a more complex type of swivel caster, sometimes called a total lock caster, has an additional rotational lock on the vertical shaft so that neither the shaft can rotate or the wheel can turn, providing very rigid support. it is possible to use these two locks together or separately. if the vertical shaft is locked but the wheel can still turn .
several oil companies and electricity producers acquired coal companies or leased federal coal reserves in the west of the united states. concerns that competition in the coal industry could decline as a result of these changes were heightened by a sharp rise in coal prices in the wake of the 1973 oil crisis. coal prices fell in the 1980s .
the cave of the patriarchs or tomb of the patriarchs, known to jews as the cave of machpelah hebrew: מערת המכפלה, me'arat ha-makhpela help · info , trans. 'cave of the double tombs' or 'cave of the double caves' and to muslims as the sanctuary of abraham arabic: الحرم الإبراهيمي , al-haram al-ibrahimi help · info , is a series of caves located in the heart .
heron's wind-powered organ, the earliest machine powered by a windwheel. sailboats and sailing ships have been using wind power for at least 5,500 years, citation needed and architects have used wind-driven natural ventilation in buildings since similarly ancient times. the use of wind to provide mechanical power came somewhat later in antiquity.
the sepecat jaguar is a british-french jet attack aircraft originally used by the british royal air force and the french air force in the close air support and nuclear strike role. it is still in service in significantly upgraded form with the indian air force.. originally conceived in the 1960s as a jet trainer with a light ground attack capability, the requirement for the aircraft soon .
in field hockey, each player carries a stick and cannot take part in the game without it. the stick for an adult is usually in the range 89–95 cm long. a maximum length of 105 cm was stipulated from 2016. the maximum permitted weight is 737 grams. the majority of players use a stick in the range 19 oz to 22 oz. traditionally hockey sticks were made of hickory, ash or mulberry wood with the head of the sticks being hand carved and therefore required skilled craftsmen to produce. sticks made .
the aérospatiale sa 330 puma is a four-bladed, twin-engined medium transport/utility helicopter. the puma was originally built by sud aviation of france, and continued to be made by aérospatiale. it was also license-built in romania as the iar 330; two advanced, unlicensed derivatives, the denel rooivalk and atlas oryx, were made in south africa.
closeup of barnard's roller mill, new hope mills complex, new york cutaway ding of a centrifugal roller mill for mining applications, 1913 roller mills are mills that use cylindrical rollers, either in opposing pairs or against flat plates, to crush or grind various materials, such as grain , ore , gravel , plastic , and others.
during the last years of the nineteenth century, benz was the largest car company in the world with 572 units produced in 1899 and, because of its size, benz & cie., became a joint-stock company. the first motor car in central europe and one of the first factory-made cars in the world, was produced by czech company nesselsdorfer wagenbau later renamed to tatra in 1897, the präsident automobil.