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Screwdriver bits in different sizes for Robertson screws. When Henry Ford tried the Robertson screws, he found that they saved considerable time in Model T production. When Robertson refused to license the design, Ford realized that the supply of screws would not be guaranteed, and chose to limit their use to his Canadian division. [4] [5] [6]
Mattress coils, also known as mattress springs, are coil springs used in a mattress. Coils are primarily used in the core (support layer) of innerspring mattresses , which is their original use. In recent years, small "micro-coils" are being used in the upholstery (comfort layer) of mattresses, primarily with a coil core ("coil-on-coil ...
Slot screw drives have a single horizontal indentation (the slot) in the fastener head and is driven by a "common blade" or flat-bladed screwdriver.This form was the first type of screw drive to be developed, and, for centuries, it was the simplest and cheapest to make because it can just be sawed or filed.
Prior to the early 1900s, springs were used as bed bases or box springs; these spring sets were not covered with fabrics. There were no "innerspring" mattresses manufactured until after 1900. Bushnell's patent has been cited [ 26 ] as an innerspring but it was an under bed spring--which in the mid-1800s was also called a mattress or base layer ...
Standard "high profile" box springs are 9 inches (23 cm) in height, whereas "low profile" box springs are between 5 and 5.5 inches (13 and 14 cm). Changing the thickness of the box spring and mattress requires revisions to the mattress and box spring coil stiffness. This is often why box springs and mattresses are matched and sold in pairs.
Marshall conceived of a mattress whereby internal independent springs would provide both support and comfort within the mattress itself. Marshall produced pre-compressed cylindrical coil springs, each sewn inside an individual cotton fabric pocket, which provided uplifting support on its own.
Mattresses are usually placed on top of a bed base which may be solid, as in the case of a platform bed, or elastic, such as an upholstered wood and wire box spring or a slatted foundation. Popular in Europe, a divan [ 2 ] incorporates both mattress and foundation in a single upholstered, footed unit.
The trade name "Yankee" screwdriver was first marketed by North Brothers Manufacturing Company in ≈16 April 1895, with the No. ≠130 spiral ratchet screwdriver. Yankee soon became and still is a well-known name in automatic spiral ratchet screwdrivers , with several other models, and model improvements patented by North Bros. over a 40-year ...