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The General Motors Research Laboratories has installed a data acquisition and control computer to be time-shared with a variety of test programs. These include vehicle emissions evaluations, safety studies, transmission investigations, metallurgical processes and materials developments. Many special interface systems have been designed to enhance the computer's compatibility with a variety of test requirements. Expandable remote scanning systems have been developed and manual input and computer display systems were designed to minimize the engineer-computer communication problem. Special vehicle emissions programs were developed utilizing the basic hardware and software systems projected for the overall Research Laboratories operation.

Two techniques were investigated to reduce the emissions of oxides of nitrogen from a conventional regenerative gas turbine burner that involved only minor changes to the burner configuration and did not impair overall burner and engine performances. These methods were to vary the primary zone equivalence ratio and to shorten the residence time of the gas in the primary zone. Significant reductions in nitric oxide emissions were obtained by applying both methods, singly and in various combinations with one another, to the burner of the General Motors GT-309 vehicular regenerative gas turbine. Reductions in emissions that were measured on a single burner test facility at simulated engine steady-state conditions were confirmed when operating a GT-309 gas turbine powered vehicle over the HEW passenger car emission test cycle.

Exhaust emission tests run on an engine dynamometer are compared with those run on a chassis dynamometer. The worst case average difference between the chassis and engine dynamometer mass emissions, obtained over a period of 6 months, was less than 7%. The elimination of the driver, vehicle, and chassis dynamometer yielded significant improvement in test reproducibility with respect to carbon monoxide and oxides of nitrogen. A digital computer was used to control speed and throttle position of the engine dynamometer experiments. No transmission was used. The computer and engine dynamometer duplicated transient effects of transmission, vehicle, and chassis dynamometer.

Understanding obtained through a research study of corrosion of decorative chromium plating systems is reviewed. From this knowledge, the development of an electrolytic corrosion test (the EC test) is traced. Measurements of corrosion sites show that electrolysis for 2 min (6 min elapsed time) in the EC test produces corrosion sites more like those from one year of Detroit service than those produced in 16 h of CASS test exposure. The EC test has been employed for four years with satisfactory results as a monitor of durability of automotive parts plated in a production line. The paper outlines the mechanism by which nickel corrodes, describes the EC test equipment, and gives the results of an evaluation made by GM production personnel.

Automotive rear axle gear noise is characterized by a tonal peak of several mph bandwidth, usually in the 40-70 mph speed range. A study of the mass-elastic system of rear axle gears predicts the existence of a nearly vertical resonance of the pinion, relative to its supports near the frequency of the observed noise peak. Experimental studies of a variety of rear axles confirm the existence of this vibration peak and its coincidence with the observed noise. The magnitude of the various orders of gear meshing quality resultant from eccentricities, wobble, heat-treatment distortion and higher harmonics can be assessed by monitoring the amplitude of this resonance at specified gear meshing frequencies.