Gears, Clutches and Bands

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Gears, Clutches and Bands
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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)

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Simpson Gearset

• Made up of two simple planetary gearsets with a
  common sun gear
• Most commonly used arrangement

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Raveneaux Gearset

• Used in Powerglide, AOD, AMX, and some import
  transmissions
• Contains
• 1 ring gear
• 2 sets of planet gears
• 2 sun gears

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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.
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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

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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)

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Clutches
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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
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Bands
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Servos
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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

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Sprag
Torque Applied
Freewheeling Sprag
Locked Sprag
Torque Applied
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Roller-clutch
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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

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Clutch and Band Application Charts (700-R4)