| 摘要 |
An improved boom section has top and bottom walls formed of sloping plate sections or flanges which define peaks between the side walls. The peaked configuration of the bottom wall increases the buckling strength of the bottom wall over the bucking strength obtained with a flat bottom wall. The sloping flanges of the top and bottom walls are disposed at acute angles of between 12 DEG and 19 DEG to horizontal planes. If the slope of the flanges is increased to an angle significantly greater than 19 DEG , the peaks in the top and bottom walls would be disposed relatively far from the central axis of the boom section and would be subjected to excessive stresses upon loading of the boom section. The boom section is advantageously formed with a height-to-width ratio which is greater than 1 and less than 3. Lateral stability of the boom section is promoted by having slider pad forces applied to the bottom wall of the boom section intersect at a point above the center of the boom section and having slider pad forces applied to the top wall of the boom section intersect at a point below the center of the boom section. To facilitate slider pad replacement, access openings are provided in the top walls of the boom sections. The slider pads advantageously move along stainless steel strips on the walls of the boom sections.
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