Connecting mechanism for pole members

Claim 1

A connecting mechanism for pole members comprising, a pole member (A) having a male screw (7a) on the periphery of an end thereof and a fittingly engaging portion (11) at the end face thereof, another pole member (B) having a fittingly engaging portion (12) at an end face thereof to engage with the fittingly engaging portion (11) of the said pole member (A) in the rotation axis thereof, a threaded member (10) of tubular shape mounted on the said another pole member (B) to be rotatable and within a predetermined range movable in the axial direction thereof, the threaded member being provided with, on the inner wall thereof, a screw engagable with the said male screw (7a) of the said pole member (A) and a plurality of openings (13) at an end face thereof, a tubular member (15) mounted on the end of the said pole member (A) to be rotatable and movable in the axial direction thereof within a predetermined range, said rotation and movement in the axial direction of the tubular member (15) being obtained by a projection (16) fixed to said pole member (A) and by a guide groove (17) formed with said tubular member (15), said tubular member being provided with at least a pin (14) engagable with the said openings (13), a spring (18) urging the said tubular member (15) in the direction of engagement of the pin (14) and in the direction of tightening of the threaded member (10), whereby the said pole member (A) and the said another pole member (B) are fixedly connected by selectingly engaging the pin (14) with one of the openings (13) in the state that the tubular member (15) is rotated against the urging force of the spring (18), and further wherein said guide groove (17) comprises a cam face (17a) formed to be capable of keeping the pin (14) in the disengaging position in which the pin is released from the opening (13) against the urging force of the spring (18) in the direction of engagement of the pin when the tubular member (15) is rotated maximally toward the returning direction of the spring (18), and a slanted cam face (17b) formed to be capable of producing, by contacting the projection (16), a component force (F'2) in the direction of tightening of the threaded member (10) by the urging force (F2) of the tubular member (15) in the direction of engagement of the pin (14) when the pin (14) is selectively fittingly engaged when the opening (13) in the state that the tubular member (15) is rotated against the urging force of the spring (18).