US2814881A - Steel measuring tapes - Google Patents

Description

STEEL MEASURING TAPES Ture Anders Ljungberg, Stockholm, Sweden Appiication October 11, 1954, Serial No. 461,599

Claims. (Cl. 33-138) This invention relates to steel measuring tapes of the type which preferably has a curved profile and is arranged in the form of a coil in a case from which it is extensible through a mouth portion and may be locked against displacement in said mouth portion by deformation by means of a spring-actuated locking member which is moved towards the tape for locking the same and is moved away from the tape for unlocking it.

One feature of the invention is that the locking member is provided with at least one tongue projecting in the direction of extension of the tape, which tongue is intended to serve as a reading mark for the scale arranged on the tape.

In the locking position said tongue is in direct contact with the tape so that parallax errors are avoided and easy and reliable reading is obtained. On unlocking the tape, the tongue is moved away from the same so that there is no risk of gradually wearing ofi the scale when the tape is moved, which is of particular importance if the scale is of the printed variety. The tongue, or tongues, also assist in giving steadiness to the part of the steel tape that projects from the case.

Other features of the invention will appear from the following description.

A preferred embodiment of the invention is illustrated in the atttached drawing.

Fig. 1 is a vertical section through the mouth portion of the case in which the tape is coiled.

Fig. 2 is a section along line 2-2 of Fig. 1, looking in the direction of the arrows.

Figs. 3 and 4 show the locking means for the tape in two different positions.

Fig. 5 is a transverse section along line 5-5 of Fig. 3.

Fig. 6 is a longitudinal section of a modified embodiment of the spring forming part of the locking means.

Fig. 7 is a perspective view of the locking means.

In Fig. 1 reference numeral 1 designates the case for the steel measuring tape 2 which is coiled therein as shown at 3, and is extensible through a mouth portion 4 of the case. The tape has a curved profile (cf. Fig. 5). The concave side of the tape is shown facing downwardly but it can also be turned upwards. To the upper wall of the case or box 1 adjacent the mouth 4 a rivet 5 is fastened against the bulged inner head on which the convex face of the tape 2 slides. Near the mouth position 4 within the case or box a transverse pin 6 is provided upon which a guide member '7 is rockably mounted, cf. also Fig. 7. The guide member is made of sheet metal and consists of a flat central portion 8 with upturned lateral edges 9 which together with the central portion 8 form a kind of channel or slide guide in which the steel tape 2 slides as it is drawn out from or pushed back into the case 1. From the central portion 8 and for a purpose indicated hereinafter a lug 10 is punched out and bent downwards. The right hand end of the guide member is bent to cylindrical shape, as indicated at 11, and fits on the above mentioned pin 6. From the left hand end of the portion 8 two tongues States Patent G ice 12 protrude in the direction of extension of the steel tape 2.

Reference numeral 13 designates a leaf spring the lower end of which engages a recess 14 having a metal lining provided therefor in the lower portion of the case 1 and the upper end of which abuts against the lower face of the central flat portion 8 of the guide member 7 on the outer side of the downwardly projecting lug 10 which is somewhat resilient and abuts against the inner side of the leaf spring 13 as shown in Fig. 1. Normally, the leaf spring 13 is straight and it is of such length that it exerts a strong pressure on the guide member 7 which pressure tends to turn the guide member clockwise about the pin 6 whereby the convex face of the steel tape 2 is pressed against the bulged head of the rivet 5 and is deformed and somewhat flattened so that, as seen in horizontal projection (Fig. 2), the tape 2 becomes a little wider at the deformed area and the edges thereof are clamped firmly in the channel of the guide member 7 which is so proportioned that the tape slides easily in the channel only in its normal curved condition, whereas a deformation of the kind referred to causes a very effective clamping of the tape in the guide member between the upwardly bent lateral edges 9 thereof.

To the middle portion of the plate spring 13 a button 21 is riveted and this button projects through an opening 15 in the lateral wall 16 of the case 1.

