General Motors Company referred to as General Motors, is an American multinational corporation headquartered in Detroit that designs, manufactures and distributes vehicles and vehicle parts, sells financial services, with global headquarters in Detroit's Renaissance Center. It was founded by William C. Durant on September 16, 1908 as a holding company; the company is the largest American automobile manufacturer, one of the world's largest. As of 2018, General Motors is ranked #10 on the Fortune 500 rankings of the largest United States corporations by total revenue. General Motors manufactures vehicles in 37 countries, it owns or holds controlling interest in foreign brands such as Holden, Wuling and Jiefang. Annual worldwide sales volume reached a milestone of 10 million vehicles in 2016. In addition to its twelve brands, General Motors holds a 20% stake in IMM, a 77% stake in GM Korea, it has a number of joint-ventures, including Shanghai GM, SAIC-GM-Wuling and FAW-GM in China, GM-AvtoVAZ in Russia, GM Uzbekistan, General Motors India, General Motors Egypt, Isuzu Truck South Africa.
General Motors does business in more than 140 countries. General Motors is divided into four business segments: GM North America, GM International Operations, GM Cruze, GM Financial; the company operates a mobility division called Maven, which operates car-sharing services in the United States, is studying alternatives to individual vehicle ownership. GM Defense is General Motors' military defense division, catering to the needs of the military for advanced technology and propulsion systems for military vehicles. General Motors led global vehicle sales for 77 consecutive years from 1931 through 2007, longer than any other automaker, in 2012 was among the world's largest automakers by vehicle unit sales. General Motors acts in most countries outside the U. S. via wholly owned subsidiaries, but operates in China through 10 joint ventures. GM's OnStar subsidiary provides vehicle safety and information services. In 2009, General Motors shed several brands, closing Saturn and Hummer, emerged from a government-backed Chapter 11 reorganization.
In 2010, the reorganized GM made an initial public offering, one of the world's top five largest IPOs to date, returned to profitability that year. General Motors Company was formed with an escrow account set up by R S McLaughlin for 15 years of Buick Motors in 1907 on September 16, 1908, in Flint, Michigan, as a holding company controlled by William C. Durant, owner of Buick. At the beginning of the 20th century, there were fewer than 8,000 automobiles in the U. S. and Durant had become a leading manufacturer of horse-drawn vehicles in Flint helped by his purchase of the Carriage Gear patent from the McLaughlin family in Canada, in the 1880s and 1890s, before making his foray into the automotive industry in 1904 by purchasing the fledgling Buick Motor Company. GM's co-founder was Charles Stewart Mott, whose carriage company was merged into Buick prior to GM's creation in 1918. Over the years, Mott became the largest single stockholder in The USA, spent his life with his Mott Foundation, which has benefited the city of Flint, his adopted home.
GM acquired Oldsmobile that year. In 1909, Durant brought in Cadillac, Elmore and several others. In 1909, GM acquired the Reliance Motor Truck Company of Owosso and the Rapid Motor Vehicle Company of Pontiac, the predecessors of GMC Truck. Durant, along with R. S. McLaughlin, lost control of GM in 1910 to a bankers who held the Escrow account' trust, because of the large amount of debt taken on in its acquisitions, coupled with a collapse in new vehicle sales; the next year, Durant started the Chevrolet Motor Car Company in the U. S. and in Canada in 1915, through this, he and McLaughlin in Canada secretly purchased a controlling interest in GM. Durant regained control of the company after one of the most dramatic proxy wars in U. S. business history. Durant reorganized General Motors Holding Company into General Motors Company in 1916, merging Chevrolet with GM and allying General Motors of Canada Limited in 1918 after McLaughlin Traded his Outstanding Stocks for GM stocks to allow the Corporation in the USA.
