Gas turbine engine clearance control apparatus

An apparatus for controlling the clearance between the tips of a row of radially outwardly extending rotor blades and an annular array of circumferentially surrounding shroud segments in a gas turbine engine having a generally axially extending engine casing, said apparatus comprising:

• (a) a radially extending torque tube rotatably mounted on said casing and having an axially extending cam disposed inside said casing;
• (b) a first member having a first cam-engaging surface and a first hooked flange;
• (c) a second member having a second cam-engaging surface and a second hooked flange;
• (d) means for disposing said members inside said casing such that said members are generally only axially moveable relative to said casing and such that said cam-engaging surfaces axially surround said cam;
• (e) means for biasing said members such that said cam-engaging surfaces axially engage said cam;
• (f) a shroud hanger having axially spaced apart third and fourth hooked flanges disposed to be engagable respectively by said first and second hooked flanges, said flanges having axially inclined slide surfaces for said engagement, and with a said shroud segment attachable to said shroud hanger;
• and
• (g) means for biasing said shroud hanger radially inward to engage said slide surfaces, wherein rotation of said torque tube axially moves said first and second members which radially moves said shroud segment;
• wherein said disposing means includes a support cone fixedly attached to said casing and having an axially extending circumferential rim and wherein said disposing means also includes one of said members having a circumferentially continuous ring portion with an axially extending circumferential groove slidably engaging said rim, and
• wherein said means for biasing said shroud hanger includes a leaf spring having one end attached to said third hooked flange and having another end compressibly and slidably contacting said first member.