PRODUCT INFORMATION BULLETIN
GARAGE DOOR EXTENSION SPRINGS
SK7155, SK7157, SK7159
The best method to determine the cycle life of an extension spring is by keeping
records of when it was installed and what is the average usage per day.
Extension springs are manufactured with a cycle life of 10,000 cycles. One cycle
is calculated as (1 opening and 1 closing) of the door. Let's assume a door opens
and closes once in the morning, once at night, and 10 times on a weekend then the average
would be 20 cycles per week. This would mean an extension spring should last about
People use their doors more frequently in summer than winter and the average cycles per
year will change from one house to the other. Another factor that must be considered
is that the temperature inside a garage can affect the resistance to breakage of any
extension spring. Metal is known to expand and contract with changes in temperature.
Extreme cold can cause the wire to become more brittle resulting in breakage.
An extension spring will probably break in an un-heated garage quicker then a
heated one. It should be safe to say that with our Canadian climate an extension
spring would last between 8 to 10 years.
The normal function of an extension spring is to stretch on the closing cycle and to
return to a relaxed stage on the open. If the spring is stretched slightly in the
open position then it is being overworked and requires a cable adjustment. This will
increase the life expectancy of your extension spring.
It is also recommended that both springs be changed should one break.
The door may shift more to one side if only one spring is changed.
prevents damage if spring should break
If you've ever heard an extension spring
for an overhead garage door break, you know the force that's generated.
They never break when the door is open because the spring is slack.
Instead, they break only when the door is closed, because the
spring is fully extended. When it breaks, the flying piece(s)
can damage the inside of your garage or you car. Or worse,
you could be seriously injured or even killed if your in the wrong
place when the spring lets go.
To prevent this danger, install a new set
of springs with safety cables (Fig. A)(SK7136). Always replace
springs in pairs. If one breaks, the other is probably weak.
The safety cable's only job is to keep the
spring pieces from flying around the garage if the spring breaks.
make any repairs or adjustments to a garage door that has torsion
springs. A torsion spring is mounted on the wood framing
header above the garage door and is under hundreds of pounds of
pressure. It will cause serious injury if you try to work
on it. Call a professional garage door installer if your
door has torsion springs.
OPEN the garage
door completely. Clamp it open with locking pliers on the
track, or hold open with ladder. The spring and the lift
cable will hang freely once the door is open.
EXTENSION SPRING WITH SAFETY CABLE
REMOVE the pulley and spring from the
lift cable. If you forget how things go to-
gether, just look at the pulley, cable and
spring on the other side of the door.
the safety cable through the spring and secure
it to the hanger bracket. The front connection of the safety cable
(usually an eye screw or a lag screw) is attached to the door
header or the door track. Remember, the safety cable doesn't help
lift the door. It's there only to keep a broken spring in place.