IR Troubleshooting on Hydraulic Systems

The predictive technology team at DMAX, Ltd. consists of a mechanical technician and an electrical technician. We primarily use the IR camera to run predictive routes on electrical panels, buss plugs, and motors. Occasionally, we are called to the plant floor to help troubleshoot a problem. This paper discusses a trouble call on a hydraulic system that supports one of our larger machines.

DMAX, Ltd. builds the Duramax Diesel engine for use in General Motors heavy duty trucks. At our facility the engine block, head, crank, and connecting rod are machined. These parts are used in our assembly area where we build and test the engine. The problem occurred on a cylinder block line transfer machine that is 54' x 30' consisting of 5 cutting stations, 2 rotate stations, a gage station, check station and 5 idle stations. Most of the cutting stations have a left and right side. Each cutting station either bores, chamfers, or mills the cylinder block. After each station finishes a cycle, the machine then transfers the cylinder block to the next station. Hydraulic cylinders are used to transfer the blocks as well as rotate them and clamp the part when it is being machined. Hydraulic cylinders are also used in several stations to assist the large cutting heads as they rise and lower. This hydraulic system has a 600 liter reservoir of hydraulic fluid. The OEM has stated that the maximum system temperature should be no higher than 120°F (49°C) when running at a normal pressure of 1200 psig. The system has a high temperature fault that is set at 117°F (47°C). The OEM used yellow zinc dichromate heavy walled steel tubing to distribute the hydraulic fluid to the desired components on the machine. There are several supply and return lines running to each station as well as to the large cylinders used to transfer the blocks as they are machined.

Electricians from the cylinder block line had been called to this operation numerous times to reset high temperature faults on the hydraulic system. The electricians asked the mechanics to check the system for any abnormalities. All pressures and flows were found to be within OEM specification. The electricians also wanted to verify that the actual temperature in the hydraulic system matched the thermal couple reading. We checked the temperature using our FLIR P65 and determined that the thermal couples where operating correctly (Fig. 1). The electricians did not want to spend their day resetting temperature faults. We needed a solution.

Hydraulic System Thermogram
Hydraulic System

Figure 1. Hydraulic system thermogram / visual pair