Power tool trigger linkage

Abstract

 A tool (10) having a frame (16), handles (22) pivotably mounted to the frame, a drive system (18) connected to the frame, and a user actuated trigger (26) pivotably connected to a first one (22L) of the handles. The drive system (18) has a longitudinally movably actuator (32). The improvement comprises a linkage (64) between an end (54) of the trigger (26) and the actuator (32) of the drive system.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to power tools and, more particularly, to a user actuated trigger and linkage to a drive system of a power tool.

[0002] The Racine division of FCI USA, Inc. manufactures and sells hydraulically powered tie tampers and breakers. U.S. Patent 5,749,421 discloses a pneumatic impact breaker having two pivotably movable handles and a trigger lever pivotably connected to one of the handles. The trigger lever can move with its associated handle. It is desired to use a similar trigger and movable handle configuration for hydraulic tools. However, in some tool hydraulic circuits, it is imperative the trigger spool remain still once it is engaged (placed in the ON position). If the spool moves while engaged, the performance of the hydraulic circuit will be reduced. Thus, a need exists to provide a tool with movable handles and a trigger that can move with one of the handles, but for a hydraulic tool and which will not move the trigger spool when the handles move.

SUMMARY OF THE INVENTION

[0003] In accordance with one embodiment of the present invention, a tool is provided comprising a frame, handles pivotably mounted to the frame, a drive system connected to the frame, and a user actuated trigger pivotably connected to a first one of the handles. The drive system has a longitudinally movably actuator. The improvement comprises a linkage between an end of the trigger and the actuator of the drive system.

[0004] In accordance with another embodiment of the present invention, a hydraulically operated tool is provided comprising a frame; a hydraulic drive system located in the frame; a handle pivotably mounted to the frame; a user actuated trigger pivotably mounted to the handle; and a link pivotably mounted to the frame. The drive system comprises a movable actuator. The link comprises a first end adapted to be contacted by the trigger and a second end adapted to contact the actuator.

[0005] In accordance with another embodiment of the present invention, a hydraulically operated tool is provided comprising a frame, handles pivotably mounted to the frame, a hydraulic drive system connected to the frame, and a user actuated trigger movably connected to a first one of the handles. The drive system comprises a longitudinally movable actuator. The improvement comprises a system for allowing the trigger to keep the actuator in an actuated position regardless of movement of the handles and regardless of movement of the trigger.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The foregoing aspects and other features of the present invention are explained in the following description, taken in connection with the accompanying drawings, wherein:

Fig. 1 is an elevational side view of a power tool incorporating features of the present invention;

Fig. 2 is a partial cross-sectional view of portions of the tool shown in Fig. 1 with the handles in an up position and the user actuatable trigger in an unactuated position;

Fig. 3 is a partial cross-sectional view as in Fig. 2 with the handles in a down position and the user actuatable trigger in an unactuated position;

Fig. 4 is a partial cross-sectional view as in Fig. 2 with the trigger in an actuated position; and

Fig. 5 is a partial cross-sectional view as in Fig. 3 with the trigger in an actuated position.

DETAILED DESCRIPTION

[0007] Referring to Fig. 1, there is shown an elevational view of a tool 10 incorporating features of the present invention. Although the present invention will be described with reference to the single embodiment shown in the drawings, it should be understood that the present invention can be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used.

[0008] The tool 10 in this embodiment is a hydraulic tie tamper also known as a railroad ballast tamper. In an alternate embodiment the tool could be a breaker or any other suitable type of tool including a pneumatically operated tool. The tool 10 generally comprises a frame 16, a drive section 18 located inside the frame, and a tool bit 20. The drive section 18 is connected to a hydraulic pump 12 by hoses 14. The tool 10 includes two handles 22. The handles 22 are pivotably connected to a top section 24 of the frame 16. The tool 10 also includes a user actuatable trigger or lever 26.

