Garage door opener installation

[PAGUY]

I read an article that stated with the emergency opener pulled the door should stay in up/down position halfway by its own weight if correctly spring loaded.

When hooked back up to door opener the result of up/down will work by movement of the opener in the position selected. The pull transfers the weight of the door to close or open it.

Hope that explanation helps.

 

[the old grind]

Sounds to me like the cable-lift type openers could use some tweaking of the assist springs to let gravity keep the cables taught. Openers have to overcome friction in the guide wheels/tracks and this should be what determines hp requirements. More of that would seem needed for taller doors with more wheels/bearings vs wider ones whether or not the weight balance is set 'neutral' by wind-up spring tension.

Horizontal operating chain/belt/screw drive openers can exert force in both directions, but vertical cable versions (Oldpath05's) seem to need a hand when closing. Someone mentioned angling the horizontal portion of the tracks to get gravity's help starting down when fully up. Perhaps biasing the partial-open condition vs 'floating' is indicated as well. (- another turn or so of counterweight spring tension?) :confused3:

 

[s219]

Sounds to me like the cable-lift type openers could use some tweaking of the assist springs to let gravity keep the cables taught. Openers have to overcome friction in the guide wheels/tracks and this should be what determines hp requirements. More of that would seem needed for taller doors with more wheels/bearings vs wider ones whether or not the weight balance is set 'neutral' by wind-up spring tension.

Horizontal operating chain/belt/screw drive openers can exert force in both directions, but vertical cable versions (Oldpath05's) seem to need a hand when closing. Someone mentioned angling the horizontal portion of the tracks to get gravity's help starting down when fully up. Perhaps biasing the partial-open condition vs 'floating' is indicated as well. (- another turn or so of counterweight spring tension?) :confused3:

There are no changes needed for these opener installs -- I have put 4-5 jackshaft openers in to replace overhead chain/track openers and had to make no adjustments.

Garage door guide tracks all have a slight pitch to the top section so that the door runs downhill when closing. I have never seen one that didn't. The angle is set by the corner track piece where it turns from vertical towards horizontal (never quite gets there though).

The cables are always tight with jackshaft tensioned doors unless something has gone wrong, and that's independent of whether it's manually actuated, driven by a jackshaft opener, or driven by an overhead opener. Now, if you have a jackshaft opener and you allow it to run after a door has stopped on the way down (whether at the bottom of travel or by accident if it encounters an obstacle) it can not only allow slack, but it can unwind the cables from the drums and leave the door in a very unsafe condition. That's why the jackshaft openers have a couple ways to detect and avoid this condition. They have cable tension monitors and also are able to track motor load (current sensing most likely) and will stop if anything triggers a condition where the door has stopped moving.

There seems to be a lot of confusion about this, but it's very simple physics. To understand how jackshaft openers work, you can go grab the end of the jackshaft on a manual door with a very small pipe wrench and turn it. You will probably be amazed how little effort it takes to open the door by cranking the end of the shaft. Same goes for closing.

 

[Oldpath05]

My son had some free time last week and called LiftMaster, explained the malfunction. They sent me new wiring for the 8500 reversing sensors yesterday, their tech people says that 4 LED blinks was indicating misaligned sensors or a staple was driven in to hard causing the wires to short out and sending false signals. Now my son is waiting for the weather to warm up and stop snowing and blowing, single digits is just too cold for door work.

Another issues I notice these past couple weeks after we got the springs rewound, one side of the door is not quite shutting down, leaving a little air gap at the bottom for snow to come in, I think one of cable drums needs to be turned a little one way or the other, more YouTube searching.

 

[Oldpath05]

Finally a weekend above freezing, warm enough so my son was able to re-staple the new wire harness that LiftMaster sent me a month ago under warrantee. The people that installed the door didn't use insulated staples and they must of shorted out the wiring, we used new insulated staples for the new harness and the door went up and down a dozen times without stopping, so I guess it's fixed, I would say when stapling a wiring harness for a garage door, use insulated staples.

