US3049194A - Apparatus for maintaining constant tension in guys - Google Patents

Description

Aug. 14, 1962 A. G. BRENDEL APPARATUS FOR MAINTAINING CONSTANT TENSION IN GUYS Filed Feb. 24, 1960 m MEDOI INVENTOR.

ARMIN G. BRENDEL AGENT United States Patent Ofitice 3,049,194 Patented Aug. 14, 1962 3,049,194 APPARATUS FOR MAINTAINING CONSTANT TENSION IN GUYS Armin G. Brendel, 42 Bayard Lane, Sutfern, N.Y. Filed Feb. 24, 1960, Ser. No. 10,796 2 Claims. (Cl. 189-315) This invention is directed to a tension compensating device which is a new and improved guy for bracing all types of structure, particularly tall structures, such as antenna towers, power line towers, bridges and similar constructions. The device is also useful in supporting lines in constant tension when suspended between towers, particularly power lines. The guy wires of this invention comprise in conjunction therewith a device for maintaining wires or cables under constant tension at all times, even under conditions of extreme changes in temperature in the surrounding atmosphere. The device which is the essential feature of this invention comprises a liquid filled cylinder, a piston therein, with the cylinder and piston being linked, as described below, with the guy wire and anchor. Generally, the compensating device is inserted between the guy wire and the anchor base, but if desirable it can have a guy wire connection at either end of the compensator. In this assembly the liquid will compensate and equalize the tension or stress which has been induced into the guy wire by changes in atmospheric temperatures.

As is generally the practice, the guy is fastened between the structure to be braced and an embedded anchor bolt by means of a tie rod which is then tightened to place the guy wire under tension. Usually, no more care is taken in tightening the tie rod than to see that practically all of the slack is taken out of the wire or cable. On particularly critical installations, the tension in the guy wire is established therein according to a predetermined optimum amount. Then the tension is thereafter periodically checked to determine Whether the original tension has changed by comparing a standard measure with the distance between marks on the guy wire or cable as is disclosed in U.S. Patent No. 2,071,694. Generally, it is the preferred practice to attach to the guy a conventional dynamometer which has been designed for this service. Since there is usually some change in tension between tests, adjustments can be made while the dynamometer is in place to increase or decrease the tension as is required. The dynamometer in question is commonly a heavy, cumbersome device that requires two or three men to put it in place on the guy wire. The amount of tension in the guy or cable is determined by the change in the curvature or catenary of the guy wire induced by attaching the heavy dynamometer thereto.

The difficulties encountered in maintaining constant optimum tension in the guy wires under varying temperature conditions will be readily apparent. If after adjustment the atmospheric temperature decreases markedly, the guy wire or cable will tend to shorten in accordance with the coeflicient of expansion of the particular metal used in the guy wire. This places the guy wire under increased tension to the extent that the wire may be stretched beyond its elastic limit. As the temperature increases, the guy wire expands, thereby leaving the structure loosely braced and subject to dangerous vibrations due to variations in wind pressures. On the other hand, if the temperature rises after adjustment, the guy wires lengthen to the extent that the supported structure will also be susceptible to vibrational forces.

It is the object of this invention to overcome the defects in the guy wires commonly used by insuring that the installed guy wire or cable will be under constant tension at all times. It is a further object of this invention that all changes in the length of the guy wire due to changes in ambient temperatures will be compensated for by the linkage inserted into the guy wire. Other objects of this invention will become readily apparent by an inspection of FIGURES 1-3 inclusive, when taken in conjunction with the following description.

FIGURE 1 is a partial cross-sectional view of the compensating device which is the essential and novel feature of this invention when combined with guy wires.

FIGURE 2 is a view of the compensating device taken at right angles to FIGURE 1.

FIGURE 3 is a view similar to that of FIGURE 2 except that one portion of the cylinder is shown to be enlarged, thus increasing the liquid reservoir within the cylinder. This figure also shows the use of a flexible liner within the cylinder reservoir to prevent leakage of fluid from the cylinder.

