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Snow chains, or tire chains, are devices fitted to the tires of vehicles to provide maximum traction when driving through snow and ice.
Snow chains attach to the drive wheels of a vehicle or special systems deploy chains which swing under the tires automatically. Although named after steel chain, snow chains may be made of other materials and in a variety of patterns and strengths. Chains are usually sold in pairs and often must be purchased to match a particular tire size (tire diameter and tread width), although some designs can be adjusted to fit various sizes of tire. Driving with chains reduces fuel efficiency, and can reduce the allowable speed of the automobile to approximately 50 km/h (30 mph), but increase traction and braking on snowy or icy surfaces. Some regions require chains to be used under some weather conditions, but other areas prohibit the use of chains, as they can deteriorate road surfaces.
Snow chains were invented in 1904 by Harry D. Weed in Canastota, New York. Weed received U.S. Patent 0,768,495 for his "Grip-Tread for Pneumatic Tires" on August 23, 1904. Weed's great-grandson, James Weed, said that Harry got the idea of creating chains for tires when he saw drivers wrap rope, or even vines, around their tires to increase traction on muddy or snowy roads, which were very common at the turn of the 20th century.[ citation needed ] (At this time, most people in rural Northern regions wouldn't bother driving automobiles in the winter at all, since roads were usually rolled for use with horse-drawn sleighs, rather than plowed. Automobiles were generally not winter vehicles, for a variety of reasons until the 1930s or 1940s in some areas. Only in urban areas was it possible to remove snow from streets.). He sought to make a traction device that was more durable and would work with snow as well as mud.
In July 1935, the Canadian Auguste Trudeau obtained a patent for his tread and anti-skidding chain.
In snowy conditions, transportation authorities may require that snow chains or other traction aids be installed on vehicles, or at least supplied for them. This can apply to all vehicles, or only those without other traction aids, such as four-wheel drive or special tires. Local requirements may be enforced at checkpoints or by other type of inspection. Snow chains should be installed on one or more drive axles of the vehicle, with requirements varying for dual-tire or multi-driven-axle vehicles that range from "one pair of tires on a driven axle" to "all tires on all driven axles", possibly also one or both steering (front) wheels, requiring snow chains whenever required by signage or conditions.
In case of running wheel loaders, it is recommended to use special protection chains due to intense pressure on tires during work.
Tires come with standardized tire code sizing information, found on the sidewalls of the tires. The first letter(s), indicate the vehicle type (P for passenger, LT for light truck). The next three digits indicate the tire's width in millimeters. The middle two digit number indicates the tire's height-to-width ratio. The next character is a letter "R", which indicates radial ply tires (rather than radius). followed by a final two digit number indicating the rim size for the vehicle's wheels.
Additionally, the correct Society of Automotive Engineers (SAE) class of snow chains must be installed, based on the wheel clearance of the vehicle.
|SAE traction device class||Minimum tread-face clearance (A)||Minimum side-wall clearance (B)|
|Class S||1.46 in (37 mm)||0.59 in (15 mm)|
|Class U||1.97 in (50 mm)||0.91 in (23 mm)|
|Class W||2.50 in (64 mm)||1.50 in (38 mm)|
The SAE Class "S" well clearance is a common requirement on newer cars, especially if after-market wider, low-profile, or larger tires and/or wheels are fitted.
The classes are defined as follows:
Tire chains are available in a variety of types that have different advantages of cost, ride smoothness, traction, durability, ease of installation, and recommended travel speed.
Materials include steel (in the form of links or cables), polyurethane, rubber, and fabric. The original-style steel-link chains are also available in a variety of carbon steel and steel alloys and link shapes. Link shapes include standard, twisted, square, and reinforced.The shape of the links changes the flexibility, grip, and strength of the chain. The links can also have added studs or V-bars for an even more aggressive traction. The use of alloy steel and hardened steel adds durability. Traction cables (cable chains, snow cables) attach like chains but are made from cable rather than chain.
Chain patterns include the ladder, diagonal, or pattern types. Ladder type chains have cross chains perpendicular to the road and look like a ladder when carefully laid on the ground. With diagonal chains, the cross chains are diagonal to the road. Pattern types form a "net" over the tire such as a diamond or multiple diamond pattern. Some industrial pattern types also include studded, metal rings to which the chains attach and thus are called ring chains.
Most tire chains are wrapped around the circumference of the tires and held in place with rim chains, which may be chain or cable, elastic or adjustable tensioners. Automatic chains do not wrap around the tire but swing under the tire from devices permanently mounted under the vehicle which deploy via an electronic solenoid activated in the cab. Some tire chains mount onto the tires from only one side. Others use a ratcheting system for easier installation.
Alternatives include studded tires, which are snow tires with metal studs individually mounted into holes in the treads; emergency traction devices which may be similar to tire chains but mount around the tire through openings in the rim; and snow socks, which are fabric rather than chain or cable. These allow higher operating speeds and don't require the operator to install them (studs), but chains generally give the best traction in severe conditions.
Mud chains are similar to snow chains but for off-road, four-wheel drive applications, and generally they are larger than snow chains; they are often seen on heavy off-road equipment like log skidders, which have to operate over very rough, muddy terrain.
Wheel tracks are heavy duty assemblies similar to chains but with rigid cross links such as sometimes used on logging equipment.
Laws vary considerably regarding the legality of snow chain use. Some countries require them in certain snowy conditions or during certain months of the year, while other countries prohibit their use altogether to preserve road surfaces.
A tire or tyre is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, which also provide a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a contact patch, that is designed to match the weight of the vehicle with the bearing strength of the surface that it rolls over by providing a bearing pressure that will not deform the surface excessively.
