| 摘要 |
497,598. Pit-props. BUTTERLEY CO., Ltd., and FLETCHER, W. S. June 24, 1937, No. 17554. [Class 20 (ii)] A pit-prop of the type comprising a section-bar main-member 10 and a sliding-sleeve member 12 providedwith side apertures, through which the wooden pack. ing disposed above the main member in the sleeve may be inserted for adjustment, and expressed by collapse of the prop under pressure, has the upper end of the sleeve closed by a cap 13. The cap may have a flattened upper surface to contact with a wooden block or a channelled upper surface to receive the end 18 of a flat or corrugated bearer-bar. Pins 16 prevent complete detachment of the sleeve from the main member, and projections 17 limit the downward movement of the sleeve on the section-bar, and thus prevent the danger of trapped fingers between the cap and the head of the section-bar. The lower end of the sleeve may be shaped to fit the section-bar.
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