The Guilds of Cybertron carefully plotted out the creation of the caste system and ran thousands of simulations to verify its effectiveness. Each simulation ended in civil war, sometimes sooner, sometimes later, but the lower castes would always revolt sometime in the future. The only solution that they found effective, besides adding a very limited amount of flexibility, was to make a new caste, the Pleasure Caste. The Guilds found the caste 'distasteful' but needed. The caste would allow Cybertronians of any caste rank a chance to relax and unwind so that silly notions like 'reform' would stay far from their processors. So far it has been effective and civil war remains a distant thought in the populace's minds even as their society continues its slow descent into decay.
Here's a very rough outline as to the caste ranks:
Each caste has its own rankings within it but seeing as how we're mainly dealing with the Pleasure Caste, we'll just concentrate on that.
The Alpha is the boss of the caste, having the final say in anything that comes to his attention. They maintain relations with the other Alphas and Cybertronians of higher caste ranks. Sets an example to those in the lower ranks, be it good or bad.
The bottom Beta is next in line for the rank 'Alpha.' The bottom Beta takes over command while the Alpha is out on business or is incapacitated, overlooks the training and orientation of new pleasure mechs, manages the finances, deals with problems that the normal Betas can't, ect, whatever the Alpha requires to be done. I got the idea after wandering around Wiki and finding this article - http://en.wikipedia.org/wiki/Bottom_Woman
My mind also came up with the idea that while the bottom Betas can initiate touch with others, no one is allowed to touch them besides their Alpha. I'm not sure why, in all honesty. My mind is just strange like that.
Betas are next in line for the rank 'bottom Beta.' The Betas deal with any minor problems within the lower ranks of their caste and usually entertain members of the highest caste.
Deltas are the internal security force for the Pleasure Caste, like bouncers in a club. They do not entertain clients. They carry out punishments if ordered by the Betas or higher and patrol the streets where the Omegas work, keeping them safe from overeager clients. They technically have the same rank as the Gammas.
Gammas are next in line for the rank 'Beta.' They usually entertain those in the high castes or lower. They are also tend to the bar in the Alpha's flat.
Omegas are next in line for the rank 'Gamma' or 'Delta.' They are the lowest ranked in the Pleasure Caste and usually work the streets of the Alpha's territory.
That's all I can think of at the moment. If anyone needs clarification or any questions, please don't hesitate to ask. :D
Edit: Fixed my whoops and added Enforcers on the Caste System. Thanks for pointing it out, thepheonixqueen!
I also went ahead and added another caste, the Entertainer caste. Those in that caste are famous actors, news reporters, ect -- mainly just mechs you see on tv.