I mentioned earlier that this apparatus had at least one prior spring replacement, with a single longer spring having been replaced by two shorter springs. The clamping of the original spring had pressed dimples and an eccentric distortion into the hollow shaft. While this distortion was large enough to block the old cones from sliding across, I was able to remove the old hardware by just sliding them in the other direction. I did not have to bother trying to press out this distortion, since I could just work around it.
End treatments: Torsion springs also are made in a variety of end treatments. The "standard torsion end" is most common, as is pictured in my examples, consisting simply of a short, straight length of wire projecting tangentially. Various non-standard end treatments have longer "ears", U-turns, ends bent in toward the center or along the axis, or even loops. Non-standard ends are used in end fasteners peculiar to various manufacturers, which would seem to serve mostly as a guarantee that you buy overpriced replacements from that one source.
This work is risky, but the risk is comparable to doing your own car repairs, or climbing on the roof of your house to clean your gutters. These are dangerous things that many people can do safely, but that safety depends on intelligent understanding and application of proper techniques. Professional door repair technicians, who are fully knowledgable, skilled, and experienced, report that they nevertheless are injured from time to time, despite their best efforts. Coldly evaluate your abilities and motivations, to judge whether you can manage the risks of this work for the benefit of the money and time you might save.
As in an elevator, the electric motor does not provide most of the power to move a heavy garage door. Instead, most of door's weight is offset by the counterbalance springs attached to the door. (Even manually operated garage doors have counterbalances; otherwise they would be too heavy for a person to open or close them.) In a typical design, torsion springs apply torque to a shaft, and that shaft applies a force to the garage door via steel counterbalance cables. The electric opener provides only a small amount of force to control how far the door opens and closes. In most cases, the garage door opener also holds the door closed in place of a lock.
Right-hand versus left-hand winding: Springs are chiral, that is, wound or "laid" in either a left- or right-hand orientation. This is a critical property of their design and specification; you cannot substitute a left for a right or vice versa. If you were to grasp the spring in your hand, and if your right hand orients the tips of your fingers like the ends of the coiled wire when your thumb points "out" of the core of the spring, then you have a right-hand spring; likewise left (which end you grasp does not matter). (This also happens to match the "right hand rule" of magnetic polarity, if you happen to be knowledgeable in such esoteric subjects.) Another way to identify the winding is to examine the spring vertically in front of you; if the coils facing you rise going to the right, it is right-hand (thus you can remember, "rise to the right is right-hand"), and likewise left indicates left-hand. Another way is to view the coil axially; a right-hand spring winds in a clockwise direction as it recedes away, and a left-hand spring counter-clockwise. Yet another way, not so easy to remember, is to hold the spring vertically and compare the coil shape to the letter "Z" (indicates right-hand lay) or the letter "S" (indicates left-hand lay).

However, if you are confident that you don’t just need new batteries, make sure to call a professional. A service person with a lot of experience will be able to look at the problem and quickly diagnose the issue, saving you precious time. Again, while you may be able to save money in the short term by taking a day off and troubleshooting the problem yourself, the amount of energy and time lost as you search out the issue will quickly surpass the cost of a professional repair.
Ryan, the tech that did the initial inspection and Kyle, the tech that did the installation were both extremely skilled, knowledgeable, and have excellent customer service. They arrived on time as scheduled. Explained well what needs to be done and did the job well. We’re very pleased and recommend Castle Garage Doors. We’re giving Ryan, Kyle 10 🌟 along with Hollie for having excellent customer service in making sure the whole process ran smoothly. Thank you 👏🏻👏🏻👏🏻 -Grandpa & Grandma Read less
Clearly there is a lot going on with your garage door and it takes trained and qualified experts to properly install, maintain, repair, and replace them. The experts and On Track Garage Door Services have the tools, skills, training to get your garage door fixed the first time. In addition we can help you fix your garage door affordably and offer many options from your basic garage door to custom wood styles. To find out how much your garage door repair will cost, give us a call at 480-641-2301 or use our Contact Page.

