a knitting machine with two needle cylinders arranged at a right angle, used to knit fabrics and sections of knitted garments, the inner and outer sides of which are identical, for example, lasting and double-faced knitwear. The major working parts of a ribber include latch needles mounted in the grooves of the needle cylinder, locks that move the needles consecutively along the needle cylinder grooves for loop formation, a guide that places the yarn on the needle, and a mechanism for removing the completed loops from the needles. Circular and flat ribbers differ in the shape of the needle cylinder used.

Circular ribbers are designed to produce tubular knitted fabrics, from which outerwear is sewn. Needle cylinders up to 760 mm in diameter are used, and the machine may have as many as 72 loop-forming systems. Circular ribbers usually have a pattern mechanism that individually selects the needles with the color of yarn needed for a given pattern. Electronic devices that have been developed for needle selection permit rapid pattern changes. Circular ribbers are capable of producing up to 2 million loops per minute.

Flat ribbers are usually designed for knitting garment sections. The needle beds used have working widths up to 1,200 mm, and the ribbers are equipped with pattern mechanisms and automatic devices for changing the width of the section being knitted. Flat ribbers are equipped with one or two loop-forming systems and have a noncontinuous knitting action owing to the change in the direction of the knitting motion; as a result, their output (500,000 loops per minute) is lower than that of circular ribbers. The design of some automatic glove-making machines is based on flat ribbers.

Manual flat ribbers are commonly used in small workshops. They are flexible in application but have a low output (three to six items of knitted outerwear in 7 hr). They are also used for knitting gloves and various hosiery items.