In 1992, Pierre A. G. Lepelletier proposed three degrees of freedom epicyclic gearset. These are now known as Lepelletier planetary gearset or Lepelletier gear mechanisms. The Lepelletier gearbox is constructed by connecting a planetary gear to a Ravigneaux gear.

History

The transmission was the first of its kind to offer additional gear ratios by combining serial and parallel power flow without increasing the complexity of the design.

Due to these advantages, this gearset concept became widely used in automatic vehicle transmissions. ZF was the first to start series production in 2000. Aisin/Toyota, Ford, and GM followed in 2005. For the first time, the construction costs could be reduced compared to the respective predecessor models.

Planetary gearset concept

Improved fuel economy

The main objective in replacing the predecessor model was to improve vehicle fuel economy with extra speeds and a wider gear span to allow the engine speed level to be lowered (downspeeding), which is a decisive factor in improving energy efficiency and thus reducing fuel consumption. In addition, the lower engine speed level improves the noise-vibration-harshness comfort and the exterior noise is reduced.

It has a torque converter lock-up for all 6 forward gears, which can be fully disengage when stationary, largely closing the fuel efficiency gap between vehicles with automatic and manual transmissions.

Reduced manufacturing complexity

In order to avoid a further increase in manufacturing complexity while expanding the number of gear ratios, all major manufacturers switched from the conventional design method—in which the planetary gearset concept was limited to a purely serial or in-line power flow—to a more modern design method that utilizes a planetary gearset concept with combined parallel and serial power flow. This was only possible thanks to computer-aided design and has resulted in a globally patented gearset concept. The resulting progress is reflected in a better ratio of the number of gears to the number of components used compared to existing layouts.

