Spring rate, torque, and lift: The spring rate K for these measurements is π*28.5*10^6 * (0.273)^4 / (32 * 140 * 1.72) = 64.5 IPPT. Applying 7.5 turns on this rate will yield a torque of 7.5 * 64.5 = 484 in-lb, which on the 4-inch drums (2-inch radius) yields a lift of (484 in*lbs)/(2 in) = 242 lbs. Again we find good agreement with the approximate door weight of 238 lbs.
They sent Doug Fussell out to my house on the day after Christmas! I had only called them three days before! Doug was a premier technician, very thorough and very efficient. I expected him to take two days, since he was replacing two doors and adding openers on each door. He only took the daylight hours of one day! I could not believe how fast he was! In addition, he thoroughly taught me how to use the remote openers. I highly recommend them to anyone!
A torsion spring counterbalance system consists of one or two tightly wound up springs on a steel shaft with cable drums at both ends. The entire apparatus mounts on the header wall above the garage door and has three supports: a center bearing plate with a steel or nylon bearing and two end bearing plates at both ends. The springs themselves consist of the steel wire with a stationary cone at one end and a winding cone at the other end. The stationary cone is attached to the center bearing plate. The winding cone consists of holes every 90 degrees for winding the springs and two set screws to secure the springs to the shaft. Steel counterbalance cables run from the roller brackets at the bottom corners of the door to a notch in the cable drums. When the door is raised, the springs unwind and the stored tension lifts the door by turning the shaft, thus turning the cable drums, wrapping the cables around the grooves on the cable drums. When the door is lowered, the cables unwrap from the drums and the springs are rewound to full tension.
And for some extra features, you'll appreciate accessing the system through the MyQ smartphone app. You can set up this Chamberlain opener to automatically close the door after 1, 5, or 10 minutes, which is great for people who are a bit forgetful. We also really like the motion-detecting control panel, which turns on lights whenever it records nearby movement.
Garage Door Repair