[0009] Referring also to Fig. 2, the drive section 18 shown in Fig. 1 includes a trigger spool 28, which is biased by a spring 30 in an upward direction, and a trigger push rod 32. The spool 28 is longitudinally movably located in a manifold 34 (see Fig. 1) of the frame 16 having the hose couplings 36. The spool 28 is longitudinally movable by moving the rod 32 or by biasing of the spring 30 between up and down positions (see Fig. 2 versus Fig. 4). The spool 28 has a channel 38 which, depending on whether the spool 28 is in its up or down position, will either cause the drive section 18 to move the tool bit 20 (ON position) or allow the tool bit to remain stationary (OFF position). In the ON position the channel 38 directs the hydraulic fluid from the pump 12 to the rest of the drive system. In the OFF position the channel 38 merely directs the hydraulic fluid back to the pump 12 without going through the rest of the drive system. In alternate embodiments any suitable type or configuration of drive system or actuator could be used. In this embodiment the actuator rod 32 is located off-center relative to a pivotable connection of the handles 22 to the top section 24.

[0010] Referring also to Fig. 3, the two handles 22 are movably mounted to the top section 24 between an up position (Fig. 2) and a down position (Fig. 3). In this embodiment to top section 24 comprises a center channel 42. In this embodiment the handles 22 are pivotably attached to the top section 24 by two pivot pins 40 (only one of which is shown). The pins 40 extend inward into the center channel 42 from opposite sides of the channel 42. The handles 22 have inward ends 44 with center open spaces 46. The inward ends 44 have general fork shapes with two arms on opposite sides of their respective spaces 46; each arm of each handle being pivotably mounted to one of the pins 40. The handles 22 also each comprise a groove 48. A pin 50 from a spring damper system located in the top section 24 extends into the grooves 48. One such spring damper system is described in U.S. Patent application No. 09/604.133 filed on the same date herewith which is hereby incorporated by reference in its entirety. However, any suitable type of spring damper system or handle biasing system could be used.

[0011] The trigger 26 includes a first end 52, an opposite second end 54, and a middle section 56. The first end 54 is a user contact section which allows the user to depress the first end 54 towards the left handle 22L. The middle section 56 extends into the space 46 at the inward end 44 of the left handle 22L and is pivotably connected to the left handle by a pivot pin 58. The second end 54 extends inward from the pivot pin 58 and includes a tip 60 and a groove 62. The tool 10 further comprises a link 64. The link 64 is pivotably connected to the top section 24 by a pivot pin 66. The link 64 includes a first end 68, an opposite second end 70, and a middle section 72. The middle section 72 is pivotably attached to the top section 24 by the pivot pin 66. The first end 68 contacts the second end 54 of the trigger 26. The second end 70 contacts the top end of the actuator rod 32. Portions of the link 64 extends into the spaces 46 at the inward ends 44 of the handles 22. The spring 30 biases the spool 28 and the actuator rod 32 in an upward direction such that the rod 32 is biased against the second end 70 of the link 64 to bias the first end 68 of the link against the second end 54 of the trigger 26. This biases the trigger 26 in an unactuated position relative to the left handle 22 as shown in Figs. 2 and 3.

[0012] Referring now to Figs. 4 and 5, the handles 22 are shown in their up and down positions, respectively, with the trigger 26 depressed or moved to its actuated position (ON position). In the actuated position of the trigger 26, the second end 54 of the trigger causes the link 64 to rotate about its pivot pin 66 to move the first end 68 upward and move the second end 70 downward relative to the top section 24. The second end 70 pushes the actuated rod 32 downward which, in turn, moves the spool 28 to its actuated position. The trigger 26 is sized and shaped such that, in its actuated position, the tip 60 of the trigger's second end 54 is substantially aligned with the pivot pins 40 regardless of the positions of the handles 22. Thus, after the trigger 26 is actuated, the tip 60 of the trigger 26 does not substantially move when the handles 22 move up and down relative to the top section 24. Likewise, in comparing Figs. 2 and 3, because of the groove or notch 62 in the second end 54 of the trigger 26, when the trigger 26 is in its unactuated position, it does not substantially move the link 64 when the handles 22 move between their up and down positions. Thus, regardless of whether the trigger is actuated or unactuated, the movement of the handles 22 up and down does not move the link 64 and, therefore, does not move the actuator rod 32 and spool 28. A linkage is established between the trigger and the trigger spool so that substantially no relative movement exists once the trigger is engaged by a user. The contact point between the trigger and the trigger link is directly in the center of the axis of rotation of the trigger handle 22L. In an alternate embodiment, alternative structural configurations of the linkage, the trigger second end, and the link could be provided so long as there is substantially no movement of the actuator once the trigger is engaged.

