Importance

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Abstract

Earthquake protector for protecting apparatus such as a circuit-breaker. The apparatus to be protected is mounted on a support member (2) which is connected to a plate assembly via jack 4. The plate assembly is supported on a base member (8,9) itself firmly connected to a foundation 1 on the ground. The plate assembly comprises a first plate (3) and a second plate (17) which are horizontally movable relative to the base member. The first plate has a first sole plate (5) on its lower surface which engages a second sole plate (7) on the other surface of the base member. Said sole plates are arranged to present a very low coefficient of friction to relative horizontal motion. The second plate (17) is fast with the first plate (3) and is connected therebelow by a connection means (15) passing through corresponding openings in the sole plates (5 and 7). The second plate engages the base member via spring means for opposing relative horizontal motion therebetween and is made fast to the base member by means of a pin (21) of predetermined shear strength such that the pin will break when the base member is subjected to acceleration exceeding a given threshold. The spring means are designed in conjunction with the total moving mass to be protected such that oscillitory frequencies dangerous to the apparatus are poorly transmitted from the ground to the apparatus.

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First Claim