LIFTING DRIVE DEVICE FOR FOUNDATION CONSTRUCTION

摘要

PROBLEM TO BE SOLVED: To prevent break of a rack tooth in a lifting drive device of a rack chain system by a method wherein a rack for engagement with chain is formed so that the ridge of a tooth of rack outside a reference pitch line is formed into a square shape in the front view and the ridge has a specific thickness and the valley is formed into a specific arcuate shape. ;SOLUTION: A rack tooth 8a of a rack 8 for engagement with a chain is formed so that the ridge M of the tooth outside a reference pitch line L of the tooth 8a has a nearly square shape in the front view, and the thickness of the ridge M is formed so as to have a value equal to chain pitch (p) minus twice the radius (r) of a chain roller 21 (p-2r). A valley N is formed so as to have an arcuate shape having a radius of curvature δ nearly equal to the radius (r). Thus when the chain is driven and the roller 21 engages the tooth 8a, the roller 21 can mesh deeply with the valley N of the tooth 8a, and the valley N and the ridge M can uniformly engage with each other, in rolling contact, so that the break of the tip end of the rack tooth can be surely avoided.;COPYRIGHT: (C)1998,JPO