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BUICK's 1956 twin-turbine Dynaflow transmission incorporates a fixed-blade stator between the two turbine elements. Added to the twin turbine (introduced in 1953) and the variable-pitch stator (introduced in 1955), the author says, this has made an important contribution to reduction in engine rpm, increased low-end performance, and improved efficiency. Stall ratio has been increased from 2.45/1 to 3.5/1, and “getaway” on low-end car performance has improved.

BEGINNING with descriptions of some past and present transmission designs, this paper goes on to describe the twin turbine Dynaflow transmission used in the 1953 Buick models. This design uses the torque multiplying characteristics of a planetary gear set and a hydro-kinetic torque converter while retaining the smooth, uninterrupted power flow typical of a fluid torque converter. A unique feature of this Dynaflow torque converter is that all the power transferred is through the gear set and first turbine at low speeds and gradually and smoothly diminishes as the power transferred through the second turbine increases until it does all the work at higher speeds. Several vector diagrams analyzing the driving and reaction torques and forces aid in explaining the operation of the twin turbine Dynaflow.