Referring now to FIGURE 1 there is disclosed a crosssectional View of cylinder 1 having a cylinder yoke which comprises a pair of arms 2, each of said arms containing a hole at the free end of the arm. The hole is to be aligned with an anchoring device 12 as shown in FIG- URE 2 and fastened thereto by means of a bolt or pin not shown. Fitted within the cylinder is a piston 3 having attached thereto a plunger arm containing on the end opposite the piston an aligned hole for attachment to a stirrup bolt 5 having an aligned stirrup bolt bearing 6, both plunger arm and stirrup bolt being attached together by means of a pin 7. Prior to assembling the piston and the cylinder a predetermined amount of liquid is introduced into the space 8 within the cylinder which will limit the distance which the piston may penetrate into the cylinder. The piston and cylinder may be machined to a close tolerance so that when pressure is placed on the piston which has been inserted in a partially filled cylinder, the liquid in the reservoir Within the cylinder will not be forced out through the space between the interior wall of the cylinder 1 and the exterior surface of the piston 2. Alternatively, the piston may be provided with O-rings made of substances such as Teflon or the piston may be provided with conventional steel sealing rings. Another means for prevention of leakage of fluid from the cylinder is to enclose the fluid within a flexible lining 16 as shown in FIG. 3. The end of the stirrup bolt 5 opposite the bearing 6 is threaded to engage the nuts 10 which hold the bridge socket 11 in place. This bridge socket is connected to the wire or cable 9 in a convention-a1 manner which is not illustrated. Throughout the description reference is made to guy wires and cables; however, it is contemplated that within the broad scope of this invention the word wire will also include metal rods which are oftentimes used in short installations. In assembling the guy wire and automatic tension compensator, the cylinder yoke is attached to the anchor base link 12 by a bolt or pin. Then the bridge socket with attached cable 9 is placed over the threaded ends of the stirrup bolts and the bridge socket is forced down by means of the nuts 10 until a suitable tension is obtained in the guy wire. The amount of tension necessary can be ascertained by means of a dynamometer or as preferentially shown in FIG. 2 a pressure gauge 13 may be attached to the reservoir portion of cylinder 1.

FIGURE 2 illustrates the assembly as in FIG. 1 which has been turned thus showing the cylinder 1, the paired arms 2 of the cylinder yoke, the stirrup bolt 5 with attached bridge socket 1i and cable 9. This view also shows a section of the anchor bolt linkage 12 which connects the automatic tension compensator to a base. There is additionally shown in FIG. 2 a pressure gauge 13 which is cornmunicatively connected to the reservoir section of the cylinder 11 through the valve 14 which is depicted schematically. During the time tension is being placed on the guy wire by screwing down nuts valve 14 may remain open in order that it can be determined when the appropriate amount of tension has been imparted to the guy wire. Thereafter the valve can remain open or be closed, as is desired. Valve 14 also serves to maintain pressure within the cylinder when it is required that the gauge 13 be removed for repair or replacement. There can also be a separate line with valve 15 attached to the line leading from the gauge to cylinder 1. This optional line can be used as a means of draining off excess fluid in the cylinder if for some reason excessive pressure has built up within the cylinder during the time the nuts 11 were being screwed down. Since this condition is rarely encountered, the chief use for the side valve 15 would be as a connection between the cylinder 1 and a master high pressure cylinder or a pumping system with a pressure reducing valve and a relief valve operating automatically to maintain a constant pressure. This latter apparatus would be particularly useful for extremely critical conditions which would require a number of guy Wires with cylinders similar to cylinder 1 to be maintained under equal and constant tension from one master cylinder.

FIGURE 3 illustrates an automatic tension compensator similar to the one shown in FIG. 2 except that the reservoir portion of the cylinder 1 is enlarged for greater liquid storage capacity. This increased storage capacity will cause greater piston movement per unit length of cylinder than when the inside bore of the cylinder is uniform throughout its whole length. Also shown within reservoir portion of cylinder 1 is a flexible lining material or balloon 16 made of rubber, neoprene or other elastic or pliable material. The required amount of liquid is sealed within the rubber lining and the thus formed bag or balloon is inserted within cylinder 1. In operation the elastic lining will change size and shape in response to the expansion or contraction of the fluid contained therein. This lining 16 is especially desirable for holding volatile liquids or where no loss of fluid can be tolerated.

