Cutting gear teeth: Cutting straight teeth is usually comparatively easier than cutting helical teeth. Equipment milling or equipment hobbing can be utilized to cut the teeth of spur and helical gears. In milling, just two simultaneous motions are desired to cut tooth of spur gears; however, three simultaneous motions are required for cutting tooth of helical gear.
Impact load, vibration and sound: Since teeth of two mating spur gears comes in sudden contact, therefore they encounter a shock or influence load. This also generates significant vibration and noise, which occasionally impose limit on maximum permissible speed of procedure. On the other hand, gradual get in touch with between mating teeth results a gradual load on one’s teeth and lower vibration and sound. Thus helical gears may be employed at higher speed without much problem.
Contact situation between mating teeth: Spur gears have straight teeth parallel to equipment axis. Two mating gears are also mounted in parallel shafts. Thus the teeth of two mating spur gears can be found in sudden get in touch with and the contact is always a type of size equals to teeth face width. On the other hand, helical gears possess helical teeth plus they are installed on parallel shafts. So teeth of two mating helical gears come in gradual get in touch with. Their engagement begins with a point and becomes a collection and then gradually disengages as a point. So contact length does not remain constant.
Orientation of driver and driven shafts: One basic advantage of gear drive over other mechanical drives (like belt or chain drive) is its probability to use for non-parallel shafts. However, various kinds gear are suitable for various orientations of driver and powered shafts. Both spur equipment and helical gears are overwhelmingly used for parallel shafts; whereas, bevel gears can be utilized for intersecting shafts and worm equipment can be used for perpendicular nonintersecting shafts. There is a particular kind of helical equipment, called crossed helical gear, which can be employed for transmitting power between perpendicular shafts. This is fairly similar to worm equipment; however, crossed helical gear cannot offer high velocity reduction. Typically, it is suitable for 1:1 to 1 1:2 velocity ratio (in comparison with 1:15 to at least one 1:100 in worm gear). Its application can be limited because of many limitations.