Tension and compression test

Compression tests machine require higher capacity than tension testing machine, because cross sectional area of the specimen increases during the test because in compression test the test sample is generally placed in between two plates that distribute the applied load across the entire surface area of two opposite faces of the test sample and then the plates are pushed together by a universal test machine causing the sample to flatten (which is opposite to what happens in tension test).

Because of this increase in area it requires higher load to be applied over the specimen than to be applied in tension test to achieve same level of stress.

Also generally compressions test specimens have larger original crossectional area as compared to tension test specimen.