Planetary gearset concept: manufacturing complexity
With AssessmentOutput: Gear RatiosInnovation Elasticity Δ Output : Δ InputInput: Main Components
TotalGearsetsBrakesClutches
6HP Ref. Objectn O 1 {\displaystyle n_{O1}} n O 2 {\displaystyle n_{O2}}Topicn I = n G + {\displaystyle n_{I}=n_{G}+} n B + n C {\displaystyle n_{B}+n_{C}}n G 1 {\displaystyle n_{G1}} n G 2 {\displaystyle n_{G2}}n B 1 {\displaystyle n_{B1}} n B 2 {\displaystyle n_{B2}}n C 1 {\displaystyle n_{C1}} n C 2 {\displaystyle n_{C2}}
Δ Numbern O 1 − n O 2 {\displaystyle n_{O1}-n_{O2}}n I 1 − n I 2 {\displaystyle n_{I1}-n_{I2}}n G 1 − n G 2 {\displaystyle n_{G1}-n_{G2}}n B 1 − n B 2 {\displaystyle n_{B1}-n_{B2}}n C 1 − n C 2 {\displaystyle n_{C1}-n_{C2}}
Relative ΔΔ Output n O 1 − n O 2 n O 2 {\displaystyle {\tfrac {n_{O1}-n_{O2}}{n_{O2}}}}n O 1 − n O 2 n O 2 : n I 1 − n I 2 n I 2 {\displaystyle {\tfrac {n_{O1}-n_{O2}}{n_{O2}}}:{\tfrac {n_{I1}-n_{I2}}{n_{I2}}}} = n O 1 − n O 2 n O 2 {\displaystyle ={\tfrac {n_{O1}-n_{O2}}{n_{O2}}}}·n I 2 n I 1 − n I 2 {\displaystyle {\tfrac {n_{I2}}{n_{I1}-n_{I2}}}}Δ Input n I 1 − n I 2 n I 2 {\displaystyle {\tfrac {n_{I1}-n_{I2}}{n_{I2}}}}n G 1 − n G 2 n G 2 {\displaystyle {\tfrac {n_{G1}-n_{G2}}{n_{G2}}}}n B 1 − n B 2 n B 2 {\displaystyle {\tfrac {n_{B1}-n_{B2}}{n_{B2}}}}n C 1 − n C 2 n C 2 {\displaystyle {\tfrac {n_{C1}-n_{C2}}{n_{C2}}}}
6HP 5HP 24/306 5Progress8 93 32 33 3
Δ Number1-10-10
Relative Δ0.200 1 5 {\displaystyle {\tfrac {1}{5}}}−1.800 1 5 : − 1 9 = 1 5 {\displaystyle {\tfrac {1}{5}}:{\tfrac {-1}{9}}={\tfrac {1}{5}}}·− 9 1 = − 9 5 {\displaystyle {\tfrac {-9}{1}}={\tfrac {-9}{5}}}−0.111 − 1 9 {\displaystyle {\tfrac {-1}{9}}}0.000 0 3 {\displaystyle {\tfrac {0}{3}}}−0.333 − 1 3 {\displaystyle {\tfrac {-1}{3}}}0.000 0 3 {\displaystyle {\tfrac {0}{3}}}
6HP 5HP 18/196 5Progress8 103 32 33 4
Δ Number1-20-1-1
Relative Δ0.200 1 5 {\displaystyle {\tfrac {1}{5}}}−1.000 1 5 : − 1 5 = 1 5 {\displaystyle {\tfrac {1}{5}}:{\tfrac {-1}{5}}={\tfrac {1}{5}}}·− 5 1 = − 1 1 {\displaystyle {\tfrac {-5}{1}}={\tfrac {-1}{1}}}−0.200 − 1 5 {\displaystyle {\tfrac {-1}{5}}}0.000 0 3 {\displaystyle {\tfrac {0}{3}}}−0.333 − 1 3 {\displaystyle {\tfrac {-1}{3}}}−0.250 − 1 4 {\displaystyle {\tfrac {-1}{4}}}
6HP 3-Speed6 3Market Position8 73 22 33 2
Δ Number311-11
Relative Δ1.000 1 1 {\displaystyle {\tfrac {1}{1}}}7.000 1 1 : 1 7 = 1 1 {\displaystyle {\tfrac {1}{1}}:{\tfrac {1}{7}}={\tfrac {1}{1}}}·7 1 = 7 1 {\displaystyle {\tfrac {7}{1}}={\tfrac {7}{1}}}0.143 1 7 {\displaystyle {\tfrac {1}{7}}}0.500 1 2 {\displaystyle {\tfrac {1}{2}}}−0.333 − 1 3 {\displaystyle {\tfrac {-1}{3}}}0.500 1 2 {\displaystyle {\tfrac {1}{2}}}

No use of 5th gear from the original concept

The Lepelletier gearset concept actually provides 7 forward gears. However, the 5th gear, which is configured as a direct gear (ratio 1.00) in this configuration, requires a releaseable brake for S1 (sun gear of the first gearset, which is the simple one) and thus a 6th shifting element without any corresponding benefit: with ratios of approximately 1.15 and 0.85, the 4th and 6th gears are so close together that the 5th gear can easily be dispensed with. This means that all manufacturers can manage with 5 shifting elements and all transmissions built have 6 gear ratios instead of the possible 7.

Quality

The ratios of the 6 gears are nicely evenly distributed in all versions. Exceptions are the large step from 1st to 2nd gear and the almost geometric steps from 3rd to 4th to 5th gear. They cannot be eliminated without affecting all other gears. As the large step is shifted due to the large span to a lower speed range than with conventional gearboxes, it is less significant. As the gear steps are smaller overall due to the additional gear(s), the geometric gear steps are still smaller than the corresponding gear steps of conventional gearboxes. Overall, therefore, the weaknesses are not overly significant. As the selected gearset concept saves up to 2 components compared to 5-speed transmissions, the advantages clearly outweigh the disadvantages.

The layout brings the ability to shift in a non-sequential manner – going from gear 6 to gear 2 in extreme situations simply by changing one shift element (actuating clutch E and releasing brake A).

