Patent ID: 8567125

Claim:
A push-pull chain ( 10 ) having a driving direction for an actuator for opening and closing a swinging part of a window, door or other panel, said chain ( 10 ) comprising: a plurality of pairs of oppositely placed inner links ( 14 , 14 ′) and a plurality of pairs of oppositely placed outer links ( 15 , 15 ′), alternate pairs of said inner links ( 14 , 14 ′) being sequentially coupled to alternate pairs ( 15 , 15 ′) of said outer links by parallel drive pins ( 19 ) with bushings ( 20 ) that separate the pairs of inner links ( 14 , 14 ′) and outer links ( 15 , 15 ′), with one link ( 14 ) of a pair of inner links and one link ( 15 ) of a pair of outer links being part of a first side of the push-pull chain and the other link ( 14 ′) of the pair of inner links and the other link ( 15 ′) of the pair of outer links being part of a second side of the push-pull chain, with said bushings between the links of said first side and the links of said second side and with said first side and said second side forming opposite sides of the push-pull chain; said drive pins ( 19 ) being received in holes in said outer links ( 15 , 15 ′) and said drive pins ( 19 ) being rotatably received in a hole in said bushings ( 20 ); the inner links ( 14 , 14 ′) and the outer links ( 15 , 15 ′) on said first side and on said second side are shaped to allow the push-pull chain ( 10 ) to bend by pivoting of the links ( 14 , 14 ′, 15 , 15 ′) about the drive pins ( 19 ) past a configuration in which the chain forms a straight line in a first bending direction and the inner links ( 14 ) and the outer links ( 15 ) on said first side are shaped to only allow the push-pull chain to bend by pivoting of the links ( 14 , 14 ′, 15 , 15 ′) about the drive pins ( 19 ) to a limited extent in a second bending direction, opposite to said first bending direction past said configuration wherein said chain forms a straight line; the inner links ( 14 ′) and the outer links ( 15 ′) on said second side of said bushings ( 20 ) allow the chain ( 10 ) to bend by pivoting of the links ( 14 , 14 ′, 15 , 15 ′) about the drive pins ( 19 ) past said configuration only to a certain extent in said second bending direction, wherein said certain extent is greater than said limited extent; and a play or backlash in said driving direction between the drive pins ( 19 ) and the hole in the bushings ( 20 ) at said second side is greater than a play or backlash between the drive pins ( 19 ) and the hole in the bushings ( 20 ) at said first side to allow said chain to laterally flex in two opposite flexing directions with said two opposite flexing directions being substantially perpendicular to said first bending direction and said second bending direction respectively.