US1987652A - Tape measure - Google Patents

Description

Jan. 15, 1935. E. J. WITCHGER 1,987,652

TAPE MEASURE Filed Feb. 16, 1933 ATTORNEY atente 5. 15, 1935 UNITED STATES PATENT OFFICE Application February 16, 1933, Serial No. 657,009

The invention relates to tape measures of the so-called push-pull type wherein the tape is drawn out from the casing by pulling and is restored to the casing by pushing, there being no crank for winding the tape, no spring for either suddenly drawing the tape into the casing or suddenly extending it, and no keeper, such as a ratchet, for holding the tape in its extended position.

It is desirable in push-pull tape measures of the kind referred to that both the withdrawal and the rewinding of the tape from and into the case shall be accomplished with a slight'amount of effort, and that the force required shall be uniform at all points of extension of the tape from the casing. That is to say, the feel, by which the user judges the satisfactory operation of a push-pull tape measure, should be substantially the same throughout the entire range of operation. Moreover, there should be no objectionable amount of over-travel, retraction, or creeping movement of the tap when 'it is released at any point in its range of operation. 0

Heretofore tape measures of this type have answered these requirements quite satisfactorily, provided the coil spring, used to balance the spring action of the tape itself, was balanced with respect to the character of the tape. In other words,

when the tape and spring are properly proportioned, the extending and windingoperations are generally smooth and even, so that each push of the tape into the case or each pull out of it requires the same effort. When so properly balanced, the tape will stay in any position to which it is drawn or pushed and has no appreciable tendency to slip either inwardly or outwardly when released.

Under conditions of quantity production of tape measures it is impracticable to balance the strength of each coil spring with the physical characteristics of its tape so accurately as to attain in every tape measure the desired smoothness of action, because there often is some unavoidable slight variation between different lots of spring material or steel tape. An individual tape measure of a manufactured lot, for example,

a will have a spring which pulls too strongly, so

that when the operator releases the tape after having pulled it out to nearly its full extent the tape will slip back a short distance into the case, or it may do so if the case is afterward jarred. Yet this same tape measure will operate satisfactorily at any less extended point in the working range of the tape.

My present invention overcomes the abovementioned commercial difflculty and insures a smooth, positive action throughout the entire range of operation of the tape and eliminates slippage. Furthermore, it makes it possible to use a considerably greater length of tape in a 5 given size casing, while giving the desired smoothness and reliability of tape action. v

One object of the invention is to provide in the tape casing a novel drag or brake device that shall operate automatically after the manner of 10 a friction brake to keep the tape from being drawn into the case by the pull of the coil spring when the user has released the tape after either drawing it out or retracting it.

Another'object of the invention is to provide novel means for securing the drag or brake element to the casing of the tape measure when the casing is assembled.

A third object is to provide an extremely simple and inexpensive device in the form of a flat, thin, and flexible partially-coiled brake band which is secured at one end to the tape measure case and which will envelop and snugly flt the coil of tape at all times while it increases or decreases in size with the winding or unwinding of the 25 tape. The device need exert only a small resistance to the action of the tapeand coil spring, both while the tape is being extended and while it is being pushed back into the casing, in order to perform its balancing function eflectively. Its action is to dampen the action of the coil spring and by its braking action to produce the desired uniform feel of the tape throughout its enti e range of operation.

My improved control device is adapted to be used with either flat tapes or with concavo-convex tapes arranged to be pulled out of the case or pushed back by hand.

For the purpose of describing the inventive subject-matter I am showing in the drawing tape measures having non-planar or concavo-convex tapes. The measures are of the push-pull type shown, first, in a-preferred form employing a revolving drum and, secondly, in a modified form 45 having no drum. The purpose of this double showing is to make apparent the adaptability of my improved device to tape measures of various known structures, and to demonstrate that my invention is not to be deemed adaptable only to one particular type of tape measure.

With the .foregoing and certain other objects in view, which will appear laterln the specification, myinvention comprises the devices described and claimed and the equivalents thereof.

In the drawing Fig. 1 is a diagrammatic view of a tape measure embodying my improvement, shown with half the case removed, the tape being almost fully wound and the coil spring being almost completely unwound.

Fig.2 is a similar view of the device shown in Fig. 1, the tape being unwound or extended nearly to its fullest extent, the coil spring being wound.

Figs. 3 and 4 are views similar to Figs. 1 and 2 respectively, but with the post and spring omitted to show more clearly the relationship of the novel brake-band to the tape coil and drum.

Fig. 5 is an edge view, partly broken away, showing a mode of securing the brake band to the tape case.

Fig. 6 is a perspective view of the resilient band element.

Fig. 7 is a fragmentary sectional view of the casing and the brake band, taken on line 7-7 of Fig. 5.

Fig. 8 is a perspective detail of the preferred fastening means, also shown in Fig. 5, by which the brake band is secured to the casing.

Fig. 9 is a detail view similar to Fig. 2, but differing therefrom in showing a tape measure structure in which there is no drum upon which to wind the tape.

