earth science

Snow chains

Snow chains is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Snow chains rather than just read about it. In short: Snow chains, or tire chains, are devices fitted to the tires of vehicles to provide increased 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.

Key takeaways

Snow chains belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Snow chains to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Snow chains from memory before moving on to harder problems.

Reference excerpt

Snow chains, or tire chains, are devices fitted to the tires of vehicles to provide increased 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 damage road surfaces.

History 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. 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 January 1923, American inventor Oscar E. Brown obtained U.S. patent 1,440,580 for his “Nonskid Attachment for Vehicle Tires”. In July 1935, the Canadian Auguste Trudeau obtained a patent for his tread and anti-skidding chain.

Deployment 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. On wheel loaders, it is recommended to use special protection chains due to the intense pressure on tires during work.

United States 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.

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:

SAE Class S: Regular (non-reinforced) passenger tire traction devices for vehicles with restricted wheel well clearance. SAE Class U: Regular (non-reinforced) and lug-reinforced passenger tire traction devices for vehicles with regular (non-restricted) wheel well clearances. SAE Class W: Passenger tire traction devices that use light truck components, as well as some light truck traction devices.

Common chain failures Driving too fast with chains. Recommended maximum speeds in the owners' manual of the chains – generally 30 to 50 km/h (20 to 30 mph) – maximum. Driving on dry roads with chains for extended periods of time. Driving on dry roads with chains can cause a vehicle to slide when braking. Driving on dry roads with chains will rapidly wear the chains. Not securing the chains tightly enough. Owners' manual of the chains recommends tightening a second time after driving a short distance and checking for tightness from time to time. If a chain comes loose, it should either be refastened or removed before it wraps around the drive axle of the vehicle. Tensioners or adjusters may be required. (Some chains have automatic tensioners and may be damaged if tensioners are used.) Installing chains on non-drive wheels. Accelerating too rapidly causing tire spin and stress on chains If a chain does break, it can cause vehicle damage by slapping around inside the wheel well, possibly wrapping around the axle and severing brake lines

Varieties and alternatives

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Snow chains

Start with the simplest possible case. Write down what Snow chains claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Snow chains before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Snow chains ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Snow chains

In research: Snow chains appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Snow chains in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Snow chains is common in secondary-school and first-year university syllabi. It links to neighbouring topics Chains, Inclement weather management, Vehicle safety technologies, so understanding it makes those chapters shorter.
In everyday life: Look for Snow chains outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Snow chains in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Snow chains means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Snow chains out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Snow chains in simple terms?

Why does Snow chains matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Snow chains?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Snow chains.