Shortly thereafter, he again lost control, this time for good, after the new vehicle market collapsed. Alfred P. Sloan was picked to take charge of the corporation, led it to its post-war global dominance when the seven manufacturing facilities operated by Chevrolet before Chevrolet acquired the company began to contribute to GM operations; these facilities were added to the individual factories that were exclusive to Cadillac, Oldsmobile and other companies acquired by the corporation. This unprecedented growth of GM would last into the early 1980s, when it employed 349,000 workers and operated 150 assembly plants in the USA. On July 10, 2009, General Motors emerged from government backed Chapter 11 reorganization after an initial filing on June 8, 2009. Through the Troubled Asset Relief Program the US Treasury invested $49.5 billion in General Motors and recovered $39 billion when it sold its shares on December 9, 2013 resulting in a loss of $10.3 billion. The Treasury invested an additional $17.2 billion into GM's former financing company, GMAC.
The shares in Ally were sold on December 2014 for $19.6 billion netting $2.4 billion. A study by the Center for Automotive Research found that the GM bailout saved 1.2 million jobs and preserved $34.9 billion in tax revenue. In 2009 General Motors of Canada Limited was not part of the General Motors Chapter 11 Bankruptcy, the company shed several brands
The Chevrolet Silverado, its mechanically identical cousin the GMC Sierra, are a series of full-size and heavy-duty pickup trucks manufactured by General Motors and introduced in 1998 as the successor to the long-running Chevrolet C/K line. The Silverado name was taken from a trim level used on its predecessor, the Chevrolet C/K pickup truck from 1975 through 1998. General Motors continues to offer a GMC-badged variant of the Chevrolet full-size pickup under the GMC Sierra name, first used in 1987 for its variant of the GMT400 platform trucks; the heavy-duty trucks are informally referred to as "Silverado HD", while the light-duty version is referred to as "Silverado". Perennially one of the best-selling vehicles in the United States 12 million Silverados have been sold since its introduction. Although General Motors introduced its first pickup truck in 1930, the term "Silverado" was a designation used only to detail the trim for the Chevrolet C/K pickup trucks and Tahoes from 1975 through 1999.
GMC used a few variations of the "Sierra" name as trim lines. The Chevrolet Silverado and GMC Sierra trucks have been the same for their entire history. However, there are some add-on option variations. Early models included variations in the engine and equipment, but the present differences are slight; the 1999 model year redesign included different grilles and interior trim, certain features were included at different times on the two trucks. The GMC Sierra has a luxury package known as "Denali" which adds additional creature comfort features and design changes. Chevrolet's equivalent to the Denali trim level is the High Country Silverado, introduced in the 2014 model year. In 2018, at the Work Truck Show, another new Silverado will be released, being the 4500 and 5500. GM webpage 2500 were released in August 1998 as 1999 models; the "classic" light-duty GMT400 C/K trucks were continued in production for that first year alongside the new models, the Heavy-Duty GMT400 pickups were continued until 2000, with the new GMT800 Silverado/Sierra HD released a year later.
A small refresh for 2003 models was introduced in 2002, bringing slight design changes and an upgrade to the audio and HVAC controls. The latter 2006 and 2007 GMT800 production units used the name Classic to denote the difference between the first and second generation trucks. In January 1993, GM began development on the GMT800 pickup program with numerous teams coming together. By the end of 1994, a final design was chosen and finalized for production in June 1995 at 36 months ahead of scheduled start in June 1998. Development sign-off was issued in late 1997, with pre-production and series production commencement in June 1998. There are a number of models of light-duty Silverados and Sierras, including the half-ton, SS, Hybrid; the light-duty trucks use the 1500 name. They are available in three cab lengths, 2-door standard/regular cab, 3 or 4-door extended cab, front-hinged 4-door crew cab. Three cargo beds are available: a 69.2 in short box, 78.7 in standard box, a 97.6 in long box. The crew cab is only available with the short box.
