Joints and connections – Articulated members – Lockable at fixed position
Patent
1994-01-24
1995-10-17
Reese, Randolph A.
Joints and connections
Articulated members
Lockable at fixed position
403203, 403110, 403314, 403370, 403383, 280820, 280822, 280823, A63C 1122, F16B 714
Patent
active
054584272
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns telescopic tubular assemblies comprising a plurality of successive tubular sections sliding one inside the other between a retracted position and a deployed position. One non-limiting example of such assemblies is a ski stick.
These telescopic sticks enable the length of the stick to be adjusted to suit the slope over which the user is travelling.
The stick is designed to withstand axial loads. Consequently, selective locking means must be provided to immobilize the sections against axial relative movement in a deployed position, a retracted position or any intermediate position.
Various structures have already been proposed for locking the sections one within the other. In most of these structures an axial end piece is fixed to and extends a smaller diameter first tubular section. The end piece usually comprises a conical bearing surface and a screwthreaded part. An expandable locking collar slides axially on the larger diameter tubular section and comprises a usually conical interior bearing surface which bears against the conical bearing surface of the axial end piece. Actuator means such as a nut slide axially in the larger diameter tubular section and can be locked against rotation in this tubular section, the actuator means screwing onto the screwthreaded part of the axial end piece in order to clamp and unclamp the collar in the axial direction by relative rotation of the tubular sections.
In the document FR-A-929 616, for example, the actuator means comprise the locking collar itself which rubs against the inside wall of the larger diameter tube. Locking of the collar against rotation is somewhat hit and miss.
In the document DE-A-2 407 464 the actuator means also comprise the collar itself which is locked against rotation in the larger diameter tube by a longitudinal rib projecting from the inside surface of the tube and accommodated in a longitudinal groove on the collar. In this design the interior rib on the larger diameter tube is an impediment to guided sliding of the smaller diameter tube inside the larger diameter tube. The two tubes are not concentric and the guiding action between them is inadequate. When bending loads are applied to the stick the interior rib deforms the smaller diameter tube which causes it to deteriorate.
In the document DE-B-1 058 889 the actuator means also comprise the locking collar itself which is able to slide in the larger diameter tube and is locked against rotation in this tube by two diametrally opposite ribs in the collar which engage in two grooves in the inside surface of the larger diameter tube. Exterior ribs project from the exterior surface of the larger diameter tube, in corresponding relationship to the interior grooves. This design may be suitable for a stick comprising only two sections. However, the exterior ribs on the larger diameter tube prevent the fitting and correct retention of a third tube over the larger diameter tube.
The problem to which the present invention is addressed is to design a new locking structure which achieves good guidance of the tubes relative to each other without imposing excessive mechanical loads on the locking collar and in a way that is compatible with the use of three or more successive tubes.
As sticks of this kind are sometimes used under severe conditions it is important that the locking and unlocking of the sections one within the other is particularly reliable: there must be no unintentional sliding of the sections one within the other and no unintentional binding.
To achieve these and other objects a telescopic tubular assembly in accordance with the invention comprises:
at least one larger diameter first tubular section and one smaller diameter second tubular section having an inside end housed inside the first tubular section and able to rotate freely and to slide inside the first tubular section between a retracted position and a deployed position,
an actuator device comprising a first actuator member sliding in the larger diameter first tubular section and comprising a secon
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patent: 2526415 (1950-10-01), Refsdal
patent: 2533733 (1950-12-01), Jensen
patent: 4238164 (1980-12-01), Mazzolla
patent: 4441837 (1984-04-01), Mastroni
Eilberg William H.
Novosad Christopher J.
Reese Randolph A.
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