TOOL WITH MOMENT INDICATION

Abstract: A tool is provided for the exertion of a turning moment, including an indication as to whether the turning moment exceeds a set value, in which a form piece (4) with parallel rectangular surfaces turns when the turning moment attains the set value and pushes a press bolt (3) situated in the shaft (2) and an indication sleeve (6) situated outside the shaft, said indication sleeve being connected with the press bolt, towards the grip (11) so that a previously hidden part of the indication sleeve (6) with a contrasting colour becomes visible.

Description: TOOL WITH MOMENT INDICATION Tools for the rotation of screws, nuts and other threaded objects are often provided with a moment measuring or moment indicating appliance in order to guarantee that the tightening moment be within the prescribed range, since too low a moment does not give a tight joint and too high a moment damages the threaded object. Also for other tools intended for exerting a turning moment, there is a need for measuring or indicating the magnitude of the turning moment, e.g. when controlling the turning moment in springs, axles or bolts. Basically, there exist two different types of tools. When using a moment measuring tool, the moment is determined as a deformation in some part of the tool, for instance in an elastic joint or in the shaft as such and the deformation can be read off by an index on a scale or by digital electronics. However, the reading off requires that the tool be moved slowly and that the scale be clearly visible, wherefore this type is unsuitable for routine installation work. Moment indicating tools merely indicate whether the moment is above or underneath an initially determined value, and is faster to work with when many screws are to be tightened with the same moment. When using moment indicating tools, the difficulty resides in achieving an indication which is easily readable also under difficult conditions with noise and bad visibility. The invention foresees a tool with which the indication is effected in several simultaneous ways. One embodiment of the present invention is a ratchet handle which is partially shown in a cross- section in figures 1 and 2, in which figure 1 shows the position of the separate parts when the moment is less than the set value and figure 2 shows the position of the different parts when the moment exceeds the set value. A ratchet handle according to the invention comprises a grip 11, a hollow shaft 2 and a head 12 with a protruding axle to which different sleeves can be coupled, depending on the size of the threaded objects. Preferrably, the head 12 comprises a stepping mechanism. The head 12 is fixedly connected to an arm 1 which protrudes into the shaft 2, the head being restricted in its angular movement in relation with the shaft tube by a joint 10. Inside the shaft 2 there is a slidable press bolt 3 which can be pressed frontwardly against the head 12 by a helical spring 7. By turning the grip 11, the helical spring 7 can be compressed to different extents so that the force in the helical spring is adjustable and can be read off on a scale on the grip 11. Between the arm 1 and the press bolt 3 a form piece 4 is inserted with parallel rectangular surfaces. The form piece 4 abuts plane surfaces on the arm 1 and on the press bolt 3, which surfaces are delimited by protruding edges. The press bolt 3 is connected to a slidable indication sleeve 6 on the outside of the shaft 2 via one or several pins 9 which penetrate elongated slots in the shaft tube, the indication sleeve preferrably being made with a contrasting colour over the other parts. Outside the indication sleeve 6 there is a covering sleeve 5 which is fixedly connected with the shaft 2 by one or several set screws 8. When the moment on the axle of the head 12 gets ) US-A-5 123 289, because of the fact that the edges are unloaded when the set moment has not been exceeded, and also gives a better defined and play-free central positioning of the arm 1. Ratchet handles for the rotation of threaded objects represent only one embodiment of tools according to the invention, which can also be formed for the rotation of threaded objects without any stepping function in the head 12, or for the control of torsional moments in springs, axles and bolts. The spring 7 can be a helical spring and also, e.g., one or several cup springs.

Claims: 4. Tool according to claim 1 or 2, characterized in that the parallel surfaces of the form piece (4) are rectangular. 5. Tool according to claim 1 or 2, characterized in that the head (12) is provided with a protruding axle in order to couple sleeves for the rotation of threaded objects.

Inventors: BERGQVIST HAAKAN, HIMBERT HANS, JANSSON CONNY, BERGQVIST, HAAKAN, HIMBERT, HANS, JANSSON, CONNY
Applicants: BERGQVIST HAAKAN, HIMBERT HANS, JANSSON CONNY, SANDVIK AB
Application year: 1993
Main classification: B25B23
IPC codes: B25B23