Because the stress is dispersed across more teeth, helical gears are more robust than spur gears. As a result, for a given weight, the force is distributed more evenly than with a spur gear, resulting in reduced wear on individual teeth. Spur gears may be quite noisy. Although helical gears usually have greater strength per tooth, they also tend to have more shallow angles which results in less surface area for the same size gear. This reduces their load-carrying capacity compared to deeper-teeth gears.
Spur and helical gears are both open-end transmissions used primarily in machinery and vehicles. The difference between them is how the teeth are shaped. In spur gears, each tooth has a flat face that contacts its neighbor; in helical gears, each tooth has a slightly curved face that wraps around its neighbor. Because of this difference in design, helical gears can transmit more power with less loss while spinning slower than spurs. This is why motor vehicles use helical gears instead of spurs for their final drive.
Additionally, helical gears can be used in places where space is limited or damage could occur if a spur gear is used. For example, some helicopters use helical gears instead of spurs because they need large numbers of low-speed gears to match the speed of the main rotor shaft. Other examples include using helical gears when maximum load capacity or accuracy is not critical such as in optical devices or computer hard drives.
The strength output is the ultimate advantage that helical gears have over spur gears. Because the helical gear tooth is diagonally positioned and hence effectively bigger, helical gears can carry greater weight than spur gears. Helical gears will give greater strength for the same tooth size and breadth. They are also less prone to break under load.
Because of these advantages, helical gears are used where greater strength or more accurate positioning is required. They are commonly used instead of spur gears in power transmissions because they can carry higher loads while being smaller in diameter. However, helical gears do have their limitations. They cannot be used in applications where large amounts of axial movement are required (as with spur gears), high torque-to-size ratios, or small diameters are needed because they aren't suitable for these uses.
Spur gears have a number of advantages over helical gears: they can take up less space, are cheaper to manufacture, and are easier to repair or replace if damaged. However, they can only carry lower loads than helical gears of equal size because they lack the diagonal support provided by the helical gear tooth.
Thus, the choice between spur and helical gears depends on how much force and how much space are available for mounting the gears. If you need great strength but don't have much room available, then a helical gear is the way to go. Otherwise, spur gears will do just fine!
Why are Helical Gears used? Angled teeth engage more slowly than spur gear teeth, allowing them to operate more smoothly. Helical gears and gearboxes are extremely robust and suited for high-load applications. It is capable of transmitting motion and power between parallel or right-angle shafts. This type of gear has many names including spiral bevel gear, helicoid gear, screw gear, and rack and pinion gear.
They have several advantages over other types of gears:
1 They can transmit very high torque ratios with little loss of speed. For example, a 1/4" diameter helix can take 12 inches from one flat side to the next without slipping even though there are 8 degrees of angle between each tooth.
2 They are easy to make and fit accurately. The helix angles can be measured easily with a protractor or compass and the shape can be cut on a band saw or drill press bedding machine.
3 They require less space than other gears - especially when mounted on cylindrical or conical surfaces. This makes them useful for small motors or turbines where space is at a premium.
4 They are self-locking - meaning they won't slip when under load. This is important because it prevents damage to other parts of the mechanism.
5 They are economical to manufacture.