Posted June 2nd, 2017 at 11:48 am by Andrew Koetters
Leaf bumpers or push down bumper springs are recommended for use on residential standard lift applications when using a jackshaft opener, as well as certain commercial applications.
Normally, if space allows, a standard overhead rail type opener is used for standard lift systems. These openers pull/push on the door directly to raise and lower it. If more overhead space is required, or you desire a nice “clean” look, a jackshaft opener can be used. This type of opener mounts on the header, and raises/lowers the door by driving the torsion spring shaft directly. For residential systems, we recommend the Liftmaster 8500. This opener is designed and mainly used on high lift assemblies, but with the proper steps, can be used on a standard lift system.
When using this opener with standard lift tracks, the spring bumpers are necessary to ensure safe operation. This is because jackshaft openers rely on the door weight to keep tension on the cable. These bumpers mount to the back of the horizontal tracks and provide forward/downward force on the door when it is in the horizontal tracks.
If the door is in the up position with minimal weight pulling down, there is a slight risk of the opener turning the shaft, the door not moving, and the cable unwinding off the drum. There is then nothing to stop the door from crashing to the floor and causing damage or injury to anything or anyone in its way. To counter this, the bumpers provide constant force pushing the door down from the back, which should keep the cable taught.
The recommend Liftmaster 8500 opener comes standard with a cable tension monitor for safety. A common question we get from customers is whether or not the cable tension monitor on the jackshaft will be sufficient to stop the opener, and hold the door if the cables were to go slack. Generally, this should work, but we do not recommend relying on it 100%. The spring bumpers are relatively cheap insurance to guarantee that the door will work properly and safely.
If you are interested in using a jackshaft operator on your standard lift door, we suggest using these spring bumpers in order to prevent property damage or serious injury.