AUTOMATIC TRANSMISSION # 1

INTRODUCTION

The main components that an automatic transmission include:-

•  Torque Converter
•  Planetary Gears set
•  Hydraulic unit

1. Planetary Gear Sets which are the mechanical systems that provide the various forward gear ratios as well as reverse.
2. The Hydraulic System which uses a special transmission fluid sent under pressure by an Oil Pump through the Valve.
3. Holing devices ,Body to control the Clutches and the Bands in order to control the planetary gear sets.
4. The Torque Converter which acts like a clutch to allow the vehicle to come to a stop in gear while the engine is still
   running.
5. The Governor and the Modulator or Throttle Cable that monitor speed and throttle position in order to determine when
   to shift.

   Planetary Gears set 

    
    The basic planetary gear set consists of a sun gear, a ring gear and two or more planet gears, all remaining in constant mesh. The planet gears are connected to each other through a common carrier which allows the gears to spin on shafts
   called "pinions" which are attached to the carrier.
    
   
   

   

   WORKING

   The input shaft is connected to the ring gear (Blue), The Output shaft is connected to the planet carrier (Green) which is also connected to a "Multi-disk" clutch pack. The sun gear is connected to a drum (yellow) which is also connected to the other half of the clutch pack. Surrounding the outside of the drum is a band (red) that can be tightened around the drum when required to prevent the drum with the attached sun gear from turning.

    The clutch pack is used, in this instance, to lock the planet carrier with the sun gear forcing both to turn at the same speed. If both the clutch pack and the band were released, the system would be in neutral. Turning the input shaft would turn the planet gears
   against the sun gear, but since nothing is holding the sun gear, it will just spin free and have no effect on the output shaft. To place the unit in first gear, the band is applied to hold the sun gear from moving. To shift from first to high gear, the band is released and the clutch is applied causing the output shaft to turn at the same speed as the input shaft

    Clutch Packs

   A clutch pack consists of alternating disks that fit inside a clutch drum. Half of the disks are steel and have splines that fit into groves on the inside of the drum. The other half have a friction material bonded to their surface and have splines on the inside edge that fit groves on the outer surface of the adjoining hub. There is a piston inside the drum that is activated by oil pressure at the appropriate
   time to squeeze the clutch pack together so that the two
   components become locked and turn as one.
      
   
   
   
   
   TO BE CONTINUE .. AUTOMATIC TRANSMISSION #2