In the world of mechanical power transmission, few components are as unique and effective as the worm gear. This specialized gear system, consisting of a screw (the worm) and a gear (the worm wheel), is renowned for its ability to provide high reduction ratios, quiet operation, and superior shock absorption in a compact space. For engineers, designers, and procurement specialists, selecting the right worm gearbox is critical for the longevity and efficiency of machinery. This guide provides a comprehensive look at the specifications, applications, and technical nuances of our high-performance worm gears.
Our worm gears are engineered with precision to meet rigorous industrial standards. Below is a detailed breakdown of our standard product parameters. Please note that custom configurations are also available to meet specific application requirements.
| Model Series | Center Distance (mm) | Reduction Ratio Range (i) | Input Power Range (kW) | Output Torque Range (Nm) | Nominal Efficiency Range (%) | Weight (Approx. kg) | Lubrication Type |
|---|---|---|---|---|---|---|---|
| WG-40 | 40 | 5:1 to 70:1 | 0.12 - 0.75 | 35 - 180 | 60% - 85% | 4.5 | Oil Bath (Mineral) |
| WG-63 | 63 | 5:1 to 100:1 | 0.18 - 2.2 | 90 - 600 | 65% - 88% | 9.8 | Oil Bath (Synthetic) |
| WG-80 | 80 | 7.5:1 to 100:1 | 0.25 - 4.0 | 150 - 1200 | 68% - 90% | 16.5 | Oil Bath (Synthetic) |
| WG-100 | 100 | 10:1 to 100:1 | 0.37 - 7.5 | 350 - 2500 | 70% - 92% | 28.0 | Oil Bath or Circulating Oil |
What is the primary advantage of using a worm gear over other gear types?
The most significant advantage is the high single-stage reduction ratio. A worm gear can achieve ratios from 5:1 to over 100:1 in a single, compact stage, whereas a helical gear set would require multiple stages for the same ratio, taking up more space. Additionally, the sliding action of the worm gear provides very smooth and quiet operation. A crucial feature is its inherent self-locking capability; the worm can easily turn the gear, but the gear cannot reverse-drive the worm, making it ideal for hoisting and lifting applications where safety is paramount.
How do I determine the correct size and ratio for my application?
Sizing a worm gear requires calculating two main factors: the required output torque and the thermal capacity. First, determine the output torque needed by your machine, factoring in service factors for shock loads and operating hours. Second, ensure the gearbox's thermal capacity is not exceeded. The power loss due to friction generates heat. If the generated heat exceeds the unit's ability to dissipate it (its thermal capacity), the oil will overheat, leading to premature failure. Refer to our selection tables, which provide rated output torque and thermal ratings for each model and ratio. Our engineering team can also assist with this calculation.
What is self-locking in a worm gear and is it always guaranteed?
Self-locking is a phenomenon where the worm gear drive cannot be back-driven; meaning the output shaft (worm wheel) cannot drive the input shaft (worm). This occurs due to the high friction and the specific lead angle of the worm thread. However, it is not an absolute guarantee for all ratios and conditions. Self-locking is more prevalent in gears with a lower ratio (e.g., 5:1 to 30:1) and a lower lead angle. High-ratio, high-efficiency worm gears may have a lead angle large enough to allow back-driving, especially if vibration is present. For critical holding applications, a secondary mechanical brake is always recommended.
What type of lubrication is required, and what are the maintenance intervals?
Proper lubrication is vital for the life and performance of a worm gear. Our standard units are factory-filled with a high-quality, extreme-pressure (EP) mineral or synthetic gear oil with rust and oxidation inhibitors. The specific oil grade (e.g., ISO VG 150, 220, 320) depends on the size, ratio, and operating temperature. Initial oil change is recommended after the first 400 hours of operation to remove any running-in wear particles. Subsequent changes are typically every 2,500 to 5,000 operating hours, or annually, whichever comes first. In demanding conditions (high temperature, dusty environments), more frequent changes are necessary. Always check the oil level regularly.
Why is the efficiency of a worm gear typically lower than that of a helical gear?
The primary power loss in a worm gear is due to sliding friction between the worm and the wheel teeth. In contrast, helical gears primarily experience rolling friction, which is inherently more efficient. The efficiency of a worm gear is highly dependent on its reduction ratio. Lower ratio worms (e.g., 5:1) generally have lower efficiencies (around 60-70%) because of the steeper sliding action. Higher ratio worms (e.g., 60:1) can achieve efficiencies of 90% or more due to a shallower sliding angle. Despite the lower efficiency, the trade-off for high reduction, compactness, and self-locking is often worthwhile.
Can your worm gears be used in applications requiring high positional accuracy?
Yes. For applications such as indexing tables, robotics, and precision rotary axes, we offer low-backlash versions of our standard worm gears. These units are manufactured with tighter tolerances, specialized grinding processes, and pre-loaded bearings to minimize the angular play between the input and output shafts. Our precision series can achieve a backlash of less than 10 arcminutes, and in some custom configurations, even lower. It is important to pair these gearboxes with a suitably controlled servo or stepper motor for optimal performance.
What are the typical industries and applications for your worm gears?
Our worm gears are versatile and are deployed across a wide range of industries. Common applications include: material handling equipment (conveyors, bucket elevators, winches), food and packaging machinery (filling machines, wrappers), industrial automation (robotic arms, rotary actuators, positioning systems), construction machinery (screening plants, concrete mixers), and entertainment industry equipment (stage lifts, turntables). Their robustness, compact design, and self-locking feature make them a preferred solution wherever high torque and controlled motion are required.
Do you offer custom modifications to your standard worm gear products?
Absolutely. We understand that standard solutions do not always fit unique application challenges. Our engineering team is equipped to handle custom requests, including special shaft dimensions (length, diameter, keyways, splines), unique mounting flanges, special surface treatments or coatings for corrosive environments, custom backlash specifications, and the integration of ancillary components like encoders, brakes, or backstops. We collaborate closely with clients from the design phase to prototype and final production to ensure the final product meets exact specifications.
