Bava Batra, Chapter Four, Mishnah Five
The mishnah which we will learn today continues to discuss which things are included in certain sales.
1) If a man sold an olive press he has sold also the vat, the grindstone, and the posts, but he has not sold the pressing-boards, the wheel or the beam.
a) But if he had said: It and all that is in it, all these are sold also.
b) Rabbi Eliezer said: If a man sold an olive press he has sold the beam also.
We learn in this mishnah that when a man sells an olive press without specifying which parts of the olive press he is selling, he has sold only the parts that are fixed in their place. These include the vat used to collect the oil, the grindstone used to crush the olives and the posts used to prop up the beam that would press the olives. The parts of the press that are not fixed in place, namely the pressing-boards, placed on top of the sacks of crushed olives, the wheel, used to lift the beam, and the beam, used to exert pressure on the olives, are all not sold with the olive press. If, however, he had stated that he was selling the press and all that was in it, than he has sold the pressing-boards, the wheel and the beam as well. Rabbi Eliezer disagrees with the first clause. According to him when one sells an olive press one sells the beam, even though it is not fixed. Since the beam is the most important part of the press, it is assumed that it is sold along with it.