As a first time homeowner, Home advisors is an invaluable tool! There is a steep learning curve that comes with buying a house!!!! Being able to have access to unbiased information is great! It really helps to have a basic idea of what costs are, and all the different things that go into each project. who knew that there was so much to consider when looking to replace garage doors!!!!


Here's a view of my door and its broken torsion spring. This door is 10 feet wide and 7 feet high, constructed of 3/4 thick hollow wood panels inside with 3/4 inch plywood siding outside to match the house exterior. This is original to the house which was constructed in 1978, and is much heavier (238 pounds, as I measured later as described below) than the steel doors most common today in new construction. The 10-foot width is a little larger than usual for a one-car garage; such doors are typically only 7 or 9 feet wide. The ceiling height is 9 feet, providing 18 inches clearance above the torsion shaft. This is in a 3-car garage with 3 separate extra-wide doors. Every man's dream! ('cept when the door is broke.)
Today's garage doors come with those door sensors, and if anything is in the path of the door the sensor detects it and raises the door back to the open position. These precautions are important for families with young children or pets. Even if you don't have a mini me or furry friend running around your yard, it's a good idea to have a garage door that is safe for you, your guests and your belongings. 
Versatile. That’s one way to describe our products. A total, one-stop solution that meets your every upward-acting-door need. Featuring premium materials, superior craftsmanship and innovative functions, our products continue to lead the industry, underscoring a legacy of quality, expertise and integrity.  This history ensures that you are making a good investment in your home with a quality product. In fact, according to the latest  Cost vs. Value Report by Remodeling Magazine, replacing a basic garage door with an upgraded one returned up to 85%​ on original cost on average – making it one of the top renovations in the study.
As a first time homeowner, Home advisors is an invaluable tool! There is a steep learning curve that comes with buying a house!!!! Being able to have access to unbiased information is great! It really helps to have a basic idea of what costs are, and all the different things that go into each project. who knew that there was so much to consider when looking to replace garage doors!!!!
Absolute Overhead Door recently launched a blog that can be found here so that readers would be able to see the benefits of a garage and what they should do in the event their newly driving teenage drove into the garage door. The blog offers many tips for “fix at home” solutions as well as giving examples of situations when calling us for a service call is the best decision. In our blog, we give professional and honest recommendations for the most reader and budget friendly options for families looking for advice that doesnt cost a fortune and an obligation to purchase a new garage door from a salesman afterwards! Check it out! We hope you enjoy it.
Garage door manufacturers typically produce garage doors fitted with torsion springs that provide a minimum of 10,000 to 15,000 cycles and are guaranteed for three to seven years. One cycle is a single opening and closing sequence. Most manufacturers offer a 30,000 cycle spring. However, it is important to remember that if the weight of the garage door is increased by adding glass, additional insulation, or even several coats of paint, the life of the torsion spring may be greatly reduced. Additionally, springs at highly humid environments, such as coastal regions tend to have a significantly shorter cycle life, due to the corrosive cracking.
