Tool with moment indication

Details Tool with moment indication Tool with moment indication

1994-06-13

1995-07-25

Chilcot, Jr., Richard E.

Measuring and testing

Dynamometers

Responsive to torque

81483, G01L 524

Patent

active

054351901

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

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 a 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 by an index on a scale or by digital electronics. However, the reading 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.


BRIEF DESCRIPTION OF THE DRAWING

One embodiment of the present invention is a ratchet handle which is partially shown in a cross-section in FIGS. 1 and 2, in which:
FIG. 1 shows the position of the separate parts when the moment is less than the set value, and
FIG. 2 shows the position of the different parts when the moment exceeds the set value.


DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A ratchet handle according to the present invention includes 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. Preferably, the head 12 includes 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 urged 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 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 preferably 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 less than a value which is dependent upon the set force in the helical spring 7, then the parallel surfaces of the form piece 4 come into contact with the plane surfaces of the arm 1 and the press bolt 3, the arm 1 being forced to a central positioning within the shaft 2, whereby the protruding edges of the plane surfaces render this central position well defined and reproducible. Thereby, the indication sleeve 6 is hidden within the cover sleeve 5.
When the moment on the axle of the head 12 exceeds the value which is dependent upon the set force in the helical spring 7, then the form piece 4 turns so that only its edges but not its parallel surfaces come into contact with the press bolt 3 and the arm 1. Then the press bolt 3 and the indication sleeve 6 move t

REFERENCES:
patent: 2743638 (1956-05-01), Woods
patent: 2934985 (1960-05-01), Mutolo et al.
patent: 3016773 (1962-01-01), Woods
patent: 3276296 (1966-10-01), Woods
patent: 4467678 (1984-08-01), Lindholm
patent: 4898068 (1990-02-01), Neuhaus
patent: 5123289 (1992-06-01), Potesta
patent: 5129293 (1992-07-01), Larson et al.
patent: 5152200 (1992-10-01), Kaplan

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