Helical gears
Helical gears are cylinder-shaped gears featuring teeth that are set at 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. The angled teeth distribute forces more evenly, reducing wear and enabling helical gears to handle higher torque compared to spur gears. However, the angled teeth generate axial thrust, which requires robust bearings to manage the resulting forces.
- Mining: Used in heavy-duty equipment like conveyors and crushers.
- Marine: Powers propulsion systems and auxiliary machinery.
- Energy: Drives turbines and generators in power plants.
- Infrastructure: Found in construction machinery and material handling systems.
Double helical gears
A double helical gear is essentially two helical gears of opposite hand (left and right) placed next to each other on the same shaft. 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.
Herringbone gears are a type of double helical gear where the two sets of angled teeth meet in the center without a gap, forming a continuous “V” or herringbone pattern. This design allows for even smoother meshing, reduced vibration, and higher load capacity — ideal for demanding industrial applications.
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: Drives high-torque turbines and generators.
- Marine: Used in ship propulsion systems for reliability.
- Oil and gas: Powers pumps and compressors in harsh environments.
- Mining: Supports heavy-duty machinery like mills and hoists.
- Cement: Operates kilns and grinding mills.
Bevel gears
Bevel gears are cone-shaped gears that are typically used to connect shafts. A bevel gear set consists of a part of bevel gears that meet at a 90-degree angle. That makes them useful for handling heavy loads in smaller setups. The precision required for bevel gear 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. Spiral bevel gears are widely used in high-performance applications.
- 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: Drives heavy machinery in manufacturing facilities.
- Off-shore: Powers drilling rigs and platform equipment.
- Ship building: Used in propulsion and steering systems.
- Turbine: Transfers power in wind and hydroelectric turbines.
- Rolling mill: Supports metal-forming processes.
- Paper pulp: Operates machinery in pulp and paper production.
Worm gears
Worm 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. A worm gear set (or worm drive) refers to the combination of the worm gear and the worm wheel.
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: Used in wind turbine pitch control systems.
- Manufacturing: Drives conveyor systems and material handling equipment.
- Agriculture: Powers irrigation systems and harvesting machinery.
- Mining applications: Operates hoists and crushers in rugged environments.
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 101Choosing the Right Gear
Selecting the appropriate gear type depends on factors like load capacity, speed, noise tolerance, space constraints, and environmental conditions. For example, industrial bevel gears excel in high-load, compact setups, while helical gears and double helical gears are preferred for smooth, high-torque applications. Worm gear sets are ideal for high-reduction ratios, and spiral bevel gears offer superior performance in high-speed, heavy-duty systems. Consulting with an experienced manufacturer like Philadelphia Gear® ensures optimal gear selection and reliable performance.
Get 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.
Contact us
We’re standing by to help with your most complex gear challenges. Connect with one of our expert specialists today.