Trading wire size for length, diameter, or cycle life: Now we are really going to save you some money, if you just recall your high school algebra class (and I don't mean that cute cheerleader who sat next to you). If you further understand the role of the 4th power of the spring wire size (letter d in the formulas above) in the numerator of the spring rate formula, and how to increase or decrease d to compensate for changes in length, diameter, and cycle life, then you're qualified for elite spring calculations. Matching springs is a matter of equating the 4th power of the proportion in wire size change to the proportion of change in the diameter or length or the product of both diameter and length. However, it is usually best to only increase wire size when substituting a spring, since this does not derate the cycle life. If you observe that the formula for bending stress is proportionate to the inverse 3rd power of the diameter, then physically a proportionate increase in wire size will result in a dramatic increase in cycle life of the 3rd power of that proportion. Trade-off example: Yawn with me while we ponder my original spring once more. Let's say I was in a fit of engineering mania, and wanted to replace my spring having a 0.2253 inch diameter wire (d = 0.2253) with a 0.262 wire version (d = 0.262). How much longer is the spring with equal torque rate, assuming we use the same coil diameter? The proportion of this change is 0.262/0.2253 = 1.163, and the 4th power of that is 1.83. This means the length must increase by a factor of 1.83 (again, not counting dead coils). Recalling that the length in Example 1 was 102 non-dead coils, the heavier wire spring must be about 1.83*102 = 187 coils, which when adding 5 dead coils and multiplying by the wire size to get the overall length, is (187+5)*0.262 = 50 inches, versus 24 inches in the original. So using this heavier wire more than doubles the length (and thus the mass and thus the cost). While the cost about doubles, the stress goes down by the inverse 3rd power of the wire size proportion, or 1/(1.163**3) = 0.64. Sress is favorably, non-linearly related to cycle lifetime (halving the stress more than doubles the lifetime), so this decreased stress should more than double the expected lifetime of the spring. While the up-front cost is more, the true cost of an amortized lifetime is much less. In short, per cycle it is cheaper. Ah, the wonders of engineering calculations! Conclusion: Observe that the stress formula (and thus the cycle lifetime) depends only on wire diameter (d) for equal torques. Thus the only way to improve cycle lifetime is to use heavier wire. For equal torques, heavier wire size, due to the exponents in the formulas, increases cycle lifetime much faster than it increases mass (and thus cost), physically speaking.
An intermediate stage of the garage door opener market eliminated the DIP switches and used remotes preprogrammed to one out of roughly 3.5 billion unique codes. The receiver would maintain a security list of remotes to which it would respond; the user could easily add the unique remote's code to the list by pressing a button on the garage door opener while activating the remote control. The large number of codes made the brute force try-all-possible-digital-codes attacks infeasible, but the systems were still vulnerable to code grabbers. For user convenience, these systems were also backward compatible with the older DIP switch remote codes, but adding an old technology remote to the security list made the garage door opener vulnerable to a brute force attack to find the DIP switch code. The larger code space approach was an improvement over the fixed DIP switch codes, but was still vulnerable to the replay attack.
Loosening or tightening the set-screws is the moment of most risk, since the end-wrench is a potential missile if you slip, and your hand is close to the cone. When the wrench is removed and only the rods are in place, it would seem that the worst that could happen is that the rod is flung out and the captive spring and cone rattle around, assuming you are keeping yourself clear of the rod's radial disk of rotation, and not leaning on the rod such as to fall into the apparatus were the rod to slip out of your grasp. The torsion shaft design has the virtue of capturing the mass of the spring and cones reliably on the shaft, preventing these parts from launching themselves as projectiles, even in an accident.
With more than 43 years of experience, Kitsap Garage Door is the trusted source for garage door and opener installation for home and business owners throughout the Kitsap, WA, area. We can dependably and expertly handle all of your garage door installation, maintenance or repair needs, and we offer a large selection of the most trusted and top-rated garage door brands and accessories available today. We’re proud to exclusively install Clopay garage doors and LiftMaster garage door openers.
As in an elevator, the electric motor does not provide most of the power to move a heavy garage door. Instead, most of door's weight is offset by the counterbalance springs attached to the door. (Even manually operated garage doors have counterbalances; otherwise they would be too heavy for a person to open or close them.) In a typical design, torsion springs apply torque to a shaft, and that shaft applies a force to the garage door via steel counterbalance cables. The electric opener provides only a small amount of force to control how far the door opens and closes. In most cases, the garage door opener also holds the door closed in place of a lock.