Planetary gearset concept: gear ratio quality
In-Depth Analysis With Assessment And Torque Ratio And Efficiency CalculationPlanetary Gearset: Teeth Lepelletier Gear MechanismCountNomi- nal Effec- tiveCen- ter
SimpleRavigneauxAvg.
Make ModelVersion First DeliveryS1 R1S2 R2S3 R3Brakes ClutchesRatio SpanGear Step
GearR123456
Gear Ratioi R {\displaystyle {i_{R}}}i 1 {\displaystyle {i_{1}}}i 2 {\displaystyle {i_{2}}}i 3 {\displaystyle {i_{3}}}i 4 {\displaystyle {i_{4}}}i 5 {\displaystyle {i_{5}}}i 6 {\displaystyle {i_{6}}}
Step− i R i 1 {\displaystyle -{\frac {i_{R}}{i_{1}}}}i 1 i 1 {\displaystyle {\frac {i_{1}}{i_{1}}}}i 1 i 2 {\displaystyle {\frac {i_{1}}{i_{2}}}}i 2 i 3 {\displaystyle {\frac {i_{2}}{i_{3}}}}i 3 i 4 {\displaystyle {\frac {i_{3}}{i_{4}}}}i 4 i 5 {\displaystyle {\frac {i_{4}}{i_{5}}}}i 5 i 6 {\displaystyle {\frac {i_{5}}{i_{6}}}}
Δ Stepi 1 i 2 : i 2 i 3 {\displaystyle {\tfrac {i_{1}}{i_{2}}}:{\tfrac {i_{2}}{i_{3}}}}i 2 i 3 : i 3 i 4 {\displaystyle {\tfrac {i_{2}}{i_{3}}}:{\tfrac {i_{3}}{i_{4}}}}i 3 i 4 : i 4 i 5 {\displaystyle {\tfrac {i_{3}}{i_{4}}}:{\tfrac {i_{4}}{i_{5}}}}i 4 i 5 : i 5 i 6 {\displaystyle {\tfrac {i_{4}}{i_{5}}}:{\tfrac {i_{5}}{i_{6}}}}
Shaft Speedi 1 i R {\displaystyle {\frac {i_{1}}{i_{R}}}}i 1 i 1 {\displaystyle {\frac {i_{1}}{i_{1}}}}i 1 i 2 {\displaystyle {\frac {i_{1}}{i_{2}}}}i 1 i 3 {\displaystyle {\frac {i_{1}}{i_{3}}}}i 1 i 4 {\displaystyle {\frac {i_{1}}{i_{4}}}}i 1 i 5 {\displaystyle {\frac {i_{1}}{i_{5}}}}i 1 i 6 {\displaystyle {\frac {i_{1}}{i_{6}}}}
Δ Shaft Speed0 − i 1 i R {\displaystyle 0-{\tfrac {i_{1}}{i_{R}}}}i 1 i 1 − 0 {\displaystyle {\tfrac {i_{1}}{i_{1}}}-0}i 1 i 2 − i 1 i 1 {\displaystyle {\tfrac {i_{1}}{i_{2}}}-{\tfrac {i_{1}}{i_{1}}}}i 1 i 3 − i 1 i 2 {\displaystyle {\tfrac {i_{1}}{i_{3}}}-{\tfrac {i_{1}}{i_{2}}}}i 1 i 4 − i 1 i 3 {\displaystyle {\tfrac {i_{1}}{i_{4}}}-{\tfrac {i_{1}}{i_{3}}}}i 1 i 5 − i 1 i 4 {\displaystyle {\tfrac {i_{1}}{i_{5}}}-{\tfrac {i_{1}}{i_{4}}}}i 1 i 6 − i 1 i 5 {\displaystyle {\tfrac {i_{1}}{i_{6}}}-{\tfrac {i_{1}}{i_{5}}}}
Torque Ratioμ R {\displaystyle \mu _{R}}μ 1 {\displaystyle \mu _{1}}μ 2 {\displaystyle \mu _{2}}μ 3 {\displaystyle \mu _{3}}μ 4 {\displaystyle \mu _{4}}μ 5 {\displaystyle \mu _{5}}μ 6 {\displaystyle \mu _{6}}
