Wednesday, February 27, 2008

Comparison Between Involute and Cycloidal Gears

In actual practice, the involute gears are more commonly used as compared to cycloidal gears, due to the following advantages:

Advantages of involute gears:
Following are the advantages of involute gears:
1) The most important advantage of the involute gears is that the center distance for a pair of involute gears can be varied within limits without changing the velocity ratio. This is not true for cycloidal gears which requires exact center distance to be maintained.

2) In involute gears, the pressure angle, from the start of the engagement of teeth to the end of the engagement, remains constant. It is necessary for smooth running and less wear of gears. But in cycloidal gears, the pressure angle is maximum at the beginning of engagement, reduces to zero at pitch point, starts increasing and again become maximum at the end of engagement. This results in less smooth running of gears.

3) The face and flank of involute teeth are generated by a single curve where as in cycloidal gears, double curves (i.e. epi-cycloid and hypo-cycloid) are required for the face and flank respectively. Thus the involute teeth are easy to manufacture than cycloidal teeth. In involute system, the basic rack has straight teeth and the same can be cut with simple tools.

Note : The only disadvantage of the involute teeth is that the interference occurs with pinions having smaller number of teeth. This may be avoided by altering the heights of addendum and dedendum of the mating teeth or the angle of obliquity of the teeth.

Advantages of cycloidal gears :
1) Since the cycloidal teeth have wider flanks, therefore the cycloidal gears are stronger than the involute gears, for the same pitch. Due to this reason, the cycloidal teeth are preferred specially for cast teeth.

2) In cycloidal gears, the contact takes place between a convex flank and concave surface, where as in involute gears, the convex surface are in contact. This condition results in less wear in cycloidal gears as compared to involute gears. However the difference in wear is negligible.

3) The cycloidal gears, the interference does not occur at all. Though there are advantages of cycloidal gears but they are outweighted by the greater simplicity and flexibility of the involute gears.

15 comments:

Unknown said...

it is very useful and quiet easy for understanding.

shivam said...

it is very important topic for mechanical engg.

Unknown said...

Thanks a lot for the article
I found it really useful.

indomitable said...

it is really very significant emissary for all mechanical engineer ..... me rocks

Unknown said...

if vibration iz not there then cycloidal is best...

Unknown said...

thanks for this article

sahil said...

Cut copy paste from rs khurmi (theory of machines) book.

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Unknown said...

this comparisons cut copy from khurmi or in khurmi

Unknown said...

thanks

Unknown said...

Nice one

Unknown said...

Nice one

smallick said...

Bismillah ur rehman ur rahim was rahamtullilah barkatu. Mashallah what an explanation? Glory be to Allah who is my Lord and Your Lord.

smallick said...

Bismillah ur rehman ur rahim was rahamtullilah barkatu. Mashallah what an explanation? Glory be to Allah who is my Lord and Your Lord.