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Transmissions with Gear Ratios and Clutch Schedules

Complex, switchable gearboxes that contain gears and clutches

In a real drivetrain, you couple an input or drive shaft to one of many outputs or driven shafts, or to one driven shaft with a choice of several gear ratios. The drivetrain then requires several clutches to switch between gears. You couple one of the driven shafts or one of the gear sets by engaging one of the clutches. You then switch to another output shaft or another gear ratio by disengaging one clutch and engaging another.

To use multiple gear sets simultaneously, you can also engage more than one clutch at a time. Transmissions engage multiple gear sets at the same time to produce a single effective gear ratio, or drive ratio. Changing gears requires disengaging one set of clutches and engaging another set. You can specify the set of clutches to engage and disengage for each gear ratio in a clutch schedule. Designing a clutch schedule and shaping and sequencing the clutch pressure signals frequently constitute the most difficult part of transmission design. A realistic transmission model must also include losses due to friction and imperfect gear meshing.

Simscape Blocks

4-Speed CR-CRClutch schedule for a four-speed carrier ring-carrier ring transmission
4-Speed RavigneauxClutch schedule for a four-speed Ravigneaux transmission
6-Speed LepelletierClutch schedule for a six-speed Lepelletier transmission
7-Speed LepelletierClutch schedule for a seven-speed Lepelletier transmission
8-SpeedClutch schedule for an eight-speed transmission
9-SpeedClutch schedule for a nine-speed transmission
10-SpeedClutch schedule for a 10-speed transmission
TransmissionAbstract transmission for system-level driveline modeling (Since R2022a)

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