WO1992020494A1

WO1992020494A1 - Hand tool to tighten and to loose a screwed organ

Info

Publication number: WO1992020494A1
Application number: PCT/SE1992/000320
Authority: WO
Inventors: Johan Pelkonen
Original assignee: Johan Pelkonen
Priority date: 1991-05-16
Filing date: 1992-05-15
Publication date: 1992-11-26
Also published as: SE9101486D0; SE9101486L; SE467532B

Abstract

A hand tool for screwing or unscrewing screws or bolt with hex-heads consists of an elbow pipe (10) with a flexible shaft (18) rotatably mounted therein. At one end the shaft is fixed to a handle (10) which is rotatable in one pipe end and displaceable therein. The other end of the flexible shaft is fixed to a hex-head tip (20) which fits the hexagonal recess in the screw head in question. When the handle is in its forward position, the tip is free outside the adjacent pipe end and can be easily rotated with the handle. When the handle is pulled back to a rear end position, the tip is retracted into the hexagonal socket (22) in the adjacent pipe end, so that the tip is locked against rotation relative to the pipe. The handle can now be swung as a wrench lever to turn the tip.

Description

HAND TOOL TO TIGHTEN AND TO LOOSE A SCREWED ORGAN.

The present invention relates to a hand tool of the type that is disclosed in the preamble to the accompaning claim 1.

A hand tool of this type is known by for exemple SE 109 337, which shows a hand tool with an elbow pipe, in which a flexible shaft is rotatably mounted. In one end of the elbow pipe a screw or nut driver is rotatably mounted. The other end of the elbow pipe is provided with a pipe extension in which a driver handle shank is rotatably mounted and securely fixed to the end of the flexible shaft. If a socket is used, a nut or bolt can be tightened with this tool when low torque is applied by rotating the handle. During final tightening, how- ever, the required torque usually increases significant¬ ly and cannot be achieved by rotating the handle. This applies even more so when the upper bolt is to be un¬ screwed, which usually requires even greater torque if the nut or bolt is "stuck". If one were to use the hand- le as a lever in the same manner as a wrench, the high torque appied to the nut or bolt will be transmitted to the handle to rotate the same. In some cases it will quite difficult to resist such a rotation of the handle about its longitudinal axis. In practice two hands are needed, one hand holding the pipe and the other hand holding the handle to attempt to prevent rotation of the handle at the same time as it is used as a lever to¬ gether with the elbow pipe.

The purpose of the present invention is to, with simple means, eliminate this disadvantage and provide a tool which can function in the same manner as a wrench when it is necessary to apply relatively large torque for screwing or unscrewing.

This is achieved with a hand tool of the type described way of introduction which has the features disclosed in the characterizing clause of claim 1. Due to the fact that the handle is both rotatable and displacable in one end of the elbow pipe it can be used to simply displace the engaging means between an extend¬ ed position in which the engaging means can be freely rotated with the aid of the handle in a manner similar to the tool described in the above mentioned pattern specification, and a retracted position in which the proximate end of the engaging means is inserted into a corresponding seat in the adjacent end of the elbow pipe to thereby prevent it from rotating relative to the pipe. With this new and simple arrangement according to the invention, the hand tool will now function as a fixed wrench, so that the handle can be used to achieve, by a relatively small hand force and the relatively long lever, a great amount of torque in the engaging means, without having to prevent rotation of the flexible shaft and the handle. The hand tool according to the invention can thus be used with one hand in the same manner as a fixed wrench.

A suitable embodiment of the hand tool according to the invention is shown in the accompanying drawing.

Fig. 1 is a longitudinal section through a hand tool ac- cording to the invention with the handle in its forward end position and the engaging means in its extended free end position.

Fig. 2 is the same longitudinal section as in Fig l but with the handle in its rear end position the engaging means in its retracted end position, where it is non- rotatable relative to the adjacent pipe end.

Fig. 3 is a cross section along the line 3-3 in fig l through the engaging means which has the form of a hex- head tip. Fig. 4 is a cross section along the line 4-4 in Fig. 1 through the hexagonal socket receiving the hex-head tip.

10 designates an elbow pipe with two portions 12, 14 forming approximately a right angle with each other.

The longer straight portion 14 is provided with a rota¬ tably and a displaceably mounted handle 16, which, in its forward end position shown in Fig. 1, abuts against the end of pipe portion 14.

One end of a flexible shaft 18 of known design is fixed to the distal end of the handle 16. The shaft extends rotatably through the pipe 10 and out through the end of pipe portion 12 to the postition shown in Fig. 1. A hex- head tip 20 is securely fixed to this end of the shaft and is designed to fit a corresponding hex-head recess in a bolt or screw head (not shown) .

To the end of pipe portion 12 there is welded a socket forming a hexagonal seat 22 for receiving the hex-head tip 20 in the manner shown in fig 2.

In the position shown in Fig. 1, the tip 20 can be easi- ly rotated by rotating the handle 16 about its own long¬ itudinal axis. This is particularely adventageous in confined spaces. When the screw has been screwed in and is to be finally tightened, this can be done in a simple manner with the tool according to the invention. The handle 16 is pulled back to its rear end position as shown in Fig. 2, pulling the flexible shaft and the tip 20 with it to a fixed position in the socket 22. The tool will now function as a fixed wrench with the handle providing a relatively long lever for achieving a signi- ficant amount of torque for final tightening or initial unscrewing of the screw or bolt. If so desired, the tip can be extended with a socket for tightening or loosening a nut or bolt in the manner described above. Alternatively, it is possible to extend the tip with detachable hex-head tips in various sizes or sockets of various sizes, or screwdriver tips of various sizes.

Claims

1. Hand tool for screwing or unscrewing a screw means, such as a bolt, screw, nut or the like with a head which can be non-rotatably engaged by an engaging means (20) , which is fixed to one end of a flexible shaft (18) , the other end of which is fixed to a handle (16) , said flex¬ ible shaft being rotatably mounted in a elbow pipe (10) with two main portions (12,14) arranged at an angle, preferably a right angle, to each other, one of said portions rotatably supporting the handle (16) for rota- tion of the engaging means at the end of the other main portion, c h a r a c t e r i z e d in that the handle (16) is axially displaceble between a forward end posi¬ tion where the engaging means (20) is free outside the adjacent pipe in an extended end position, and a rear end position where the engaging means is retracted to a retracted end position with its approximate end nonrot- atably received in a seat (22) in the adjacent pipe end for locking the engaging means, whereby the screw means, when the required torque is small, can be screwed or unscrewed by rotating the handle in its forward position and, when the required torque is great, can be screwed or unscrewed by swinging the handle when the handle is in its rear position.

2. Hand tool according to Claim 1, c h a r a c t e r i z- e d in that the engaging means is a hexagonal tip (24) engaging a corresponding hex-head screw or bolt, and in that to the pipe end remote from the handle there is welded a hex-socket forming a seat (22) for the hexa- gonal tip.

3. Hand tool according to Claim l or 2, c h a r a c t¬ e r i z e d in that the engaging means can be extended by detachable hexagonal tips of various dimensions, or sockets of various sizes, or screwdriver tips of various sizes.