Identified Skid Steer Root Cause

Identified Skid Steer Root Cause

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Shainin method used to find root cause of skid steer problem

Fig 1: Skid Steer Valve


My company produced over 15,000 skid steer loader valves per year in a production cell that ran at max. capacity three shifts, seven days per year. We did keep a few days buffer inventory on hand, but any production downtime lasting longer than that put us at risk of putting our customer line-down.

I received a desperate call from the production manager asking for my help. She informed me that they had lost a full shift of production due to a quality problem with no sign that the root cause of the problem was being identified.


I suggested that they abandon the time consuming¬† speculate – validate approach they had been using and instead use an approach popularized by Dorian Shainin called “talking to the parts”.

We quickly determined that the family of variation was unit to unit. We identified “best of best” and “worst of worst” sample and conducted a component search study. The study showed that the root cause was related to main casted body.

We disassembled the samples and ran a paired comparison study to identify the specific root cause factor.


Five factors were studied and one – flycut 4 – was found to be the significant factor. The machining group was informed of the problem and they quickly determined that an expandable grooving tool was intermittently failing to retract causing the flycut problem.

The tool was repaired and the problem went away.

Shainin component search found root cause

FIg 2: Shainin Component Search - Skid Steer Root Cause

paired comparison study identified root cause

Fig 3: Paired Comparision Study - Skid Steer Root Cause