US2285471A - Cable tension indicator - Google Patents

Description

June 9, 1942. A .1. STURGESS 2,285,471

CABLE TENSION INDICATOR Filed March 29, 1940 IN VEN TOR. c/OHN J'Tue 658 3 TTORNEY Patented June 9, 1942 CABLE TENSION INDICATOR John Sturgess, Glendale, Calii'., assignor to Sturgess, Inc., Los Angeles, Caiil'., a corporation of California Application March 29, 1940-, Serial No. 326,734

16 Claims.

This invention relates to instruments for indicating'the degree of tension existing in a tensioned cable by measuring the force required to deflect the cable at a point between two supported points, particularly such cables as the various control cables of air craft in which it is very important to maintain definite operating tension.

The principal object of the invention is to provide an improved small portable instrument to facilitate the checking of the tension in such cables.

A feature of the invention is a simple spring and leverage system which greatly amplifies the movement of the spring caused by the pressure of the deflected cable.

Another feature is the combination with such a spring of means for releasing the same to permit free application of the instrument to a taut cable without first bending or deflecting the same.

Another feature is the provision of means for locking the indicator needle in pressure indicated position before removal of the instrument from the cable, so that the instrument may be applied to a cable in a dark or cramped position and the reading made after the instrum'ents removal to a light place.

A further object of the invention is such an instrument which may be applied to a cable and operated with but one hand, and in but a few moments time.

Other objects are the provision of means to overcome the tendency of the cables to wear the abutments or fulcrum points of the instrument, and to overcome errors of reading due to hill and valley effect of the cable surface.

Still other objects and advantages of the invention will appear in the following description and accompanying drawing.

In the drawing- Fig. 1 is a reduced size perspective view of my improved cable tension indicator in position on a cable for testing its tension.

Fig. 2 is a front view of the instrument with indicator needle and dial omitted to show the mechanism.

tween which is a pressure applying block or riser 5 mounted on a leaf spring 6 and forced outward against the cable 1 at a point between the ful- Fig. 3 is a vertical cross section of Fig. 2 as seen from the line 3-3 thereof.

Fig. 4 is a detached fragmentary vertical seccrum members by means of a lever or trigger 8 to deflect the tensioned cable slightly. Another lever 9 is provided for locking the needle in reading position when the pressure applying member or block is lowered by releasing the trigger.

In detail the body I forms a flat box of substantially half round form when viewed from the front and its rear wall has upwardly-extending corner portions l' on which the cable engaging members or fulcrum blocks 4 are each pivotally mounted at III so as to swing on their pivots in the plane of the tensioned cable as it is deflected by the pressure applying or riser block 5. The lower edges 4 of the fulcrum blocks are formed on a radius R from the pivot center, and their corners rounded oil, and in effect they constitute roller equal in diameter to twice R and the slightly curved working edge is of a length to straddle the ridges formed by the cable strands so as to form a contact with its outer diameter and thus avoid errors from sinking into a depression or valley between the strands.

As the slight movement of the fulcrum blocks is only inward or toward one another during the deflection of the cable being tested, stop means is provided to prevent outward swinging of the blocks and spring means is provided to urge the blocks to the end of the stops or the central position shown in Fig. 2. The means shown consists of a pin H projecting rearwardly from each block and into a slot l2 formed in lug l and within which slot is a small coiled compression spring l3 bearing against the side of the pin to resiliently force it to the end of the slot.

This pin, slot and spring arrangement is shown in Figs. 2 and 3, though in the latter the pin ll would strictly not show as it is to the right of the section line 3-3 of Fig. 2, but may be considered as indicating the relation of the pin to the slot.

Leaf spring 6 upon which the riser block 5 is mounted is pivotally supported at one end on a pivot l4 directly under one of the fulcrum blocks. The pivotal connection including a bracket J5 rigidly secured as by riveting IE or welding to the end only of the spring, while an arm 2| extending along one side of the spring and freely supported on pivot M carries a pin I! which projects forwardly over spring 6 to freely enter a hole drilled through the riser block, so that the block may freely be slipped oif of the pin I (forwardly in Fig. 2) and quickly replaced with a higher or lower one to suit the particular cable being tested-each block being suitably marked to identify it, such as the figure stamped on the riser block of Fig. 2. This change of blocks is made to simplify the dial readings for different cables, though it may be dispensed with by suitable interpolation of the readings from a chart or by having several series of figures on the dial similar to any computing scale.

