Reduction gears, helical

FIGURE 5.31 THple-reduction spiral bevel-helical FIGURE 5.32 Shaft-mounted double-reduction gear gear drive. (Falk Corporation.) drive. (RockwellAutomation.)... 

Top entering mixers are heavy duty equipment. They are usually fixed to a rigid structure or tank mounting. Either radial flow or axial flow turbines may be used. Speeds vary from 50 to 100 rpm and usually require a double set of helical gearing or a single set of worm gears to achieve these low speeds. Therefore, they are more expensive than single reduction mixers. 

Single reduction/helical gearing for quiet operation... 

Spray-lubr icated, single-reduction helical gear (plain bearings). ... 

Drive type Direct gearing Single reduction helical... 

The high-speed drive motor is coupled to the low-speed screw with a reducer or gearbox. Typical reduction rations are 15 1 or 20 1. Although helical gears are most common, worm gears are used on older or very small machines. 

FIGURE 5.26 High-speed single-reduction helical gear drive. (Philadelphia Gear Corporation.)... 

Stan(Jar(J Speeds for common agitator drives are 230,190,155,125,100, 84,68,56,45, and 37 r/min based on actual speeds of nominal 1800 and 1200 r/min motors and standard gear reductions, which are a geometric progression of the VT3 for enclosed, helical, and spiral bevel gearing (American Gear Manufacturers Association Standard 420.04, December 1975, p. 29). 

Other types of motors that may be encountered in mixer applications are gear motors, pony motors, and brake motors. Gear motors are composed of an electric motor with an attached gear reducer. Spur, helical, or worm gears can be used in single or multiple reductions to achieve a wide range of output speeds. Motor power, output speed, and output torque are all essential design variables. 

Helical gears (Figure 21-16) provide parallel-shaft gear reduction. The term helical comes from the fact that the teeth are cut along a helical path with respect to the axis of rotation. A typical spur gear is similar to this arrangement, except... 

The crown of this reduction could not be used to transfer motion to the rack because of its shape coupled with the worm, so in the same axis it was placed a helical gear teeth to transmit the movement to the rack, so the gear box is divided into two parts, facilitating the scaling ... 

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