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Overview of the article: Gearhead Construction and Use
Spur Gear Type Gearheads Spur gear type gearheads are probably the best possible choice for relatively low torque applications. They tend to be less expensive than comparably sized planetary gearheads and are likely to be quieter in operation as well. Engineers designing high accuracy positioning servos are occasionally surprised to find that many of the small gearhead series supplied by MicroMo use non-integer gear ratios, This fact is often discovered after the engineer has repeatedly tried to reconcile motor encoder counts with gearhead shaft position only to find small but persistent position error. At first glance, the use of non-integer gear ratios appears to have no apparent purpose (with the possible exception of frustrating servo designers). There is a fundamentally sound reason for designing gearheads with such gear ratios, however, and the servo designer who has sufficient information will generally have no problems using them.
Planetary Gears Planetary gearheads are typically used in applications where relatively high torques are involved. By distributing the forces over several gears per stage rather than just one gear/pinion pair as used in spur gears, the gearhead is capable of carrying higher torques without damage to gears or premature lubrication degradation. Planetary gearheads are composed of satellite gears, a carrier plate with pins to fit the inside diameters of the satellite gears, an annular gear which usually forms the gearhead case on the outside and has gear teeth cut in the inside diameter, and a pinion from the driving motor. Figure 27 illustrates a single-stage planetary gearhead having three satellite gears. Attached to the carrier plate in Figure 27 is a shaft that protrudes through the bearings at the far end of the gearhead case for coupling to the load to be driven. In multi-stage gearheads, only the final stage has a shaft attached to the carrier plate. In the other stages, there is a gear (called a sun gear) attached to the carrier plate that serves to drive the next stage in the system. High gear ratios can be produced by lengthening the annular gear/case and stacking multiple stages. For each stage of the planetary gearhead, the exact gear ratio can be determined. To DownLoad the Complete Article Click Here: MicroMo and the FAULHABER Group specialize in the design, assembly and application of high precision, miniature DC drive systems, components, and controls. This includes highly customized DC motion control systems to our standardized, off-the-shelf products. MicroMo maintains a 73,000 sq.ft. facility complete with state-of-the-art CNC machine shop. Our applications engineers provide full customer support for the specification and design for all FAULHABER Group products. Visit our web site at www.micromo.com or call 800-807-9166 and speak to one of our Application Engineers today. And please say, "I saw it on MotionShop.com."www.micromo.com.
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