Pneumatic pruning hook with a telescopic shank

[0001] 1. Field of the Invention

[0002] The present invention relates to a pneumatic pruning hook with a telescopic shank, and more particularly to a pneumatic pruning hook with a telescopic shank that has an excellent airtight effect.

[0003] 2. Description of Related Art

[0004] A conventional telescopic shank (6) of a pneumatic pruning hook in accordance with the prior art shown in FIG. 11 comprises an outer tube (62) and an inner tube (61) partially slidably received in the outer tube (62). A convey element (7) is longitudinally and separately received in the shank (6) for conveying compressed air. The convey element (7) includes an outer pipe (72) corresponding to the outer tube (62) of the shank (6) and an inner pipe (71) partially and slidably received in the outer pipe (72). The inner pipe (71) is moved with the inner tube (61) to adjacent a total length of the conventional pruning hook.

[0005] The inner pipe (71) is airtightly connected to the inner pipe (72) to prevent the compressed air from leaking between the inner pipe (71) and the outer pipe (72). A first O-ring (711) is mounted around one end of the inner pipe (711) and airtightly abuts an inner periphery of the outer pipe (72), and a second O-ring (721) is annularly mounted in the inner periphery of the outer pipe (72) and airtightly abuts an outer periphery of the inner pipe (71) to prevent the compressed air in the convey element (7) from leaking between the inner pipe (71) and the outer pipe (72).

[0006] However, the first O-ring (711) rubs against the inner periphery of the outer pipe (72) and the second O-ring (721) rubs against the outer periphery of the inner pipe (71) when adjusting the length of the shank (6) of the conventional pneumatic pruning hook. The airtight effect between the inner pipe (71) and the outer pipe (72) will be disappeared when the first O-ring (711) and the second O-ring (721) are worn out.

[0007] The present invention has arisen to mitigate and/or obviate the disadvantage of the conventional telescopic shank of a pneumatic pruning hook.

[0008] The main objective of the present invention is to provide an improved pneumatic pruning hook with a telescopic shank that has an excellent airtight effect.

[0009] To achieve the objective, the pneumatic pruning hook in accordance with the present invention comprises a handle having a chamber defined therein and connected to a compressed air source, a valve mounted in the chamber for selectively allowing the compressed flowing into the chamber. The telescopic shank includes an outer tube longitudinally secured to the handle and an inner tube partially slidably received in the outer tube. A work device is secured on the inner tube opposite to the handle. A spiraled hose is received in the telescopic shank and respectively connected the handle and the work device for guiding the compressed air into the work device. A safety is mounted to the work device for selectively engaged to the work device to prevent the work device from an unexpected operation.

[0010] Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.

[0022] Referring to the drawings and initially to FIGS. 1–6, a pneumatic pruning hook with a telescopic shank in accordance with the present invention comprises a handle (1), a telescopic shank (3) with a first end connected to the handle (1), a connecting device (4) longitudinally connected to a second end of the telescopic shank (3), a work device (2) longitudinally pivotally connected to the connecting device (4) and a safety (5) mounted to the work device (2).

[0023] The handle (1) is adapted to a compressed air source and has a chamber (11) defined in the handle (1). A valve (12) is mounted in the handle (1) for controlling the compressed air flowing into the chamber (11) and a lever (13) is pivotally mounted to the handle (1) for actuating the valve (12).

[0024] The telescopic shank (3) includes a first connector (33) mounted to the handle (1) and having a first passage (331) defined in the first connector (33). The first connector (33) has a threaded section and a nut (332) is screwed onto the threaded section of the first connector (33). The nut (332) is screwed to abut the handle (1) to enhance the connection between the handle (1) and the first connector (33). The first passage (331) longitudinally extends through the first connector (33) and communicates with the chamber (11) in the handle (1). An outer tube (31) includes a first end longitudinally securely connected to the first connector (33) and a second end having a locking device (36) mounted to the outer tube (31). A first through hole (311) is defined in the outer tube (31) near the second of the outer tube (31). An inner tube (32) partially slidably received in the outer tube (31). The inner tube (32) includes a first end inserted into the outer tube (31) and a second end having a second connector (34) longitudinally mounted to the inner tube (32). The inner tube (32) has a series of second holes (321) defined in the first end of the inner tube (32) and each selectively communicating with the first hole (311) in the outer tube (31). The second connector (34) has a second passage (341) longitudinally defined therein and extending through the second connector (34). A spiraled hose (35) is received in the telescopic shank (3). The spiraled hose (35) has two opposite ends each having a joint (37) secured thereon. The two joints (37) respectively secured mounted to the first connector (33) and the second connector (34) so that the first passage (331) and the second passage (341) is communicated with each other due to the spiraled hose (35).

