External diameter / number of gear = pitch
Planetary gears can be spur or helical gears.
mostly helical gears !1.
Spur gears have straight teeth while helical gears have curved teeth. Generally, helical gears are usually quieter and smoother in operation, while spur gears are easier to make and much less expensive.Helical gears are stronger than spur gears.
they have no difference.. they are same
Divide 3.14 by the diametral pitch. Worm gears are a compact, efficient means of substantially decreasing speed and increasing torque.
bevel gears are used for power transmitting between the shafts which intersect at some angel ( usually right angel) , but the spur gear is used for shafts which are parallel and coplanar.
A helical is a spur gear with an angle along the face to increase the gear contact ratio. The gear teeth are cut at angles http://www.motioncontrolguide.com/learn/faqs/gearboxes-and-gears/helical-gears/what-is-the-difference-between-a-helical-gearbox-and-a-straight-gear-tooth-gearbox/ hope this helps
There are three main types of gear combinations used in mechanical systems: spur gears, helical gears, and bevel gears. Spur gears have straight teeth and are used for simple applications. Helical gears have angled teeth for smoother operation and higher loads. Bevel gears have cone-shaped teeth and are used to change the direction of rotation.
Car
none. Henry fords engineers found that helical cut gears for transmissions ran much quieter and the transmissions were easier to shift. The same year that ford went to helical cut gears they added syncromesh to the transmission.
herringbone gears are used when the speed requirement is even higher than that can be taken by the helical gears and they are even more noiseless and vibration free. This is because the bending moment that gets induced in the gear shaft of a helical gear is neutralised by another force acting against it in a herringbone gear.
Sliding Gears in a transmission are straight-tooth spur gears with a taper (also known as a lead) to make engaging easier. Helical gears are mostly used in a transmission because spur gears produce gear noise and have a great strain on the teeth of the gear since only one tooth can be in contact at any given time. But because helical gears cannot be taken out of mesh, spur gears are used for the reverse gear because reverse spins the opposite way and cannot be in constant mesh.