Engineering

I'd check the alignment at operating temperature, if that's what you mean. Or, if there is a test specification involved, follow the instructions of the specification.

I'm not sure if I understand the question.

Thanks..But that is an ok thing..i need to have alingment done at operating temps.. But i want to know what will be the timing in the day or in the night at which i will get most precise reading. As temperature has considerable effect in the metal contraction and expansion and that much effect is valid to be taken in the alingnment precision. I hope you got my point.. J

What we have here is failure to communicate. The parts to be tested should be at whatever the specified temperature is. If you must rely on the sun to heat the parts, get a thermometer and measure the temperature.

Please, don't be so obtuse!!!!!

Thanks... Catch u soon

What is the ambient temperature during day time and during night time and what is coresponding operating temperature of the gear-pinion set?

If the operating temperature variation as compared to ambient is too high, there must be some protocol for the cold alignment of the machine so that coresponding thermal growth will make the alignment within acceptable limits in running condition.

If you want the measurement at the minimum temperature take the readings in the coldest part of the night.

Having read your OP again "when metal contraction in minimum". So do you want maximum expansion? If so the hottest part of the day.

Good grief! You make things hard work!