Line descent braking device

Claim 1

IN A CARGO OR PERSONNEL LOWERING DEVICE OF THE TYPE WHEREIN A FRAME HAS A TORTUOUS PASSAGE THERETHROUGH THROUGH WHICH A ROPE IS ROVE AND WHEREIN A LOAD CARRIED BY SAID FRAME DESCENDS THEREWITH ALONG SAID ROPE AT A RETARDED RATE OF SPEED, THE IMPROVEMENT COMPRISING SAID FRAME BEING OF INVERTED U-SHAPED CONFIGURATION AND INCLUDING A BRIGHT AND LEGS, SAID LEGS BEING OF CHANNEL SHAPE AND INCLUDING WEBS AND SPACED FLANGES, SAID WEBS BEING ADJACENT EACH OTHER, SAID FLANGES OF ONE LEG EXTENDING LATERALLY OUTWARDLY THEREOF IN THE OPPOSITE DIRECTION TO SAID FLANGES OF THE OTHER LEG, VERTICALLY SPACED HOLLOW RUNGS CONNECTING SAID LEGS TOGETHER TO PROVIDE SAID TORTUOUS PASSAGE, SAID RUNGS BEING OPEN AT BOTH ENDS TO PROVIDE AIR PASSAGES THERETHROUGH, SAID FRAME AND RUNGS BEING FORMED OF LIGHTWEIGHT METAL HAVING A HIGH RATE OF HEAT CONDUCTIVITY, AND SAID WEBS AND FLANGES PROVIDING COOLING FINS FOR DISSIPATING HEAT GENERATED IN SAID RUNGS BY THE FRICTION OF THE PASSAGE OF THE SAME ALONG SAID ROPE.