Gear Alignment

Takes experience.

Look here for some basics.

HowStuffWorks "How Gears Work"

What is the profile of the bevel?

The straight bevel I am not much aware of.

However if it is spiral/ palloidal system, there are lots of literature available on net.

In brief the technique we use is

a) Put a thin prussian blue coat on the driving member (pinion)- we put on 3-4 consecutive teeth- both flanks.

b) rotate the pinion both sides (CW and CCW) 3-4 times.

c) Check the bl;us contact pattern transferred - you can have the information from pinion where the blue would have been removed (transferred to bevel).

d) Check the back-lash at the pitch-line diameter of bevel.

e) Adjust till simultaneously the recommended back lash and contact is achieved.

f) Expected contact can be obtained from the manufacturer's test bench pattern. Alternatively aim for almost center of the tooth length contact. The length of contact should be almost 1/3rd of the tooth length and centered on the rolling pitch-line.