In the position shown in Fig. l the steel tape is thus effectively locked against displacement by the action exerted by the plate spring 13 on the guide member 7. If now the button 21 is pressed inwardly, the leaf spring 13 is bent, as shown in Fig. 4, whereby the guide memher 7 is turned counter-clockwise about the pin 6 and the pressure of the rivet 5 against the steel tape 2 ceases so that the tape reassumes its normal curved profile and is easily slidable within the guide and can be drawn out from the case 1 or pushed back into the latter, or automatically retracted by the action of a coil spring, if the device is provided with such automatically acting retraction spring.

It may be desirable to provide for the locking means two points, here termed trigger points, in the travel of button 21, at which definite transitions, sensible by the operator, occur in the tape releasing operation, viz. a first trigger point at which the tape 2 may still be manually displaced in the guide member 7 but at which the retraction spring is not capable of retracting the tape into the case, and a second trigger point at which the tape has wholly reassumed its natural curved profile so that it slides easily in the guide member and is automatically drawn into the case by its retraction spring.

As seen in Figs. 1, 3 and 4, it is possible for this purpose to arrange a stop member 17 some distance above the lower anchorage 14 for the leaf spring 13. When the button 21 is pressed inwards, the leaf spring 13 is brought to contact this stop member (Fig. 3) whereby the effective spring length is reduced and the spring characteristics are altered so that the force needed to further bend the spring 13 suddenly increases. The position shown in Fig. 3 corresponds to the first trigger point, the conditions being then such that the steel tape 2 has only in part reassumed its curved profile and is displaceable in the guide member 7 when a certain force is exerted on the tape.

The second trigger point is reached when the button 21 has been depressed as much as possible (Fig. 4) so that the steel tape has wholly reassumed its natural curved profile and slides easily in the guide 7. The central port-ion 8 of the guide member 7 has then moved into contact with the lower wall 18 of the mouth portion 4 and the plate spring 13 has put the downwardly projecting resilient lug 10' under a certain tension, so that upon cessation of the pressing force against the button 21 said lug 1t), owing to its resiliency, assists in bringing the plate spring 13 back into the position according to Fig. 1 (locking position).

The leaf spring 13 has preferably a curved or other channel-shaped profile, as shown in Fig. 5. When such a spring is bent by depression of the button 21 a buckling of the spring occurs after a certain movement of the button, whereby the resistance of the spring against 1 bending suddenly decreases and thereafter again gradually increases. When using a spring of this kind the said buckling point may preferably serve as the first trigger point. The stop member 17 reducing the eflective spring length may be utilized in the case of a spring having a flat profile. I

As mentioned above, two spaced tongues 12 protrude from the central portion 8 of the guide member 7 in the direction of extension of the steel tape 2. The leading edges of these tongues are intended to serve as a reading mark for the scale on the under side of the tape 2. As, in the locked condition of the tape 2, the tongues rest on the scale, parallax errors in reading are eliminated and the reading can be made accurately and easily. When the tape 2 is unlocked by depressing the button 21, the tongues 12 are moved away from the scale so that friction is obviated and the scale is protected against wearing. Each tongue cc-operates with one edge of the scale so that the middle portion of the scale, with the numerals commonly arranged thereon, is perfectly visible. The two protruding tongues 12 also contribute to giving steadiness to the tape in front of the deformation area at the rivet 5 where the tape is more or less flattened so that it has a tendency to bend in the transverse direction.

In order to secure perfect locking also in the case of variations in the width of the steel tape and the guide, for instance due to wearing of the locking means, it is preferable to use a leaf spring 13 exhibiting a certain resiliency also in its longitudinal direction. Such resiliency can be obtained by having the lower end of the leaf spring rest upon a strong screw spring or other spring, or by providing a transverse bulge 20 on the leaf spring 13, as shown in Fig. 6.

