One-way twist lock for telescopic tubes

Claim 2

A twist lock mechanism for telescopic tubes, comprising: a. a first tube having a multi-sided cross section; b. a second tube telescopically disposed within the first tube; c. a split lock ring formed with a bore and slidably disposed within the first tube, the lock ring having a multisided external periphery sized to prevent rotation between the lock ring and first tube and a notch in one end intersecting both sides of said split; d. a lock base fixed to one end of the second tube; e. an eccentric pin extending from the lock base and disposed within the bore of the lock ring, the eccentric pin and lock ring being structured to wedge and accomplish locking when the tubes are relatively rotated in one direction; and, f. turn limiting means for preventing the eccentric pin and lock ring from locking when the tubes are relatively rotated in the opposite direction.

Claim 3

The structure according to claim 1 wherein the turn limiting means includes: a peg projecting laterally outwardly from the eccentric pin; and, a stop shoulder formed on the lock ring by said notch and positioned for engagement by the peg when the tubes are relatively rotated in said opposite direction.

Claim 4

The structure according to claim 1 wherein the turn limiting means includes: a stop element for preventing the eccentric pin and lock ring from exceeding a predetermined locking force.

Claim 5

The structure according to claim 1 wherein the turn limiting means includes: a peg projecting laterally outwardly from the eccentric pin; and, a pair of stop shoulders formed by the lock ring notch and positioned on opposite sides of the peg to limit angular displacement by the peg, wherein engagement of one stop shoulder by the peg prevents locking between the eccentric pin and lock ring, and, engagement of the other stop shoulder by the peg prevents the eccentric pin and lock ring from exceeding a predetermined locking force and becoming jammed.

Claim 6

The structure according to claim 1 wherein the lock ring is constructed from resilient material and has said split along one side by which the lock ring can be laterally slipped over and removed from the eccentric pin.

Claim 7

The structure according to claim 5, wherein: the cross section of the first tube and external periphery of the lock ring are generally rectangular.

Claim 8

The structure according to claim 1 wherein the lock base includes; a plug inserted within and fixed to the second tube; and, a pair of longitudinally spaced flanges of larger size than the eccentric pin which restrict axial movement by the lock ring.

Claim 9

The structure according to claim 7 wherein: an inwardly directed catch is formed by said one end of the first tube; and, one of the flanges is sufficiently large to engage the catch and prevent the tubes from separating when they are being fully extended.

Claim 10

A one-way twist lock mechanism for telescopic tubes, comprising: a. a first tube having a rectangular cross section; b. a second tube telescopically disposed within the first tube; c. a resilient split lock ring formed with a bore and slidably disposed within the first tube, the lock ring having a rectangular external periphery sized to prevent rotation between the lock ring and first tube; d. a lock base fixed to one end of the second tube; e. an eccentric pin extending from the lock base and disposed within the bore of the lock ring, the eccentric pin and lock ring being structured to wedge and accomplish locking when the tubes are relatively rotated in one direction; f. said split defining means along one side of the lock ring by which it can be laterally slipped over and removed from the eccentric pin; and, g. turn limiting means including a peg projecting laterally outwardly from the eccentric pin, and a notch in one end of said ring intersecting both sides of said split to define a pair of stop shoulders formed by the lock ring and positioned on opposite sides of the peg to limit angular displacement by the peg wherein engagement of one stop shoulder by the peg prevents locking between the eccentric pin and lock ring, and, engagement of the other stop shoulder by the peg prevents the eccentric pin and lock ring from exceeding a predetermined locking force and becoming jammed.

Claim 11

A one-way twist lock mechanism for telescopic tubes, comprising: a. a first tube having a rectangular cross section; b. a second tube telescopically disposed within the first tube; c. a resilient split lock ring formed with a bore and slidably disposed within the first tube, the lock ring having a rectangular external periphery sized to prevent rotation between the lock ring and first tube; d. a lock base fixed to one end of the second tube; e. an eccentric pin extending from the lock base and disposed within the bore of the lock ring, the eccentric pin and lock ring being structured to wedge and accomplish locking when the tubes are relatively rotated in one direction; f. said split defining means along one side of the lock ring by which it can be laterally slipped over and removed from the eccentric pin; and, g. turn limiting means including a peg projecting laterally outwardly from the eccentric pin, and a notch in one end of said ring intersecting both sides of said split to define a pair of stop shoulders formed by the lock ring and positioned on opposite sides of the peg to limit angular displacement by the peg wherein engagement of one stop shoulder by the peg prevents locking between the eccentric pin and lock ring, and, engagement of the other stop shoulder by the peg prevents the eccentric pin and lock ring from exceeding a predetermined locking force and becoming jammed.

Claim 12

The structure according to claim 9 including: indicating means for indicating the direction in which to twist the second tube to effect locking and the opposite direction in which to twist the second tube to effect unlocking.