Recirculating ball, also known as recirculating ball and nut or worm and sector, is a steering mechanism commonly found in older automobiles, off-road vehicles, and some

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

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

Mercedes-Benz Mercedes-Benz (), commonly referred to as Mercedes and sometimes as Benz, is a German luxury and commercial vehicle automotive brand established in 1926. Mercedes-Benz AG (a Mercedes-Benz Group subsidiary established in 2019) is headquarte ...

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

Chrysler Stellantis North America (officially FCA US and formerly Chrysler ()) is one of the " Big Three" automobile manufacturers in the United States, headquartered in Auburn Hills, Michigan. It is the American subsidiary of the multinational automotiv ...

, General Motors and Lada, 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 and the Lada Niva.

Mechanism

The recirculating ball steering mechanism contains a

worm gear A worm drive is a gear arrangement in which a worm (which is a gear in the form of a screw) meshes with a worm wheel (which is similar in appearance to a spur gear). The two elements are also called the worm screw and worm gear. The terminol ...

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; 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 A power steering is a mechanical device equipped on a motor vehicle that helps drivers steer the vehicle by reducing steering effort needed to turn the steering wheel, making it easier for the vehicle to turn or maneuver at lower speeds. Hydra ...

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