Parallel to leaf spring 6 and riveted or welded to it at the left hand end as at I8 (as seen in Fig. 2) is a lever strip II! which is bent downward at'its free end and then horizontally as at I8 just under bracket I and where it overlies the upper end of a screw 28 which forms an adjustable operating contact between the end of lever I 9 and the dial needleoperating mechanism to be later described. Arm 2I has an ear 2 I to which a tension sprin 22 is hooked and the other end of which spring is anchored at 23 to the frame I so as to tend to pull the riser block and its leaf spring and lever down to released position indicated by the dotted position when trigger 8 is released.

Trigger 8 is a cam lever pivoted at 24 to the a frame of the instrument and preferably carries a roller 25 at its upper end which operates against the under side of lever I8 from released dotted position to upper full line position directly under the left end fulcrum block 4 as shown, as the lower end of the trigger 8 is moved on its pivot 24 toward the frame or casing I of the instrument. Cam lever 8 or trigger, is stabilized in both applied and released position by means of a sliding spring link of well known construction. This device is what may be termed an over center spring as used on all kinds of pivoted devices which in operation snap to either side of a central unstable position, such as in electric snap switches, and is here shown as operating with a compression spring 28 coiled around a rod or stifi wire 51, the upper end of which rod is looped around a pivot 26 projecting from the side of the trigger 8,- and the lower end of which rod passes through a very free opening ,58 in a stud 21 projecting from the frame I, while the spring reacts at one end against a collar 59 freely slidable on rod 51, and at the opposite end against a collar 60 secured at the outer end of a tube 58 which encloses the upper half of the rod and bears at its upper end against the loop 5| of the rod 51. This arrangement, through the swinging of pivot 28 to points above and below fixed pivot 24 changes the angle of the spring link to direct its force successively to either side of pivot 24, and thus holds the trigger in either extreme position.

When the riser i fully lowered by releasing the trigger, the instrument is free for placing over a tensioned cable to bring the fulcrum blocks 4 upon it without forcing or bending the cable, and upon pushing the trigger to position shown in Fig. 2 the leaf spring and its riser or pressure applying member will impinge the cable to deflect it slightly and at the same time deflect the leaf spring downwardly as indicated in Fig. 5 and cause multiplying lever I8 to project substantially tangentially from the convexly arched lower surface of the leaf spring and thereby produce a relatively great downward movement to screw to operate the needle turning mechanism, and this simple multiplying lever and spring arrangement constitutes one of the most important features of theinven-tion as it is reliable, rugged and has no loose parts.

, It should be noted that while lever I8 functions a a rigid arm in operating the dial needle turning mechanism, it nevertheless is actually made of a strip of spring metal and can therefore yield if overloaded 'or the needle mechanism was clamped or out of order for any reason and thus avoid injury to the instrument.

The needle operating mechanism is of the well known common type as used on pressure gage generally and this specification will not be unnecessarily lengthened by describing it in detail, except as to special features. Its elements include a lower frame plate 88, upper plate 8|, needle and pinion shaft 32, pivoted gear sector 88 for operating the pinion 84, and a hair spring 55 for normally returning the needle to zero. At the end of the arm of the gear sector is a link 36 pivoted atone end thereto at 31, and at the opposite end at 38 to a lever 39 pivoted at one end at 39 to the frame and its free end provided with a threaded split boss 40 embracing adjusting screw 20. 7

Gear sector 33 is flat and passing across it is a flat stiff spring blade 4I or brake secured at one end as at H to the frame; and biased in direction of the gear sector so as to tend to press tightly upon the sector and frictionally hold it against movement unless the spring brake is lifted from contact with the sector. To so lift the spring brake, a pin 42 (see Fig. 4) is slidably mounted in a hole formed in a boss 48 on the wall of the frame I in a position directly under the free end H of the spring so that when the pin is pushed toward the flat spring it will be lifted from the gear sector and free it for operation, and when the pin is released the spring blade will clamp the sector immovable with the dial needle at the point to which it was turned by the cable tension test made with the instrument. To slide the pin 38 I provide a small cam surface 44 on a disk 45 pivoted at 48 to the outer back wall of the instrument and provided with an operating lever or handle 8 extending just above the upper edge of the frame adjacent the cable being tested. Thus by swinging this lever 9 one way it will release. the spring brake so that the instrument is ready to apply to the cable, and after pressing the trigger 8 to position against the body or frame I, the lever is moved in the opposite direction, the needle is clamped in position for reading later on after removal of the instrument from the cable, and thereby facilitating'the taking of readings in dark, or places awkward to reach. It should be noted that all operations in using the instrument may be made by one hand of a user.

