Cutting gear teeth: Trimming straight teeth can be comparatively easier than cutting helical teeth. Gear milling or equipment hobbing can be used to cut tooth of spur and helical gears. In milling, only two simultaneous motions are desired to cut tooth of spur gears; nevertheless, three simultaneous motions are required for cutting tooth of helical gear.

Effect load, vibration and sound: Since teeth of two mating spur gears will come in sudden contact, so they encounter a shock or effect load. This also creates significant vibration and sound, which occasionally impose limit on optimum permissible speed of operation. On the contrary, gradual get in touch with between mating teeth results a gradual load on the teeth and lower vibration and noise. Thus helical gears may be employed at higher swiftness without much problem.

Contact situation between mating teeth: Spur gears have directly teeth parallel to equipment axis. Two mating gears are also installed in parallel shafts. Thus teeth of two mating spur gears come in sudden get in touch with and the get in touch with is always a line of size equals to teeth encounter width. On the other hand, helical gears possess helical teeth plus they are installed on parallel shafts. So teeth of two mating helical gears can be found in gradual contact. Their engagement starts with a spot and becomes a series and then gradually disengages as a spot. So contact length will 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 likelihood to use for nonparallel shafts. However, various kinds gear are ideal for varying orientations of driver and driven shafts. Both spur equipment and helical gears are overwhelmingly utilized for parallel shafts; whereas, bevel gears can be used for intersecting shafts and worm equipment can be utilized for perpendicular nonintersecting shafts. There is a particular kind of helical equipment, called crossed helical gear, which can be useful for transmitting power between perpendicular shafts. This is very similar to worm gear; however, crossed helical equipment cannot offer high velocity reduction. Typically, it really is suitable for 1:1 to at least one 1:2 speed ratio (as compared to 1:15 to at least one 1:100 in worm gear). Its application is also limited because of many limitations.