An anti-roll bar ( roll bar , anti-sway bar , sway bar , stabilizer bar ) is an automobile suspension part that helps reduce the body roll of a vehicle during fast cornering or over road irregularities. It links opposite front or rear wheels to a torsion spring using short lever arms for anchors. This increases the suspension's roll stiffness—its resistance to roll in turns.
28-613: The Logitech G27 is a racing wheel made by Logitech . It supports PlayStation 3 , PlayStation 2 and PC . It replaced the Logitech G25 in 2010, with some new features including the use of helical gearing instead of the previous straight gears used on the G25. As of December 2015, the G27 is no longer sold by Logitech, in favor of the newer G29 and G920 steering wheels now offered by Logitech. It features: Racing wheel A sim racing wheel
56-429: A reduction in unsprung weight . As the anti-roll bar is required to control wheel position, the bars of a MacPherson strut suspension may be connected through ball joints. However many later "MacPherson strut" suspensions have reverted to using wishbones rather than the simplified track control arm of the original design. Various methods of decoupling the anti-roll bar have been proposed. The first production car to use
84-537: A rotary potentiometer, which were sprung by springs or bungees. These spring-based wheels had a reactive torque that increased proportionally only to the steering angle, without regard for the simulated vehicle dynamics. Eventually manufacturers began to use electric motors in the controllers, in place of springs, in order to achieve a level of force feedback (sometimes abbreviated FFB ), first seen in Microsoft's Sidewinder wheel. At first this technology simply provided
112-453: A semi-active anti-roll bar was the 1988 Mitsubishi Mirage Cyborg. The 16-valve turbo model's "Dual Mode Suspension" has a dashboard- operated hydraulic actuator built into the front anti-roll bar link, allowing it to toggle between sport and touring modes. The Jeep Wrangler (JK, JL) and Jeep Gladiator (JT) also have a switchable decoupler on Rubicon models, to increase wheel articulation for off-roading. The first active anti-roll bar system
140-485: Is a common form of strut suspension. This was not the first attempt at strut suspension, but in MacPherson 's original patent, the anti-roll bar forms an integral and essential part of the suspension, in addition to its usual function in controlling body roll. A strut suspension like MacPherson's requires a hinged lower member between the chassis and wheel hub to control the wheel position both inwards and outwards (controlling
168-402: Is a control device for use in racing games , racing simulators , and driving simulators . They are usually packaged with a large paddle styled as a steering wheel , along with a set of pedals for the accelerator, brake, and clutch , as well as transmission controls . An analog wheel and pedal set such as this allows the user to accurately manipulate steering angle and pedal control that
196-434: Is intended to reduce the lateral tilt (roll) of the vehicle on curves, sharp corners, or large bumps. Although there are many variations in design, the object is to induce a vehicle's body to remain as level as possible by forcing the opposite wheel's shock absorber , spring, or suspension rod in the same direction as the one being impacted. In a turn, a vehicle compresses its outer wheel's suspension. The anti-roll bar forces
224-604: Is no input from the gas pedal, i.e. whether the engine contributes to the car slowing down or is keeping its speed), etc.), seeing sideways or in the mirror, or to browse various menus (for example using a 7-way «funky switch»). Subsections by motor type: no FFB, gear- or belt-driven, and direct-drive wheels. Other features by which pedals can be compared are whether they can be inverted (hanging pedals), build material (plastic, aluminum), adjustability (position, pressure, travel), measured pressure, travel length, sensor resolution. Anti-roll bar The first stabilizer bar patent
252-415: Is positive camber of the wheels on the outside of the turn and negative on the inside, which reduces their cornering grip (especially with cross ply tires). Anti-roll bars provide two main functions. The first is to reduce body lean. This is dependent on the total roll stiffness of the vehicle. Increasing this stiffness does not change the steady state total load (weight) transfer from the inside wheels to
280-402: Is required to properly manage a simulated car, as opposed to digital control such as a keyboard. The relatively large range of motion further allows the user to more accurately apply the controls. Racing wheels have been developed for use with arcade games , game consoles , personal computers , and also for professional driving simulators for race drivers. One of the earliest racing wheels for
308-419: Is resisted by the suspension roll stiffness, which is a function of the spring rate of the vehicle's springs and of the anti-roll bars, if any. The use of anti-roll bars allows designers to reduce roll without making the suspension's springs stiffer in the vertical plane, which allows improved body control with less compromise of ride quality . One effect of body lean, for typical unibody suspension geometry,
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#1732881257740336-407: Is usually a torsion spring anchored to resist body roll motions. It is usually constructed out of a cylindrical steel bar, formed into a "U" shape, that connects to the body at two points along its longer center section, and on each end. When the left and right wheels move together the bar simply rotates on its central mounting points. When the wheels move relative to each other, torsion forces cause
364-563: The pit lane , button for flashing lights , windscreen wipers , radio communication with the team, adjustments to the racing setup (such as brake balance , brake migration , differential braking (entry, mid+, exit, hi-speed; to make use of torque effectively at different points in a corner ), traction control (amplitude and sensitivity), anti-roll bar adjustment (front and rear), engine program (strat mode/ engine mode to get extra power or conserve fuel and engine life), engine braking (the engine's throttle or absence of throttle when there
