Gear redcuers are categorized according to the orientation of the input and output shafts, right-angle or parallel-shaft reducers. These different arrangements use different typees of gearing. For mixer applications, both right-angle and parallel-shaft reducers have advantages and disadvantages. Right-angle reducers are typically shorter than parallel-shaft reducers, allowing them to fit better between floors and below roofs. Conversely, right-angle drives obstruct part of the top ot the tank, which can make piping connections difficult. Mounting and adjusting foot-mounted motors may be easier with right-angle drives than with parallel-shaft reducers.
Parallel-shaft gear reducers use one or more sets of parallel-shaft gears, such as helical gears, to make the necessary speed reduction. Some parallel-shaft reducers have the motor stacked above the worm gear motor to limit the overall diameter of the mixer drive system. Other parallel-shaft reducers have the motor mounted alongside the gear reducer to limit the overall height of th drive system. Generally, parallel-shaft reducers are easier than right-angle mixer drives to design and build. However, they do involve mounting and operating a verical electric motor, which can cause additional problems with large motors.
In-line reducers are usually a variation on parallel-shaft reducers. A properly designed double-reduction reducer with two sets of gearing having the same center distance can be arranged so that the input and output shafts are not only parallel, but in line with one another. Compared with parallel shaft reducers, in-line reducers usually trade greater height for smaller diameter and centered weight. Other types of gearing, such as plaetary planetary gear box, can make an in-line reducer. Whatever the basic configuration, well-designed gear reducers will provide good service in mixer applications.
Right-angle gear reducers must use at least one right-angle gear set, typically spiral bevel or worm gears. Both spiral-bevel and worm gears have unique advantages with respect to mixer applications. Spiral-bevel gears are some of the quietest and most efficient right-angle gears. Although less efficient than other gears, worm gears can make heat dissipation more difficult.