Garage door pulley wheels are used in the extension garage door system.
Diagramme of Garage door extension spring system

Garage Door Extension Spring System

The extension system can be used only for single doors. This is because tension springs are not strong enough to carry the heavier weight of a double door. They can carry weights of only up to 75kg. The door is lifted through the action of the the contraction of the springs.

Garage door pulley wheels

Garage door pulley wheels
Each garage door cable glides over 2 pulley wheels. One pulley wheel is attached to the spring while the other one is situated near the top of the garage door. As the springs contract they pull the cables and therefore the door lifts.
garage door extension spring system

Pulley Wheel Problems

There are two ways in which pulley wheels break and cause problems with the opening and closing of a garage door. Firstly, when the ball bearings wear down. As a result of this, the pulley starts to scrape against the track of the garage door. Secondly, when the rivets break and the pulley pulls apart. Because of this, the door cable gets stuck. Often when a garage door is not opening or closing properly this is because of pulley wheels that have broken or become worn. Usually what will happen is that the garage door closes partially and then it opens again. The door sticks and can become jammed altogether. You will also hear a scraping sound if it can be opened and closed. One of the first signs of a worn or broken pulley is a garage door cable that is frayed or broken. Another indication of pulley wheel problems is an extension spring that is hanging. Replacing an extension spring pulley wheels is dangerous and should be handled only by a trained technician who also has the correct tools. Always ensure all items, cars and people are out of the garage while garage door repair work is being done in order to avoid damage to property or injury to people.

Cable Problems

Another problem that can occur is that the cable comes off the pulley wheel but it doesn’t actually break. This can happen for a number of reasons.
  • Age – over time the cable becomes twisted and moves up and over the edge of the pulley.
  • Uneven weight or imbalance when the door is opening or closing.
  • Problems with a spring such as: it breaks, there is a loss in spring tension, or the spring tension is uneven.
  • When the garage door is slammed too hard closed, the cable can “jump off” the pulley.
  • Insufficient maintenance e.g dirt build-up or using the incorrect lubricant