A heavy plate is a flat and heavy object, usually made of cast iron, used in combination with a barbell or dumbbell to produce a bar of total weight desired for physical exercise purposes.
Two general categories exist: "standard" plates, which have a center hole about an inch (25 mm), and an "Olympic" plate, intended to fit on two inches (50 mm) Olympic barbell arms. Standard plates are usually paired with customizable dumbbells and Olympic plates with full-sized barbells, although standard barbells and Olympic dumbbells exist.
Heavy plates can incorporate holes for easy carrying (called "handle plates") or into compact discs (especially those used for competition). Non-competition plates often have variable diameters and widths, such as in adjustable dumbbells depicted correctly, with heavier plates generally larger in diameter, thickness, or both. Weight plates are usually round, although there are 12 sides and other polygonal varieties. Most plates are coated with enamel or hammertone to resist corrosion; more expensive varieties can be coated with chrome, rubber, or plastic.
Video Weight plate
Plate size
The dishes are available in various weights. Standard plates (1-inch center holes) are generally available in 2.5, 5, 10, and 25 lb denominations, with 1.25, 7.5, 12.5, 50, and 100 pound plates less visible. Generally available dishes with denominations of kilogram are 1.25, 2.5, 5, 10, 15, and 20 kilograms, with plates of 0.5, 7.5, and 25 kilograms less visible.
Denominations of the General Olympic plates (2-inch center holes) are 2.5, 5, 10, 25, 35, and 45 lbs, with 1.25 and 100 pound platters less visible. Kilogram-denominated plates are available in sizes of 1.25, 2.5, 5, 10, 15, 20, and 25 kg, with 0.25, 0.5, and 50 kilograms less visible.
Bumper plates are generally available in denominations of 10, 15, 25, 35, 45, and 55 lb, or 5, 10, 15, 20, and 25 in kilograms.
Some companies sell "1" lb (0.5 kg) "or less" fractional "weight plates. This allows "microloading" from the bar to achieve a very small increase in strength for advanced strength trainees. An alternative to microloading is to use a set of washing machines with one or two inch center holes.
Maps Weight plate
Accuracy weight
Inexpensive plates can vary greatly from the weight they are marked. Unusual 2% or 3% variations, with plates of some manufacturers often 10% or more above or below (45-lb plate weighing about 40 lbs, or as much as 50). Tom Lincir, founder of Ivanko Barbell Company, has found a 45-lb weighing 38 pounds, or as much as 59 pounds.
Plates can be weighed, and marked equipment (using paint pens or other permanent markers) with the correct weight.
Calibration plates are available from high-end manufacturers; many who advertise these plates as accurate to within 10 grams (0.02 lb) of the marked weight, which is a tolerance mandated by the International Weightlifting Federation for plates used in the competition.
Bumper plate
Olympic plates may come in the form of bumper plates, made of durable rubber. It's used for Olympic heavy lifting, a category of movement that involves lifting a high load of barbells, then letting it fall.
Bottom bumper plates are generally made of solid rubber with steel or brass hubs. The competition class bumper plate is more compact, with a rubber layer that surrounds the steel core. The bumper plate allows the barbells to be loaded for dropping (and to rise) after removal, with meaningless damage to floors, plates, and bars.
The bumper plate used in the competition has a diameter mandated by the International Weightlifting Federation 450 millimeters (17.72 inches) Â ± 1 millimeter (0.04 in), with a lighter plate that is narrower than the heavier plate. The lightest bumper plates available are generally 5 kilograms (11 pounds), or 10 pounds (4.5 kg) in pound-denomination units. Lighter plates of this are generally smaller in diameter and are known as "change plates" when paired with bumper plates.
As an alternative to rubber plates, "engineering plates", made of plastic, are available. The engineering plate is more expensive than rubber, but it holds better against repetitive droplets. Their main goal is to allow beginner trainers to practice lifting the Olympics on lighter weight that can put too much lateral pressure on a single pair of rubber plates, damaging them.
vinyl plate
Standard (1-inch) "vinyl" plates are often sold in pairs with dumbbells or barbell as a low-cost option for casual strength training. This plate is made of cement or sand coated with polyvinyl chloride sheath. The cement tends to break down over time and leaks out of the holes in the sheath, and the weight is less dense than the iron so that it loads less on the given rod.
Weight stack
Heavy machinery generally uses a special dish (called "heavy pile"), which consists of a set of rectangular plates mounted on the rails. Loads are transmitted to machine users via cable and pulley settings. The weights used are selected by inserting pins in the stack causing each plate above the pin to be pulled by the cable. This setting is known as a "picky" weight machine.
Some heavy machinery, such as a sleeve type foot press, or a Smith machine, are designed to be loaded with an Olympic plate instead of using a wire pile.
References
Source of the article : Wikipedia
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