Tests simulate harsh environments

During a visit to Caterpillar's Engine Systems Technologies and Solutions laboratory in Mossville, IL, I met with Stephen Bolton, director of sales and marketing, and Russell (Rob) Graze, senior engineering specialist. Our conversation focused on the facility's harsh environment testing, since all automotive and aerospace engines must perform in severe conditions.

Caterpillar (CAT) delivers engines, transmissions, and power trains to other OEMs. While most of its customers work on commercial vehicle applications, the company also delivers equipment for military applications. The technical center creates test protocols based on customer requirements, and it performs testing, product development, and evaluation processes that qualify parts and systems for internal consumption and external sale.

Before embarking on our tour of the facility, Bolton commented, “Test engineers and technicians who work at this facility are internally driven. We operate as a microcosmic culture within the larger CAT culture. Self-provoked innovation defines our thought processes.”

For altitude tests, the company's engineers combine a 150-year old technology (steam) with modern capabilities. Steam is injected into the engine test cell exhaust header in order to simulate altitude conditions from 500 to 15,000 ft. The engineers can then parse the recorded data to assess engine performance across the full range of altitude capability.

For example, pressure can vary from 100 kPa at sea level to 50 kPa at higher elevations. Without exhaustive lab development at accurately simulated altitude levels, a product could perform poorly due to lack of power or response, component failure, or elevated emissions levels.

Fig. 1 The C175 locomotive engine goes through a test that accelerates wear and tear through prolonged cold stress. Courtesy of Caterpillar.

Along the falling temperature thresholds, extreme operation characteristics such as “start to full throttle” determine the potential for unacceptable results. For example, in evaluating the lube system's performance, the engineers monitor and measure characteristics such as the structural integrity of the oil filter housing and the center support tube, the oil pump priming delay, the oil pump bypass valve motion response, and the oil pressure at multiple engine locations.

When the brutal test sequence ends, engineers disassemble the engine to observe and record damage such as piston scuffing, bearing distress (excessive wear), and the effects of little-to-no lubrication on moving parts. The accelerated exposure to extreme conditions yields data that can assist the engineers in redesigning a component or projecting engine life.

Fig. 2 Tilt test measures engine performance at various angles up to an extreme of 45°. Courtesy of Caterpillar.

In summarizing the CAT engineers' efforts, Graze said, “We are serial innovators who seek to capitalize on narrow windows of economic opportunity. Despite working in a mature culture with existing product lines, we seek, develop, and refine new test methods that prove the products' mettle.”