What I claim is:

1. A measuring device comprising a casing having a mouth portion, a flexible steel measuring tape of the concave-convex type and provided with a scale coiled within said casing and etxensible through said mouth portion, a guide member for said measuring tape movably mounted in said mouth portion, a spring actuating said guide member and normally urging it in a direction causing the measuring tape to be applied to an inner surface of the mouth portion and to be frictionally held against displacement in extended positions, means for manually moving the guide member in a direction opposite to that normally imparted to the same by said spring so as to unlock said measuring tape, and at least one tongue provided on said guide member at the outer end thereof and visible at the outer end of said mouth portion, said tongue having a cross-sectional shape different from that of said measuring tape so as to be unable to touch the latter except at its edges and serving as a reading mark for said scale, and said tongue in the locking position of said guide member being close to said scale so as to avoid parallax errors in reading and in the unlocking position being moved away from said measuring tape.

2. A measuring device comprising a casing having a mouth portion, a flexible steel measuring tape provided with a scale coiled within said casing and extensible through said mouth portion, a guide member for said measuring tape movably mounted in said mouth portion, a spring actuating said guide member and urging it in a direction causing the measuring tape to be applied to aninner surface of the mouth portion and to be frictionally held against displacement in extended positions, means for manually moving said guide member in a direction opposite to that imparted to the same by said spring so as to unlock said measuring tape, two spaced tongues provided at the outer end of said guide member at opposite edges of the same, said tongues serving as a reading mark for said scale, and said tongues in the locking position of said guide member being close to said scale so as to avoid parallax errors in reading and in the unlocking position being moved away from said measuring tape.

3. A measuring device comprising a casing having a mouth portion, a flexible steel measuring tape provided with a scale coiled in said casing and extensible through said mouth portion, a guide member for said measuring tape rockably mounted in said mouth portion, a leaf spring engaging said guide member and extending between the same and a fixed point in said casing so as to exert a prsesure endwise of itself on the guide member to apply said measuring tape against an inner surface of the mouth portion and hold it frictionally against displacement, a push button mounted in an opening in said casing adjacent said leaf spring and adapted upon actuation to bend the spring and to swing the guide member so as to remove it from the measuring tape and unlock the latter, and at least one tongue provided at the outer end of said guide member and visible at the outer end of said mouth portion, said tongue serving as a reading mark for said scale, and said tongue in the locking position of said guide member being close to said scale so as to avoid parallax errors in reading and in the unlocking position being moved away from said measuring tape.

4. A measuring device as claimed in claim 3, in which the leaf spring has a curved profile and a transverse bulge which latter imparts resiliency to the same also in longitudinal direction.

5. A measuring device comprising a casing having a mouth portion, a flexible steel measuring tape provided with a scale coiled in said casing and extensible through said mouth portion, a guide member for said measuring tape rockably mounted in said mouth portion, a leaf spring engaging said guide member and extending between the same and a fixed point in said casing so as to exert a pressure endwise of itself on the guide member to apply said measuring tape against an inner surface of the mouth portion and hold it frictionally against displacement, 2. push button mounted in an opening in said casing adjacent said leaf spring and adapted upon actuation to bend the spring and to swing the guide member so as to remove it from the measuring tape and unlock the latter, a stop member for said leaf spring in said casing arranged intermediate the ends of the spring and adapted when contacted by the spring upon bending of the latter to cause a sudden increase in spring resistance to the advance of the push button and a transition to a higher rate of brake retraction which is signaled thereby, said point of transition corresponding to such unlocking of the measuring tape that the same is displaceable but not easily displaceable in the mouth portion, and at least one tongue provided at the outer end of said guide member and visible at the outer end of said mouth portion, said tongue serving as a reading mark for said scale and said tongue in the locking position of said guide member being close to said scale so as to avoid parallax errors in reading and in the unlocking position being moved away from said measuring tape.

References Cited in the file of this patent UNITED STATES PATENTS 2,055,281 Dulczewski Sept. 22, 1936 2,142,387 Udell Jan. 3, 1939 2,684,534 Ljungberg July 27, 1954 FOREIGN PATENTS 229,107 Great Britain Feb. 19, 1925

Images