Garage doors break on their own schedule which is why we offer 24/7 Same Day Garage Door Repair. Emergency Service is also available upon request 7 Days a week. Say Goodbye to return trips because our expert Technicians Service Major Brands and are Equipped with Fully Stocked Trucks. When the garage door breaks, J&S Overhead Garage Door Service is your local Garage Door Repair Specialist. Whether your garage door or opener is not working our expert technicians will repair or replace any garage door system on the spot. Proudly serving Hampton Roads including Virginia Beach, Newport News, Chesapeake, Hampton, Yorktown, Suffolk, Portsmouth, Poquoson, Norfolk, Gloucester, Smithfield, Franklin, and Williamsburg, Virginia.
The Chamberlain Whisper Drive takes control to a higher level than other models with its door and light automation features. The internal control panel has a sensor for motion-activated lighting. In addition, door closing can be instant or set automatically for 1, 5 or 10 minutes. We give this feature a top-notch rating because, should you forget to close your door, your garage will secure itself.
Even if one could somehow stretch and clamp the springs to the proper extra length, the process would still be more trouble, and there would be little or no reduction of risk. Lifting the full weight of the unsprung door by hand and clamping it in the raised position is dangerous in itself, and creates the same amount of stored energy as winding the springs, ready to slip out of your hands. Many doors won't travel far enough up the track to provide clearance to access the springs. You're also going to have to deal with winding stiff steel cables onto both lift drums at once without any resistance to maintain tension. Finally, even if you managed to complete the installation with the door raised, you then have to lower the massive door against an untested balancing torque. If you've made a mistake, then that massive door has nothing but your skeletal force applied through your meat clamps (hands) to prevent it from falling down and crushing whatever is in the way (perhaps your feet?).
At this point I weighed the unlifted door to confirm and fine-tune my calculations. This is not strictly necessary, but it makes the adjustments easier to perform, if you happen to have a scale with the requisite capacity. With some helpers, we first lifted the door a few inches and rested it on blocks of wood to provide clearance underneath. Then I slid a 400-pound-capacity freight scale under the center of the door, we lifted again to remove the blocks, and lowered the door gently onto the scale. This door weighed in at 238 pounds, which is very heavy for a single-car door. Since the outside of the door carries the 3/4-inch plywood paneling to match the house, and that plywood weighs about 2 lbs/sq-ft, I estimate the door weight to be about 7 x 10 x 2 = 140 lbs of paneling with the rest 238 - 140 = 98 lbs the interior panels, hardware, and cobwebs. Knowing this total weight will help later in adjusting the torsion on the springs. After weighing, we removed the scale and blocks, leaving the door fully lowered again. Had I not had a high-capacity freight scale, I might have improvised a crude weighing device from levers and smaller weights of known mass, or a lever arm pressing a reduced proportion of the full weight onto a lower-capacity scale. Another factor to remember is that The weight of a wood door can vary with humidity.
The Chain Drive Rail Extension Kit for 10'-High The Chain Drive Rail Extension Kit for 10'-High Garage Doors is required for reliable everyday operation of Chamberlain chain drive models in 10-ft. garage door applications. Featuring a quick-install extension rail and replacement chain the kit includes everything needed for quick and easy installation. Includes one-year warranty rail extension replacement ...  More + Product Details Close
Torsion springs have three advantages over extension springs: They’re quieter, safer and easier to fine-tune. Torsion springs are quieter because you don’t have a spring knocking against a roller track. They’re safer because when a spring breaks, it usually stays on the bar. Finally, you can fine-tune the tension on a torsion spring so the door is perfectly balanced. Setting the tension on torsion springs has always been very dangerous, but torsion and extension spring systems with easy, do-it-yourself tensioning (Photo 7) are available. If you don’t use one of these DIY-friendly, easy tensioning systems (Clopay EZ-Set Spring and Wayne-Dalton TorqueMaster are two brands), you should hire a professional to release and set the tension on a torsion spring.
