| 摘要 |
Telescoping lower and upper tracks which comprises nested open channel sections. The lower track includes a three sided channel with opposing sides each forming one half of a bearing race. The open portion of the channel is defined by in-turned lips which enhance structural rigidity thereof. The upper track also includes a three sided channel with opposing sides forming the second half of a bearing race. The open portion of the channel is defined by outwardly extending lips which enhance structural rigidity thereof. A series of balls located in the bearing race established by the upper and lower track define a structural relationship therebetween. A retainer is disposed on the upper track and includes a laterally extending portion which occupies the opening defined by the inner track. The retainer limits the amount of dimensional displacement which may occur between the upper and lower tracks to an amount within the elastic range of deformation of the balls used to define the structural relationship therebetween.
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