start Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 OBJECTIVES: After studying Chapter 101, the reader should be able to: • • • • Explain how apply drives function in an automatic transmission/transaxle Describe how clutches and bands work Discuss one-way clutches and how they are used Explain how shifts are controlled in an electronically controlled automatic transmission/transaxle Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: apply devices balanced valve check balls • clutch drum • clutch pack • clutch plates default gear force motors governor valve independent accumulator • integral accumulator Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: manual valve • multiple-disc clutch one-way clutch • one-way sprag clutch • one-way valve pressure control solenoids • pressure plate • pressure regulator valve • primary spring reaction member • rod servo • shift valve • sprags • strut transmission band • variable force solenoids (VFS) worm holes • worm tracks Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 APPLY DEVICES Apply devices are the mechanical assemblies that provide holding and driving forces. Automatic  transmissions typically use transmission bands, multiple­disc clutches, and one­way clutches Transmission bands are holding devices. While bands always provide a holding force, they cannot  provide a driving force The planetary gear set member held by the band is known as a reaction member A transmission band stops and holds one planetary gear set member so that another member can react  against the held member and develop output motion. The reaction member has a control surface for the  band to ride on known as a drum Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 The band provides holding force around the outside of the drum,  closing tightly to keep it from turning.  Transmission bands are made of cast iron or steel with friction  material lining the inside surface. Transmission design and  component size dictate the type of band used.  Figure 101–1 Gear set members are attached to a drum and are held stationary when the band applies Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Bands fall into one of two categories: Single­wrap Double­wrap  The single­wrap band is a simple one­piece design, while the  double­wrap band is a split band with overlapping ends Bands may also be classified as either flexible or fixed depending  on how well they hold their shape when they are off the drum Figure 101–2 Transmission bands come in several designs and thicknesses Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 HYDRAULIC SERVOS A hydraulically­operated piston that travels inside a machined cylinder bore applies the transmission band. This piston  and cylinder assembly is known as a servo A piston return spring normally holds the servo piston in its unapplied position. To apply the band, hydraulic fluid  under pressure enters the servo cylinder and acts on the piston The piston begins moving once hydraulic pressure overcomes spring force. A mechanical rod and linkage attaches to  the piston and connects it to the band. As the piston moves, the linkage applies the band by tightening it around the  drum See Figure 101–3.  Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 101–3 A servo uses hydraulic pressure to move a piston, which applies a band Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Servo Linkages  Servo rods and struts transfer the servo apply  force to the transmission band. Rods are round metal bars and struts  are flat metal plates. These may be used at either, or both, ends of  the band. Linkages connect the band to the servo or an anchor.  Figure 101–4 Notice that one end of the band is held stationary and the other end is attached to the servo Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Parking Brake before Parking Pawl To prevent possible damage to the transmission/transaxle case or other internal components, most experts agree that the parking brake should be applied before placing the gear selector into the park position, especially when parking on a hill This procedure keeps the weight of the vehicle from being exerted entirely on the parking pawl and makes it easier to move the gear selector out of the park position Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 TYPICAL TORQUE FLOW The General Motors 4L60­E can provide an example of how a  typical electronically shifted rear­wheel­drive automatic  transmission works.  Park and Neutral  With the gear selector level in P or N, there is  no torque flow through the gear set, even though the low­reverse  clutch applies in the 4L60­E. The clutch holds the reaction carrier  stationary; torque input to the gear set stops at the input housing The torque converter cover and impeller rotate clockwise at engine  speed to hydraulically drive the turbine and mechanically drive the  oil pump. The transmission input drum assembly rotates clockwise  at turbine speed to drive the gear set. Turbine speed is slightly less  than engine crankshaft speed.  Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 101–28 The General Motors 4L60-E electronically shifted rear-wheel-drive automatic transmission clutch, band, and solenoid application chart See the chart on Page 1310 of your textbook.  Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman Continued ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Overdrive First  With the gear selector lever in overdrive, the transmission starts off in first gear,  then upshifts into second, third, and fourth gears as the vehicle continues to accelerate To engage first gear, the forward clutch applies, transferring engine torque from the input shaft to  the input sun gear through the forward sprag clutch, and driving the sun gear clockwise With the input sun gear turning clockwise, the input pinion gears spin counterclockwise in the  stationary carrier and attempt to drive the input internal gear and reaction carrier counterclockwise.  The forward sprag clutch is holding, so the pinions walk clockwise inside the internal gear, turning  the input carrier clockwise. Then, the input carrier drives the output shaft clockwise in gear  reduction. See Figure 101–29 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 101–29 A 4L60-E torque flow in overdrive first gear Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Overdrive Second  As the vehicle continues to accelerate in the overdrive range, the  transmission upshifts to second gear by applying the 2–4 band The band holds the reverse drum, input shell, and reaction sun gear stationary. The forward  clutch remains applied, while the input shaft drives the input sun gear clockwise through the  forward sprag clutch As in first gear, the input sun gear rotates clockwise and drives the input pinions  counterclockwise. Since the 2–4 band is holding, the input pinions walk inside the internal  gear, driving the input carrier and output shaft clockwise in gear reduction See Figure 101–30 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 101–30 A 4L60-E torque flow in overdrive second gear Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Overdrive Third  To automatically upshift into third gear as the vehicle continues to accelerate, the  transmission releases the 2–4 band and applies the 3–4 clutch. Also, the forward clutch remains  applied so the input shaft drives the input sun gear clockwise through the forward sprag clutch.  Applying the 3–4 clutch connects the input shaft to the input internal gear, which drives the internal  gear clockwise at turbine speed. Now that two members of the input gear set—sun and internal—are  being driven at turbine speed, the gear set provides direct drive as it locks up and turns as a unit As long as the vehicle is accelerating in overdrive third, torque transfers through the planetary gear  set to the output shaft. There is no engine braking because the forward one­way clutch overruns and  allows the input sun gear to freewheel. See Figure 101–31 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 101–31 A 4L60-E torque flow in overdrive third gear Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Overdrive Fourth The transmission upshifts into fourth gear by applying the 2–4 band as the vehicle  continues to accelerate in overdrive range The 2–4 band holds the reverse drum and reaction sun gear stationary. Both the 3–4 and forward clutches  remain applied, and the input drum continues to drive the input internal gear clockwise This drives the reaction carrier clockwise, as well, since it is in common with the input internal gear As the carrier turns, the reaction pinions walk clockwise around the stationary reaction sun gear. This drives the reaction internal gear and output shaft clockwise at an  overdrive ratio See Figure 101–32 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 101–32 A 4L60-E torque flow in overdrive fourth gear Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Reverse  With the gear selector lever in reverse, the low­reverse clutch applies to drive the reaction  sun gear clockwise with the input shaft.  The reaction carrier and input internal gear are held stationary by the applied reverse input clutch.  This turns the reaction pinions counterclockwise and drives the carrier counterclockwise in gear  reduction.  In reverse gear, the input internal gear is held, while the input carrier is driven counterclockwise.  This causes the input pinions to rotate clockwise and drive the input sun gear counterclockwise.  However, the forward sprag clutch overruns, so the input gear set freewheels. See Figure 101–33 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 101–33 A 4L60-E torque flow in reverse Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY List three planetary gear set holding devices Describe how shift points are achieved with a hydraulically  shifted automatic transmission/transaxle Explain how solenoids are used to control the shifting on  electronically shifted automatic transmissions/transaxles Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 end Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 ... are flat metal plates. These may be used? ?at? ?either, or both, ends? ?of? ? the band. Linkages connect the band to the servo or an anchor.  Figure 101–4 Notice that one end of the band is held stationary... loaded ball check valve is an example? ?of? ?one type? ?of? ?one­way valve.  Valve operation is similar to that? ?of? ?a poppet valve. The spring holds the ball against its  seat? ?at? ?the inlet port until fluid pressure overcomes spring force to push the ball from its ... can be nylon, rubber, or some composite material as well. Which  material is used depends on the manufacturer and application. Steel  balls generally hold up better, but cause greater seat wear because  of? ?their hardness. The softer composite balls are easier on seats and