The difference between a spur gear and a helical gear

　　 The difference between a spur gear and a helical gear

　　What is the main difference between a worm gear and a helical gear?

　　Definition of a worm gear and definition of a helical gear

　　The Differences Between Worm Gears and Helical Gears—Whether you’re using servo gears, worm gears, or any other type of industrial gear, gears are a critical component in many industrial motors and machinery, enabling increased torque output and the adjustment of rotational direction. Worm gears and helical gears are two fundamental types of gears; in this article, we’ll explore the distinctions between them.

        What is the main difference between a worm gear and a helical gear?

　　A common assumption is that helical gearboxes deliver higher system efficiency than worm‑gear types. However, advances in worm‑gear design and improvements in lubrication have narrowed the efficiency gap, making worm gears increasingly competitive in terms of efficiency compared to helical designs.

　　Previously, right-angle worm gearboxes had efficiencies ranging from 82% to 84%; today, their efficiency has improved to over 80%. Meanwhile, worm gearboxes that once boasted efficiencies above 80% now achieve levels of 93% to 95%. Some manufacturers have made greater strides in these efficiency improvements than others.

　　In general, right-angle worm gear reducers begin to experience a decline in efficiency as they transition to higher gear ratios. Worm gear reducers with larger center distances typically exhibit higher efficiency than those with smaller center distances. For example, a standard worm gear reducer with a 2.6‑inch center distance shows a gradual reduction in efficiency as the gear ratio increases.

　　Similarly, as the center clearance increases, efficiency also improves; as shown here, the efficiency gain for seven center clearances is in a ratio of 10:1.

　　 The difference between worm gears and helical gears

　　Right-angle worm gear diagram (Reference: designworldonline.com)

　　Right-angle worm gear reducers tend to experience reduced efficiency as they operate at higher speed ratios. Worm gear reducers with larger center distances generally exhibit higher efficiency than those with smaller center distances. For instance, in a standard unit with a 2.6‑inch center distance, efficiency declines gradually as the ratio increases.

　　The question is: What is the trade-off between acquisition cost and storage efficiency? Is it more cost-effective to pay for additives that boost efficiency, or is the efficiency gain so costly that it cannot be recouped through reduced operating expenses?

　　Under identical conditions, when comparing the power‑saving benefits of helical gearboxes to those of worm‑gearbox designs, there are several scenarios in which the cost savings are minimal. In general, helical gearboxes require multiple stages, which increases both cost and complexity. For the same gear ratio and horsepower, helical gearboxes are typically more expensive than worm‑gear types. When the electricity‑cost savings are weighed against the initial purchase price of the gearbox, there are compelling reasons to opt for right‑angle worm‑gear designs in many applications with lower horsepower requirements.

　　To compare cost savings under several common low‑horsepower scenarios, we evaluated the dollar cost of operating a system at full load current using a standard AC motor over an 8‑hour shift. Motor costs were estimated using the U.S. Department of Energy’s website, which reports the national average industrial rate as of March 2020.   The energy rate is 7.5 cents per kilowatt-hour.