Posted November 8th, 2021 at 12:53 pm by Dan Musick
The old Allister and Allstar openers use two black sprockets. The one above the motorhead moves to activate the limit switches as the limit dogs reach their shut-off points.
The one above the garage door acts as an idler. Raynor also used similar black sprockets just for idlers above the door.
Over the years the chains stretch and loosen. As a result, the pitch of the chain breaks the teeth on the sprocket. In order to prevent this problem, Allstar stopped producing the black sprockets and replaced them with black pulleys.
In 2021 Allstar quit selling parts for their openers, so now we carry a white idler pulley that has a similar shape as the black pulley. The outside diameter is 2 1/2 inches, and the bolt hole for securing the pulley to the end bracket is 1/2 inch. These pulleys don’t break when the chain loosens.
If the sprocket above the door breaks, you can replace the black sprocket with the pulley. However, if the sprocket above the motorhead breaks, you will need to get a new opener. Those sprockets are no longer available.