It’s important to pick a door that suits the style of your house. If you live in a Craftsman bungalow, for example, you might want something that looks like the swing-out doors found on garages behind early Craftsman houses. Manufacturers of modern roll-up doors make them in styles that mimic the old swing doors, complete with faux strap hinges on the sides and a pair of handles flanking a deep groove in the center. 
Wood doors range from midprice to very expensive, depending on whether they consist of a lightweight wooden frame filled with foam insulation and wrapped in a plywood or hardboard skin (the least expensive) or are true frame-and-panel doors made of durable mahogany, redwood, or cedar. Wood doors usually carry a short warranty, perhaps only one year. 
Containment cables. When old extension springs break, the springs and cables become heavy whips that damage cars and even injure people. To solve the whipping problem, manufacturers now offer containment cables that run through the center of side-mounted extension springs. If you have extension springs and don’t plan to replace your door, make sure the springs have these containment cables, or have a professional install them.
I repeat my caution about the uncertainty of interpreting color codes. A professional installer reading this page emailed me to say that the red color indicates the springs are right-hand windings, not the DASMA color code for the wire size. But this photo shows both a right- and a left-hand spring, and both have the red paint on the cones and set-screws. I conclude it is prudent to make your own measurements and analysis. Do not rely on the colors on old installations. The only time I would respect them would be on new parts that carried documentation giving the code.
Permits must be applied for when you are building a new home or structure. This permit will cover the building of the structure and cover the inspection for your garage door. The inspection process for a new door is pretty simple. The county will want to make sure that you have a garage door installed that meets local wind rating standards. In Mecklenburg County, that standard is 90 mph. That means that your door must be rigid enough to withstand 3 second gust by winds of up to 90 miles per hour.
Annual maintenance. Make an annual check of all nuts and bolts on rails and rollers to make sure they’re firmly tightened. Check the condition of all cables to make sure they’re not worn or frayed. Lubricate rollers and springs with a garage-door lubricant (see How to Fix a Noisy Garage Door for maintenance and problem-solving tips). The door should operate smoothly and be properly balanced. Check the balance by disconnecting the opener and lowering the door halfway- the door should hold its position. If it doesn’t, adjust the spring tension or replace the springs.
Although you can replace your garage door opener on your own, it’s more difficult than most DIY projects, so following the installation instructions is a must. If you’re not confident you can replace the opener on your own, you should consider hiring a professional, which further increases your costs. You can also expect to pay more if you’re replacing a garage door in addition to the opener.
Stress and lifetime: Calculating the maximal stress in the wire is useful for estimating the lifetime. Using the formula above, the bending stress S in the spring wire is 32*238/(π*0.2253^3) = 212 Kpsi. The spring index C is D/d = 2.23 / 0.225 = 9.88. The Wahl correction factor is Kw = (4C-1)/(4C-4) + 0.615/C = 1.15. The Wahl-corrected stress is Kw * S = 1.15 * 212 Kpsi = 244 Kpsi. This predicts about a 10,000-cycle lifetime, which is the standard "cheap spring" configuration originally installed. Note that while this stress is proportional to the torque being applied, it is also in proportion to the inverse third-power of the wire size. Thus slightly heavier wire sizes (and suitably adjusted D and/or L) radically improve the expected cycle lifetime of the spring.
Depending on the type and location of the damage you might have an alternative to replacing panels, or entire garage doors. One solution to give new life to your garage door is repair. Small dents, rot, rust or holes can be repair without replacing. Depending on what wrong with the panel, average prices for repair are $130 for steel door repairs, $190 for wood, $170 for aluminum and $150 for fiberglass. Garage door panel repair can save homeowners money, but should be weighed against garage door panel replacment.
