the "Big Three (automobile manufacturers), Big Three" automobile manufacturers in the United States, headquartered in Auburn H ...

General Motors General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. The company is most known for owning and manufacturing f ...

Lada LadaAccording to various sources, the name Lada is derived from a Russian word for Viking longships (). (, , marketed as LADAFrom 2004 onwards Lada is marketed worldwide, including in Russia, using the all-capitals brand name written in Latin sc ...

and Ineos, still use this technology in certain models including the Jeep Wrangler,{{Cite book , url=https://books.google.com/books?id=HlbCM7VEmroC&q=wrangler+Recirculating+ball&pg=PA91 , title=High-Performance Jeep Wrangler TJ Builder's Guide, isbn=9781932494266, last1=Lee, first1=Christian, year=2007, publisher=CarTech, Incorporated the Ineos Grenadier Quartermaster and the

Lada Niva The Lada Niva Legend, formerly called the Lada Niva, VAZ-2121, VAZ-2131, and Lada 4×4 (), is a series of four-wheel drive, small (hatchback), and compact (wagon and pickup) Off-road vehicle, off-road cars designed and produced by AvtoVAZ sinc ...

Mechanism

The recirculating ball steering mechanism contains a worm gear inside a block with a threaded hole in it; this block has gear teeth cut into the outside to engage the sector shaft (also called a sector gear) which moves the Pitman arm. The steering wheel connects to a shaft, which rotates the worm gear inside of the block. Instead of twisting further into the block, the worm gear is fixed so that when it rotates, it moves the block, which transmits the motion through the gear to the Pitman arm, causing the roadwheels to turn.

Bearing balls

The worm gear is similar in design to a

ball screw A ball screw (or ballscrew) is a mechanical linear actuator that translates rotational motion to linear motion with little friction. A threaded shaft provides a helical raceway for ball bearings which act as a precision screw. As well as bein ...

; the threads are filled with steel balls that recirculate through the gear and rack as it turns. The balls serve to reduce friction and wear in the gear, and reduce slop. Slop, when the gears come out of contact with each other, would be felt when changing the direction of the steering wheel, causing the wheel to feel loose.Nice, Kare
"How Car Steering Works"
"HowStuffWorks", Accessed August 13, 2007

Power assistance

Power steering in a recirculating-ball system works similarly to that in a rack-and-pinion system. Assistance is provided by supplying higher-pressure fluid to one side of the block.

References

Mechanisms (engineering) Automotive steering technologies

Mechanism

Bearing balls

Power assistance

See also

References