Telescoping leg lock with thumb actuator
A telescoping leg particularly adapted for use in supporting geomatic equipment is capable of locking in different selected positions of extension. A lock is provided for holding the leg at the selected position of extension. The lock is biased to a lock position, but is capable of being moved and retained in an unlock position by operation of a single thumb on one hand so that locking and unlocking the leg for telescoping movement occupies only one hand.
1. A leg for use in supporting geomatic equipment comprising a first leg section and a second leg section, the first leg section being telescopingly received into an interior of the second leg section for selective extension from and retraction into the second leg section to lengthen and shorten the leg, and a locking device including an actuator and an engagement portion positioned to act on the interior of the second leg section to lock the first and second leg sections relative to each other to fix a length of the leg, the locking device being operable in a lock position in which the engagement portion of the locking device bears against the second leg section on the interior thereof with a force selected to lock the first and second leg sections, and an unlock position in which the engagement portion is spaced from the second leg section such that the leg sections are free to move in telescoping relation to change the length of the leg, the actuator being operable by action of a thumb to move the locking device between the lock and unlock positions, the actuator being biased to the lock position and capable of releasably retaining itself in the unlock position, wherein the actuator comprises an actuator rod and a button capable of being depressed for moving the rod lengthwise of the leg to the unlock position, and wherein the button has a first connector element thereon and the first leg section has a second connector element releasably engagable with the first connector element by thumb manipulation of the button to retain the actuator in the unlock position of the locking device and to release the actuator to return to the lock position.
2. A leg for use in supporting geomatic equipment as set forth in claim 1 wherein the first connector element of the button comprises a toe projecting outwardly therefrom, and the first leg section has a cavity receiving the button therein, the second connector element of the first leg section comprising a ledge formed in the cavity, the toe being selectively positionable under the ledge in the unlock position to retain the actuator in the unlock position.
3. A leg for use in supporting geomatic equipment as set forth in claim 1 wherein the locking device further comprises a wedge and first and second lock members having the engagement portion thereon, the wedge being moveable relative to the lock members to move the lock members apart in the lock position and to allow the lock members to move closer together in the unlock position, the wedge being connected to the actuator rod.
4. A leg for use in supporting geomatic equipment as set forth in claim 1 wherein the button has an upper surface which is skew to a longitudinal axis of the leg.
5. A leg for use in supporting geomatic equipment comprising a first leg section and a second leg section, the first leg section being telescopingly received into an interior of the second leg section for selective extension from and retraction into the second leg section to lengthen and shorten the leg, and a locking device including an actuator and an engagement portion positioned to act on the interior of the second leg section to lock the first and second leg sections relative to each other to fix a length of the leg, the locking device being operable in a lock position in which the engagement portion of the locking device bears against the second leg section on the interior thereof with a force selected to lock the first and second leg sections, and an unlock position in which the engagement portion is spaced from the second leg section such that the leg sections are free to move in telescoping relation to change the length of the leg, the actuator being operable by action of a thumb to move the locking device between the lock and unlock positions, the actuator being biased to the lock position and capable of releasably retaining itself in the unlock position, the actuator including a first connector element and the first leg section including a second connector element releasably engageable with the first connector element by thumb manipulation of the actuator to retain the actuator in the unlock position of the locking device and to release the actuator to return to the lock position, wherein the actuator comprises a button capable of being depressed for moving the locking device to the unlock position, and wherein the first connector element of the actuator comprises a toe projecting outwardly from the button and the first leg section has a cavity receiving the button therein, the second connector element of the first leg section comprising a ledge formed in the cavity, the toe being selectively positionable under the ledge in the unlock position to retain the actuator in the unlock position.
6. A leg for use in supporting geomatic equipment as set forth in claim 5 wherein the locking device further comprises a wedge and first and second lock members having the engagement portion thereon, the wedge being moveable relative to the lock members to move the lock members apart in the lock position and to allow the lock members to move closer together in the unlock position, the wedge being connected to the actuator rod.