Speed Queen FL - Picture of shock that failed

[jben]

I dissected the front shock that failed on my SQ FL. This is from the prior generation residential FL model AFN50FSP111TW01 from 2013.

We can see the spring broke in two places. When I first took it out, the two smaller sections where both wound up inside of that larger section. At first it looked like a spring that had another spring wound within; but with further review that was not the case, it's just the one spring.

There was an abundance of what appears to be a high-quality dark gray grease inside but most of it was removed before taking the picture. Lack of lubrication would not seem to be a contributing factor in the spring breakage - but why then ?. I don't know what caused that dark "ring" that showed up circling around the shock body.

I've noted that the subsequent and I believe still current Gen. of SQ FL are using a shock that has an external spring. I have no idea how or why the design change or what might be internal on these type shocks.

I did install a new replacement shock and it lifted and leveled the drum back into it's proper position, but have yet to put the machine back in service. Hopefully that will be done later this year.

 

[turbokinetic]

Springs often break due to metal fatigue beginning with a tiny flaw and then progresses to a full fracture separating the spring into multiple pieces. Often the metal hardness is wrong, the surface finish is poor, or there is some other imperfection from manufacturing which sets up the failure. If we could see the fracture faces of the end of the spring, it could tell more. 

 

When springs fail in the equipment I work on, often we have to analyze the root cause. It's really interesting.  It may be that the diameter of the spring was too small for the stresses imposed with the loads and speed of movement; therefore there was a high number of failures. That might be why the manufacturer went with a larger, less highly stressed external spring on the new design.