For the first year, only the regular cab and a 3-door extended cab were available, along with the Vortec 4300 V6, Vortec 4800 V8, the Vortec 5300 V8. In 2000, a driver's side door option became available for the extended cab, giving it four doors, the crew-cab body was added to the lineup in 2004. Output on the 5.3 L engine increased to 285 hp and 325 lb⋅ft. The 6.0 L Vortec 6000 V8 was standard on the 2500 and was added for the 2001 Heavy Duty models, rated at 300 hp, with the GMC Sierra 1500 C3 getting an uprated 325 hp version of this engine. The Silverado Z71 got an optional lighter composite box, with a suspension package for towing, but lacked the high-output engine; the C3 became the Denali for 2002, Quadrasteer was added. GM introduced a reworked version of the Silverado and Sierra in 2003, with a new front end and a updated rear end. In 2006 the Silverado received another facelift, similar to the HD version introduced in 2005 HD models. In addition to that, Chevrolet has deleted the "Chevrolet" badge off the tailgate, used from 1998-2005.
Its SUV counterparts retained the use of the pre-facelift sheetmetal. During the 2005 model year, all light duty GMT800 pickups reverted to front disc/rear drum brakes as a cost cutting measure; the Insurance Institute for Highway Safety gave the Silverado an overall "marginal" score on the frontal offset crash test for poor structural integrity and poor dummy control, although no injuries were recorded on the dummy's body regions. GMC created an upscale version of its Sierra 1500 in 2001 called the Sierra C3, it used all-wheel drive with a 3.73 final drive gear ratio and included the 6.0 L Vortec 6000 LQ4 V8 rated at 325 hp at 5000 rpm and 370 lb•ft of torque at 4000 rpm coupled to a 4L60E-HD four-speed automatic transmission along with other upscale equipment. For 2002, the name was changed to Sierra Denali, but the specifications remained the same except for the addition of Quadrasteer and GM changed from the 4L60E-HD to the 4L65E in conjunction with a 4.10 final drive gear ratio. The Denali is rated for towing 9,100 pounds and hauling 1,595 pounds (723 k
The Dana/Spicer Model 60 is an automotive axle manufactured by Dana Holding Corporation and used in OEM pickup and limited passenger car applications by Chevrolet, Chrysler, Jeep and Land Rover. There are front and rear versions of the Dana 60, it can be identified by its straight axle tubes, 10 bolt asymmetrical cover, a "60" cast in to the housing. Gross axle weight ratings are lowered by the vehicle manufacturer for safety and tire reasons, they are lowered to reduce loads on other powertrain components such as transmissions and transfer cases. Dana 60 Axles are increasingly swapped into many custom offroad applications to accommodate larger tires and deep compound gearing with locking differentials; every Dana 60, manufactured by Dana Corp is stamped with a build date and bill of materials on the back of the right hand axle tube. Gross Axle Weight Rating 6500 lbs. Ring gear measures 93⁄4". OEM Inner axle shaft spline counts are 16, 23, 30, 32, 33 and 35. 40 Spline inner axle shafts and carriers are made for after market, high performance Dana 60 axles.
Pinion shaft diameter: 1.625" Pinion shaft splines: 10 and 29 Gear ratios: 3.31:1 - 7.17:1 Carrier break: 3.31:1 - 4.10:1 and 4.56:1 - 7.17:1 Axle Shaft diameter 1.41” Front 1.46” Rear 1.50” Front 1.50” Rear In the mid-1970s the Big Three all started using this axle. GM began phasing it out in 1988 in favor of Independent suspension, while still offering it in some higher GVWR trucks until 1991. Dodge used a Dana 60 up to 2002. 3rd Generation Dodge Rams dropped the Dana 60 in favor of AAM axles. Ford still uses the Dana 60 front axle. Manufactured in both Kingpin and Ball joint variations, "standard" and "reverse cut" rotation variations and open and limited slip, locking variations; the housing material is Gray iron in early axles and Ductile iron in axles. GM and Ford Dana 60 axles utilize locking hubs. Dodge Dana 60 axles utilized locking hubs until 1994 when a Center Axle Disconnect system was adopted. However, model year 2002 Rams phased out the CAD system leaving some 2002 Dana 60 axles permanently locked in.
