GB2238744A

GB2238744A - Fastener extracting tool

Info

Publication number: GB2238744A
Application number: GB8923883A
Authority: GB
Inventors: Michael John Turner
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-10-24
Filing date: 1989-10-24
Publication date: 1991-06-12
Anticipated expiration: 2009-10-24
Also published as: GB8923883D0; GB2238744B

Abstract

The tool has a bar 11 and a screwed-on adaptor 14 carrying an appropriately sized anchor bolt 54. The anchor bolt 54 is screwed into a free bore adjacent to a jammed screw. A block 12 is slid along the bar 11 until the driver bit 60 carried thereby is directly ever the jammed screw. In this position the free end 21 of the lever bar 11 is axially farther from the bit 60 than the bit is from the anchor bolt 54. By pressing down hard on the free end 21 to engage the bit 60 in the head of the jammed screw and with the aid of a ratchet spanner, the bit assembly 15 can be turned to loosen and remove the jammed screw. <IMAGE>

Description

FASTENER EXTRACTING TOOL The invention concerns a fastener extracting tool for removing excessively tight or jammed threaded screws or bolts.

Although it is not so restricted, it will hereafter be described with reference to a portable tool which does not require a source of power e.g. electricity of compressed air, for its use.

The tool of this invention is of great versatility and is usable whenever (a) a screw to be removed has become jammed or very tight so that normally it would have to be drilled out, and (b) there is a reasonably continuous 'good' screw that can be removed by conventional means. Again, without any restriction on the scope of the invention being intended thereby, the preferred field of use of the tool according to the invention is servicing/maintenance of aircraft: aircraft panels commonly have rows of adjacent screws or bolts.

According to one aspect of the present invention, there is provided a tool for extracting a jammed or excessively tight threaded fastener, comprising a lever bar, a slide block mounted on, and for sliding along the longitudinal axis of, the lever bar, a driver bit assembly mounted on said block, an adaptor mounted at one end of the lever bar for pivotal movement about an axis transverse to said longitudinal axis and exchangeably carrying one of a set of threaded anchors of differing diameters and/or lengths.

Preferably, the means for pivotal mounting the adaptor at the end of the lever bar includes a spring-loaded plunger engaging in a detent formed in an eye-bolt carried on a pivot shaft secured at said bar and, the eye-bolt being connectable, e.g. by a threaded connection, with the adaptor.

The said pivotal movement is at least 900 n that at a detent position the lever bar and the anchor are suDstantially collinear while in an extract position the anchor and the bit assembly are generally parallel with each other.

According to another aspect of the present invention, there is provided a method for extracting a jammed or excessively tight threaded fastener by means of the tool set forth above, comprising extracting a contiguous threaded fastener, threadedly engaging the anchor in the bore of the extracted fastener, pivoting the lever bar relative to the anchor so as to extend over the location of the jammed or excessively tight threaded fastener to be extracted, sliding said block along the lever bar until it is positioned over said jammed or excessively tight threaded fastener and engaging the driver bit assembly therewith, pressing the free end of the lever bar towards the workpiece containing said jammed or excessively tight threaded fastener, and rotating the driver bit assembly (e.g. with a ratchetspanner) while maintaining said pressure to loosen and extract said jammed or excessively tight threaded fastener.

The invention will be described, purely by way of example, with reference to the accompanying drawings, wherein: Figure 1 is a perspective view of the tool according to the invention, in the operative position, Figure 2a is a side elevation corresponding to, but on a scale different from, Figure 1, Figure 2b is a side elevation orthogonal to Figure 2a but showing the tool without the adaptor and anchor, Figure 2c is an end elevation, with the adaptor and anchor having been pivotally displaced by 1800 relative to Figure 2a, Figure 3 is an elevation on an enlarged scale of the plunger forming part of the tool, and Figures 4a and b are, respectively, mutually orthogonal elevations on an enlarged scale of the eye-bolt forming part of the tool.

Referring to the drawings, there is shown a screw/bolt extractor tool 10 having as its main parts an elongated lever bar 11, a slide block 12 slidable along the lever bar 11, a pivotal mounting assembly 13, an adaptor 14 carrying an anchor bolt and a driver bit assembly 15 attached to the slide block 12.