Efficiency η n {\displaystyle \eta _{n}}μ R i R {\displaystyle {\frac {\mu _{R}}{i_{R}}}}μ 1 i 1 {\displaystyle {\frac {\mu _{1}}{i_{1}}}}μ 2 i 2 {\displaystyle {\frac {\mu _{2}}{i_{2}}}}μ 3 i 3 {\displaystyle {\frac {\mu _{3}}{i_{3}}}}μ 4 i 4 {\displaystyle {\frac {\mu _{4}}{i_{4}}}}μ 5 i 5 {\displaystyle {\frac {\mu _{5}}{i_{5}}}}μ 6 i 6 {\displaystyle {\frac {\mu _{6}}{i_{6}}}}
2000: first manufacturer to use the Lepelletier gearset mechanism: ZF 6HP 1st generation
ZF 6HP 26 ZF 6HP 19 ZF 6HP 32600 N⋅m (443 lb⋅ft) 400 N⋅m (295 lb⋅ft) 750 N⋅m (553 lb⋅ft) 2000 (all)37 7131 3838 852 36.0354 4.92361.6977
1.4327
GearR123456
Gear Ratio−3.4025 − 4 , 590 1 , 349 {\displaystyle -{\tfrac {4,590}{1,349}}}4.1708 9 , 180 2 , 201 {\displaystyle {\tfrac {9,180}{2,201}}}2.3397 211 , 140 90 , 241 {\displaystyle {\tfrac {211,140}{90,241}}}1.5211 108 71 {\displaystyle {\tfrac {108}{71}}}1.1428 9 , 180 8 , 033 {\displaystyle {\tfrac {9,180}{8,033}}}0.8672 4 , 590 5 , 293 {\displaystyle {\tfrac {4,590}{5,293}}}0.6911 85 123 {\displaystyle {\tfrac {85}{123}}}
Step0.81581.00001.78261.53821.33111.31781.2549
Δ Step1.15891.15591.01011.0502
Speed-1.22581.00001.78262.74193.64974.80966.0354
Δ Speed1.22581.00000.78260.95930.90781.15991.2258
Torque Ratio–3.3116 –3.26654.0186 3.94362.2837 2.25591.5107 1.50551.1359 1.13250.8633 0.86130.6867 0.6845
Efficiency η n {\displaystyle \eta _{n}}0.9733 0.96000.9635 0.94550.9761 0.96420.9931 0.98970.9939 0.99100.9955 0.99320.9937 0.9905
2007: ZF 6HP 2nd generation
ZF 6HP 28 ZF 6HP 21 ZF 6HP 34600 N⋅m (443 lb⋅ft) 450 N⋅m (332 lb⋅ft) 750 N⋅m (553 lb⋅ft) 2007 (all)37 7131 3838 852 36.0354 4.92361.6977
1.4327
GearR123456
Gear Ratio−3.40254.17082.33971.52111.14280.86720.6911
Other manufacturer using the Lepelletier gear mechanism
Aisin AWTF-80 SC450 N⋅m (332 lb⋅ft) 200550 9036 4444 962 36.0494 4.94951.6865
1.4333
GearR123456
Gear Ratio−3.3939 − 112 33 {\displaystyle -{\tfrac {112}{33}}}4.1481 112 27 {\displaystyle {\tfrac {112}{27}}}2.3704 64 27 {\displaystyle {\tfrac {64}{27}}}1.5556 14 9 {\displaystyle {\tfrac {14}{9}}}1.1546 112 97 {\displaystyle {\tfrac {112}{97}}}0.8593 336 391 {\displaystyle {\tfrac {336}{391}}}0.6857 24 35 {\displaystyle {\tfrac {24}{35}}}
