my reserch
my review on belt, rope, chain drives
Introduction
A rope is a length of fibres, twisted or braided together to improve strength for pulling and connecting. It has tensile strength but is too flexible to provide compressive strength (i.e. it can be used for pulling, but not pushing). Rope is thicker and stronger than similarly constructed cord, line, string, and twine.
A belt is a loop of flexible material used to link two or more rotating shafts mechanically. Belts may be used as a source of motion, to transmit power efficiently, or to track relative movement. Belts are looped over pulleys. In a two pulley system, the belt can either drive the pulleys in the same direction, or the belt may be crossed, so that the direction of the shafts is opposite. As a source of motion, a conveyor belt is one application where the belt is adapted to continually carry a load between two points.
Chain drive is a way of transmitting mechanical power from one place to another. It is often used to convey power to the wheels of a vehicle, particularly bicycles and motorcycles. It is also used in a wide variety of machines besides vehicles.
Most often, the power is conveyed by a roller chain, known as the drive chain or transmission chain,[1] passing over a sprocket gear, with the teeth of the gear meshing with the holes in the links of the chain. The gear is turned, and this pulls the chain putting mechanical force into the system. Another type of drive chain is the Morse chain, invented by the Morse Chain Company of Ithaca, New York, USA. This has inverted teeth. [
Content
Common materials for rope include natural fibres such as manila hemp, hemp, linen, cotton, coir, jute, and sisal.Synthetic fibres in use for rope-making include polypropylene, nylon, polyesters (e.g. PET, LCP, HPE, Vectran), polyethylene (e.g. Spectra), Aramids (e.g. Twaron, Technora and Kevlar) and polyaramids (e.g. Dralon, Tiptolon). Some ropes are constructed of mixtures of several fibres or use co-polymer fibres. Rope can also be made out of metal. Ropes have been constructed of other fibrous materials such as silk, wool, and hair, but such ropes are not generally available. Rayon is a regenerated fibre used to make decorative rope.
Rope are of many kind:
Laid or twisted rope
Laid rope, also called twisted rope, is historically the prevalent form of rope, at least in modern western history. Common twisted rope generally consists of three strands and is normally right-laid, or given a final right-handed twist.
Braided rope
Braided ropes are generally made from nylon, polyester or polypropylene. Nylon is chosen for its elastic stretch properties though it has limited resistance to ultraviolet light. Polyester is about 90% as strong as nylon but stretches less under load, is more abrasion resistant, has better UV resistance, and has less change in length when wet
Plaited rope
Plaited rope is made by braiding twisted strands, and is also called square braid. It is not as round as twisted rope and coarser to the touch. It is less prone to kinking than twisted rope and, depending on the material, very flexible and therefore easy to handle and knot.
fig1. rope
Belts are the cheapest utility for power transmission between shafts that may not be axially aligned. Power transmission is achieved by specially designed belts and pulleys. The demands on a belt drive transmission system are large and this has led to many variations on the theme.
Belt drive, moreover, is simple, inexpensive, and does not require axially aligned shafts. It helps protect the machinery from overload and jam, and damps and isolates noise and vibration.
Belt are of many kind:
Flat belts
Flat belts beltwere used early in line shafting to transmit power in factories.[1] It is a simple system of power transmission that was well suited for its day.
Round belts
Round belts are a circular cross section belt designed to run in a pulley with a circular (or near circular) groove.
Vee belts
Vee belts (also known as V-belt or wedge rope) solved the slippage and alignment problem. It is now the basic belt for power transmission. They provide the best combination of traction, speed of movement, load of the bearings, and long service life
Ribbed belt
A ribbed belt is a power transmission belt featuring lengthwise grooves. It operates from contact between the ribs of the belt and the grooves in the pulley.
fig.2 belts
Chain drive was a popular power transmission system from the earliest days of the automobile. It gained prominence as an alternative to the Système 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.
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.
fig.3 chain drive
