US 2683937 A
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Description (OCR text may contain errors)
July 20, 1954 'R. E. cRlswELl.
PLUMBBOB DJUSTER Filed July l5, 1952 JNVENTOR.
rroQA/EK Patented July 20, 1954 PLUMB BOB ADJUSTER Ralph Elton Criswell, El Monte, Calif., assignor of fifty per cent to Lewisl B. Kingsley, Santa Barbara, Calif.
Application July 15,
Thepresent invention relates to line length adjusters in general and particularly to an adjuster for Varying the effective length of a supporting cord or string for a plumb bob.
Plumb bobs are widely used in construction work by the builder, carpenter and by the surveyor. Conventionally the plumb bob is suspended by a string or cord from a support or plumb line above a selectedpoint and at a height such that its lower pointed end is positioned immediately above that point. Upon being moved from one position to another, or upon changes in the height of the support, the length oir Jthe supporting cordV must be changed in order to retain the plumb bob in its optimum relationship the undesirable characteristicV of slipping and again of becoming so tight that a, readjustment can be made only with difficulty. The delay following such developments is undesirable.
The adjuster constructed inv accordance with the present invention is adapted to eliminate the undesirable factors characterizing the conventional slip knot adjustment. It comprises basically a reel upon which the cord or string can be wound and about which the unused length of string remains wound when the plumb bob is in use. Additionally it incorporates friction seating means through which the cord extends to the end that with the plumb bob supported above its point the eiiective length of the supporting cord can be readily varied simply by lifting the plumb .1
boband sliding the adjuster along the runz o-fcord which passes through it. Upon the plum-b bob again being released its weight causes the eii'ective cord length to be fixed until a readjustment is made.
With an appreciation of the problemswhich characterize the use of plumb bobs it is an object of the present invention to provide a new and improved adjuster for readily effecting changes in the length of cord or string supporting a plumb bob. It is another object of the invention to provide a new and improved cord reel and adjuster for plumb bobs which is economically manufactured and which can serve as a storage unit for the cord when not in use. These and other more specic objects will appear upon reading the following specications and claims and upon considering in connection therewith the attached drawing to which they relate.
Referring now to the drawing in which a pre- 1952,v Serial No. 298,960Y
ferred embodimentof the invention isillustrated:
Figure` 1 comprisesa View of a plumb bob supported by its; own cord from a Support; and at, a height determined; by the position of theadjuster comprising the present invention the entire unit being Shown inl ad second adjusted position in phantom lines;V
Figure` 2i is an enlarged' Side elevational View of the adjuster per se;
Figure 3 is a View of the adjuster taken at right angles to the4 view oi Figure 2,;
Figure 4 is a transverseA section upon the line fl-A of Figure 2; and,
Figure 5 is a secondv exempliiication embodying a modified form4 of cord slot. v
Referring again tothe drawing, a plumb bob of conventional shape and Size is illustratedv and is indicated generally bythe reference character It. It comprises a conical body pointed at its lower end and formed. at its upper enlarged end with a longitudinally extending neck` portion l2 removably seating an interiorly threaded cap. I3 in which one end of a cord Ill extends, bei-ngy iixed therein as by having its end knotted. The. cord I4, is adapted. toi support plumb. bob. I I by extending upwardly andr over a* suitable support which in the drawingY in Figure 1 is shown as a conventional hook. lli. It. isl to be understood, however, that the support. isv not a part of the inventipn and may comprisel a., wire or a; survey-s ing nstrument.l The Opposite end, of the cord I4 is attached to. the, adjusten indicated general- 1v by. the reference character il'. which, as illustrated in Figures 3 and 4,: is I-I sectioned both transversely and longitudinally, beine termed 0f parallel elongated sides I8 and i9 connected by a central elongated hub 2I oi lesser length.` As is seen clearly in Figures `2 and 4, the thickness and length of hub 2l: is less than the length and width oil sidel walls I8 and L9 so that a continuous channel is formed around the hub and between side plates I8 and I9. The adjuster body forms a suitable reel upon which the cord I d can be wound. To secure the end of the cord hub 2| is formed with a transverse bore 22 through which the cord I4 is extended to be knotted at its end. That portion of the cord which is not required for the support of plumb bob I I is simply Wound on the adjuster or reel between the plates I8 and I 9 and about the hub 2I in the manner clearly illustrated in Figures 2, 3 and 4.
