| 摘要 |
1,141,884. Toothed gearing. IMPERIAL METAL INDUSTRIES (KYNOCH) Ltd. 27 April, 1967 [23 May, 1966], No. 22873/66. Heading F2Q. In a gear train comprising driving and driven gear-wheel units 4, 5 (Fig. 2), the distance between their axes of rotation being variable, connected by an idler gear unit 12, each unit comprising a gear-wheel 8, 10, 13, and at least one coaxial cylindrical spacer 9,11, 14, the spacer 14 of the idler unit being in rolling contact with those of the driving and driven units when the gear teeth are in correct mesh, the relative disposition of the units is such that the resultant of the forces applied to the idler gear teeth acts in a line passing between the axes of rotation of units 4, 5 to hold the idler teeth constantly in correct mesh with those of the driving and driven gears. This is so when the angle between a line through the axes of rotation of the units 4, 12 and a line through the axes of rotation of the units 5, 12 is greater than twice the pressure angle of the meshing gear teeth. The spacers have diameters equal to the pitch circle diameters of their respective gear-wheels and are integral therewith. To retain the idler unit when stationary, or on overrun, a spring 15 may be used, or a slipper block (22) (Fig. 6, not shown), or a fixed peg (19) within an annular idler unit (18) (Fig. 5, not shown). If the axes of the units 4, 5 lie substantially in the same horizontal plane and the idler is above them, gravity suffices. In Fig. 7, a belt 29 round pulleys 30, 31 forming axial extensions of the driving and driven units 25, 26 prevents relative rotation of the latter when they are unloaded, to prevent the idler unit 24 from falling out of mesh. In Fig. 8 (not shown) an idler (12) is carried on an arm (34) pivoted on the shaft (6) of the driving unit (4) for use in opposite directions of rotation, a friction coupling between the arm (34) and the shaft (6) moving the idler from one drive position to the other when the drive is reversed. In Fig. 11 the pitch circles of the driving and driven units 35, 40 overlap, the unit 35 having two gear-wheels 36 spaced apart and the spacers 43 of the unit 40 being axially spaced from the gear-wheel 41. Gears 36, 41 mesh a wide idler gear (46) (Fig. 10, not shown). In Fig. 13, a driving unit 52 lies within an internally toothed annular driven unit 49 and is connected thereto by an idler unit 53. The gears may be of metal, rubber, or plastics |
