We discovered an issue on our Hydraulic Power Unit Assembly line in which a Tool that the line uses to insert the Pick-Up tube into the Pump Body of the HPU had worn and therefore was not inserting the Pick-Up tube to the proper depth. This improper insertion would cause the Pick-Up tube to rest on the bottom of the fluid reservoir which in turn did not allow the ATF to flow as designed and the HPU’s would not function properly or at all. The failure was sporadic over several months of production starting mid-year 2019. While every HPU we manufacture is tested twice prior to completion and delivery to our Finished Goods department, our assembly and testing method was not designed to capture this type of failure.
Based on this discovery, we have implemented two new in-process quality inspection points that were designed specifically for this issue. One measures the insertion height of every Pick-Up tube using a Go / No Go gage and the second is a visual method in which a cutout reservoir is used for the operators to actually see clearance heights. The first inspection is used 100% and the second 25%. We have also mandated a Tool inspection and replacement policy that is verified on a monthly basis.
Should any HPU’s be discovered that experience this failure, it can be easily resolved by disconnecting power to the unit, removing the Lexan cover and unscrewing one side of the motor strap. Then carefully lift the motor assembly from the fluid reservoir (as not to spill ATF) to expose the Pick-Up tube. Once removed from the reservoir cutaway with either a snip or hack saw, approximately 1/16” to ¼” of the tube, making certain the opening is free off debris and then re-insert the unit back into the reservoir.
We apologize for any inconvenience this issue may have caused and are available for further guidance should you or your customers require it.