Worm Gears

Worm Gears Application Range

Our productions mainly used in fields of mining, metallurgy, cement, sugar plant, petrochemical industry, construction, and recycling facilities, aggregate.

Which is including non-standard machinery components, custom castings, forged parts, gears, shafts, ball mill spares, rotary kiln etc.

Specification

Low carbon steel

Alloy structure steel 

45 steel

Bronze and cast iron

QT, carburizing and quenching

Applications

Conveyor Systems: For applications where slow but powerful motion is needed, such as in conveyors.

Elevators and Lifts: Worm gears can provide self-locking features that prevent backdriving.

Differential Gears in Vehicles: Some vehicles use worm gears in their drive trains, although bevel gears are more common for most applications.

Rotary Actuators: Worm gears are used in various industrial machines where precise, controlled rotation is needed.

Worm Gears Design

1. Gear Ratio:

The gear ratio is determined by the number of teeth on the worm wheel relative to the number of threads on the worm. For example, if the worm has a single thread (single-start) and the worm wheel has 40 teeth, the gear ratio is 40:1.

A higher gear ratio means a larger reduction in speed, which increases torque but decreases efficiency.

2. Worm Thread:

Single-start worms have one thread, while multi-start worms have more than one thread. A multi-start worm can achieve higher efficiency and smoother operation.
The lead angle (the angle between the axis of the worm and the helix of the thread) significantly impacts the gear’s efficiency and load capacity. A lower lead angle means more torque but lower efficiency, while a higher lead angle offers better efficiency but reduces the torque-transmitting capacity.

3. Material Selection:

Worm gears are typically made from high-strength materials, as they experience sliding contact, which generates high friction. Common materials include:

Worms: High-carbon steel or bronze.

Worm Wheels: Bronze, brass, or cast iron for better wear resistance and lower friction.

4. Pitch and Pressure Angle:

The pitch refers to the distance between corresponding points on adjacent threads, and the pressure angle is the angle between the line of action and the line of centers. These parameters are vital in ensuring smooth engagement between the worm and the worm wheel.

Typically, a pressure angle of 20 degrees is used for worm gears, but values from 15 to 30 degrees are common.

5. Efficiency Considerations:

Worm gears are often less efficient than other types of gears due to the sliding friction between the worm and the worm wheel. Efficiency typically ranges between 50% to 80% depending on the design and lubrication.

To improve efficiency, a lubricant with high pressure and load-bearing capacity, like oil, is usually applied.

6. Self-Locking Property:

Worm gears often exhibit the property of being self-locking, meaning that the worm can turn the worm wheel, but the worm wheel cannot turn the worm under normal conditions. This is beneficial in applications where backdriving is undesirable (e.g., lifts or winches).

7. Backlash:

Backlash refers to the slight gap between teeth when the direction of motion is reversed. In worm gears, backlash is typically greater than in other types of gears due to the sliding contact, which affects the precision of motion.

Adjusting for backlash might involve precise manufacturing tolerances or the use of preloaded gears.

8. Size and Compactness:

Worm gears can offer high reductions in a very compact form factor. They are often used when space is limited, and a significant reduction in speed is required.

9. Lubrication:

Due to the sliding contact, effective lubrication is critical. Proper lubrication reduces wear, minimizes friction, and enhances the lifespan of the gears.

Grease or oil lubrication is common, and special types of lubricants may be required for high-performance or high-load conditions.

10. Mounting and Orientation:

Worm gears are typically designed for a 90-degree shaft orientation, though they can be adapted for different angles depending on the application.
The worm typically drives the wheel, so the worm shaft is often horizontal while the worm wheel is vertical or vice versa.