One end 20 of the lever bar 11 and the adaptor 14 are connected together by means of the mounting assembly 13 which will now be described in greater detail. The end 20 contains a stepped hollow blind bore 21. A plunger 22 having a head 23 terminating in a rounded nose 24 and a reduced-section stem 25 is disposed in the bore 21 and is urged leftward (as viewed in Figures 1 and 2b) by a compression spring 27 supported in the bore 21 and by the shoulder 28 formed behind the head 23. The end 20 is forked and has a transverse bore 30 through which extends a clevis pin 32 held in a conventional manner by a washer 34 and a split pin 36.

An eye-bolt 38 is mounted on the clevis pin 32. The eye-bolt 38 has a rounded head 40 apertured at 42 for the clevis pin 32 and notched at 44 to receive and form an overridable detent for the nose 24. The head 40 of the eye-bolt 38 is connected to a threaded stem 46.

The adaptor 14 has a body 50 with an internally threaded bore 52 threadedly engageable with the stem 46. The body 50 carries a threaded anchor bolt 54, this unit being one of a set wherein the length and especially the diameter of the bolt 54 varies.

The slide block 12 and the driver bit assembly 15 require no detailed description; the assembly has a conventional chuck for holding and retaining a driver bit 60.

In use, a jammed screw or bolt is extracted by means of the illustrated tool as follows.

In all practical situations, there will always be one 'good screw or bolt, e.g. on an aircraft panel (not shown) near the jammed one, neither being shown. This good fastener is then extracted as usual. (If there is no good fastener at all, then just one fastener requires to be drilled out.) In this way, a bore is 'liberated'. With the bar 11 and screwed-on adaptor 14 (carrying an appropriately sized anchor bolt 54) coaxial, i.e.

the plunger head 24 engaged in detent 44, the anchor bolt 54 is screwed into the liberated bore. The lever bar 11 is then pivoted relative to the anchor bolt 54 by approximately 900, the bias of the spring 27 being overcome and the plunger 23 being retracted into the bore 21. The block 12 is slid long the bar 11 until the driver bit 60 is directly over the head of the jammed fastener.

In this position the free end 21 of the lever bar 11 is axially farther from the bit 60 than the latter is from the anchor bolt 54 which represents the fulcrum of a lever arm system. By pressing down hard on the free end 21, great pressure is exerted on the bit 60 properly to engage the slit orlike recess in the head of the jammed fastener. By the use of a suitable tool, e.g.

a ratched spanner, the bit assembly 15 can be turned to loosen and remove the jammed fastener.

Claims

1. A tool for extracting a jammed or excessively tight threaded fastener, comprising a lever bar; a slide block mounted on, and for sliding along the longitudinal axis of, the lever bar; a driver bit assembly mounted on said block; an adaptor mounted at one end of the lever bar for pivotal movement about an axis transverse to said longitudinal axis and exchangeably carrying one of a set of threaded anchors of differing diameters and/or lengths.

2. A tool according to claim 1, wherein the means for pivotal mounting the adaptor at the end of the lever bar includes a springloaded plunger engaging in a detent formed in an eye-bolt carried on a pivot shaft secured at said bar, the eye-bolt being connectable with the adaptor.

3. A tool according to claim 1 or 2, wherein the said pivotal movement is at least 900 so that at a detent position the lever bar and the anchor are substantially collinear while in an extract position the anchor and the bit assembly are generally parallel with each other.

4. A tool according to claim 1 substantially as herein described with reference to and as shown in the accompanying drawings.

5. A method for extracting a jammed or excessively tight threaded fastener by means of the tool according to any preceding claim comprising the preliminary steps of extracting a threaded fastener contiguous with the one to be extracted, then threadedly engaging the anchor in the bore of the previously extracted fastener; the method further comprising pivoting the lever bar relative to the anchor so as to extend over the location of the jammed or excessively tight threaded fastener to be extracted, sliding said block along the lever bar until it is positioned over said jammed or excessively tight threaded fastener and engaging the driver bit assembly therewith, pressing the free end of the lever bar towards the workpiece containing said jammed or excessively tight threaded fastener, and rotating the driver bit assembly while maintaining said pressure to loosen and extract said jammed or excessively tight threaded fastener.

6. A method according to claim 5 substantially as herein described with reference to and as shown in the accompanying drawings.