A downhole tool for dampening vibrational, lateral, compressive, and tensile forces exerted on sensor equipment inside a drillstring is described. The downhole tool is housed inside the drill string. The tool generally includes a bottom end shaft for connection to the drillstring and that is telescopically engaged within a compression housing and a torsional housing. The torsional housing enables the bottom end shaft to slide axially with respect to the torsional housing whilst preventing torsional movement of the bottom end shaft relative to the torsional housing. The compression housing is connected to the sensor equipment and operatively contains a first spring between the compression housing and the bottom end shaft that absorbs compression forces between bottom end shaft and compression housing.

A mechanical seal (100) is configured such that an annular sealed space (S1) is formed by a first bellows (141), a second bellows (151), and members respectively provided on both end sides of the first bellows (141) and the second bellows (151), and that the first bellows (141) and the second bellows (151) expand and contract in a central axial direction of a rotating shaft (200) in accordance with fluid pressure inside the sealed space (S1). The first bellows (141) and the second bellows (151) are arranged at positions distant to each other in the central axial direction, and are arranged such that a part of the first bellows (141) on a radially inward side and a part of the second bellows (151) on a radially outward side overlap when viewed in the central axial direction.

A mechanical seal (100) is configured such that an annular sealed space (S1) is formed by a first bellows (141), a second bellows (151), and members respectively provided on both end sides of the first bellows (141) and the second bellows (151), and that the first bellows (141) and the second bellows (151) expand and contract in a central axial direction of a rotating shaft (200) in accordance with fluid pressure inside the sealed space (S1). The first bellows (141) and the second bellows (151) are arranged at positions distant to each other in the central axial direction, and are arranged such that a part of the first bellows (141) on a radially inward side and a part of the second bellows (151) on a radially outward side overlap when viewed in the central axial direction.