(1) A hydraulic prop is by far superior to any friction prop in so far as acceptance of a sufficiently high-and uniform load in the underground application is concerned. The friction prop has irregular behaviour under load and it slides more than a hydraulic prop under a similar load.
(2) A high setting load is obtained in a hydraulic prop.
(3) Friction prop is lighter in weight and has a superior extensibility.
(4) Friction props serve a long life on sand stowing Paces.
(5) Friction as well as hydraulic props can be easily withdrawn.
Wooden lids are not used with friction props and hydraulic props. Where such props have to accommodate steel roof bars, the prop heads have prongs which prevent the prop from, being jolted or forced out of position by an accidental heavy blow or roof pressure.
No comments:
Post a Comment