Because spiral bevel gears don’t have the offset, they have less sliding between your teeth and are better than hypoids and produce less heat during procedure. Also, one of the main advantages of spiral bevel gears may be the relatively large amount of tooth surface that’s in mesh during their rotation. Because of this, spiral bevel gears are an ideal option for high acceleration, high torque applications.
Spiral bevel gears, like various other hypoid gears, are made to be what is called either correct or left handed. A right hands spiral bevel gear is defined as having the outer half of a tooth curved in the clockwise path at the midpoint of the tooth when it’s viewed by looking at the face of the gear. For a left hands spiral bevel equipment, the tooth curvature would be in a counterclockwise direction.
A equipment drive has three main functions: to increase torque from the traveling equipment (motor) to the driven apparatus, to reduce the speed generated by the motor, and/or to change the path of the rotating shafts. The bond of the equipment to the gear box can be achieved by the use of couplings, belts, chains, or through hollow shaft connections.
Speed and torque are inversely and proportionately related when power is held constant. Therefore, as speed decreases, torque improves at the same 
ratio.
The center of a gear drive is actually the gears within it. Gears function in pairs, engaging one another to transmit power.
Spur gears transmit power through shafts that are parallel. One’s teeth of the spur gears are parallel to the shaft axis. This causes the gears to create radial reaction loads on the shaft, however, not axial loads. Spur gears tend to be noisier than helical gears because they operate with a single type of contact between teeth. While the tooth are rolling through mesh, they roll from contact with one tooth and accelerate to contact with another tooth. This is different than helical gears, which have more than one tooth connected and transmit torque more easily.
Helical gears have teeth that are oriented at an angle to the shaft, in contrast to spur gears which are parallel. This causes several tooth to be in contact during procedure and helical gears are capable of carrying more load than spur gears. Due to the load sharing between teeth, this arrangement also allows helical gears to operate smoother and quieter than spur gears. Helical gears create a thrust load during procedure which needs to be considered when they are used. The majority of enclosed gear drives make use of helical gears.
Double helical gears are a variation of helical gears where two helical faces are positioned next to one another with a gap separating them. Each face has identical, but opposite, helix angles. Having a double helical group of gears eliminates thrust loads and will be offering the possibility of even greater tooth overlap and smoother operation. Like the helical gear, double helical gears are commonly found in enclosed gear drives.
Herringbone gears are very similar to the double helical equipment, but they do not have a gap separating the two helical faces. Herringbone gears are helical spiral bevel gear motor typically smaller than the comparable double helical, and are ideally suited for high shock and vibration applications. Herringbone gearing is not used very often because of their manufacturing issues and high cost.
While the spiral bevel gear is truly a hypoid gear, it is not always seen as one because it does not have an offset between the shafts.
The teeth on spiral bevel gears are curved and have one concave and one convex side. They also have a spiral angle. The spiral angle of a spiral bevel gear is thought as the angle between the tooth trace and an component of the pitch cone, like the helix angle within helical gear teeth. Generally, the spiral angle of a spiral bevel gear is thought as the suggest spiral angle.
