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Newer automatic transmission designs often use many pressure control solenoids, and sometimes allow the shift solenoids themselves to provide precise pressure control during shifts by ramping the solenoid on and off. The shift pressure affects the shift quality (too high a pressure will result in rough shifting; too low a pressure will cause ...
In some V8 installations a small control unit activates the kick down solenoid when the brake pedal is released so that the car moves off in 1st gear. Other attributes of this transmission include a 2-3 shift delay when the engine is cold in order to speed up catalyst warm-up. 4th gear is a 1:1 ratio.
A transmission solenoid or cylinoid is an electro-hydraulic valve that controls fluid flow into and throughout an automatic transmission. Solenoids can be normally open or normally closed. They operate via a voltage or current supplied by the transmission computer or controller.
The 4L80-E uses two shift solenoids, initially called Shift Solenoid A and Shift Solenoid B; they were later changed to comply with OBD-II regulations to 1-2 shift solenoid and 2-3 shift solenoid. By activating and deactivating the solenoids in a predetermined pattern by the PCM, four distinct gear ratios can be achieved.
Pushing a button on the shift control preselected the chosen gear. The electrical circuit was closed only after the driver fully depressed the clutch pedal. This energized the appropriate transmission mounted solenoids necessary for returning the transmission to neutral and then completing engagement of the preselected gear.
Shift blocking is a feature of automobile manual transmissions added to improve fuel economy ratings in the Corporate Average Fuel Economy (CAFE) system by preventing a driver from switching from first gear to second or third as would be done normally. A solenoid prevents the shifter from engaging these gears, forcing the driver to shift from ...
A variable force solenoid (VFS) is an electro-hydraulic device that controls pressure proportionally or inversely proportionally to a signal (voltage or current) obtained from the on-board controller of a powertrain. A low flow VFS is used as a signal level devices for transmission line pressure control or application of clutches.
A direct-shift gearbox (DSG, German: Direktschaltgetriebe [1]) [2] [3] is an electronically controlled, dual-clutch, [2] multiple-shaft, automatic gearbox, in either a transaxle or traditional transmission layout (depending on engine/drive configuration), with automated clutch operation, and with fully-automatic [2] or semi-manual gear selection.