Step0.81821.00001.75001.52381.34721.34361.2532
Δ Step1.14841.13111.00271.0722
Speed-1.22221.00001.75002.66673.59264.82726.0494
Δ Speed1.22221.00000.75000.91670.92591.23461.2222
Torque Ratio–3.3023 –3.25683.9956 3.92042.3127 2.28411.5444 1.53891.1471 1.14340.8553 0.85320.6813 0.6791
Efficiency η n {\displaystyle \eta _{n}}0.9730 0.95960.9632 0.94510.9757 0.96360.9929 0.98930.9935 0.99030.9953 0.99280.9936 0.9904
Ford 6R 60 6R 80600 N⋅m (443 lb⋅ft) 800 N⋅m (590 lb⋅ft) 2005 (all)37 7131 3838 852 36.0354 4.92361.6977
1.4327
GearR123456
Gear Ratio−3.40254.17082.33971.52111.14280.86720.6911
Ford 6R 1401,400 N⋅m (1,033 lb⋅ft) 200549 9537 4747 972 35.8993 4.64411.6361
1.4261
GearR123456
Gear Ratio−3.1283 − 13 , 968 4 , 485 {\displaystyle -{\tfrac {13,968}{4,485}}}3.9738 13 , 968 3 , 515 {\displaystyle {\tfrac {13,968}{3,515}}}2.3181 8 , 148 3 , 515 {\displaystyle {\tfrac {8,148}{3,515}}}1.5158 144 95 {\displaystyle {\tfrac {144}{95}}}1.1492 13 , 968 12 , 155 {\displaystyle {\tfrac {13,968}{12,155}}}0.8585 13 , 968 16 , 271 {\displaystyle {\tfrac {13,968}{16,271}}}0.6736 97 144 {\displaystyle {\tfrac {97}{144}}}
Step0.78721.00001.71431.52931.31901.33891.2744
Δ Step1.12101.15940.98541.0504
Speed-1.27031.00001.71432.62163.45804.62905.8993
Δ Speed1.27031.00000.71430.90730.83641.17101.2703
Torque Ratio–3.0449 –3.00353.8290 3.75762.2615 2.23331.5055 1.50031.1419 1.13830.8543 0.85220.6692 0.6669
Efficiency η n {\displaystyle \eta _{n}}0.9733 0.96010.9635 0.94560.9756 0.96350.9932 0.98980.9937 0.99060.9952 0.99270.9934 0.9900
GM 6L 45 6L 50500 N⋅m (369 lb⋅ft) 200649 8937 4747 972 36.0346 4.75071.6548
1.4326
GearR123456
Gear Ratio−3.2001 − 13 , 386 4 , 183 {\displaystyle -{\tfrac {13,386}{4,183}}}4.0650 13 , 386 3 , 293 {\displaystyle {\tfrac {13,386}{3,293}}}2.3712 15 , 617 63586 {\displaystyle {\tfrac {15,617}{63586}}}1.5506 138 89 {\displaystyle {\tfrac {138}{89}}}1.1567 13 , 386 11 , 573 {\displaystyle {\tfrac {13,386}{11,573}}}0.8532 13 , 386 15 , 689 {\displaystyle {\tfrac {13,386}{15,689}}}0.6736 97 144 {\displaystyle {\tfrac {97}{144}}}
Step0.78721.00001.71431.52931.34061.35571.2662
Δ Step1.12101.14080.98891.0703
