US 3430733 A
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E. A. SMITH ELEVATOR CABLE PROTECTOR AND METHOD March 4, 1969 Filed April 24, 1967 INVENTOR.
United States Patent 3,430,733 ELEVATOR CABLE PROTECTOR AND METHOD Ethan A. Smith, Balboa, Calif., assignor to Walter A. Plummer, Sherman Oaks, Calif. Filed Apr. 24, 1967, Ser. No. 633,154 US. Cl. 187-1 Claims Int. Cl. B6611 9/00; F161 11/00 ABSTRACT OF THE DISELOSURE This invention relates to the operation of elevators and more particularly to a simple, inexpensive efiicient means and method of protecting elevator service cables from damage by impact with structural members of the elevator shaft. It is well known that the operation of elevators and more particularly high speed elevators in higher buildings causes the various service cablings associated with such elevators to swing pendulum-fashion leading to serious and costly damage by impact with structural members along the shaft. Cabling must be highly flexible and this is incompatible with thick walled insulation. The present invention provides short lengths of highly supple, lightweight dielectric material selected for its resistance to impact. These protectors are assembled about those portions only of the cabling likely to contact structural members. The protectors are held in place by stressed frictional contact with the cable insulation and are formed in one piece with seam-forming means by which the protectors can be quickly assembled and disassembled without need for tools, or change in the service cabling being protected. All parts of the one-piece protector assembly are formed of dielectric material and the protector does not add significantly to the weight of the cable or change its flex characteristics in any measurable amount and may be replaced as frequently as necessary to avoid risk of damage to the cable proper.
The present invention resolves a serious problem encontered in the operation of high speed elevators, the several service cables of which must be left free of attachment to other structure except at their opposite ends. Owing to the lengths of these cables and the forces imparted to the cables as the return bend loop shifts during travel of the elevator along the shaft, the cables swing pendulum-fashion. The very considerable weight together with their length results in wide are swinging and the repeated impact of portions only of the cabling against the structural members forming the framing for the shaft.
Numerous efforts have been made heretofore to protect the-cables along the portions subject to injury but these have not met with more than mediocre success for numerous reasons. Not only has the labor and cost of such prior expedients been excessive but such expedients have added to the weight of the cable, interfered objectionably with the flexing characteristics of the cable and have augmented the swing and impact forces acting on the cabling with the undesirable consequences.
These various objections and other have been overcome by the present invention which utilizes the high impact resistance of certain exible and supple elastomeric dielectric materials now available, such as certain of the 3,430,733 Patented Mar. 4, 1969 thermoplastic materials. Relatively thin-walled sheets of such materials are easily fabricated into split tubes provided with interlocking seam-forming tapes along their lateral edges. These tapes are readily interlocked by finger pressure applied to the overlapped edges and are readily separated from one another when the protectors are in need of servicing or replacement.
Another feature of the invention protector is the provision of thick spongy dielectric material preferably bonded or otherwise secured along one interior side of the protector and so dimensioned that it is partially compressed when the protectors are assembled to cabling. This material serves to hold the protectors snugly tensioned against the cabling and provides additional impact absorbing capabilities to the protector, particularly if the spongy material underlies the area of contact with the structural members, as is desirable.
It is therefore a primary object of the present invention to provide an improved article of manufacture and a method of utilizing the same to protect areas of elevator service cabling likely to impact structural members during travel of the elevator cage lengthwise of the shaft.
Another object of the invention is the provision of an article of manufacture comprising a simple lightweight separable tube of dielectric material adapted to be quickly assembled under tension about elevator cabling to provide impact protection therefor without interfering with normal flexing of the cabling.
Another object of the invention is the provision of a unitary article of manufacture provided with interlocking seam-forming means lengthwise thereof and proportioned to be held snugly assembled about an elevator service cable in areas thereof in need of impact protection.
These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawing to which they relate.
Referring now to the drawing in which a preferred embodiment of the invention is illustrated:
FIGURE 1 is a fragmentary elevational view of an elevator shaft showing a preferred embodiment of the invention protectors assembled about one of the service cables for the elevator cage;
FIGURE 2 is an enlarged cross-sectional view taken along line 2--2 on FIGURE 1;
FIGURE 3 is a fragmentary perspective View of one end portion of the protector; and
FIGURE 4 is a cross-sectional view through the protector while assembled about a service cable.
