The bogie pivots around it using the center pivot pin. A fulcrum is the support about which a lever pivots. This is a body that pivots on a fulcrum. In the second-class lever design, the arm pivots below the rim. In the first-class lever design, the arm pivots above the rim. His technique uses simple machines such as levers aided by counterweights and pivots. The levers between the key cups and the pivots are called "key arms". This is particularly the case for linear sliding joints, rather than rotating pivots. The wagon-like wheels were usually fastened by wood pivots and iron axles. These were often mounted on pivots and slides. This change pivots the budget constraint outwards. It achieves this by having a surface that pivots about a "virtual polar axis". The entire tail assembly pivots at the rear of the fuselage to provide pitch trim. After feathering and extending the arms, the rower pivots the body forward. In lower quadrant signals, the arm pivots down for less restrictive aspects.