Speed-1.27031.00001.71432.62163.51444.76436.0346
Δ Speed1.27031.00000.71430.90730.89281.24991.2703
Torque Ratio–3.1138 –3.07103.9156 3.84212.3127 2.28261.5396 1.53401.1490 1.14530.8490 0.84680.6692 0.6692
Efficiency η n {\displaystyle \eta _{n}}0.9730 0.95970.9633 0.94520.9753 0.96300.9929 0.98930.9934 0.99020.9951 0.99250.9934 0.9900
GM 6L 80 6L 90800 N⋅m (590 lb⋅ft) 200550 9435 4646 922 36.0401 4.59571.6384
1.4329
GearR123456
Gear Ratio−3.0638 − 144 47 {\displaystyle -{\tfrac {144}{47}}}4.0267 6 , 624 1 , 645 {\displaystyle {\tfrac {6,624}{1,645}}}2.3635 3 , 888 1 , 645 {\displaystyle {\tfrac {3,888}{1,645}}}1.5319 72 47 {\displaystyle {\tfrac {72}{47}}}1.1522 6 , 624 5 , 749 {\displaystyle {\tfrac {6,624}{5,749}}}0.8521 144 169 {\displaystyle {\tfrac {144}{169}}}0.6667 2 3 {\displaystyle {\tfrac {2}{3}}}
Step0.76091.00001.70371.54291.32961.35221.2781
Δ Step1.10431.16040.98321.0580
Speed-1.31431.00001.70372.62863.49484.72586.0401
Δ Speed1.31431.00000.70370.92490.86621.23101.3143
Torque Ratio–2.9817 –2.94103.8794 3.80682.3048 2.27561.5213 1.51601.1448 1.14120.8478 0.84560.6622 0.6599
Efficiency η n {\displaystyle \eta _{n}}0.9732 0.95990.9634 0.94540.9751 0.96280.9931 0.98960.9936 0.99040.9950 0.99240.9932 0.9898
Actuated Shift Elements
Brake A❶❶❶❶
Brake B❶❶❶
Clutch C❶❶
Clutch D❶❶
Clutch E❶❶❶
Geometric Ratios: Speed Conversion
Gear Ratio R & 3 & 6 Ordinary Elementary Notedi R = − R 3 ( S 1 + R 1 ) R 1 S 3 {\displaystyle i_{R}=-{\frac {R_{3}(S_{1}+R_{1})}{R_{1}S_{3}}}}i 3 = S 1 + R 1 R 1 {\displaystyle i_{3}={\frac {S_{1}+R_{1}}{R_{1}}}}i 6 = R 3 S 3 + R 3 {\displaystyle i_{6}={\frac {R_{3}}{S_{3}+R_{3}}}}
i R = − ( 1 + S 1 R 1 ) R 3 S 3 {\displaystyle i_{R}=-\left(1+{\tfrac {S_{1}}{R_{1}}}\right){\tfrac {R_{3}}{S_{3}}}}i 3 = 1 + S 1 R 1 {\displaystyle i_{3}=1+{\tfrac {S_{1}}{R_{1}}}}i 6 = 1 1 + S 3 R 3 {\displaystyle i_{6}={\tfrac {1}{1+{\tfrac {S_{3}}{R_{3}}}}}}
Gear Ratio 1 & 2 Ordinary Elementary Notedi 1 = R 2 R 3 ( S 1 + R 1 ) R 1 S 2 S 3 {\displaystyle i_{1}={\frac {R_{2}R_{3}(S_{1}+R_{1})}{R_{1}S_{2}S_{3}}}}i 2 = R 3 ( S 1 + R 1 ) ( S 2 + R 2 ) R 1 S 2 ( S 3 + R 3 ) {\displaystyle i_{2}={\frac {R_{3}(S_{1}+R_{1})(S_{2}+R_{2})}{R_{1}S_{2}(S_{3}+R_{3})}}}