392-763: The PC mass market was the Thrustmaster Formula T1, released in 1994. It had no force feedback, only some form of spring-based centering resistance proportional to the steering angle. Two of the earliest FFB wheels for the consumer PC market were the Microsoft Sidewinder Force Feedback Wheel, released in 1997, and the Logitech Wingman Formula Force. Force feedback sim wheels have motors to simulate steering kickback . Racing wheels started off as simple plastic wheels hooked up to
420-412: The bar to twist. Each end of the bar is connected to an end link through a flexible joint. The link is connected in turn to a spot near a wheel or axle, transferring forces from the heavily loaded side of a suspension to the opposite. Forces are therefore transferred: The bar resists the torsion through its stiffness. The stiffness of an anti-roll bar is proportional to the stiffness of the material,
448-464: The body roll. In a turn the sprung mass of the vehicle's body produces a lateral force at the centre of gravity (CG), proportional to lateral acceleration. Because the CG is usually not on the roll axis, the lateral force creates a moment about the roll axis that tends to roll the body. (The roll axis is a line that joins the front and rear roll centers ). The moment is called the roll couple . Roll couple
476-450: The centering force and other artificial effects such as shaking the wheel in a crash or other vibrations. However, as driving simulations have evolved, their physics engines have become more elaborate, allowing also for linking the force feedback close to the simulated vehicle dynamics of the in-game physics. This allows the user to truly feel what forces go through the steering rack, instead of just artificial effects, and genuinely enhance
504-478: The driver from inside the car, such as in Super GT . This allows the stiffness to be altered, for example by increasing or reducing the length of the lever arms on some systems, or by rotating a flat lever arm from a stiff edge-on position to a more flexible flat-side-on position on other systems. This lets a mechanic tune the roll stiffness for different situations without replacing the entire bar. The MacPherson strut
532-402: The fourth power of its radius, and the inverse of the length of the lever arms (i.e., the shorter the lever arm, the stiffer the bar). Stiffness is also related to the geometry of the mounting points and the rigidity of the bar's mounting points. The stiffer the bar, the more force required to move the left and right wheels relative to each other. This increases the amount of force required to make
560-417: The inside wheels lift off the ground during hard cornering. This can be used to advantage: many front wheel drive production cars lift a rear wheel when cornering hard in order to overload the opposite wheel, limiting understeer . Some anti-roll bars, particularly those intended for use in auto racing , are externally adjustable while the car is in the pit, whereas some systems can be adjusted in real time by
588-412: The opposite (inner) wheel's suspension to compress as well, thereby keeping the body in a more level lateral attitude. This has the additional benefit of lowering its center of gravity during a turn, increasing its stability. When both front and rear anti-roll bars are fitted, their combined effect can help maintain a vehicle's tendency to roll towards the general slope of the terrain. An anti-roll bar
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#1732881257740616-410: The outside, it only reduces body lean. The total lateral load transfer is determined by the center of gravity height and track width. The other function of anti-roll bars is to tune the handling balance of a car. Understeer or oversteer can be reduced by changing the proportion of the total roll stiffness that comes from the front and rear axles. Increasing it at the front increases the proportion of
644-624: The realism of the game. A fundamental factor for an adequate subjective steering-feel and perception of drivability from a force feedback wheel, is the transfer function from steering torque to steering angle. In 2015, a preliminary comparison of gear-driven and direct-drive wheels in the 0–30 Hz frequency range, for a study on hard real-time multibody simulation and high-fidelity steering wheel force feedback, concluded that direct-drive wheels are preferable. Sim racing wheels, like real-world racing steering wheels, can have many buttons. Some examples are cruise control or pit-lane limiter for
672-435: The total load transfer that the front axle reacts to—and decreases it in the rear. In general, this makes the outer front wheel run at a comparatively higher slip angle, and the outer rear wheel to run at a comparatively lower slip angle, increasing understeer. Increasing the proportion of roll stiffness at the rear axle has the opposite effect, decreasing understeer. Because an anti-roll bar connects wheels on opposite sides of
700-464: The track), and also forwards and backwards. This may be provided by a wishbone with a number of joints, or by using an additional radius rod . MacPherson's design replaced the wishbone with a simpler and cheaper track control arm , with a single inboard joint, to control the track. Forward and backward position was controlled through the anti-roll bar. Overall this required a simpler and cheaper set of suspension members than with wishbones, also allowing
728-474: The vehicle, the bar transmits the force of a bump on one wheel to the opposite wheel. On rough or broken pavement, anti-roll bars can produce jarring, side-to-side body motions (a "waddling" sensation), which increase in severity with the diameter and stiffness of the anti-roll bars. Other suspension techniques can delay or dampen this effect of the connecting bar. Excessive roll stiffness, typically achieved by configuring an anti-roll bar too aggressively, can make
756-434: Was Citroën 's SC.CAR (Systeme Citroën de Contrôle Actif du Roulis), debuted in its 1994 Xantia Activa , a medium-sized European sedan. The anti-roll bar could be stiffened by the suspension ECU during hard cornering, minimizing body roll to 2 degrees. The Mercedes-Benz S-Class Active Body Control system eliminates the anti-roll bar, instead using sensors to detect lateral load, lateral force, and height difference in
784-406: Was awarded to Canadian inventor Stephen Coleman of Fredericton, New Brunswick on April 22, 1919. Anti-roll bars were unusual on pre-WW2 cars due to the generally much stiffer suspension and acceptance of body roll. From the 1950s on, however, production cars were more commonly fitted with anti-roll bars, especially those vehicles with softer coil spring suspension. An anti-sway or anti-roll bar
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