Garage door industry magazine for garage door dealers, garage door manufacturers, garage door distributors, garage door installers, loading docks, garage door operators and openers, gates, and tools for the door industry.
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54 International Door & Operator Industry™ TECHNICAL By Gary Lombard Cable Assembly Replacement in the Field/The Facts If you are a Service Technician and have been working on overhead doors for any length of time, you know that one of the more common repairs needed are cable assembly replacements. Whether an existing cable on a door has broken, become frayed, or has tangled itself around the shaft, knowing the proper method of fabricating and replacing cables on site is critical to the proper operation of the overhead door that is being serviced. Here are some common questions and concerns raised by technicians: Why don't the cables last longer than they do? What causes them to wear out prematurely from what you think the expectation should be? I installed new cables a few months ago, and the cables went bad, did I receive some bad cable? Should I fabricate the assembly in the feld or use a "pre- made" set of cables assemblies? What is the proper method to fabricate a cable assembly in the feld, and what are the risks? Let's frst understand the players involved. First there is the manufacturer of the "bulk cable". Most bulk cable used in the overhead door industry is produced in South Korea or China. Next, there is the manufacturer or fabricator of the "cable assembly" which uses the bulk cable to fabricate the cable assembly. Most cable assemblies are fabricated in factories located in the USA or China. Cable assemblies can also be fabricated in the feld by door technicians. Just as there are many ways to install a door, so have there been many ways technicians have created to replace cables on a door. What will be addressed in this article is the correct method to perform this task; both from a cable assembly manufacturers' point of view and what has proven to be fact in the feld as this task takes place. 54 International Door & Operator Industry™ Continued on page 56 From the cable assembly manufacturers point of view; here are some of the key points to be considered anytime cables are going to be replaced: • Understanding cable is a machine with many moving parts; • Identify the proper cable diameter, construction and type; • The Cable Assembly - use a pre-made set of cable assemblies, or follow the proper steps to fabricate a cable assembly in the feld; and • Installation - follow the proper steps to replace and install the cable assembly. UNDERSTANDING A CABLE IS A MACHINE WITH MANY MOVING PARTS: A cable is in reality a complicated machine. A typical 7x19 cable (discussed later) has 133 wires in its seven strands. When cable bends over a drum, each of these the wires and strands must be able to slide and adjust in relation to one another to accommodate the differences in length between the inside and outside of the bend. The sharper the bend, the greater the movement. Understanding and accepting the "machine idea" gives a cable user a greater understanding of cable, and enables the user to obtain better performance and longer useful life from the cable. Anyone who uses a cable can use it more effciently and effectively when they fully understand this machine concept. IDENTIFY THE PROPER CABLE DIAMETER, CONSTRUCTION AND TYPE: First and foremost, the cable must have suffcient strength to handle the ultimate applied load. To make sense of this statement, one must be able to identify the diameter, construction and type of cable being replaced. 1/24/14 10:54 AM