At this point I weighed the unlifted door to confirm and fine-tune my calculations. This is not strictly necessary, but it makes the adjustments easier to perform, if you happen to have a scale with the requisite capacity. With some helpers, we first lifted the door a few inches and rested it on blocks of wood to provide clearance underneath. Then I slid a 400-pound-capacity freight scale under the center of the door, we lifted again to remove the blocks, and lowered the door gently onto the scale. This door weighed in at 238 pounds, which is very heavy for a single-car door. Since the outside of the door carries the 3/4-inch plywood paneling to match the house, and that plywood weighs about 2 lbs/sq-ft, I estimate the door weight to be about 7 x 10 x 2 = 140 lbs of paneling with the rest 238 - 140 = 98 lbs the interior panels, hardware, and cobwebs. Knowing this total weight will help later in adjusting the torsion on the springs. After weighing, we removed the scale and blocks, leaving the door fully lowered again. Had I not had a high-capacity freight scale, I might have improvised a crude weighing device from levers and smaller weights of known mass, or a lever arm pressing a reduced proportion of the full weight onto a lower-capacity scale. Another factor to remember is that The weight of a wood door can vary with humidity.
Versatile. That’s one way to describe our products. A total, one-stop solution that meets your every upward-acting-door need. Featuring premium materials, superior craftsmanship and innovative functions, our products continue to lead the industry, underscoring a legacy of quality, expertise and integrity.  This history ensures that you are making a good investment in your home with a quality product. In fact, according to the latest  Cost vs. Value Report by Remodeling Magazine, replacing a basic garage door with an upgraded one returned up to 85%​ on original cost on average – making it one of the top renovations in the study.
Prices, like the garage doors themselves, run the gamut. You can pay as little as $400 for a door that you install yourself, or several thousand dollars for a high-end premium door that includes all the bells and whistles, including installation. A mid-range, 16-by-7-foot door will typically cost from $750 to $1,500, installed. Premium insulated steel doors run from $750 to $3,500. According to Remodeling Magazine’s 2017 Cost vs. Value report, the average national cost of a garage door replacement is $3,304.
Manufacturers and distributors of torsion springs believe they are better off not retailing their product directly to the public. They believe they are maintaining higher prices for their product by restricting sales "to the trade." One brochure for parts even flatly stated, "We do not sell to the end user. We protect our dealers," which would seem to be prima facie evidence of an illegal restraint-of-trade scheme. But this is an old story which is true of virtually every product and service, going back to medieval guilds and before.
We love the fact that you can connect the Chamberlain Whisper Drive with a phone app for long-distance control, as well as the fact that the door will secure itself if you forget to do so. As with any technology, there is a learning curve in which the kinks will need to be worked out. But overall, very few owners have anything bad to say about the Whisper Drive. One smartphone user expressed his satisfaction with the product by saying, “I can check if I've left the garage door open and close it from my office!”
Torsion springs are devices that lift most of the weight of a garage door so that the door can be opened manually or by an electric opener. The torsion principle is applied via an efficient and economical apparatus consisting of a torsion shaft under spring torsion, which turns lift drums, which wind cables attached to the door near the bottom. All of this apparatus is mounted over the top of the door. The energy stored is sufficient, in an uncontrolled release, to break things, hurt you, or perhaps even kill you. The same could be said of jacking up your car to change a tire, or mowing your lawn, or raising children, so it is not crazy to want to do this yourself.
Not sure what’s wrong with your garage door? Don’t know how much it will cost to repair? With Precision Garage Door Service of Lincoln, you’ll never have to worry about an unexpected bill. Contact one of our professionals today for a free technical evaluation and repair estimate. Once we’ve given you a price, you’ll be able to confidently make the decision whether you’ll want to move forward with the repair.
Ryan, the tech that did the initial inspection and Kyle, the tech that did the installation were both extremely skilled, knowledgeable, and have excellent customer service. They arrived on time as scheduled. Explained well what needs to be done and did the job well. We’re very pleased and recommend Castle Garage Doors. We’re giving Ryan, Kyle 10 🌟 along with Hollie for having excellent customer service in making sure the whole process ran smoothly. Thank you 👏🏻👏🏻👏🏻 -Grandpa & Grandma Read less
Thus it is humanly impossible to dodge a falling door. If the spring happens to break when the door is moving up or down somewhere in the middle of travel, as is more likely, then you'll have even less time. Hence it is not prudent to stand or walk beneath a moving garage door. Of course people often do, and the only reason this does not frequently kill people is that springs typically break at the bottom of travel, where they are stressed the most.
