Dodging a falling door:: Reversing this equation gives us x=gt^2/2 as the fallen distance x for a given time t. How much time would you have to dodge a falling door if the spring were to suddenly break at the top of travel? Let us assume you are 5.5 feet tall, so the door will hit your head after falling 2 feet from its 7.5 foot fully-raised height. This 2-foot fall takes sqrt(2*2/32.2) = 0.35 seconds (350 milliseconds). The quickest human response time is about 200 milliseconds, so even if you are alert to the hazard, this leaves you only about 150 milliseconds to accelerate and move your noggin out of the way. If you are an Olympic gold medalist in the 100 meter dash, you can accelerate (horizontally) about 10 feet/second^2, and your 150 milliseconds of wide-eyed panic will move you all of 10*0.15^2/2 = 0.11 foot = 1.35 inch.
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Measurements: With the door in the down position, I measure a wire size of 0.273 inches, outside diameter of 2.0 inches, and overall length of 41.5 inches. Relaxing the spring shortens the length by about 7.5 coils of wire, so to estimate the relaxed length, we deduct the wire diamter of 0.273 inches times 7.5 from the 41.5 inch wound length, yielding an estimated relaxed length of 39.5 inches. The mean coil diameter is 2.0 - 0.273, or 1.73 inches. Perhaps this was actually a 40-inch-long spring with a 1.5 ID, 1.75 mean diameter, and 2.0 OD, but let's continue on calculating with the actually observed sizes. The number of coils in the relaxed spring is the relaxed length of 39.5 inches divided by the wire size of 0.273 inches, or about 145 coils. Deducting about 5 dead coils at the ends yields 140 active coils.
The German-made, .75-horsepower (equivalent) Direct Drive 1042V004 garage door opener doesn't use a belt drive or a chain drive. Instead, the mobile motor crawls along a stationary chain, making it exceptionally quiet. This garage door opener is also feature-packed, though the wireless entry keypad is an extra-cost accessory. Reliability is excellent, and installation is at least a little easier than some other garage door openers. This opener is also sold under the Sommer brand and with different model numbers, but all are similar.
Drive type Garage door openers work in a variety of ways. A chain-drive model raises and lowers doors with a metal chain — these tend to be inexpensive and able to handle heavier doors, but they’re loud. A belt-drive opener uses a belt and operates more smoothly and quietly. Screw-drive openers, which lift doors with a threaded steel rod, are also quiet and don’t require much maintenance. Finally, a direct-drive opener operates as a single unit — the whole contraption moves to lift the door. These tend to be the quietest, smoothest mechanisms available.
Carriage: These doors mimic the look of doors found on old carriage houses in the days of horses and buggies. Because of their rustic look, they are often favored in the West and Southwest of the United States. The doors swing open like oversized French doors and hang from jambs on hinges. With their unique look, they create an area of visual interest for your home and are quite energy efficient. The downside is they require a considerable amount of clearance to work properly. Because most carriage garage doors are largely composed of wood, you may need to replace deteriorating or rotting door materials. The average cost for carriage garage door repairs is $133.
Another recent innovation in the garage door opener is a fingerprint-based wireless keypad. This unit attaches to the outside of the garage door on the jamb and allows users to open and close their doors with the press of a finger, rather than creating a personal identification number (PIN). This is especially helpful for families with children who may forget a code and are latchkey kids.

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.)
Beware of improprer prior installations: Sometimes the existing door installation is not correct, and the old springs should not be used as a specification for replacements. For example, the old springs might have been replaced with incorrect sizes because the last repairman didn't have the right one on his truck. If your door has never worked quite right, something like this might be the cause. To correct this, you must use the weight of the door to specify the spring, either from a spring rate manual giving spring torque constants, or from the formulas below.
Additionally, the B970 includes encryption features that prevent others from hacking the system to gain entry to your garage. Expert reviewers like this garage door opener a lot. The Tool Spy says the Chamberlain B970 justifies its higher price point by delivering excellent build quality and anti-vibration features. Consumer Search and Garage How To also approve of this unit.
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.
Every thing the tech demostrated was helpful, he knew how to do his job even if his eyes were shut. Very knowledgeable, took time out to explain every detail about the install process. Very highly satisfied. A d would love to have him for future additional repairs. Would definitely recommend sears and would use you guys again thanks mr.technician for a job well done.

The door and tracks at this stage of the repair are in a minimum-energy condition. This is a good opportunity to work on any hinges, bearings, rollers, cables, or tracks that need tightening, repair, lubrication, or replacement. Again, these parts should be available from the spring source, and should be ordered based on a pre-inspection. Home-improvement stores carry some of these parts, but the type and quality may not be the best.

Smartphone Control: Many newer garage door openers allow you to connect the device to your home's Wi-Fi network, according to RW Garage Doors. You then can open and close the door through a smartphone app. In fact, many of these apps will give you an alert on the smartphone when the garage door is open for a certain period. Some opener models even can connect to your existing Smart Home system, incorporating all your appliances on one system.

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