The fluid for the cylinder can be any fluid which does not have a freezing point within the temperature ranges encountered in the coldest weather. The fluid must also resist oxidation under the most extreme conditions and be able to perform for long periods of time without gumming, carbonizing, or thickening. The preferred fluids are silicone fluids which meet all these requirements. A highly useful silicone fluid of commerce, for example, is one which has a viscosity of 5 centistokes at C., a flash point of about 275 F., a pour point of about 85 F. and a coeflicient of expansion of 0.00105 cc./cc./ C. While this particular silicone fluid has performed satisfactorily, other silicone fluids having varying viscosities, flash points and pour points, as well as different coefficients of expansion, can be used. One other important factor in the use of fluids for the automatic tension compensator is that the liquid to be employed must have an extremely low volatility as well as low compressibility. The silicone oils having a viscosity in the range of 1 up to about 100 centistckes at 25 C. have these properties and are thus the preferred silicone fluids for use in the device of this invention.

For purposes of simple illustration it can be assumed that the fluid in the cylinder has a coeflicient of expansion that is 100 times that of steel used in the guy wire. This means that a guy wire 100 feet long will expand the same amount as a column of fluid 1 foot long under the same temperature conditions. In other words, a cable 100 feet long which has elongated 1 inch because of temperature change will require a liquid cylinder 12 inches long to compensatae for the 1 inch expansion. When the cylinder 1 and piston 3 are assembled with the 12 inch column of silicone fluid and placed under tension between the guy Wire or cable and the anchor base link, no amount of change in ambient temperatures will change the tension in the guy. As the cable expands on heating, the silicone fluid also expands in like amount, thereby forcing the piston, when it is connected adjacent the base, towards the anchor base and thus maintains the same tension in cable. Conversely, on cooling the cable contracts as does the silicone fluid allowing the piston to move towards the bridge socket, thus keeping the tension constant. The particular amount of liquid to be used within the cylinder can be readily calculated when the length of cable required has been determined. Knowing the coefiicient of expansion of the wire or cable and of the liquid to be used in the cylinder, simple mathematics will indicate the length of the column needed to offset the expansion or contraction of the guy wire or cable.

While this invention has been described only by one embodiment, namely, silicone fluids, it is apparent that other substances could be substituted therefor. Mercury, having a coeflicient of expansion of 0.018 per degree C., is another fluid which could be used in the space defined by the cylinder walls and the end of the piston 3. Cylinders of solid material having coeflicients of expansion significantly higher than that of steel could also be used. An example of a solid material that could be used is a cylinder of silicon which has a linear coefficient of expansion of 0.0012 per degree C.

I claim:

1. A new and improved guy which comprises in conjunction with a guy wire, an imperforate cylinder having a closed end and open end, a column of flowable material in said cylinder, said flowable material having a coefficient of expansion markedly greater than the coeflicient of expansion of the guy wire, the quantity of said flowable material being selected such that the expansion and contraction of said flowable material in a longitudinal direction is approximately equal to the longitudinal expansion and contraction of the guy at any temperature, thereby maintaining a constant tension in said guy, said open end of the cylinder terminating in a pair of arms forming a yoke, means at the end of the yoke to attach the yoke and cylinder to one section of the guy wire, a piston within said cylinder and having an arm external of the cylinder and being positioned between the arms of the yoke, a pair of tie rods attached to the end of piston arm and disposed in a direction opposite to the yoke arms, said tie rods being attached to another section of the guy wire.

2. A new and improved guy which comprises in conjunction with a guy wire, a cylinder having a closed end and open end, a column of flowable material in said cylinder, said flowable material having a coeflicient of expansion markedly greater than the coeflicient of expansion of the guy wire, the quantity of said flowable material being selected such that the expansion and contraction of said flowable material in a longitudinal direction is approximately equal to the longitudinal expansion and contraction of the guy at any temperature thereby maintaining a constant tension in said guy, said cylinder having a single opening in the wall through which the column of selected quantity of flowable material is established, said open end of the cylinder terminating in a pair of arms forming a yoke, means at the end of the yoke to attach the yoke and cylinder to one section of the guy wire, a piston within said cylinder and having an arm external of the cylinder and being positioned between the arms of the yoke, a pair of tie rods attached to the end of piston arm and disposed in a direction opposite to the yoke arms, said tie rods being attached to another section of the guy wire.

References Cited in the file of this patent UNITED STATES PATENTS 2,390,324 Peters Dec. 4, 1945 2,417,504 Knaggs Mar. 18, 1947 2,597,270 White et al May 20, 1952 2,736,604 Albright Feb. 28, 1956

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