Ford versions are driver's side differential drop, reverse-cut gears, kingpin knuckles up to 1991. The axles have ball joints. Ford Dana 60 axles feature 35 spline inner axle shafts, but some are 30 spline. Larger brakes and 35 spline outer shafts were made standard in 2005. Dodge versions were passenger side differential drop, standard rotation gears, kingpin knuckles and 35 spline axle shafts in early models; the 2nd Generation axles were driver's side with ball joints. 30 spline axle shafts were used instead of 35 splines, except 2000, 2001 and 2002 models which were equipped with 32 spline axle shafts. GM versions are passenger side differential drop, standard rotation gears, kingpin knuckles and 35 spline axle shafts; the Dana 60 front axle has a great deal including many upgrades. Stronger axle shafts, universal joints and ball joints are available, as well as a large selection of traction-control devices such as locking differentials and limited slip differentials. Axle shafts, universal joints and carriers made from chromoly steel are available.
High capacity differential covers are available that increase the amount of oil the differential holds. These covers feature heat sinks that help keep the axle cool; the Dana Super 60 is an upgraded version of the Dana 60 axle. Differences in the Dana Super 60 versus the regular Dana 60: Larger and thicker diameter steel tubes Larger ring and pinion which increase the contact area and overall strength; some use larger Universal Joints which increase steering angle. Net formed spider gears for increased strength; the Dana Super 60 housing is found on 2005+ F250/F350, but the internals are 9.75" ring gear and smaller universal joint. All made with 37 spline axle shafts. 2019 Ram 1500 option rear drive only. The Dana 60 rear axle was first introduced in 1955 as a full floating axle in Ford F-250's and is still used today. Manufactured in both full float and semi float variations; the semi float axles have GAWR up to 5,500 lbs and the full float axles were rated up to 6,500 lbs. Full floating variants are common while Semi-floating axles are less common.
Axle spline count varies, with 30 spline being the most common. For 1967, GMC introduced a semi-float Dana 60 to accompany the optional 396 big block engine in their C15 line of trucks; this axle used a traditional Dana 60 center section but with Dana 44 shaft brakes. Open differentials as well as the Dana Powr-Lok system were available. Quadrasteer was an option in 2002 -- single rear wheel trucks. Constant-velocity joints were used instead of universal joints. A variation of the Dana 60 known as a Dana 61 was made to accommodate gear ratios that allowed for better fuel mileage; this was done as a direct result of the 1973 oil crisis. A 3.07:1 gear ratio was common for these axles and unachievable in a regular Dana 60. To allow for the different gearing, the Dana 61 had a greater pinion offset; this offset meant that a different ring and pinion had to be used. Dodge Cummins pickups from the "First Generation" that are not equipped with an overdrive transmission have the 3.07:1 Dana 61 front axle because the higher gears are necessary to achieve reasonable road speeds at the low 2500 rpm governed speed of the Cummins engine in those pickups.
The Dana 61 was made in semi-float and full-float axles for select 4×2 and 4x4 For
The Chevrolet Suburban is a full-size SUV from Chevrolet. It is the longest continuous use automobile nameplate in production, starting in 1935 for the 1935 U. S. model year, has traditionally been one of General Motors' most profitable vehicles. The 1935 first generation Carryall Suburban was one of the first production all-metal bodied station wagons. In addition to the Chevrolet brand, the Suburban was produced under the GMC marque until its version was rebranded Yukon XL, briefly as a Holden. For most of its recent history, the Suburban has been a station wagon-bodied version of the Chevrolet pickup truck, including the Chevrolet C/K and Silverado series of truck-based vehicles. Cadillac offers a version called the Escalade ESV; the Suburban is sold in the United States, Central America, Myanmar, Angola, the Philippines, the Middle East while the Yukon XL is sold only in North America and the Middle East territories. Several automotive companies in the United States used the "Suburban" designation to indicate a windowed, station wagon type body on a commercial frame including DeSoto, Plymouth, Nash, GMC.
