Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
B66C23/60—Derricks
B66C23/605—Derricks employing ships' masts
H—ELECTRICITY
H03—ELECTRONIC CIRCUITRY
H03F—AMPLIFIERS
H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
H03F1/52—Circuit arrangements for protecting such amplifiers
H03F1/54—Circuit arrangements for protecting such amplifiers with tubes only