Q: The chain on my garage door opener broke. What should i do?
A: A chain drive garage door opener uses a chain and sprocket drive to open door. Just like a bicycle. Other types of openers use a rubber belt instead of a chain some use a screw drive.
chain is hanging down?
If a chain is hanging down from the opener then something has broken. The sprocket that turns the chain commonly break off and will make the chain hang down. The plastic wheel or sprocket at the front of opener where it attaches above garage door will break and fall apart. causing the same effect. Now i have never seen the chain itself break apart. They are far too strong. But the places where the chain attaches to the opener can break. Now most opener manufacturers sell their openers to the public at Home Depot, Lowes, Sears etc.. These openers are designed for homeowners to install themselves. These openers sometimes come with a chain that has a metal cable attached. So its half chain and half cable. These types will commonly break where the cable attaches to the actual chain. This is caused by too much stress or most commonly rust.
sprocket has broken off?
If your sprocket has broken off of the top of the unit than the chain was too tight when opener was installed. You will need a gear and sprocket replacement inside the unit. Also for the wheel or sprocket at the front will need to be replaced. A cable chain combo is easily fixable by reattaching cable to the chain. If the chain broke away from where it attaches to the opener than those parts will need replacement.
In the past I have worked for home warranty companies that repair appliances in your home when they break down. I will tell you the most common malfunction on an chain drive opener is a worn out or broken gear and sprocket assembly. I had to have at least 5 of these kits on my truck every day. All the other causes i have just explained are not very common at all.
These issues need to be fixed by a technician. Attempting to open the cover of opener unit can void warranties you may have. And unless if you know what you’re doing you are not going to be able to fix it.