Question: Why are pork bellies put into a tumbler?
About the article "Bacon", section "Process".

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First, pork bellies are sorted by size and fat percentage.
They are then placed into a large machine that rotates (often called a tumbler).
This softens the bellies, which makes it easier to remove the rinds.
The bellies are then cut, either manually or mechanically, to remove the skin from the meat.
The skins may be used to be processed into pork rinds.
The bacon is then treated by a brine solution.
The brine solution may contain the flavorings, or the flavorings may be added later.
After being brined, the bacon is smoked.
Depending on where the bacon is made, the smoking process is different.
The bacon is then cooked in an oven and soon after chilled for a few days.
The cooling makes the meat firm which makes it easier to slice.
After being cooled, the bacon is sliced into strips.
The bacon is then cooked.
The fat that cooks off the bacon is sometimes collected to be used for things like gravy and pet foods.
The bacon strips are then ready for consumption.
If the bacon is made for commercial use then the strips are packaged.
According to food historian John Mariani, it is the second most popular sandwich in the US, after the ham sandwich, and a poll by OnePoll in 2008 showed that it was the "nation's favourite" sandwich in the UK.
BLT sandwiches are popular especially in the summer, following the tomato harvest.
In the USA, the BLT-season is associated with an increase in the price of pork-bellies, which are processed into bacon. 
The Armenian Tumbler is a breed of tumblers that originated in Armenia, where they are bred for their color and flight.
As the name suggests the Armenian Tumbler is a part of the Tumbler family.
This breed was developed in Armenia, the Armenian Tumbler is a flying type and color pigeon. 
Pork belly is a boneless cut of fatty meat from the belly of a pig.
Pork belly is popular in Asian cuisine, including the Rafute of Okinawan cuisine, and forms a part of many traditional European dishes such as the Alsatian "Choucroute garnie", the Swiss "", and the German "Schlachtplatte".
In the United States, bacon is most often made from pork bellies.
In Colombian cuisine pork belly strips are fried and served as part of bandeja paisa (chicharon).
A 100-gram serving of pork belly typically has about 520 calories.
The calorie breakdown is: 92% fat (53 g), 0% (0 g) carbohydrates, and 8% (9 g) protein.
This cut of meat is enormously popular in Chinese cuisine and Korean cuisine.
In Chinese cuisine, it is usually diced, browned then slowly braised with skin on, or sometimes marinated and cooked as a whole slab.
Pork belly is used to make Slowly Braised Pork Belly (紅燒肉) or "Dongpo pork" (東坡肉) in China (Sweet and Sour Pork is made with pork fillet).
Koreans cook "Samgyeopsal" on a grill with garlic, often accompanied by "soju".
Uncured whole pork belly is a popular dish in American cuisine as well. 
After it is cut into pieces, the meat from the animal is then processed further into edible products.
The buttocks are salted and pressed in order to eventually produce ham.
The ribcage meat is salted and smoked in order to get bacon.
Salt is rubbed thoroughly into each piece of meat and all surfaces are covered.
Some formulas also include lots of black pepper.
The bulk of the meat is cut and ground to produce various sausages, which are traditionally wrapped into the intestines of various sizes.
The bulk of the fat is cut into small pieces.
Some of it is fried to produce cracklings.
Lard is made by rendering - heating fragments of fat in a large iron pot over a fire until it is reduced to simmering grease which congeals when cooled.
Lard is then stored in lard tins with tin covers.
The typical tins in the US are five gallons.
The intestines are stripped by drawing them through a clenched fist.
They are then washed, cut into short pieces, and fried to make chitlins.
The various "leftovers" are put into various forms of headcheese jelly, etc.
Most parts of the pig are used in this traditional process, even parts of the skin that would normally be thrown away are preserved to be cooked with beans.
The smoke house is essential for the preservation and long term storage of hams, shoulders, bacon sides, and pork bellies.
The meat is hung on racks and hooks in the smokehouse; and later smoked.
Fragrant hardwood, such as hickory, beech, or cherry is allowed to smolder slowly in a pit below the hanging meat.
This gives added flavor and color to the meat as well as serving to dry cure the pork.