The Suburban name was, in fact, a trademark of U. S. Body and Forging Co. of Tell City, which built wooden station wagon bodies for all of these automobile and light truck chassis and more. Chevrolet began production of its all-steel "carryall-suburban" in 1935. GMC brought out its version in 1937; these vehicles were known as the "Suburban Carryall" until GM shortened the name to "Suburban". GMC's equivalent to the Chevrolet model was named "Suburban" as well, until being rebranded as "Yukon XL" for the 2000 model year. With the end of production of the Dodge Town Wagon in 1966 and the Plymouth Fury Suburban station wagon in 1978, only General Motors continued to manufacture a vehicle branded as a "Suburban", GM was awarded an exclusive trademark on the name in 1988; the Chevrolet Suburban is one of the largest SUVs on the market today. It has outlasted competitive vehicles such as the International Harvester Travelall, Jeep Wagoneer, the Ford Excursion; the latest competitor is the extended Ford Expedition EL.
The Suburban of today is a full-size SUV with three rows of seating, a full pickup truck frame, V8 engine. It is one of the few station wagons available with all bench rows; the Suburban is the same height and width as the Chevrolet Tahoe, although the Suburban is 20 inches longer. The extra length provides a full-sized cargo area behind the 9 passenger seating area. From 1973 to 2013 it had been available in half-ton and 3/4-ton versions, the latter discontinued after the 2013 model year, but was revived in 2015 as a fleet-exclusive vehicle for the 2016 model year. In recent years, the Suburban has been used as fire chief's vehicle, or EMS vehicle. Suburbans are used as limousines. Gothic black Suburban vehicles are used by federal intelligence services, such as Secret Service for example. Secret Service operates armored versions of the Suburban for the President of the United States when he attends less formal engagements. In the late 1990s, GM introduced a RHD version of the Suburban, badged as a Holden, for the Australian market.
Sales were low and GM withdrew the model in 2000 from Holden's lineup. There have been twelve generations of Chevrolet Suburbans since its 1935 debut, the most recent entering showrooms in February 2014. In 2015, Chevrolet celebrated the Suburban's 80th anniversary with the Arlington Assembly plant unveiling the ten millionth vehicle built at the facility since its 1954 opening, a black 2015 Suburban LTZ; this marked the second time in the Suburban's history that it has achieved this honor, as the tenth generation Suburban from the 2011 model year was the nine millionth vehicle built there. A 2018 iSeeCars.com study identified the Chevrolet Suburban as the car, driven the most each year. A 2019 iSeeCars.com study named the Chevrolet Suburban the second-ranked longest-lasting vehicle. In 2015, the Suburban commemorated its 80th anniversary at General Motors Arlington Assembly Plant where the 10 millionth Suburban was produced. A video was posted on Chevrolet's YouTube channel about its eighty-year legacy.
In a February 26, 2018 article celebrating the vehicle's 83rd year and Driver notes that the Suburban's longevity is due to being one of GM's best selling brands, its appeal to customers across the board regardless of race, class, or political affiliation, a unique loyalty to the SUV. In an interview from Chevrolet's truck/SUV marketing executive Sandor Piszar, who recalls an event celebrating the truck division's 100th anniversary when they asked about what they named their vehicles, “It’s a funny question, but it is an intriguing point,” Piszar says. "People name. And they love their Suburbans.” Prior to this first generation Suburban, in 1933 Chevrolet had offered a station wagon body, built on the 1/2 ton truck frame. This model was built for National Guard and Civilian Conservation Corps units. Much of the body was constructed from wood, could seat up to eight occupants; the actual first generation model was offered by Chevrolet as a "Carryall Suburban" – a tough, no-nonsense load carrier featuring a station wagon body on the chassis of a small truck.
