Abstract: A valve operating mechanism comprises a hollow shaft (10), a sleeve journalled on the hollow shaft and having a cam, a coupling yoke (16) connected by a first pivot pin (18) to the hollow shaft (10) and by a second pivot pin (20) to the sleeve and means for pivoting the yoke (16) to effect a phase change between the hollow shaft (10) and the sleeve, wherein the means for pivoting the yoke (16) comprises an actuating rod (24) slidably received in the hollow shaft (10), a cam surface on the actuating rod (24) and a plunger (22) passing through a generally radial bore in the hollow shaft (10) to cause the yoke (16) to pivot in response to axial movement of the actuating rod (24).

Abstract: A dual duct porting system comprises a pair of juxtaposed bent, side entry supply ducts (14, 15) merging into a single supply passage (16) encircling a valve stem (13). Each supply duct (14, 15) has eddy creating means (20) provided at a radially inner region of the duct bend and an outwardly bulging portion (21) at a radially outer region of the duct bend to provide a flow in the merged passage (16) which is more evenly spread around the valve head to be shed therefrom as evenly distributed toroidal vortices.

Abstract: A differential gear mechanism of the type having a gear carrier (1A, 1B) mounted for rotation about the output axis of the differential, a pair of spaced coaxial helical output gears (4A, 4B) mounted for rotation in the carrier about the output axis, and gear trains mounted in the gear carrier and interconnecting the two output gears, each gear train comprising two worm members (5A-D) and a worm wheel (7A,C; 7B,D) is characterized by the following equations: ##EQU1##

Abstract: Limted slip differential mechanism for dividing input torque, applied to a splined sleeve (5) unequally between a front propeller shaft (7) and a rear propeller shaft (8) comprises a casing (10) (carrying the sleeve 5) in which are mounted for rotation about their respective axes a wormwheel (21ad) and front and rear worms (18D, 18A) meshing with opposite sides of the wormwheel (21ad) and being of sufficient length also to mesh with helical output gears (15,16) on the respective shafts (7,8). The rear output gear (16) is larger than the front output gear (15) so the torque is divided between the output gears in the ratio of their pitch circle diameters in the absence of substantial relative rotation while normal traction is maintained, but with limited slip if potential loss of traction occurs.