[0025] The locking device (36) includes a collar (361) mounted around the outer tube (31) and a lever (362) pivotally mounted on the collar (361). A stub (364) is pivotally connected to a first end of the lever (362) and extending through the first hole (311) and a corresponding one of the series of second holes (321) to hold the inner tube (32) in place relative to the outer tube (31). A torsion spring (363) is mounted between the collar (361) and the lever (362) to provide a restitution force to the lever (362) after being pushed.

[0026] The connecting device (4) includes a body (42) having a protrusion (421) extending therefrom and longitudinally mounted into the second connector (34). A third passage (422) is defined in and extends through the body (42) and the protrusion (421) to communicate with the passage (341) in the second connector (34). A connecting seat (41) is slidably mounted to the body (42). The connecting seat (41) has a recess (412) defined in a bottom thereof and communicating with the third passage (422). A path (411) is defined in the connecting seat (41) and communicates with the recess (412).

[0027] The work device (2) includes a cylinder (20) longitudinally mounted to the connecting seat (41) and communicating with the path (411) in the connecting seat (41). A piston (23) is reciprocally movably received in the cylinder (20) and has a block (231) secured on a bottom of the piston (23) to airtightly close the path (411) when the piston (23) abuts the connecting seat (41) after working. A fixed blade (21) is secured on a top of the cylinder (20) and a spring (25) is compressively mounted between the piston (23) and the fixed blade (21) to provide a restitution force to the piston (23) after being upwardly moved. A movable blade (22) is pivotally mounted to the fixed blade (21) for forming a scissors structure. A crank (24) includes a first end pivotally connected to the piston (23) and a second end pivotally connected to the movable blade (22) to drive the movable blade (22) moved toward the fixed blade (21) when the piston (23) is upwardly moved in the cylinder (20).

[0028] A safety (5) is secured on the work device (2). With reference to FIGS. 8-10, the safety (5) has two rails (51) extending from the work device (2) and each has a groove (511) laterally defined therein. The two grooves (511) are opposite to each other. Each rail (51) includes a top having a first dimple (512) defined near the work device (2) and a second dimple (513) defined near a free end of each of the rail (51). A slider (52) is slidably mounted on the two rails (51) and selectively engaged to the movable blade (22). The slider (52) has two blind holes (521) each aligning with a corresponding one of the two rails (51) and receiving a spring (522). A steel ball (523) is received in a corresponding one of the two blind holes (521) and partially extending out of the slider (52) for being received in a corresponding first/second dimple (512/513) to hold the slider (52) in place due to a restitution force of each of the two springs (522). The slider (52) has two opposite sides each has a buckle (524) laterally extending therefrom and slidably received in a corresponding one of the two grooves (511) in the two rails (51).

[0029] With reference to FIGS. 3 and 4, when adjusting the length of the telescopic shank (3), the lever (362) of the locking device (36) is pushed toward the collar (361) to make the stub (264) be moved and detached from the first hole (311) and the second hole (321), thereby the inner tube (32) can be freely moved relative to the outer tube (31). The lever (362) is released and then the stub (364) inserted the first hole (311) and a corresponding one of the series of second holes (321) to fix the inner tube (32) again when the inner tube (32) extends to a suitable length relative to the outer tube. The spiraled hose (35) extends with the inner tube (32) due to the spiral-shape thereof.

[0030] With reference to FIGS. 6–10, the movable blade (22) is limited by the slider (52) and cannot be operated to prevent the pneumatic pruning hook from an unexpected operation and enhance the safe effect of the pneumatic pruning hook when each steel ball (523) is partially received in the first dimple (512). The movable blade (22) can be freely operated to cut branch when the slider (52) is laterally moved and each steel ball (523) is partially received in a corresponding one of the two second dimples (513) and the compressed air is guided into the cylinder (20).

[0031] As described above, the telescopic shank (3) of the present invention provides an excellent airtight effect to the pneumatic pruning hook because the spiraled hose (35) is airtightly connected to the first connector (33) and the second connector (34) by the joints (37). Furthermore, the safety (5) enhances the safe effect of the pneumatic pruning hook to prevent the pneumatic pruning hook from an unexpected operation.

[0032] Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.