Precision: I got a call from my wife instructing me to come home right away - my neighbors daughter had backed our truck thru our double garage door. When I arrived home there was a Precision truck in my driveway, wow you're fast! The door was pretty badly damaged, unsecure and could've come down more. Your technician Dannie Ray told us no touch, extremely dangerous". Since our door is out of production Dannie started calling and found a door in Tacoma, and Dannie takes off for Tacoma. He calls me at about 3:00 pm. and tells me he's about 1/2 hour away and he's coming back to install both new doors. Second wow! About 1/2 hour later here comes Dannie with 2 new doors and proceeds to go about his business. My wife and I had to leave we asked Dannie if he was good, he said no problem. We arrived home around 10 pm to brand new doors that work and look terrific. As a business owner and full time Realtor I appreciate it when I see such outstanding service and concern that truly is "above and beyond". Now if I or one of my clients needs anything to do with a garage door I now have you on speed dial. Again, Thanks for such a great experience in a difficult moment. Thanks again Dannie, come by anytime!

My garage door broke on a Saturday night as I was getting ready to leave for a holiday party. Kelvin was here within 30 minutes. He reviewed everything with me that was happening with my door. He gave me the estimates of what was immediately needed to be done in order for my door to raise and then what I will need to have done very soon. I could see all the problems he pointed out to me and I decided to have everything done. He completed everything that night. I was very satisfied with Kelvin’s professionalism and the work he did. Thank you again.
Two of the spring references specifically for the garage-door industry are the APCO Spring Manual by Bill Eichenberger, and the Torsion Spring Rate Book by Clarence Veigel; these give tables of spring sizes and torque constants. Spring engineering principles in general are described in the Handbook of Spring Design published by the Spring Manufacturer's Institute; the formulas allow you to calculate torque constants knowing only the geometry and the Young's modulus of the material. You can also find some brief spring information in standard references like Machinery's Handbook and Marks' Standard Handbook for Mechanical Engineers.
The second stage of the wireless garage door opener system solved the opening-the-neighbor's-garage-door problem. The remote controls on these systems transmitted a digital code, and the receiver in the garage responded only to that code. The codes were typically set by eight to twelve DIP switches on the receiver and transmitter, so they allowed for 28 = 256 to 212 = 4,096 different codes. As long as neighbors used different codes, they would not open each other's garage doors. The intent of these systems was to avoid interference with nearby garage doors; the systems were not designed with security in mind. Intruders were able to defeat the security of these systems and gain entry to the garage and the house. The number of codes was small enough that even an unsophisticated intruder with a compatible remote control transmitter could just start transmitting all possible codes until he found one that opened the door. More sophisticated intruders could acquire a black box master key that automatically transmitted every possible code in a short time. An even more sophisticated method is known as a replay attack. The attacker would use a code grabber, which has a receiver that captures the remote's digital code and can retransmit that digital code at a later time. The attacker with a code grabber would wait nearby for the homeowner to use his remote, capture the code, and then replay the code to open the door when the homeowner was gone. Multicode openers became unpopular in areas where security was important, but due to their ease of programming, such openers are often used to operate such things as the gates in gated apartment complexes.
An extension spring counterbalance system consists of a pair of stretched springs running parallel to the horizontal tracks. The springs lift the door through a system of pulleys and counterbalance cables running from the bottom corner brackets through the pulleys. When the door is raised, the springs contract, thus lifting the door as the tension is released. Typically these springs are made of 11 gauge galvanized steel, and the lengths of these springs are based on the height of the garage door in question. Their lifting weight capacity can best be identified by the color that is painted on the ends of the springs.
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