Focused on functionality, the concept was to "carry all": the whole family and their gear were to find sufficient space in one truck. It shared the front sheetmetal and frames of th
The fifth-wheel coupling provides the link between a semi-trailer and the towing truck, tractor unit, leading trailer or dolly. The coupling consists of a kingpin, a 2-or-3 1⁄2-inch-diameter vertical steel pin protruding from the bottom of the front of the semi-trailer, a horseshoe-shaped coupling device called a fifth wheel on the rear of the towing vehicle; as the connected truck turns, the downward-facing surface of the semi-trailer rotates against the upward-facing surface of the fixed fifth wheel, which does not rotate. To reduce friction, grease is applied to the surface of the fifth wheel; the configuration is sometimes called a turn-table in Australia and New Zealand if it is a rotating ball-race-bearing type. The advantage of this type of coupling is towing stability; some camper trailers use a fifth-wheel configuration, with the coupling installed in the bed of a pickup truck as a towing vehicle. The term fifth wheel comes from a similar coupling used on four-wheel horse-drawn carriages and wagons.
The device allowed the front axle assembly to pivot in the horizontal plane. A wheel would be placed on the rear frame section of the truck, which at the time had only four wheels, making the additional wheel the "fifth wheel"; the trailer needed to be raised so that the trailer's pin would be able to drop into the central hole of the fifth wheel. Fifth wheels were not a complete circle and were hand forged; when mass production of buggy parts began in the early 19th century, fifth wheels were among the first products to be made. There were a number of patents awarded for fifth-wheel design. Edward and Charles Everett, Illinois patented a type of fifth wheel in 1850, followed by Gutches' metallic head block and fifth wheel in 1870 and Wilcox fifth wheel in 1905; the invention of the fifth wheel for motorized trucks is credited to US inventor Charles H. Martin of the Martin Rocking Fifth Wheel Co. who invented the device in 1915. It was submitted for patent in 1915 and finalized in 1916, with Herman Farr as inventor and Martin as assignee.
When they formed the Martin Fifth Wheel company Martin was president and Farr was named secretary. "It's a fair question whether you can consider the fifth wheel as a milestone separate from the semi-trailer. After all, the purpose of the fifth wheel is to link the trailer. At the time, the fifth wheel was a wheel that moved with the trailer—unlike today’s technology that secures a kingpin. What makes the fifth wheel so important is the ability it gave fleet owners to attach large trailers to tractors and safely and the freedom it gave them to switch out trailers. Without a fifth wheel, the modern distribution system would look quite different as drop-and-hook would not be easy; the semi-trailer increased the capacity of trucks, but it was the fifth wheel that brought the flexibility for drivers to keep moving while receivers unloaded the loads they just delivered. The Fruehauf Trailer Corporation helped to make the Martin Rocking 5th Wheel a success by installing them on their popular new semi-trailer design.
August Fruehauf invented the semi-trailer in 1914 with their own 5th wheel hitch. They adopted the Martin Rocking 5th wheel in 1916. By 1916 Fruehauf was producing semi-trailers in tandem with Federal Truck; these two Detroit companies contracted with the military in WWI sending a convoy of supplies and equipment from Detroit to Norfolk, Virginia shipyards for travel to the front in Europe. Fruehauf's success with semi-trailer sales surpassed the million dollar sales mark by 1920. Opening a branch in Chicago and in Des Moines their trailers and hence, the Martin Rocking 5th Wheel became the top selling commercial vehicle of this era. Fruehauf's slogan, "A Horse can pull more than it can carry, so can a truck" became their advertising motto. Merchants and businesses in every industry clamored for a semi-trailer and the shuttle concept introduced by Fruehauf using one tractor truck and 2 or more semi-trailers. Fruehauf used the Martin Rocking 5th Wheel up until at least 1919. Early that year, the manual coupler was introduced to the industry by Fruehauf and the jacks acting as front supports for the semi-trailer were supplanted by wheels and lowered manually.
