Looking for some garage door opener lift arms in Calgary. (And a story of how to push a chain.)

[Perry]

First off. I'm looking for the piece that attaches your garage door to the slider on the garage door opener rail. Hopefully someone in Calgary might have this chunk laying around. (So I don't have to make something up. )




Now a story.

I've been asked to help get a garage door opener working. Apparently the owner drove out of the garage without opening the door. (All the way out. lol Not just a bump.)
The insurance company was good with them at the time . They replaced the door and repaired the vehicle. This was a while ago and the garage door opener was never set back up.

The owner lives a fair way out of town and I have not seen the setup in person, so I got a few pictures to look at to see what I was up against. I spent a fair bit of time trying to figure out what was going on here. I can only see one chain. Was something else missing? My guess was the door installers ripped out the old door and possibly parts that may be needed to hook the unit back up. From the photos I could not see an idler(sprocket /pulley) on the end off the door opener rail. Was it missing?




Well it took a fair bit of time but I did find a video on Yotube that got me to wrap my head around this.

So this Genie GTG350ML "PUSHES THE CHAIN" in one direction to close door and pulls the chain in the other direction to open it. The chain does not loop around to form a loop to get the pull force in either direction. I'm amazed by this whole thing. Now I want to see it in life.

This is the link to the video that got me to figure out this mess.

I think all I would need to get this back up and running is the door hardware that attaches the door to the rail slider and some time to set everything back up.


Just trying to get everything I need before I head out there. If you see something else I might have missed let me know.


Cheers.

 

[Susquatch]

Hi @Perry

I think you will find its still a push/pull system. A lot of the newer Openers don't have a full chain loop. Instead a Chain is only used on half the system and a cable handles the other half. The cable wraps around the pulley at the garage door end and the chain wraps around the sprocket at the opener end. The opener only ever sees chain and the pulley only ever sees cable. But it's still a full loop.

Its quieter and cheaper that way.

 

[Perry]

Merry Christmas and Happy New Year Susquatch.

This is a screen shot from the link for the video above. This unit actually pushes the chain down the rail to close door and pull the chain to open it. (There is no pulley at the garage door end. )

 

[Susquatch]

Same to you Perry!

I can't imagine how pushing a chain could close a door, nor why a dogs breakfast of a chain track like that makes sense, but who knows! Stranger things happen in this world every day!

 

[combustable herbage]

I just happen to have these, found on a walk I could never leave metal like that just lying at the end of someone's driveway.
Free to you if it can help someone out I am in Ottawa, willing to ship it out.

 

[Doggggboy]

Same to you Perry!

I can't imagine how pushing a chain could close a door, nor why a dogs breakfast of a chain track like that makes sense, but who knows! Stranger things happen in this world every day!

If the roller chain was constrained by an enclosure, wouldn't it act much like a solid rod?

 

[Former Member]

I believe I have the same operator. They work well.

 

[Perry]

Thank you combustable herbage. (I wouldn't walk by that either. ) I'm not too sure if it would be worth shipping it. Something will fall into place.

@Doggggboy . I was thinking the same thing. Will be interesting to see this thing in real life.

 

[Susquatch]

If the roller chain was constrained by an enclosure, wouldn't it act much like a solid rod?

I suppose, but then the enclosure would have to constrain it all the way to the door and at that point the enclosure is what opens the door.

Im not saying it can't be done. Just that I'm not seeing it. Somedays that ain't saying much.

Maybe the spring is deliberately weak so the chain lifts and "lowers" the door against its weight?

 

[Former Member]

If you've ever assembled a garage door, the springs (or counter balance) is not weak or light it is the exact same as the doors themselves. (This should be a hint, if you haven't already figured out the system).

This works when adjusted properly the door stops at any position in the opening (hint.....counter balanced) and when opening or closing it feels like there is almost no effort required (hint) other than friction.

This is why a simple push or pull by a chain in a flimsy formed channel works as all that is required is to over come is friction in either direction.

So.....safety lesson, these things (springs) have a lot of stored energy in them, if they fail, well I don't want to be near. When do they fail most often? Generally when you are messing with them and you are close. Enjoy the videos

.

Play safe we have enough dangers in the shop.

 

[Dabbler]

@Perry, I have an extra in the yard. I'll drop by today (28th)

 

[Perry]

@Dabbler
Thank you J. No rush. I'm up late this evening. Probably be sleeping in tomorrow. I won't be heading out to try a repair for a least a couple days.

 

[Susquatch]

This is why a simple push or pull by a chain in a flimsy formed channel works as all that is required is to over come is friction in either direction.

Yes, I've both installed and repaired many doors in my time. Balanced is a good way to describe the way they are typically installed.

To be clear here, I am not arguing about this chain affair. I am just struggling to understand how it works.

Inquiring minds have a need to know such things.

In my mind, an unconstrained chain can only pull, it cannot push. A constrained chain in a channel can both push and pull. But a channel cannot follow a moving door. So how does the chain continue to push when it no longer has a channel to constrain it?

That's why I suggested that maybe in this particular installation the door isn't balanced and rather is biased toward closing. That way, a chain can let it go down slowly instead of pushing it.

A link to an installation procedure would probably help me understand if anyone has one.

 

[Former Member]

Yes, I've both installed and repaired many doors in my time. Balanced is a good way to describe the way they are typically installed.

To be clear here, I am not arguing about this chain affair. I am just struggling to understand how it works.

Inquiring minds have a need to know such things.

In my mind, an unconstrained chain can only pull, it cannot push. A constrained chain in a channel can both push and pull. But a channel cannot follow a moving door. So how does the chain continue to push when it no longer has a channel to constrain it?

That's why I suggested that maybe in this particular installation the door isn't balanced and rather is biased toward closing. That way, a chain can let it go down slowly instead of pushing it.

A link to an installation procedure would probably help me understand if anyone has one.

Since I have the same operator, the chain is constrained within the channel which acts as the guide for the shoe which the bar the moves the door attaches to. Don't forget unconstrained end is at the end is without any load so no constraint is required just a place for the excess chain to coil up when the door is in the up position.

You are over thinking it and tripping yourself up.

 

[Susquatch]

the chain is constrained within the channel which acts as the guide for the shoe which the bar the moves the door attaches to.

Ah, I see. So the channel for the chain isn't really an enclosed tube. It has a slot in it for the shoe that drives the door.

I think I get it now.

Still, I think I prefer the continuous loop design - much less friction and less to go wrong. But if it works, it works!

 

[Former Member]

Ah, I see. So the channel for the chain isn't really an enclosed tube. It has a slot in it for the shoe that drives the door.

I think I get it now.

Still, I think I prefer the continuous loop design - much less friction and less to go wrong. But if it works, it works!

The loop systems are quieter hence sold at a high price, overall IMHO for residential doors unless you have a living space above both do exactly the same thing.

Commercial doors there are better systems.

 

[Susquatch]

Commercial doors there are better systems.

I have Lift Master Commercial Openers on all 4 doors (2 large tractor doors & 2 small car doors) on the shop/barn. Love them. No drive chain or overhead motor. They drive the axle shaft for the door directly. They are quiet, smooth, and smell of quality. I'd do them on the garage too if they didn't cost so much.