Continuous track is a system of vehicle propulsion used in tracked vehicles, running on a continuous band of treads or track plates driven by two or more wheels. The large surface area of the tracks distributes the weight of the vehicle better than steel or rubber tyres on an equivalent vehicle, enabling continuous tracked vehicles to traverse soft ground with less likelihood of becoming stuck due to sinking.
An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle is supported. In the latter case, a bearing or bushing sits inside a central hole in the wheel to allow the wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type axle is referred to as a spindle.
A differential is a gear train with three shafts that has the property that the rotational speed of one shaft is the average of the speeds of the others, or a fixed multiple of that average.
Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering. Oversteer is what occurs when a car turns (steers) by more than the amount commanded by the driver. Conversely, understeer is what occurs when a car steers less than the amount commanded by the driver.
A racing slick is a type of tyre that has a smooth tread used mostly in auto racing. The first production "slick tyre" was developed by M&H Tires in the early 1950s for use in drag racing. By eliminating any grooves cut into the tread, such tyres provide the largest possible contact patch to the road, and maximize traction for any given tyre dimension. Slick tyres are used on road or oval track racing, where steering and braking require maximum traction from each wheel, but are typically used on only the driven (powered) wheels in drag racing, where the only concern is maximum traction to put power to the ground.
An off-road vehicle is considered to be any type of vehicle which is capable of driving on and off paved or gravel surface. It is generally characterized by having large tires with deep, open treads, a flexible suspension, or even caterpillar tracks. Other vehicles that do not travel public streets or highways are generally termed off-highway vehicles, including tractors, forklifts, cranes, backhoes, bulldozers, and golf carts.
A locking differential is designed to overcome the chief limitation of a standard open differential by essentially "locking" both wheels on an axle together as if on a common shaft. This forces both wheels to turn in unison, regardless of the traction available to either wheel individually.
The wheel size for a motor vehicle or similar wheel has a number of parameters.
Aquaplaning or hydroplaning by the tires of a road vehicle, aircraft or other wheeled vehicle occurs when a layer of water builds between the wheels of the vehicle and the road surface, leading to a loss of traction that prevents the vehicle from responding to control inputs. If it occurs to all wheels simultaneously, the vehicle becomes, in effect, an uncontrolled sled. Aquaplaning is a different phenomenon from when water on the surface of the roadway merely acts as a lubricant. Traction is diminished on wet pavement even when aquaplaning is not occurring.
Off-roading is the activity of driving or riding a vehicle on unsurfaced roads or tracks, made of materials such as sand, gravel, riverbeds, mud, snow, rocks, and other natural terrain. Types of off-roading range in intensity, from leisure drives with unmodified vehicles to competitions with customized vehicles and professional drivers. Off-roaders have been met with criticism for the environmental damage caused by their vehicles. There have also been extensive debates over the role of government in regulating the sport, including a Supreme Court case brought against the Bureau of Land Management.
A de Dion tube is an automobile suspension technology. It is a sophisticated form of non-independent suspension and is a considerable improvement over the swing axle, Hotchkiss drive, or live axle. Because it plays no part in transmitting power to the drive wheels, it is sometimes called a "dead axle".
A beadlock or bead lock is a mechanical device that secures the bead of a tire to the wheel of a vehicle. Tires and wheels are designed so that, when the tire is inflated, the tire pressure pushes the bead of the tire against the inside of the wheel rim so that the tire stays on the wheel and the two rotate together. In situations where tire pressure is insufficient to hold the bead of the tire in place, a beadlock is needed.
Traction, or tractive force, is the force used to generate motion between a body and a tangential surface, through the use of dry friction, though the use of shear force of the surface is also commonly used.
A beam axle, rigid axle or solid axle is a dependent suspension design, in which a set of wheels is connected laterally by a single beam or shaft. Beam axles were once commonly used at the rear wheels of a vehicle, but historically they have also been used as front axles in four-wheel-drive vehicles. In most automobiles, beam axles have been replaced with front and rear independent suspensions.
Snow tires, also known as winter tires, are tires designed for use on snow and ice. Snow tires have a tread design with larger gaps than those on conventional tires, increasing traction on snow and ice. Such tires that have passed a specific winter traction performance test are entitled to display a "Three-Peak Mountain Snow Flake" symbol on their sidewalls. Tires designed for winter conditions are optimized to drive at temperatures below 7 °C (45 °F). Some snow tires have metal or ceramic studs that protrude from the tire to increase traction on hard-packed snow or ice. Studs abrade dry pavement, causing dust and creating wear in the wheel path. Regulations that require the use of snow tires or permit the use of studs vary by country in Asia and Europe, and by state or province in North America.
Roths Industries, Inc. (1945–1960) was a manufacturer of small garden tractors and other agricultural equipment founded by Herbert C. Roths in Alma, Michigan. The company manufactured Garden King Walking Tractors, BesRo Riding Tractors, and Till Ro Stalk Cutters.
Grousers are devices intended to increase the traction of continuous tracks, especially in loose material such as soil or snow. This is done by increasing contact with the ground with protrusions, similar to conventional tire treads, and analogous to athletes' cleated shoes. On tanks and armoured vehicles, grousers are usually pads attached to the tracks; but on construction vehicles they may take the form of flat plates or bars.
Snow socks are textile alternatives to snow chains. Snow sock devices wrap around the tires of a vehicle to increase traction on snow and ice. Snow socks are normally composed of a woven fabric with an elastomer attached to the inner and/or outer edge. The woven fabric covers the tire tread and is the contact point between the vehicle and the road. The elastomer keeps the snow sock in place and facilitates with installation. Some snow sock models have an additional component that covers the rim of the tire, which prevents snow or debris from gathering between the tread of the tire and the inner side of the woven fabric.
Bar grip tyres, or 'NDT' in US military parlance, are an early tyre tread pattern developed for off-road use.
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