Abstract: This invention relates to a system for mounting a helicopter rotor on a flapping axis and, more particularly, to use of an improved unitary trunnion-bearing structure of minimal parts which may be selectively preloaded and which is readily installed.

Abstract: A laminated bearing comprises a plurality of alternating and bonded together annular layers of elastomeric material and non-extensible material. The layers alternate along a common axis extending lengthwise of the bearing so that the bearing can support substantial compressive loads applied generally normal to the layers. The layers include at least one elastomeric layer which, if formed to have a nominally constant modulus of elasticity throughout and if subjected to a compressive load, would experience a shear strain adjacent one of its inner and outer circumferences greater than the shear strain adjacent the other circumference. Such a difference in compression-induced shear strains would tend to cause uneven wearing of and a reduced service life for the elastomeric layer in question and for the bearing as a whole. To avoid or minimize uneven wear, the elastomeric layer is formed to have at least two different moduli of elasticity.

Abstract: A laminated bearing comprises a plurality of alternating and bonded layers of elastomeric material and nonextensible material. The layers alternate along a common axis extending lengthwise of the bearing so that the bearing can support substantial compressive loads applied generally normal to the layers. Each layer is contoured to have, in section taken radially of the common axis, a portion projecting longitudinally toward one end of the bearing. Under large compressive loads, the contour of the layers may contribute to excessive strains in the elastomeric layers adjacent the end of the bearing toward which the layers project. To accommodate the compressive stresses without excessive strains, the layers of elastomeric material in a central lengthwise portion of the bearing have smaller compression moduli than the layers of elastomeric material adjacent the one end of the bearing.

Abstract: A rotor blade retention system connects an elongated rotor blade to a rotor hub that is rotatable about its central axis. The connected rotor blade normally extends generally radially from the hub and is rotatable with the hub. The retention system includes at least three laminated elastomeric bearings connected together in serial compression load transmitting relationship. Each laminated bearing includes a plurality of alternating and bonded together layers of elastomeric material and substantially inextensible material. The layers of each of the serially interconnected bearings are at least partially inclined relative to the longitudinal axis of the rotor blade. In section taken radially of the longitudinal axis of the blade, at least a portion of each layer of each bearing projects longitudinally toward an end of the rotor blade. Preferably, only one of the serially interconnected bearings is rigidly connected to the rotor blade.