[0013] It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.

Claims

1. A tool (10) having a frame (16), handles (22) pivotably mounted to the frame, a drive system (18) connected to the frame, the drive system having a longitudinally movably actuator (32), and a user actuated trigger (26) pivotably connected to a first one of the handles (22), characterized in that it comprises:

a linkage (64) between an end (54) of the trigger (26) and the actuator (32) of the drive system.

2. A tool as in Claim 1 wherein the linkage comprises a link (64) pivotably connected to the frame (16).

3. A tool as in Claim 2 wherein the link (64) comprises a first end (68) which is adapted to be contacted by the end (54) of the trigger (26) and an opposite second end (70) which contacts the actuator 32), and wherein a pivot point (66) of the link with the frame is located between the first and second ends.

4. A tool as in Claim 3 wherein the link (64) is movable between an actuated position and an unactuated position, and wherein the first end (68) of the link is located proximate a pivot axis (40) of connection of the handles (22) to the frame when the link (64) is located at the actuated position.

5. A tool as in Claim 4 wherein, when the trigger (26) is moved to an actuated position, the end (54) of the trigger is located proximate the pivot axis (40) regardless of location of the handles (22) relative to the frame.

6. A tool as in Claim 3 wherein, when the trigger (26) is moved to an actuated position, the end (54) of the trigger is located at a pivot axis (40) of connection of the handles (22) to the frame regardless of movement of the handles relative to the frame.

7. A tool as in Claim 1 wherein the trigger (26) comprises a first end (52) adapted to be contacted by a user, an opposite second end (54), and a pivotable connection (58) to the handle (22) between the first and second ends, wherein the second end (54) is adapted to contact the linkage (64).

8. A tool as in Claim 1 wherein the actuator (32) is movably located in an axis offset from an axis (40) of rotation of the handles (22) to the frame.

9. A hydraulically operated tool comprising:

- a frame (16);

- a hydraulic drive system (18) located in the frame, the drive system comprising a movable actuator (32);

- a handle (22) pivotably mounted to the frame;

- a user actuated trigger (26) pivotably mounted to the handle; and

- a link (64) pivotably mounted to the frame, the link comprising a first end (68) adapted to be contacted by the trigger (26) and a second end (70) adapted to contact the actuator (32).

10. A tool as in Claim 9 wherein a pivot connection (66) of the link (64) with the frame is located between the first (68) and second (70) ends.

11. A tool as in Claim 10 wherein the link (64) is movable between an actuated position and an unactuated position, and wherein the first end (68) of the link is located proximate a pivot axis (40) of connection of the handle (22) to the frame when the link is located at the actuated position.

12. A tool as in Claim 11 wherein, when the trigger (26) is moved to an actuated position, an end (54) of the trigger is located proximate the pivot axis (40) regardless of location of the handle (22) relative to the frame.

13. A tool as in Claim 9 wherein, when the trigger (26) is moved to an actuated position, an end (54) of the trigger is located at a pivot axis (40) of connection of the handle (22) to the frame regardless of movement of the handle relative to the frame.

14. A tool as in Claim 9 wherein the trigger (26) comprises a first end (52) adapted to be contacted by a user, an opposite second end (54), and a pivotable connection (58) to the frame between the first and second ends, wherein the second end (54) of the trigger (26) is adapted to contact the link (64).

15. A tool as in Claim 9 wherein the actuator (32) is movably located in an axis offset from an axis (40) of rotation of the handle (22) to the frame.

16. An hydraulically operated tool (10) having a frame (16), handles (22) pivotably mounted to the frame, a hydraulic drive system (18) connected to the frame, the drive system comprising a longitudinally movable actuator (32), and a user actuated trigger (26) movably connected to a first one (22L) of the handles,
characterized in that it comprises:

a system (64) for allowing the trigger to keep the actuator (32) in an actuated position regardless of movement of the handles (22) and

regardless of movement of the trigger (26) with the first handle (22L).

Drawing