The Turboglide is a Chevrolet constant torque, continuously variable automatic transmission first offered as an option on Chevrolet V8 passenger cars for 1957. It consisted of a turbine-driven planetary gearbox with a 'switch pitch' dual-pitch torque converter stator. It had a die-cast aluminum transmission case, like Packard's Ultramatic of 1956. Turboglide cost about $50 more than the Powerglide 2-speed automatic. It was available in all V8-powered 1957-1961 Chevrolet models except the Corvette. General Motors produced 646,000 of these transmissions during its production. Concept The Turboglide was modeled along the lines of the concurrently-geared (as opposed to sequentially-geared) Buick Flight Pitch Dynaflow transmission, and operated very similarly. Using a five-element torque converter (pump, 3 turbines; low, intermediate, and direct ranges, and a dual stator), the Turboglide offered very smooth operation, as no shift occurred between ranges and hence there was no disruption in the flow of power. Concurrently-spinning turbines, each geared for the same torque multiplication as a different gear in a 3-speed unit, overlapped in effectively varying total power multiplication on a continuous basis. For extra acceleration at any road speed, the stator vanes could be directed to a steeper angle which raised the stall speed of the torque converter and increased torque multiplication, as well as directing the oil flow at the turbine for the next-lower range. The selector quadrant order was Park, Reverse, Neutral, Drive, Hill Retarder (early 1957 only) as P R N D Hr or Grade Retarder (late 1957–1961) as P R N D Gr. Some owners of the early 1957 models with the Turboglide transmission marked with HR [Hill Retarder] mistook the HR to mean High Range so the marking was changed early in the model year to Gr [Grade Retarder]. Operation The basis of the Turboglide's unique abilities was its five-element torque converter. Most automatic transmissions have a three-element torque converter, consisting of an impeller (an engine-driven pump); a turbine that rotates with the flywheel; a transmission-driven turbine that receives the energy of the oil propelled by the impeller, and a stator that redirects the recirculating oil so that it strikes the back side of impeller blades to assist the engine rotation and to recapture energy from the fast-moving oil. The stator is one of two things that gives to the torque converter its torque multiplication ability, allowing it to reduce the ratio for increasing the torque when the turbine is rotating slower than