History

Polybolos (reconstruction) described by the Hellenistic writer Philo of Byzantium (3rd century BC). The semi-automated arrow thrower features the earliest known chain drive.

Oldest known illustration of an endless power-transmitting chain drive, from Su Song’s book of 1092 describing his clock tower of Kaifeng

The oldest known application of a chain drive appears in the Polybolos, a repeating crossbow described by the Greek engineer Philon of Byzantium (3rd century BC). Two flat-linked chains were connected to a windlass, which by winding back and forth would automatically fire the machine’s arrows until its magazine was empty. Although the device did not transmit power continuously since the chains “did not transmit power from shaft to shaft”, the Greek design marks the beginning of the history of the chain drive since “no earlier instance of such a cam is known, and none as complex is known until the 16th century. It is here that the flat-link chain, often attributed to Leonardo da Vinci, actually made its first appearance.”

The first continuous power-transmitting chain drive was depicted in the written horological treatise of the Song Dynasty (9601279) Chinese engineer Su Song (1020-1101 AD), who used it to operate the armillary sphere of his astronomical clock tower as well as the clock jack figurines presenting the time of day by mechanically banging gongs and drums. The chain drive itself was given power via the hydraulic works of Su’s water clock tank and waterwheel, the latter which acted as a large gear.

The endless power-transmitting chain drive was invented separately in Europe by Jacques de Vaucanson in 1770 for a silk reeling and throwing mill. J. F. Tretz was the first to apply the chain drive to the bicycle in 1869.

Chains versus belts

Drive chains are most often made of metal, while belts are often rubber, plastic, or other substances. Although well-made chains may prove stronger than belts, their greater mass increases drive train inertia.

Drive belts can often slip (unless they have teeth) which means that the output side may not rotate at a precise speed, and some work gets lost to the friction of the belt against its rollers. Teeth on toothed drive belts generally wear faster than links on chains, but wear on rubber or plastic belts and their teeth is often easier to observe; you can often tell a belt is wearing out and about to break more easily than a chain.

Chains are often narrower than belts, and this can make it easier to shift them to larger or smaller gears in order to vary the gear ratio. Multi-speed bicycles with derailleurs make use of this. Also, the more positive meshing of a chain can make it easier to build gears that can increase or shrink in diameter, again altering the gear ratio.

Both can be used to move objects by attaching pockets, buckets, or frames to them; chains are often used to move things vertically by holding them in frames, as in industrial toasters, while belts are good at moving things horizontally in the form of conveyor belts. It is not unusual for the systems to be used in combination; for example the rollers that drive conveyor belts are themselves often driven by drive chains.

Drive shafts are another common method used to move mechanical power around that is sometimes evaluated in comparison to chain drive; in particular shaft drive versus chain drive is a key design decision for most motorcycles. Drive shafts tend to be even tougher and more reliable than chain drive, but weigh even more (robbing more power), and impart rotational torque.

Use in vehicles

Bicycles

Main article: Bicycle chain

Chain drive was the main feature which differentiated the safety bicycle introduced in 1885, with its two equal-sized wheels, from the direct-drive penny-farthing or “high wheeler” type of bicycle. The popularity of the chain-driven safety bicycle brought about the demise of the penny-farthing, and is still a basic feature of bicycle design today.

Automobiles

Transmitting power to the wheels

Chain final drive, 1912 illustration

Chain drive was a popular power transmission system from the earliest days of the automobile. It gained prominence as an alternative to the Systme Panhard with its rigid Hotchkiss driveshaft and universal joints.

A chain drive system uses one or more roller chains to transmit power from a differential to the rear axle. This system allowed for a great deal of vertical axle movement (for example, over bumps), and was simpler to design and build than a rigid driveshaft in a workable suspension. Also, it had less unsprung weight at the rear wheels than the Hotchkiss drive, which would have had the weight of the driveshaft to carry as well, which in turn meant that the tires would last longer.

Frazer Nash were strong proponents of this system using one chain per gear selected by dog clutches. The Frazer Nash chain drive system, (designed for the GN Cyclecar Company by Archibald Frazer-Nash and Henry Ronald Godfrey) was very effective, allowing extremely fast gear selections. The Frazer Nash (or GN) transmission system provided the basis for many “special” racing cars of the 1920s and 1930s, the most famous being Basil Davenport’s Spider which held the outright record at the Shelsley Walsh Speed Hill Climb in the 1920s. Frazer Nash cars are still raced in the UK.

Parry-Thomas was killed during a land speed record attempt in his car ‘Babs’ when the chain final-drive broke, decapitating him.

The last popular chain drive automobile was the Honda S600 of the 1960s.

