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Gears, Clutches and Bands. Planetary Gearsets. Simple planetary gearsets contain three components Internal (ring) gear / (annulus gear) Planet gears (and carrier) Sun gear One component will be the drive member, one the driven, and one will be held (except direct drive and neutral).
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Planetary Gearsets • Simple planetary gearsets contain three components • Internal (ring) gear / (annulus gear) • Planet gears (and carrier) • Sun gear • One component will be the drive member, one the driven, and one will be held (except direct drive and neutral)
Simpson Gearset • Made up of two simple planetary gearsets with a common sun gear • Most commonly used arrangement
Raveneaux Gearset • Used in Powerglide, AOD, AMX, and some import transmissions • Contains: • 1 ring gear • 2 sets of planet gears • 2 sun gears
Raveneaux Gearset (Powerglide) When the transmission is in low gear, the band is holding the high gear drum stationary which also means that sun gear S1 (flange gear) is stationary. Input is provided through sun gear S2 (center gear). This input is transmitted to pinion gear P2/P3 then to pinion gear P1 (auxiliary gear). Since S1 is being held, P1 is driven around S1 along with the carrier and output shaft.
Planetary Control • For a planetary gearset to function properly various planetary components must be held and/or driven. Clutches and bands are used to accomplish this. • Clutches. • Can be used to drive or hold a component. • Band. • Can be used to hold a component. • One-way clutch or Sprag
Clutches • Can be used to drive or hold a member • When applied it may: • Lock a member of the gear train to a shaft or another member of the gear train • Lock a member of the gear train to the case • Made up of frictions, steels and an apply piston • Frictions are internally splined (generally) • Steels are externally splined (generally)
Bands Single Wrap • Used to hold a planetary component • Can NOT drive a planetary component • Applied by a servo • Types • Single Wrap • Double Wrap • Adjustment methods • “Torque & loosen” (727) • Gauge (700-R4) Double Wrap
One-Way Clutches • Types • Roller clutches • Uses cylindrical rollers and small springs • Sprags • Uses offset sprags • May be used to hold or drive a planetary member • Is mechanically, not hydraulically controlled • Allows the member to rotate freely in one direction and lock in the other • Directional – if installed upside down transmission will not work correctly
Sprag Torque Applied Freewheeling Sprag Locked Sprag Torque Applied
Clutch and Band Application Charts • Clutch and band application charts should be listed in the repair manual • They tell you which components are engaged in various gears • Very helpful when diagnosing a transmission fault which only occurs in specific gears