In 1926, Fruehauf introduced the automatic semi-trailer in which the coupling and the uncoupling of the tractor were accomplished mechanically by the motion of the tractor. Fruehauf's introduction of the automatic semi-trailer was recognized by transportation experts as a major contribution to the industry; the automatic semi-trailer coupling patented by Fruehauf dominated the semi-trailer market until the Fruehauf Trailer Corporation's assets were sold in bankruptcy to Wabash National in 1997. Documentation for a patent of a fifth wheel is in patent number 2,053,812 issued to Charles E. Bradshaw of Wellville, filed March 18, 1936 and granted September 8, 1936. One third of the patent was assigned to Charles Martin of Wellville. Today's fifth wheels allow the trailers to slide into the fifth wheel and lock into it, are a reliable unit when maintained and serviced properly; the engagement of the king pin into the fifth-wheel locking mechanism is the only means of connection between tractor and trailer.
Couplers and pintle hooks use safety chains in the event of a trailer separation while going down the road. Trailer-to-trailer connection can be made by using fifth wheels. Drawbar Fifth Wheel and Gooseneck Ringfed
Steering is the collection of components, etc. which allows any vehicle to follow the desired course. An exception is the case of rail transport by which rail tracks combined together with railroad switches provide the steering function; the primary purpose of the steering system is to allow the driver to guide the vehicle. The most conventional steering arrangement is to turn the front wheels using a hand–operated steering wheel, positioned in front of the driver, via the steering column, which may contain universal joints, to allow it to deviate somewhat from a straight line. Other arrangements are sometimes found on different types of vehicles, for example, a tiller or rear–wheel steering. Tracked vehicles such as bulldozers and tanks employ differential steering—that is, the tracks are made to move at different speeds or in opposite directions, using clutches and brakes, to bring about a change of course or direction; the basic aim of steering is to ensure. This is achieved by a series of linkages, rods and gears.
One of the fundamental concepts is that of caster angle – each wheel is steered with a pivot point ahead of the wheel. The steering linkages connecting the steering box and the wheels conform to a variation of Ackermann steering geometry, to account for the fact that in a turn, the inner wheel is travelling a path of smaller radius than the outer wheel, so that the degree of toe suitable for driving in a straight path is not suitable for turns; the angle the wheels make with the vertical plane influences steering dynamics as do the tires. Many modern cars use rack and pinion steering mechanisms, where the steering wheel turns the pinion gear; this motion applies steering torque to the swivel pin ball joints that replaced used kingpins of the stub axle of the steered wheels via tie rods and a short lever arm called the steering arm. The rack and pinion design has the advantages of a large degree of feedback and direct steering "feel". A disadvantage is that it is not adjustable, so that when it does wear and develop lash, the only cure is replacement.
BMW began to use rack and pinion steering systems in the 1930s, many other European manufacturers adopted the technology. American automakers adopted pinion steering beginning with the 1974 Ford Pinto. Older designs use two main principles: the screw and nut. Both types were enhanced by reducing the friction; the steering column turns a large screw. The nut moves a sector of a gear; the recirculating ball version of this apparatus reduces the considerable friction by placing large ball bearings between the screw and the nut. The recirculating ball mechanism has the advantage of a much greater mechanical advantage, so that it was found on larger, heavier vehicles while the rack and pinion was limited to smaller and lighter ones; the recirculating ball design has a perceptible lash, or "dead spot" on center, where a minute turn of the steering wheel in either direction does not move the steering apparatus. This design is still in use in trucks and other large vehicles, where rapidity of steering and direct feel are less important than robustness and mechanical advantage.
The worm and sector was an older design, used for example in Willys and Chrysler vehicles, the Ford Falcon. To reduce friction the sector is replaced by rotating pins on the rocker shaft arm. Older vehicles use the recirculating ball mechanism, only newer vehicles use rack-and-pinion steering; this division is not strict and rack-and-pinion steering systems can be found on British sports cars of the mid-1950s, some German carmakers did not give up recirculating ball technology until the early 1990s. Other systems for steering are uncommon on road vehicles. Children's toys and go-karts use a direct linkage in the form of a bellcrank attached directly between the steering column and the steering arms, the use of cable-operated steering linkages is found on some home-built vehicles such as soapbox cars and recumbent tricycles. Power steering helps the driver of a vehicle to steer by directing some of its power to assist in swiveling the steered road wheels about their steering axes; as vehicles have become heavier and switched to