Negative torque sensor for a gas turbine engine

Claim 1

Negative torque sensing and propeller feathering apparatus for use on aircraft having a variable pitch propeller, said propeller feathering apparatus including both a mechanism for varying the pitch of said propeller and a source of oil pressure applied to said mechanism, the pressurizing of said source enabling the setting of the pitch of said propeller, said propeller returning to a feathered state when the pressure of said source is reduced below a predetermined level, said propeller being coupled to a gas turbine engine through planetary gearing including therein an input member, an output member and a rotatable reaction member, said torque sensing and feathering apparatus comprising: an annular disk rotatably mounted concentric with the axis of said reaction member; coupling means from said disk to said reaction member for transferring reaction forces to said disk in response to torque being applied to said planetary gearing, said coupling means including a torque indicator for providing instantaneous indications of torque applied to said planetary gearing; means for providing an angular stop for said disk, said means providing reaction for said reaction member in response to positive torque applied to said planetary gearing from said engine; means responsive to angular motion of said disk away from said positive stop in response to negative torque applied to said output member from said propeller for rapidly reducing the pressure of said source below said predetermined level for altering the pitch of said propeller to its feathered position; and means responsive to a decrease in negative torque for automatically enabling the repressurizing of said source.