The cam disk 45 is frictionally held in either position of adjustment by friction induced by a coiled compression spring 52 surrounding the inwardly projecting end of the pivot pin 46, and which spring reacts against the inner wall of theframe I and a washer 58 on the end of the pin held in place as by a cotter 54, the pin being free to slide in its bore in the rear wall and provided with ahead 45 for pulling the cam disk in frictional contact with the rear wall of the frame.

The mechanism is covered by the graduated dial 3 in turn covered by-a glass sheet 48 held in place by an outer frame rim 48 suitably securedto the body frame I, and the trigger projects from a slot 58 in; the edge of the body which is closed by the trigger when same is pressed against the body as shown in Fig. 2, and the leaf spring 8 also closes the opening in the upper edge of the body so that the mechanism is protected from injury.

In regard to the dial graduations, actually these indicate the amount of deflection of the ures may be merely arbitrary as from to 100 and be read in connection with a chart giving the tension values for cables of various sizes, all such graduation of scale reading dials being well understood in the art of measuring and weighing instruments, and forming no feature of the present invention.

Each instrument with a given weight of deflecting spring 6 may be used on several size cables, thus A and 4" within the capacity of its spring, and with change in height of riser block to obtain the proper deflection of the cable being tested. For larger cables, stronger springs, and preferably larger instruments are used, and vice versa.

From the above description of the construction and operation of the various parts of the instrument no rsum of its operation would seem necessary and in respect to the various minor details incorporated in the instrument it is manifest that variation in arrangement and substitution of equivalents may be made by one skilled in the art within the spirit of the invention and any such are intended to come within the scope of my appended claims.

I claim:

1. In a cable tension indicator provided with a pair of spaced supports for the cable to be tested and an intermediate oppositely disposed pressure applying member for deflecting the cable between said supports, a leaf spring upon which said member is supported at an intermediate point, means pivotally mounting said spring at one end for swinging said member into the path of the cable for deflecting the cable, manually operated means at the opposite end of said spring for forcing it toward the cable and locking the spring in cable deflecting position, a lever secured to said spring for amplifying its movement, and means operated by said lever indicating the amount of deflection of said spring.

2. In a cable tension indicator of the character described and having a frame, a spring-lever combination for taking the pressure of deflection of the cable and transmitting a multiplied movement to an indicator dial mechanism, comprising a leaf spring adapted to be supported at opposite ends and bowed at an intermediate point by pressure of the deflected cable, and a motion amplifying lever secured at one end to one end of said leaf spring and extending back along the same so as to project substantially tangentially from said spring when bowed, means supporting said leaf spring at one end on said frame, a hand operated lever pivoted to said frame arranged for swinging the opposite end of said spring to operative position, and for releasing the same, means for localizing said pressure upon the leaf spring at said intermediate point to deflect said spring when in such operativeposition, and an indicator needle operated by movement of the free end of said motion amplifying lever.

3. In a cable tension indicator of the character described and having a frame, a spring-lever combination for taking the pressure of deflection of the cable and transmitting a multiplied movement to an' indicator dial mechanism, comprising a leaf spring adapted to be supported at opposite ends and bowed at an intermediate point by pressure of the deflected cable, and a motion amplifying lever secured at'one end to one end of said leaf spring and extending back along the same so as to project substantially tangentially from said spring when bowed, means supporting said leaf spring at one end on said frame, a hand operated lever pivoted to said frame arranged for swinging the opposite end of said spring to operative position, and for releasing the same, means for localizing said pressure upon the leaf spring at said intermediate point to deflect said spring when in such operative position, an indicator needle operated by movement of the free end of said motion amplifying lever, and a spring normally urging said leaf spring toward released position.

4. In a cable tension indicator of the character described and having a frame, a spring-lever combination for taking the pressure of deflection of the cable and transmitting a multiplied movement to an indicator dial mechanism, comprising a leaf spring adapted to be support ed at opposite ends and bowed at an intermediate point by pressure of the deflected cable,

- and a motion amplifying lever secured at one end to one end of said leaf spring and extending back along the same so as to project substantially tangentially from said spring when bowed, means supporting said leaf spring at one end on said frame, a hand operated lever pivoted to said frame arranged for swinging the opposite end of said spring to operative position, and releasing the same, means for localizing said pressure upon the leaf spring at said intermediate point to deflect said spring when in such operative position, anindicator needle operated by movement of the free end of said motion amplifying lever, and a spring arranged to urge said pivoted lever to final locked position and also to final released position.

