Secondary Leaf Springs

Recently one of our CVSA inspectors was inspecting a school bus. Upon completion a mechanic showed him a defective spring that the inspector overlooked. The inspector in question did some research and could not find any information in the PMVI or CVSA out of service criteria dealing with this issue. As a group we all looked into this and have not been able to find this listed as a defect in any material we have found. The secondary leaf spring has worn into the main leaf at the eye and looks as though it was manufactured that way. The part of the secondary leaf that contacts the main leaf over the eye is 3” and the main leaf is 4’’ wide. The local spring shop contacted the spring provider and was informed that this wear would not be an issue. As you can see in the pictures this clearly would soon be an issue. As a result of this inspection, this has resulted in 15 School Buses having their leaf springs being replaced in the last month in our area alone. Our Motor Vehicle Inspector has informed me that this is an issue on 2008 and newer International trucks. Freightliner has the same set up but the secondary spring is the full width of the main spring. Please feel free to contact me. Thank You, Walt McKinney

This was found on a school bus and has resulted in 15 School Buses having these springs replaced anlong with as many as 25 other International trucks. Their is a need to be able to inform the operators that there is an excessive amount of wear in their springs and alow them to address this issue.

We are looking for a minimum and maximum thickness. At what point would this wear become an issue.