| 摘要 |
610,456. Change-speed gears. TRACTORS (LONDON), Ltd., and MINES, F. R. April 5, 1946, No. 10637. [Class 80 (ii)] In a change-speed gear a driving shaft 10 is arranged to drive a planet carrier 11 through a centrifugal clutch 12, and compound planetwheels 14, 18 mounted on the carrier mesh with a sun-wheel 15 on a sleeve 16 attached to a driven sprocket-wheel 17, and a sun-wheel 19 respectively. A flange member 20 keyed to the sun-wheel 19 has clamped thereon one end of a helical spring 24, the other end of which is secured to the inside of a brake-drum 27. The helical spring is arranged normally to lightly embrace a cylindrical surface 25 of the planet carrier 11. Studs 31 on the brake-drum 27 engage slots in the flange member 20 and also engage cam faces on centrifugal masses 29 pivoted at 28 on the member 20. The brakedrum 27 is encircled by a brake-band not shown. Anti-clockwise rotation of the driving shaft (looking in the direction of arrows 2, 2) produces anti-clockwise rotation of the planet carrier and member 20, the brake-drum being free. The centrifugal masses 30 acting on the studs 31, cause the brake-drum to move anticlockwise with respect to the member 20, causing the spring to contract on to the cylindrical surface 25, thus establishing a locked forward drive. Application of the brake-band to the brake-drum causes the spring to expand and engage the internal surface of the brakedrum. Thus, sun-wheel 19 is brought to rest and a reverse drive effected. |
