CONTINOUS VARIABLE TRANSMISSIONC V TBY : Ziad Zohdy
Basics of Transmission• The job of the transmission is to change thespeed ratio between the engine and the wheels ofan automobile• The transmission uses a range of gears -- fromlow to high -- to make more effective use of theengines torque as driving conditions change. Thegears can be engaged manually or automatically.
Benefits of CVT Provide engine torque in optimum condition (roadloads / drive shaft torque) No shift clonk Transmission ratio can be adjusted continuously Better acceleration Improved fuel efficiency
CVT MAIN TYPES Pulley based CVT Toroidal CVT Hydrostatic CVT
Pulley based CVT The gear ratio is changed by moving the two sheavesof one pulley closer together and the two sheaves ofthe other pulley farther apart. The distance between the pulleys does not change and neither does the length of the belt so changing the gear ratio means both pulleys mustbe adjusted (one bigger, the other smaller)simultaneously in order to maintain the proper amountof tension on the belt.
Hydrostatic CVT Power transmitted by hydraulic fluid variable displacment pump& hydraulic motor• RotationalmotionENGINE• Fluid flowHYDROSTATICPUMP• RotationalmotionHYDROSTATICMOTOR
Hydrostatic CVT often,hydrostatic transmission is combined with aplanetary gearset and clutches to create a hybrid systemknown as a hydromechanical transmission. Hydromechanical transmissions transfer power from theengine to the wheels in three different modes At a low speed power is transmitted hydraulically at a high speed, power is transmitted mechanically Between these extremes, the transmission uses bothhydraulic and mechanical means to transfer power. Hydromechanical transmissions are ideal for heavy-dutyapplications, which is why they are common in agriculturaltractors