5. In a cable tension indicator provided with a pair of spaced supports for the cable to be tested and an intermediate oppositely disposed pressure applying member for deflecting the cable between said supports,- a leaf spring means supporting said member at an intermediate point on said spring, means pivotally mounting said spring at one end for swinging said member into the path of the cable for deflecting the cable, manually operated means at the opposite end of said spring for forcing it toward the cable and looking the spring in cable deflecting position,

a lever secured at one end to said opposite end of said spring and extending along the same toward its pivoted end and means operated by the free end of said lever indicating the amount of deflection of said spring.

6. In a cable tension indicator provided with a pair of spaced supports for the cable to be tested and an intermediate oppositely disposed pressure applying member for deflecting the cable between said supports, a leaf spring means supporting said member at an intermediate point on said spring, means pivotally mountingsaid spring at one end for swinging said member into the path of the cable for deflecting the cable, manually operated means at the opposite end of said spring for forcing it toward the cable and locking the spring in cable deflecting position, and means indicating the amount of demeans retaining said member in position to bear on said spring, so that no frictional movement occurs between said member and said spring when said spring is deflected or bowed.

7. In a cable tension indicator provided with I a reading dial needle operating mechanismhavto be tested and forcing said member in contact with said cable to deflect said spring, and a motion amplifying lever secured at one end to the free end of said spring and with the free end of said lever extending toward the pivoted end of said spring and arranged in contact with said operating lever of said reading dial needle operating mechanism.

8. In a cable tension indicator provided with a pair of spaced supports for the cable to be tested and an intermediate oppositely disposed pressure applying member for deflecting the cable between said supports, a leaf spring, means supporting said member at an intermediate point on said spring, means'pivotally mounting said spring at 'one end for swingingsaid member into the path of the cable for deflecting the cable, manually operated-means at the opposite end of said spring for forcing it toward the cable and locking the spring in cable deflecting position, and a lever secured at one end to said opposite end of said spring and extending along the same toward its pivoted end to a point overlying the axis of the pivot, and means operated by the free end of said lever by contact therewith at a point substantially in line with said axis; of the pivot indicating the amount of deflection of said spring.

9. In a cable tension indicator provided with a reading dial needle operating mechanism having an operating lever, pressure operated means for operating said mechanism comprising a leaf spring pivotally supported at one end and carrying a cable deflecting member at an intermediate point, manually operated means for swinging the fre end of said spring toward the cable to be tested and forcing said member in contact with said cable to deflect said spring, and a motion amplifying lever secured at one end to the free end of said spring and with the free end of said lever extending toward the pivoted end of said spring and arranged normally in contact with said operating lever of said reading dial needle operating mechanism, and means for locking the dial needle in pressure reading position, while permitting free return of said leaf spring to released position when released.

10. In a cable tension indicator provided with a reading dial needle operating mechanism having an operating lever, pressure operated means for operating said mechanism comprising a leaf spring pivotally supported at one end and car-' rying a cable deflecting member at an intermediate point, manually operated means for swinging the free end of said spring toward the cable to be tested and forcing said member in contact with said cable to deflect said spring, and a motion amplifying lever secured at one end to the free end of said spring and with the free end of said amplifying lever extending toward the pivoted end of said spring and arranged in contact with said operating lever of said dial needle operating mechanism, and means for locking the dial needle in pressure reading position while permitting free return of said leaf spring and its amplifying lever to released position.

when released, and spring means for returning said leaf spring and its amplifying lever to re-.

leased position.

11. In a structure as set out in claim '7, means for adjusting the spacing of the amplifying lever and said operating lever for setting said needle to zero.

applying members.

l4. In-a cable tension indicator, a frame, a

pair of spaced supports on said frame for the cable to be tested and an intermediate oppositely disposed pressure applying member for deflecting the cable, said spaced supports being pivotally supported on said frame in a manner to move with the cable surface when the cable is deflected, and means for returning the supports to initial position when the cable is released, said supports being blocks arranged to contact the cable at one edge of the block and the pivotal support of the block being adjacent the remote edge of the block.

15. In a cable tension indicator, a frame, a pair of spaced supports on said frame for the cable to be tested and an intermediate oppositely disposed pressure applying member for deflecting the cable, said spaced supports being pivotally supported on said frame in a manner to move with the cable surface when the cable is deflected, and means for returning the supports to initial position when the cable is released, said supports being segments of a roller of a diameter to provide a cable contacting surface of an arc to straddle the valleys between the strands of cables being tested.

16. In a cable tension indicator, a frame, a pair of spaced supports on said frame for the cable to be tested and an intermediate oppositely disposed pressure applying member for deflecting the cable, said spaced supports being pivotally supported on said frame in a manner to move against the side of which one end of the spring reacts. v

JOHN STURGESS.

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