856,480. Turbine and compressor bladed rotors. GENERAL MOTORS CORPORATION. Aug. 7, 1959 [Aug. 13, 1958], No. 27019/59. Class 110 (3). [Also in Group XXV] In a turbine or compressor rotor, the blades are mounted with freedom to rock so as to balance centrifugal and gas loads on the blade, each blade being mounted by means of a split-pin inserted through holes in the blade and in the rim of the rotor disc, one part of the pin being secured to the blade and the other part to the rotor disc rim, the first part of the pin being capable of rolling on the other part, at least one of the abutting surfaces of the parts of the pin being convexly curved to permit this rolling. The blades comprise a vane portion 10 secured to a platform 14 having two lugs 16 which are disposed one on each side of the disc rim 18, the lugs being formed with apertures 22 and the rim with apertures 24 through which the split-pins formed of parts 28, 30 are passed. The radially outer split-pin part 28 is formed with a ridge 42 which engages in a corresponding slot 44 formed in the disc rim 18 so that the part 28 is fixed relative to the disc rim. The radially inner split-pin part 30 is formed with a groove 46 which co-operates with similar grooves 48 formed in the blade lugs 16, a locking-pin 50 engaging with the grooves 46, 48 so as to secure the part 30 relative to the blade. The upper surface 34 of the pin part 30 is convex and the lower surface of the pin part 28 is concave so that limited rolling may occur between the pin parts 28, 30. Transverse holes 52, 54, are formed at the ends of the pin parts 28, 30 and locking-pins 56, 58 are engaged therein, the ends of the pins engaging against the sides of the blade lugs, and against the ends of the pin 50 to prevent endwise movement thereof. The pins 56, 58 are loosely fitted into the pin part 28 so that movement can occur between the pin parts. In Fig. 5, the pin part 28<SP>1</SP> is secured to the disc rim 18<SP>1</SP> by means of a retaining-pin 68 engaging in grooves 70, 72 in the pin part and disc rim respectively, the pin 501 being similarly received in grooves in the blade lugs 16<SP>1</SP> and in the pin part 30<SP>1</SP>. Annular grooves 80, 82 are formed at the ends of the split-pin and circlips 84, 86 are engaged therein to prevent axial movement of the split-pin and of the retaining-pins. In Fig. 7, the pin part 28<SP>11</SP> is secured to the disc rim 18<SP>11</SP> and the pin part 30<SP>11</SP> is secured to the blade lugs 1611 as in the first embodiment, but the pin part 30<SP>11</SP> has one end 88 larger in diameter than the hole provided in the blade lug 16<SP>11</SP>, one part of the end 88 engaging against the pin part 28<SP>11</SP> and the other part engaging against the side of the blade lug 16<SP>11</SP>. The other end of the pin part 30<SP>11</SP> is of smaller diameter than the holes in the blade lugs 16<SP>11</SP> but large enough to overlap the pin part 28<SP>11</SP>. A retaining-pin 100 engaged in a transverse bore in the pin part 30<SP>11</SP> abuts against the blade lug 16<SP>11</SP> and against the retaining-pin 50<SP>11</SP> so as to secure the parts against axial displacement. In Fig. 9, the pin part 30111 has screwed portions 108 at its ends, locking tab washers 110 and nuts 112 being engaged thereon. A tab 114 on each washer is bent into a slot 116 formed in the pin part 30<SP>111</SP> and other tabs 118 are bent to engage the nuts 112. In a further embodiment, Fig. 12, the pin part 28<SP>1111</SP> is secured to the rotor disc as in Fig. 2, and the ends of the pin parts 28<SP>1111</SP>, 30<SP>1111</SP> are formed with transverse slots 131, 130 shaped to receive keys 126. The blade lugs 16<SP>1111</SP> are formed with bosses 120 which are slotted at 122, 124 to receive the keys 126, and formed with annular recesses 134 to receive circlips 136 which prevent disengagement of the keys.