Since the fourth century BC, humans have used basic gears to pass rotational motion from one part of a machine to another.
Today, you can choose from several types of gears designed for a variety of purposes and settings. For instance, differently shaped gears can meet other gears at different angles. And different tooth designs impact how smoothly or loudly the gear operates.
Those and other factors like material, speed, and load capacity play a major role in how and where a gear works best. Use this guide as general overview of the most common gears in your industry.
Helical gears
These cylinder-shaped gears feature teeth that are set an angle. Compared to gears with teeth that run parallel to the shaft axis, called spur gears, helical gears have multiple teeth touching at once, allowing for smoother, quieter operations, constant velocity, and greater load capacity.
- Mining
- Marine
- Energy
- Infrastructure
Double helical gears
One disadvantage of helical gears is the thrust that occurs along the gear’s axis, caused by the teeth’s asymmetrical design. Double helical gears counterbalance that thrust with two sets of angled teeth mirroring each other, creating a “V” shape with a gap in the middle.
These doubled, symmetrical sets of teeth allow for even smoother operation and greater strength. Double helical gears require complex production, alignment, and assembly, highlighting the importance of a trusted manufacturer like Philadelphia Gear®.
- Power generation
- Marine
- Oil and gas
- Mining
- Cement
Bevel gears
These cone-shaped gears are typically used to connect shafts that meet at a 90-degree angle. That makes them useful for handling heavy loads in smaller setups. The precision required for their machining can make them pricier than cylindrical gears.
There are five common types of bevel gears:
- Straight tooth bevel gears have straight teeth that taper towards the axis of the gear. They’re commonly used at slower speeds.
- Spiral bevel gears feature teeth that curve at an angle, allowing them to connect more smoothly and gradually for better load capacity.
- Coniflex bevel gears bridge the gap between straight and spiral bevel gears with slightly curved teeth that provide smoother engagement and greater durability.
- Zerol gears also feature curved teeth but with a zero-spiral angle, providing more balanced load distribution and reduced noise for high-torque, high-speed applications.
- Hypoid gears look similar to spiral bevel gears but are arranged with non-intersecting, offset shafts, running even more smoothly and quietly with greater strength.
- Plant equipment
- Off-shore
- Ship building
- Turbine
- Rolling mill
- Paper pulp
Worm gears
These gears are named after the worm-like, screw-shaped gear that drives the system. As the worm spins, it rotates a worm wheel — a simpler wheel-shaped gear with straight teeth.
The screw-like action allows for quiet, vibration-free performance with constant output speeds, ideal for compact spaces and projects with heavy shock loading. However, the friction produced between the worm and the worm wheel makes them less efficient than other gear types.
- Energy
- Manufacturing
- Agriculture
- Mining applications
Learn gear fundamentals in four hours
Get your maintenance and operations teams trained with Gear 101: An Introduction to Gearing Concepts and Elemental Gearbox Operation.
Philadelphia Gear’s four-hour program provides a concise yet comprehensive overview of complex rotating equipment — and their foundational operating principles — that keep plants running smoothly.
Go to Gear 101Get the gears you need. Contact Philadelphia Gear today.We’re standing by to help with your most complex gear challenges. Connect with one of our expert specialists today.
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We’re standing by to help with your most complex gear challenges. Connect with one of our expert specialists today.