Inside motors

Internal combustion engines often use chain drive to power the timing chain used to drive overhead camshaft valvetrains. This is an area in which chain drives frequently compete directly with belt drive systems, and an excellent example of some of the differences and similarities between the two approaches. For this application, chains last longer, but are often harder to replace. Being heavier, the chain robs more power, but is also less likely to fail. The camshaft of a four stroke engine must rotate at half crankshaft speed, so some form of reduction gearing is needed and a direct drive from the crankshaft isn’t possible. Alternatives to chain drives include gear trains, bevel gear and shaft drives, or toothed flexible belt drives.

Transfer cases

‘Silent chain’ drives inside a 1912 gearbox

Today, inverted tooth drive chains are commonly used in passenger car and light truck transfer cases.

Motorcycles

Chain drive versus belt drive or use of a driveshaft is a fundamental design decision in motorcycle design; nearly all motorcycles use one of these three designs. See Motorcycle construction for more details.

See also

Bicycle chain

Chain pump

References

^ Green 1996, pp. 2337-2361

^ Cross & Morse in Birmingham, http://www.crossmorse.com

^ a b Werner Soedel, Vernard Foley: Ancient Catapults, Scientific American, Vol. 240, No. 3 (March 1979), p.124-125

^ Needham, Joseph (1986). Science and Civilization in China: Volume 4, Part 2, Mechanical Engineering. Cave Books, Ltd. Page 109.

^ Needham, Joseph (1986). Science and Civilization in China: Volume 4, Part 2, Mechanical Engineering. Cave Books, Ltd. Page 111, 165, 456457.

^ a b c Temple, Robert. (1986). The Genius of China: 3,000 Years of Science, Discovery, and Invention. With a forward by Joseph Needham. New York: Simon and Schuster, Inc. ISBN 0671620282. Page 72.

Bibliography

Green, Robert E. et al. (eds) (1996), Machinery’s Handbook (25 ed.), New York: Industrial Press, ISBN 978-0-8311-2575-2 .

External links

Wikimedia Commons has media related to: Drive chains

The Complete Guide to Chain

Motorcycle primary and drive chains explained

Categories: Mechanics | Automotive transmission technologies | Mechanical power transmission | Mechanical power control

More Windlass Articles

(PRWeb UK) February 25, 2011

In capacities from 125 to 5000Kg, the new LX chain hoist from Street Crane Company opens a new market segment and is certain to attract attention. Already the UK’s largest crane manufacturer and a major exporter, Street Crane has designed the new hoists for precise and safe lifting for a range of industries such as automotive, commercial transport, construction, aviation, light marine and general engineering workshops.

Flexibility was a key project goal – there are hoists to meet every need. Eye suspension models for stationary lifting, powered or push trolley options, standard height models or chain hoists configured for low/restricted headroom situations are just a few of the choices. Other options include choices of hoist and travel speed, dual speed hoisting, enhanced environmental protection to IP55 and variable frequency travel drives. IP54 is the default environmental protection standard and all models are suited for temperatures from -20 to +50 degrees C.

Safety is paramount. A slipping clutch provides overload protection and chain hoists feature high performance disk brakes. Plug and socket electrical connections simplify final fix installation. Limit switches can be set for both hoisting and lateral travel.

There are several answers to problems of height limitation. On low headroom hoists the hook rises to the side of the motor gearbox to give an exceptionally low profile. Where the available operating envelope for the hoist is more limited, the hoist can be installed between the beams of a double beam crane to give an even greater clear working height.

Control options include 48 Volt standard pendant control or remote operation by radio device for greater convenience and safety. Control units can be set-up for solo operation or to work twin hoists for tandem lifts.

Built for world markets, LX chain hoists have rated capacities expressed as Metric tonnes or US tons. A wide selection of motor voltages allows hoists to meet different national requirements. Products are fully tested and certified under relevant EU and other international regulations.

Street Crane is a world leader in overhead cranes and wire rope hoists used for factory applications requiring lifts of up to 200 tonnes. Andrew Pimblett explained, “The new LX hoists are aimed at the volume market and are ideal for localised workstations and production line applications where they might typically be used on jibs, monorails, and light track crane systems. It has taken many years to establish Street Crane as a global player in wire rope hoists and we are confident that the value offered by the LX electric chain hoist will be very attractive to our customers. Feedback from our international distributors has already been highly favourable.”

More information

Gus Zona, Tel. +44 (0)1298 812456 Fax. +44 (0)1298 814 945

Street Crane Company, Chapel-en-le-Frith, High Peak, SK23 0PH, UK

Is it good to start off with 180lbs, then dropping down 10lbs at a time to 170lbs, etc. ( you get the picture ) ?

Basically, what’s better starting off with light weight, and adding more, or starting off heavy, and reducing weight ?

