Why is the constitutional governments has one breach is often checked by the other branch?

The Founding Father devised the government of the United States of America so that no one branch could gain too much power. It was a way of breaking up the power into smaller pieces, each branch would naturally want to have the maximum power so they would try to over reach, but if there were other branches that also wanted to have the most power, they would check each other and prevent one branch from gaining too much power and becoming a tyranny. They wanted to avoid what happened in Britain where the King's power was supreme and nothing checked it.