GB860205A - Controllable pitch marine propeller system - Google Patents

Abstract

860,205. Variable pitch propellers. GENERAL DYNAMICS CORPORATION. Dec. 16, 1958 [Dec. 18, 1957], No. 40506/58. Class 114. A controllable pitch marine propeller system comprises a propeller assembly which is rotated by a hollow drive shaft having an inner control shaft which is mechanically coupled to the propeller blades and control means for selectively rotating the inner shaft simultaneously with the drive shaft or in either direction relative to the drive shaft, said mechanical coupling being arranged to change the pitch of the blades in accordance with the relative rotation of the inner and drive shafts. Figs. 4 and 5, which may be joined along the line AA, show the outboard portion of the system, Figs. 8 and 9, which may be joined along CC, show the inboard portion. Each blade 15 is secured to a crank ring 19, Figs. 4 and 6, having shoulders which bear against surfaces 16b of the hub housing 16. Each crank ring has crank pins 19a, 19b connected by rods 22, 22a, Fig. 3, and pins 24, 24a to cross heads 23, 23a to which are secured nuts 28, 28a, Figs. 4 and 5, engaged by a lead screw 27 with right and left hand threads coupled at 33a to the inner control shaft 34 so that rotation of said shaft by said control means (air brakes 7, 7a, Figs. 8 and 9, causes opposed fore-andaft motion of the crossheads 23, 23a and hence rotation of the blades 15 to change their pitch. The housing 16 is secured by an end cover 32, Fig. 5, to the hollow propeller drive shaft 2 and at its forward end, Fig. 4, to an inner cover 37 housing a piston 39 loaded by a spring 40 to urge lubricant in bore 37c into the hub. Nuts 28, 28a are lubricated by felt 28c fitted in grooves therein. Outer cover 38 and end cover 42 are open to the sea. The outboard section 2 of the drive shaft is connected to an inboard section 2<SP>1</SP> Fig. 8, and via flanges 54, 55 to an inner section 211, Fig. 9. The control means (air brakes 7, 7a) comprises two annular brake drums 58, 59 mounted on the shafts 21, 211 to normally rotate therewith and having compressed air actuated clutches 60, 61. A gear 66 on brake drum 58 engages a pinion 70 having a concentric pinion 72 secured thereto, Fig. 10. Similarly brake drum 59 has a gear 67 engaging a pinion 74 fast with a wide pinion 76, the latter meshing with the pinion 72 and a gear 77 which is rotatably mounted on a control shaft extension 34<SP>1</SP> and is formed with a concentric pinion 79 which acts as the sun gear for planet gears 81, 81a (not shown), 81b, on a spider 83 secured to the control shaft 34, within a ring gear 80 secured to the drive shaft 2<SP>1</SP>. If clutch 61 is energised, the brake drum 59 is stopped, which is equivalent to rotating the drum relative to the drive shaft with corresponding rotation of the drum gear 67. The latter drives pinion 74 and thus pinion 76 which drives the gear 77 and thus sun gear 79, causing rotation of the planet gears. Since the planet gears are carried on the spider 83 secured to the control shaft 34 and the ring gear 80 is secured to the drive shaft 2<SP>1</SP> ,relative rotation between the control and drive shafts will occur resulting in a turning of the screw 27 in the nuts 28, 28a and thus a change in pitch of the blades 15. Similarly, if clutch 60 is energised, gear 66 will drive pinion 70 and hence pinion 72 which will drive pinion 76 but in opposite direction to that when clutch 61 is energised. Hence the subsequent gearing rotates, and causes pitch change, in the opposite direction. When the engine is stopped, pitch change may be effected by a tool 14 having a pinion 91 to mesh with a gear 92 secured to the brake drum 58. The control shaft extension 34<SP>1</SP> has an end 94 in threaded engagement with a bore in the control shaft 34. The other end is attached by a disc 96, rod 100 (which prevents rotation of the disc and hence of extension 341), collar 109 and block 115, to a rack 114 engaged by a pinion 123 connected to a remote indicating pitch device since rotational movement of the control shaft 34 to change the pitch of the blades causes fore-and-aft movement of the extension 34<SP>1</SP> and hence of the rack 114. Microswitches associated with the compressed air control for the clutches 60, 61 are operated by the rack 114 at each end of its linear travel.