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Ultimate successful measurement of riding-qualities is indicated by the design and construction of several new accelerometers. Experimental work with these new instruments has served to emphasize the desirable and the undesirable instrument-characteristics essential to accuracy, and thrown light upon some conflicting results heretofore obtained. One of the chief detriments to the development of accurate riding-qualities instruments has been the lack of satisfactory calibration. In the past, space-time curves have been used largely for calibration but, from the viewpoint of accuracy, these curves generally are acknowledged to be unsatisfactory. An elaborate machine has been constructed which will produce simple harmonic-motion to a very high degree of accuracy.

AN accelerometer of the contact type, that employs a new means of suspending the weight, has been developed which is said to eliminate all the contact error and troubles previously experienced with this type of instrument. A counter of sufficient speed to count accurately the accelerations which occur in road service has been developed also, and a complete instrument comprising six elements has been constructed and is described. Due to the relatively small size of the accelerometer and to its remote connection with the counter, the instrument can be mounted on a vehicle axle or on any other portion of the vehicle desired. This enables measurement to be made of the accelerations transmitted through the tires alone, through the tires and springs, or, if desired, through the tires, springs, body, and seat cushions.

METHODS are outlined for measuring the characteristics of tires that affect riding-qualities, and typical curves showing rate of deflection and contact area versus tire size are presented. Coordination of service performance with simple laboratory tests is illustrated. Means of securing the inter-effect of tires and springs are outlined and curves of typical axle-body frequency versus tire size are shown. Use of the solenoid accelerometer in conjunction with equipment for interpretation of physical effect of accelerations is suggested for service tests. Secondary riding-quality factors such as tire traction, horsepower and rim diameter are discussed and numerous others mentioned. The influence of tread design and other factors of tire design is indicated.

THE results of an extensive research in motorcar suspension fundamentals are presented with a description of a new-type spring member using air as the load-carrying means. Methods of actually realizing extremely low spring rates with attendant comfort to the passenger are shown. Shock absorption and anti-body-roll devices are incorporated in, and function as integral parts of, the new suspension. A series of new tools are presented for the chassis engineer's consideration in designing better riding comfort into the new car. These include in a simple, practical light-weight unit, variation of spring rate with wheel position, approximate aperiodic body damping, body roll reduced to better than that secured with high-rate springs, wide range of load capacity with practically constant body frequency, and ability to adjust wheel position to the optimum point. Typical applications are illustrated together with numerous curves outlining the stated characteristics.