STEMCO Chooses ANCO to Deliver "Torture Chamber"
Seal Testing System
(ANCONEWS VOL. 6, NO. 2)

STEMCO of Longview Texas, a subsidiary of Coltec, is a major manufacturer of truck hub seals. These seals separate the truck axle bearing lubricating oil from harsh road conditions and contaminants. They must also accommodate manufacturing variations and vibration which cause eccentricity and relative oscillating motion between the rotating hub and stationary axle shaft. Until recently, seals were routinely replaced when the truck brakes were serviced, every 50 to 100 thousand miles. New brake designs do not require seal replacement upon brake servicing. This design change and new operating requirements, as well as demands for increased reliability, require longer lasting seals, with lives of 200 thousand miles or more. STEMCO's seal life target is 500 thousand miles.

STEMCO has contracted ANCO to provide an environmental and dynamic seal test system for evaluation of existing and improved seal products. The test parameters that the system can apply, control, and sense include:

Air temperature (-70 F to +250 F)

Water, salt water, and mud spray

Air blown dust and sand

Variable hub speed (0-1200 RPM)

Adjustable shaft to hub axial oscillation (0-0.1")

Variable shaft to hub oscillating freq. (0-20 Hz)

Adjustable shaft to hub eccentricity (+/- 0.04 ")

Oil temperature (electric heating up to 325 F)

Oil moisture content (100 -20,000 PPM)

Oil leakage from seal (Ultra Violet sensor)

Induced seal temperature

Induced seal torque (+/- 200 ft-lbs)

The test system has interchangeable shaft and hub inserts. These allow accommodation of almost any size seal (from 1.5 inch inside diameter to 8.0 inch outside diameter). The system is designed for hundreds of hours of unattended testing. Variable hub rotation and shaft reciprocation are provided by two Siemens AC motor Vector drives.

The test system is controlled and logged using a Siemens S7300 PLC, programmed and interrogated by a DELL PC using the CITEC graphics interface. The software allows operating in an automatic trip profile mode, and in an operator control mode. Extensive logging and system alarm and hold functions are provided. All data can be graphed. Burst high speed (200 samples/sec) and low speed data logging acquisition are possible.

Using the ANCO-supplied test system, STEMCO plans to document and enhance its product quality and reliability and meet ever more demanding industry requirements.