Best answer:

Answer by pyroflame647
Starting off small and then getting heavier. Then stay with your max and lift it over and over.

What do you think? Answer below!

Demag Cranes & Components Corp. 29201 Aurora Road Solon Ohio 44129 1-800-756-8221 www.demagbridgecrane.com

Kito’s Maurie Bergstrom shows how the L5LB slip clutch hoists make for safer worksites
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Dallas Fields from Fields Dive Service shows what it takes to change the top chain on a mooring in Rockport Maine in 55′ of water. Water was 39 degrees and visibility was great for Maine at about 15′-20′
Video Rating: 5 / 5

my frist power lifting video i hope you guys enjoy. i just had my frist power lifting comp such a blast ok guys thank!
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Bench press part of Power Lifting Contest in Rochester NY in Aug. 2008.
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One of the best things that one can do, in order to be safe with regard to anchor rope when tossing the anchor in the water is to braid the anchor rope to the anchor chain. This is must when one is boating. Anchor rope made from nylon should be used because this rope has the maximum elasticity that can take in the shocks that it bears due to the force of the water current. For a long life of the anchor, try your best to keep it in shade when the anchor rope is not in use.

To braid the anchor rope, untie it almost 12 inches from the end at the lower part. The anchor rope is always melted so that it does not untie. You will have to cut or pull apart the strands. In case there is no way out other than cutting, put an electric tape to prevent it from opening.
Form the end of the link of the chain; pass two of the three rope sections. And the third one has to be passed from the opposite side. Now two strands must strike out from one side and the third from the other side. One end has to be brought down far from the chain and the Swedish fid has to be stuck into a section of the rope. Now, it must be pulled from the opposite direction to twist but very firmly.

Then twist the anchor rope in a way that one side faces up and the fid can be slide into the other one. Pull down and hold the next section. Repeat the same for the remaining strand. Now tuck back all the section on the anchor rope. Keep twisting the sections and each strand. You must have a set of 6 tucks in each strand. Now untie each strand in a way that there are two sections for each strand. At the end twist the anchor rope at the top where the anchor meets the rope.

Best answer:

Answer by injanier
There are many alloys under the general category of stainless steel. 400-series alloys are all magnetic to some degree. 300-series alloys are generally non-magnetic, but some alloys become magnetic when cold-worked (i.e. rolled or drawn).

What do you think? Answer below!

Although the purpose of rules is to make things less complicated, they can sometimes do the opposite– especially if technical government jargon is involved.

If you’re a truck driver, the last thing you need is some Town Car driving bureaucrat to tell you how to do your job. Everyone knows that load securement is important; no one wants to be the poor guy standing on the side of the highway with his load scattered across the road for miles.

The official rules are complicated and get more complicated everyday; and to many experienced drivers they have little to do with reality. But unfortunately, it’s the law to follow them, no matter how much we may disagree.

There are many intricacies to direct and indirect truck tie downs. The old standards of working load limits, tensile strength, and “the weakest link” that have worked for decades, even centuries, no longer meet government standards.

First off, the rule according to the DOT handbook states that you must have half of the weight of your load in tie down strength. This refers to the holding power of your winch straps, rachet straps, load binders, truck tie downs and other important items used for cargo securement.

Here’s how to make sure your next load is secured according to the law:

1) First off, the bigger chains the better off you are as they are much more capable of holding larger loads. Your best bet is half inch chains. Anything smaller just wouldn’t do the job and anything bigger would be really heavy and hard to work with.

2) In the rear of the load, try 2 half inch chains and load binders crossed. This is so the load doesn’t move sideways in either direction. You do it at an angle so the load doesn’t shift and go forward when you hit the brakes.

3) The chains should have grab hooks on the trailer side and should be attached through a D-Ring that’s attached to the trailer. D rings are great because they’re rated at 10,000 lbs.

4) On the load side, having slip hooks on the chains to connect to the D-rings really come in handy. 5/8 Slip hooks fit nicely with a half-inch chain.

5) Chain positioning is really important. Many drivers prefer to have chain going through the rub rail, around the chain spool, and back under the stake pocket, finally hooking it. (Make sure you’re cross-chaining again to keep your load from moving sideways or backwards.) You should also do it this way, because the chain is stronger than the standard trailer connect spots. It may take more time to do it this way, but if you get in a wreck you don’t have to worry about the trailer connects and stake pockets becoming loose. This is also done because if there’s slack in your chain for any reason, the hook won’t come out.

All in all, your best bet is to read the DOT handbook or get someone to translate the jargon for you. One key thing to remember is that half of your load weight must be in tie-downs. Invest in some quality truck tie downs and use them properly to ensure you’re following proper regulations.

Matt and Joe go over proper wet-sanding techniques for stainless steel moldings.
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