The SK range from Vogel are right-angle gearboxes ideally suited to servo motors. Whilst in-line servo geared motors will generally use planetary gearing, the SK uses a ground hypoid gearset to give similar levels of performance but with a 90º output. Hypoid gears deliver high efficiency at 94 to 95%, and offer other features to suit servo motors such as low inertia, low backlash and high input speeds.
Hypoid gears resemble bevel gears except that the shaft axes do not intersect. They look like a cross between worm and a bevel gearset. Tooth contact is progressive and smoother than spiral bevel gears with a large contact area leading to lower noise levels and a long service life.
The Vogel SK has a pair of hypoid gears fully supported on the input and output shafts giving a range of ratios from 3 to 10. Rated output torques in three sizes run from 40 to 150Nm with a standard backlash of 4 to 5 arcmins measured at the input shaft. On request this can be reduced to 2 to 3 arcmins by gear matching. Maximum input speed is 7500 r/min on an intermittent basis and noise levels are little lower than planetary gearboxes.
SK gearboxes can be supplied with inputs to match common servo motor frame sizes, for example shafts from 9 to 28mm and flange diameters 90 to 250mm. A common variant is the SKH where the solid output shaft is replaced by a hollow shaft and a locking bush connection. This gives a useful possibility to mount directly on to a machine shaft creating a very compact assembly with zero backlash and the minimum of components.
Where higher ratios above 10 are needed, a planetary stage can be added to the output. Standard models are available for ratios 12 to 100 and rated output torques up to 550Nm. Options of male or hollow output shafts remain.
The hypoid gearing in the Vogel SK range of gearboxes creates a right-angle drive ideally matched to servo motors with small size, low noise and a rated lifetime of 20000 hours. The SK is available as gearbox only or as a complete servo geared motor from Techdrives, a division of Lenze Ltd.