Referring more particularly to FIGURE 1, there is shown a typical operating environment utilizing a preferred form of the present invention. There shown is an elevator shaft 10 and a diagrammatic representation of the elevator cage or car 11 suspended by cables 12. In accordance with customary practice, car 11 is provided with guide rollers 13, 13 cooperating with guide rails 14, 14 to hold the car accurately centered along its path of travel. These guide rails are secured in knOWn manner to structural members of the shaft such as those indicated at 15, 16.
Car 11 is serviced by numerous power communication and control conductors which in a typical case are grouped into five to seven different service cables 18. One end of each is suspended from a control box assembly 19 attached to the underside of the car and the other end is connected similarly to a control box at the top of the elevator shaft.
The cable protector per se, designated generally 20 (FIGURE 3), comprises a unitary tubular jacket having a thick main body 21 of soft supple highly flexible dielectric material capable of withstanding repeated impact blows such as a suitable thermoplastic composition or an elastomeric material. Soft sheet plastic is particularly desirable because of its high impact resistance and because of the ease with which the seam-forming tapes 22, 23, can be fuse bonded to the edges of the main body.
The seam proper 24 may be made in numerous ways but preferably includes interlocking tongues and grooves best shown in FIGURES 3 and 4 and adapted to be pressed into interlocking engagement by pressure applied against the overlapped edges of the tapes. The details of the seam structure here shown are well known commercially and are described more fully in Patent 2,960,561 granted to Walter A. Plummer on Nov. 15, 1960. However, it is to be understood that various other configurations are equally suitable. The identical tapes 22, 23 are extruded from plastic material, have excellent dielectric properties and are readily bonded or heat fused to main body 21.
Protectors 20 are made slightly oversized with respect to the circumference of cabling 18 and include either a plurality or a continuous length of suitable highly spongy elastomeric material 25 bonded or fused to the interior surface of the main body. As here shown, spony material 25 is restricted to a portion only of the interior circumference of the main body but it will be understood that it may extend over substantially the entire surface of the main body if desired. The spongy pad 25 serves several important functions. Not only does it compensate for wide range tolerance variations between the outer circumference of the cable being fitted and protector 2.0 as well, it being understood that the given jacket-will serve equally satisfactorily over a small range or cable sizes, but its high frictional qualities enable it to form a positive grip with the cable surface. Additionally, it will be observed from a comparison of FIGURES 3 and 4 that a relatively narrow but thick pad 25 is readily expanded to encompass a third or more of the exterior of the cable as it is compressed during closing of seam 24. The lateral expansion of the spongy pad is therefore seen to provide a wide area resilient backing for the main body of the protector and provides a buffer highly effective in absorbing the impact blows as the cable swings to and fro relative to structural members 16. The spongy pad also prevents the protector from creeping or migrating lengthwise of the cable or from twisting about its axis. It is a simple matter to assemble the protector about the cabling with the pad properly oriented to lie directly opposite the structural member or other sharp edged surface against which the cable may swing during operation of the elevator. The soft supple material comprising the protector also has high frictional contact with the cable covering and augments the frictional characteristics of pad 25 in holding the protector firmly in a desired assembled position.
Since a given length of cables 18 is always located pposite the same structural members when the car is in one of its lower positions, it is unnecessary to extend the protectors more than a few inches beyond the upper and lower edges of members presenting a hazard to the cable. This is of importance both for economic reasons as well as the fact that it is undesirable to alter the flexibility of the cables as this can interfere objectionably with the passage of the cable through loop 18' incident to car travel along the shaft. As is well known, the lower half of all elevator service cables must continually pass through loop 18 as the elevator travels along the shaft and this is equally true respecting any protector embracing the cable; otherwise, the presence of the protector causes forces to be generated which can augment swinging of the cables and can generate traveling waves along the cable increasing the hazard to the cables and the likelihood of premature failure thereof. Actual experience with the invention protector has demonstrated its efliciency and effectiveness and the fact that it does not interfere with the functioning of the cable, the formation of loop 18, nor does its presence set up traveling waves nor increase the tendency of the cable to swing laterally.