Side plate I8 of adjuster Il is formed at its opposite rounded ends with open ended slots 28 which lead into friction seats 2l comprising recesses having offset ends extended towards the 3 adjacent end of the adjuster body. The slots 26 provide entrances or ways through which the cord can be slid into the seats 21.
For purposes of explanation the upwardly extending run of cord I4 from the adjuster will be identified by the reference character I4a and the return downward run by the reference character leb. The cord from the hub 2l is taken out through the lower seat 21, along the outside of wall I8, back through the upper seat 21 to the interior of the adjuster, 'then up and over the support I6, then downwardly as the run Mb through the seat 21 from the interior of the adjuster to the exterior, down along the exterior of wall I8, in through the lower seat 21 to the interior of the adjuster, and finally directly downwardly to the plumb bob Il. The portion of run Mb between the upper and lower seats 21 is seen to be laterally displaced from its portions above and below the adjuster by the thickness of wall I8. Where it extends through the seats 21 it contacts the adjacent edges of the seats upon entering and leaving at points 28 and 29. The weight of the plumb bob II tends to straighten the run I4b causing the seats 21 effectively to exert a frictional resistance at points 28 and 29, as shown most clearly in Figure 3. That resistance is sufficient to bind the cord in place so that no slippage occurs and the length of the cord is xed. Because of this friction clamping action the recesses 21 can properly be referred to as friction seats, for they effectively perform the function of frictionally clamping the cord run extended therethrough.
The exact shape and configuration of the seats 21 and of the slots 26 leading therein are not of the essence and, as shown in Figure 5 the slot, here indicated by the reference character 26a, may enter at a different angle into the seat 21a. The relationship in all forms is characterized in that the cord once positioned within the seats 21 and drawn taut by the weight of the plumb bob is fractionally held against sliding action until the weight of the plumb bob is withdrawn to remove tautness whereupon the adjuster is freely slidable along the run Mb.
To adjust the length of the supporting cord I4 to effect a variation in the height of the plumb bob Il, let us say from the full line posi- Y tion of Figure 1 to the dotted line position, it is only necessary to lift the plumb bob II whereupon the binding action present in the seats 21 is removed and the adjuster I1 can be slid upwardly along the cord from the full line posi- Q along the run I4b in the opposite direction.
While the particular apparatus herein shown and described in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.
l. In a plumb bob unit a plumb bob, a cord connected at one end to said plumb bob, an adjuster to which the opposite end of said cord is connected, said adjuster comprising a reel having spaced parallel side walls and a central hub about which said cord is wound, one of said side walls including spaced friction seats through which said cord extends, each of said seats being formed with a slot through which said cord can be fed, said seats being arranged so that a vertical run of said cord can pass from the interior of said reel to its exterior and then, after extending vertically down along the exterior of said reel, can pass from the exterior into the interior of said reel, the extensions of the cord above and below said reel being displaced from the extension along the exterior of said reel by the thickness of said one side wall, said adjuster being slidable along said cord to vary the length of said cord upon the weight of said plumb bob tending to move said extensions into alignment being withdrawn.
2. An adjuster for plumb bob cords, which comprises a reel formed with a pair of corresponding spaced parallel side walls and a connecting central hub of lesser dimensions, said side walls forming a channel adapted to receive a plumb bob cord wound around said hub, one of said side walls having substantial thickness and being formed at opposite sides of said hub with aligned cord seats to direct a cord run from the exterior to the interior of said reel and vice versa, each of said seats being formed with a connecting open-ended slot through which a cord run can be advanced into said seat, each of said seats being also formed with relatively adjacent outer and inner edges which are offset the thickness of said one side wall to provide a binding action with said cord.
References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 76,146 Barnum Mar. 31, 1868 2,421,256 Galford May 27, 1947 2,451,933 England Oct. 19, 1948 FOREIGN PATENTS Number Country Date 8,099 Great Britain June 1, 1915