Fig. 10 is a plan view showing the manner of connecting the tape to the 'coil spring in the structure of Fig. 9.

In Figs. 1 to 5 inclusive I have shown my improved brake device as applied to a tape measure having the usual casing, comprising two pieces 1 and 2, formed with a tape opening 3. One of the casing members, 2,.has a central post 4 to serve as an anchorage'for the coil spring 5.

Inthe form shown in Figs. 1 and 2 the coil spring 5 has its inner end anchored to the post a and is coiled'around the post, the outer end 5a of the coilspring being riveted or otherwise secured to a floating drum or hoop 6. The end 7a of the tape 7 is secured to the drum 6. Tape 7 and coil spring 5 are wound in the same sense, so that when the tape is pulled out the coil spring is tensioned.

In Figs. 9 and 10 I have shown a modified form wherein the drum 6 is omitted. Here one end of the coil spring 5 is secured as before to post 4 and its other end 5a is secured directly to I the end 7a. of the tape 7.

' In Fig. 6 I have shown the thin resilient, brake bandfia which is adapted to envelop and The drum arrangement above described shown and claimed in my co-pending application, Serial No. 594,114, filed February 19, 193 patented June 26, 1934, No. 1,964,280.

In the structure shown in Figs. 1 and 2 the drum 6 is adapted for shifting movements in its own plane independently of the casing, as is fully described in the patent referred to.

I will-now point out the features whereby a new and improved mode of operation of tape, made possible by my improved struc measuresis Dress lightly against -the periphery of the coil of tape 7. One end 8 of the brake element is secured to the casing members 1, 2, adjacent the tape opening 3, and the body 8a of the brake band is so shaped that it closely envelops the outermost convolution of the tape .Tand ex pands or shrinks in size accordingto the size of the tape coil. It distributes friction'al' presf sure against the face of the outer convolution of the tape throughout the greater of the;

circumference of the coil. When the tape 7 is pushed in,-assisted somewhat by the balancing spring 5, the tape coil rotates clockwise, as seen in Figs. 1, 4 and 9. The brake element 8a wraps around the coil of tape and acts in the manner of a. band brake. When the tape 7 is pulled out the coil of tape rotates counter-clockwise and the brake band 8a follows up the coil, automatically reducing its frictional resistance. The coil then slides somewhat more freely beneath the band as the coil unwinds.

Thus the brake element acts as a dampener, or corrective for any residual unbalance between the resistance of the tape 7 and the winding effort of the coil spring 5, so that throughout the tape. This resistance does not interfere with winding or unwinding, but on the contrary controls and balances those manipulations so as to insure even and smooth operation.

Various means may be employed for securing the end of the resilient brake band element 8a to the tape case, but a preferred structure for this purpose is shown in Figs. 7 and 8, where the upper casing member 1 is formed with an outwardly and downwardly projecting lug 1a struck from the flange of the casing and the lower casing member 2 is provided with a complementary lug 2a which is struck inwardly'from the edge of the casing. One end 8 of the brake element is formed with a notch 81) to slip over and engage the lug 2a. When the case is assembled the brake element 8a is secured to it by slipping the notch 8b down over the lug 2a of the lower casing member 2 and then putting the upper casing member 1 in place, so that the lug 1a will form a closure overlying the lug 2a, as shown in Figs. 5 and 7.

'Inaddition to the improved operation of tape measures made possible by the invention, it makes it practicable to house a given tape in a smaller case than before, for the following reasons:

A materially smaller case requires a smaller coil of tape with more turns when wound up. This means more revolutions of the cofl spring 5 and greater tension of the spring when the tape is fully extended from the case. This increased tension will undesirably draw the last part of the released tape into the case, in the absence of a braking device. The addition of the new brake element completely eliminates the dimculty described.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

"of said coil, said band adapted to auto- I "uniform action to namesamatically conform to and closely fit the periphery of said coil as the coil increases or decreases in size during winding and unwinding of the tape, and also adapted to exert appropriate resistance to the action of the winding spring to produce a frictional braking effect to impart smooth and the said coil-spring and said tape.

i 2. Means for fixing a frictional brake band to the casing of a tape measure, comprising two casing members, a notch formed in the band near one end thereof and 9. lug in the edge of one of the casing members formed to engage said notch; and a second lug formed in the edge of the coinplementary casingmember and overlying the first 111g.,for the purposes set forth.

3. In a tape measure including a casing, means for keeping a tape of the non-planar push-pull w 3 me in neutral condition with respect to forces that tend to produce undesirable creeping move meuta thereof, said means comprising a winding spring located within the convolutions of the tape and operatirely connected thereto, the winding strength of said spring being insunicient to wind the tape unaided, but suflicient to-efl'ect the winding of the inner convoiutions 'of the tape when its outer end is manually pushed in the direction of its length toward said spring and a brake element mounted in the casing and engaging the tape coil, the strength of said brake being'only suflipient to appropriately reduce by braking action the residual unbalance of the coil spring and the tape and to' produce auniform;

feel of the tape throughout its entire range of operation.

EUGENE J. wrmnqm.

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