Protector 20 is easily assembled to lengths of service cabling 18 likely to impact any object which can injure the cabling. The workman merely encircles the section of the cabling opposite such an object with the protector, overlaps the mating lateral edges of tapes 22 and 23 and then applies finger pressure along the seam causing the tongues and grooves to interlock. No tools are necessary nor is it necessary to apply any adhesive or tacky material to any component. Whenever one of the protectors shows signs of failure it is a simple matter to replace it with a new one by applying an opening force to one end of scam 24 and pulling it open. Thereafter, the new protector is applied in the manner just described, care being taken to locate the spongy material on the side of cable disposed opposite a structural member.
Although the cable protector described hereinabove has been disclosed with respect to particularly vexatious problems attending the operation and safeguarding of elevator service cabling it is to be understood that the pro tector and the principles embodied therein lend themselves equally to the protection of cabling and flexible lines generally from damage by repeated contact with other objects.
1. An elevator cable protector for protecing cable insulation from damage and failure through repeated impact with elevator shaft structural members, said protector having a split tubular main body of supple flexible dielectric material capable of withstanding repeated impact blows, means carried by said protector for holding the same snugly assembled about portions of elevator cabling suspended closely beside a shaft structural member, and said tubular protector being sufliciently long to embrace those portions of elevator cabling likely to swing into contact with a shaft structural member during travel of an elevator car along the shaft and being freely flexible with the cable as the return bend of the cable traverses the protector during travel of an elevator car.
2. A cable protector as defined in claim 1 characterized in that said means for holding the same snugly assembled comprises spongy dielectric material adapted to be held at least partially compressed between said protector and the cabling when the protector is assembled thereabout, said spongy material being freely flexible with the cabling and being in high frictional contact therewith and effective to prevent migration of the protector circumferentially and axially of the cabling.
3. A cable protector as defined in claim 2 characterized in that said spongy material comprises a thick strip thereof secured to one interior side of the protector.
4. A cable protector as defined in claim 2 characterized in that said means for holding the same assembled as a tube about the cabling comprises flexible seam forming tapes of thermoplastic material formed to interlock as pressure is applied to the overlapped lateral edges thereof.
5. That method of safeguarding elevator service cabling from injury by swinging impact against shaft structural members caused by travel of the car along the shaft, said method comprising embracing those portions of the service cabling positioned to contact a structural member with short lengths of highly supple and flexible tubing of dielectric material having high impact resistance and capable of flexing readily with the cabling as a traveling loop passes therealong during travel of an elevator car.
6. That method defined in claim 5 which includes the step of inserting resilient spongy material having dielectric properties between the exterior of the cabling and the interior of said flexible tubing and utilizing the resiliency and frictional properties of the partially compressed spongy material to hold said tubing against slippage and creepage on the cabling.
7. That method defined in claim 6 characterized in the step of placing similar protective tubing only about those particular portions of the lower half of the cabling located opposite shaft structural members likely to be contacted by the service cabling as the elevator car travels along the shaft.
8'. That method defined in claim 6 characterized in the step of providing said protective tubing with an interlocking seam forming means of dielectric material readily :closable by the application of finger pressure to the seam forming means when positioned for interlocking engagement.
9. A cable protector for safeguarding cable insulation from damage and failure through repeated impact with another object, said protector having an elongated main body strip of dielectric material capable of withstanding repeated impact blows, a strip of porous spongy material extending lengthwise of said main body strip and secured thereto, and fastener means along the opposite lateral edges of said main body for holding said protector snugly assembled about portions of cabling likely to be subjected to impact blows to absorb said blows and protect the cabling proper from damage.
10. An article of manufacture adapted to be secured snugly about a flexible line, cabling and the like without interfering materially with the flexibility thereof While safeguarding the same from abrasion and impact damage, said article comprising an elongated strip of flexible spongy resilient material, and fastener means secured to the opposite lateral edges thereof and interengageable with one another when encircling cabling to be protected to hold said strip of flexible spongy material partially compressed and securely in place by frictional pressure along a length of cabling to be protected.
References Cited UNITED STATES PATENTS 3,106,941 10/1963 Plummer 138-128 3,279,503 10/1966 Carbone et a1 138-128 3,344,888 10/ 1967 Connelly et al. 1871 HENRY S. JAUDON, Primary Examiner.
US. Cl. X.R. 138-128