The bad news is as I watched the door go up and down several times, I still don't understand how the cables are making the door go down, cant be gravity because when the opener wasn't working for past 6 weeks, I had to grab the rope and PULL PULL the door down, but then again, I don't understand why Feb. was so cold and how I ended up with so much snow this year ether.

 

[Xfaxman]

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The bad news is as I watched the door go up and down several times, I still don't understand how the cables are making the door go down, cant be gravity because when the opener wasn't working for past 6 weeks, I had to grab the rope and PULL PULL the door down, ------------------------------------

I don't understand why you don't understand.

When you pull the door down, you are pulling against the spring tension that is holding the door up by the cables. When you pull, the cables pull the drums, turning the shaft.

When the opener closes the door, it turns the shaft and the drums. The cables spool out letting the weight of the door (gravity) keep the cables tight as the door closes.

 

[Oldpath05]

I don't understand why you don't understand. When you pull the door down, you are pulling against the spring tension that is holding the door up by the cables. When you pull, the cables pull the drums, turning the shaft.

When the opener closes the door, it turns the shaft and the drums. The cables spool out letting the weight of the door (gravity) keep the cables tight as the door closes.

"I don't understand why you don't understand", Thanks for the humor, nice to read something funny after welding all day.
So if I'm reading your LiftMaster 8500 lesson right, when I pull the door down, I'm pulling against the spring, turning the shaft and winding up the spring as the door comes down, the cable on the drum that's on the shaft, free spools out, because it's hooked to the bottom of the door, staying tight by the weight of the door (gravity).

Now lets see if I understand this so far, according to Einstein's Theory of Relativity, this means when the door is all the way up, there is very little tension on springs, I cut the cables on both sides of the door, the springs will finish unwinding a little, then there's nothing holding my 12X12 foot door up, and the door come down fast, staving it all to pieces, (gravity). I'm still not sure I understand this, to prove it to me, someone should buy 12 foot door and with camera rolling, cut the cables, put the video on YouTube, then I'll be able to understand how my overhead door works, thanks for your understanding

 

[aczlan]

Lift your door up all the way, then put a pair of vise grips on the pipe and turn it to loosen the cables, your door will go down.

Aaron Z

 

[s219]

Lift your door up all the way, then put a pair of vise grips on the pipe and turn it to loosen the cables, your door will go down.

Aaron Z

Yep, that's what I was going to suggest (but use a pipe wrench). You'll see how little torque it takes to unwind the cable and let the door go down under the "opposing" action of the spring. That's all the opener is doing.

 

[Xfaxman]

I don't understand why you don't understand.

When you pull the door down, you are pulling against the spring tension that is holding the door up by the cables. When you pull, the cables pull the drums, turning the shaft.

When the opener closes the door, it turns the shaft and the drums. The cables spool out letting the weight of the door (gravity) keep the cables tight as the door closes.

"I don't understand why you don't understand", Thanks for the humor, nice to read something funny after welding all day.
So if I'm reading your LiftMaster 8500 lesson right, when I pull the door down, I'm pulling against the spring, turning the shaft and winding up the spring as the door comes down, the cable on the drum that's on the shaft, free spools out, because it's hooked to the bottom of the door, staying tight by the weight of the door (gravity).

Now lets see if I understand this so far, according to Einstein's Theory of Relativity, this means when the door is all the way up, there is very little tension on springs, I cut the cables on both sides of the door, the springs will finish unwinding a little, then there's nothing holding my 12X12 foot door up, and the door come down fast, staving it all to pieces, (gravity). I'm still not sure I understand this, to prove it to me, someone should buy 12 foot door and with camera rolling, cut the cables, put the video on YouTube, then I'll be able to understand how my overhead door works, thanks for your understanding

I think now you understand the understanding! :thumbsup:

MithBusters is on the way to your place with a camera crew so you can watch it live on your door! :laughing: