Wo
rm gears are a type of ancient gear and one of the six simple machines. A worm gear is essentially a screw butted up against a standard spur gear with slightly angled and curved teeth.
Because of the worm's position on the worm wheel, it shifts the rotational movement by 90 degrees, and the plane of movement shifts as well (or simply "the wheel"). They are typically composed of a steel worm and a brass wheel.
What Is a Worm Gear, Exactly?
A worm gear is a gear that consists of a shaft with a spiral thread that engages and drives a toothed wheel.
Worm gears are a type of ancient gear and one of the six simple machines. A worm gear is essentially a screw butted up against a standard spur gear with slightly angled and curved teeth.
Because of the worm's position on the worm wheel, it shifts the rotational movement by 90 degrees, and the plane of movement shifts as well (or simply "the wheel"). They are typically composed of a steel worm and a brass wheel.
Worm Gears at Work
An electric motor or engine provides rotational power to the worm. The worm spins against the wheel, and the screw face pushes against the teeth of the wheel. The load presses up against the wheel.
Applications for Worm Gear
A worm gear is preferable to a standard gear for a number of reasons.
The first characteristic is a high reduction ratio. If the circumference of the wheel is increased, a worm gear can have a massive reduction ratio with little effort. As a result, it can be used to either significantly increase torque or significantly decrease speed.
A conventional gearset will usually require multiple reductions to achieve the same reduction level as a single worm gear, implying that worm gear users have fewer moving parts and fewer failure points.
Another reason to use a worm gear is the inability to reverse the direction of power. Due to friction between the worm and the wheel, it is nearly impossible for a wheel with force applied to it to start the worm moving.
When sufficient force is applied to a standard gear, the input and output can be independently turned. The addition of a backstop to a standard gearbox is required, further complicating the gear set.
What is Worm Gear Lubrication
Worm gears' main problem is how they transfer power. It's a blessing and a curse. When compared to a standard helical gear, the spiral motion allows for massive reduction in a relatively small amount of space.
Because of this spiral motion, the primary mode of power transfer becomes extremely problematic. This is called sliding friction or sliding wear.
Summary
In a typical gear set, power is transferred at the peak load point on the tooth (known as the apex or pitchline), at least in a rolling wear condition. Sliding occurs on both sides of the apex, but at a low velocity.