i 1 = ( 1 + S 1 R 1 ) R 2 R 3 S 2 S 3 {\displaystyle i_{1}=\left(1+{\tfrac {S_{1}}{R_{1}}}\right){\tfrac {R_{2}R_{3}}{S_{2}S_{3}}}}i 2 = ( 1 + S 1 R 1 ) ( 1 + R 2 S 2 ) 1 + S 3 R 3 {\displaystyle i_{2}={\tfrac {\left(1+{\tfrac {S_{1}}{R_{1}}}\right)\left(1+{\tfrac {R_{2}}{S_{2}}}\right)}{1+{\tfrac {S_{3}}{R_{3}}}}}}
Gear Ratio 4 & 5 Ordinary Elementary Notedi 4 = R 2 R 3 ( S 1 + R 1 ) R 2 R 3 ( S 1 + R 1 ) − S 1 S 2 S 3 {\displaystyle i_{4}={\frac {R_{2}R_{3}(S_{1}+R_{1})}{R_{2}R_{3}(S_{1}+R_{1})-S_{1}S_{2}S_{3}}}}i 5 = R 3 ( S 1 + R 1 ) R 3 ( S 1 + R 1 ) + S 1 S 3 {\displaystyle i_{5}={\frac {R_{3}(S_{1}+R_{1})}{R_{3}(S_{1}+R_{1})+S_{1}S_{3}}}}
i 4 = 1 1 − S 2 S 3 R 2 R 3 1 + R 1 S 1 {\displaystyle i_{4}={\tfrac {1}{1-{\tfrac {\tfrac {S_{2}S_{3}}{R_{2}R_{3}}}{1+{\tfrac {R_{1}}{S_{1}}}}}}}}i 5 = 1 1 + S 3 R 3 1 + R 1 S 1 {\displaystyle i_{5}={\tfrac {1}{1+{\tfrac {\tfrac {S_{3}}{R_{3}}}{1+{\tfrac {R_{1}}{S_{1}}}}}}}}
Kinetic Ratios: Torque Conversion
Torque Ratio R & 3 & 6μ R = − ( 1 + S 1 R 1 η 0 ) R 3 S 3 η 0 {\displaystyle \mu _{R}=-\left(1+{\tfrac {S_{1}}{R_{1}}}\eta _{0}\right){\tfrac {R_{3}}{S_{3}}}\eta _{0}}μ 3 = 1 + S 1 R 1 η 0 {\displaystyle \mu _{3}=1+{\tfrac {S_{1}}{R_{1}}}\eta _{0}}μ 6 = 1 1 + S 3 R 3 ⋅ 1 η 0 {\displaystyle \mu _{6}={\tfrac {1}{1+{\tfrac {S_{3}}{R_{3}}}\cdot {\tfrac {1}{\eta _{0}}}}}}
Torque Ratio 1 & 2μ 1 = ( 1 + S 1 R 1 η 0 ) R 2 R 3 S 2 S 3 η 0 3 2 {\displaystyle \mu _{1}=\left(1+{\tfrac {S_{1}}{R_{1}}}\eta _{0}\right){\tfrac {R_{2}R_{3}}{S_{2}S_{3}}}{\eta _{0}}^{\tfrac {3}{2}}}μ 2 = ( 1 + S 1 R 1 η 0 ) ( 1 + R 2 S 2 η 0 ) 1 + S 3 R 3 ⋅ 1 η 0 {\displaystyle \mu _{2}={\tfrac {\left(1+{\tfrac {S_{1}}{R_{1}}}\eta _{0}\right)\left(1+{\tfrac {R_{2}}{S_{2}}}\eta _{0}\right)}{1+{\tfrac {S_{3}}{R_{3}}}\cdot {\tfrac {1}{\eta _{0}}}}}}
Torque Ratio 4 & 5μ 4 = 1 1 − S 2 S 3 R 2 R 3 η 0 3 2 1 + R 1 S 1 ⋅ 1 η 0 {\displaystyle \mu _{4}={\tfrac {1}{1-{\tfrac {{\tfrac {S_{2}S_{3}}{R_{2}R_{3}}}{\eta _{0}}^{\tfrac {3}{2}}}{1+{\tfrac {R_{1}}{S_{1}}}\cdot {\tfrac {1}{\eta _{0}}}}}}}}μ 5 = 1 1 + S 3 R 3 ⋅ 1 η 0 1 + R 1 S 1 η 0 {\displaystyle \mu _{5}={\tfrac {1}{1+{\tfrac {{\tfrac {S_{3}}{R_{3}}}\cdot {\tfrac {1}{\eta _{0}}}}{1+{\tfrac {R_{1}}{S_{1}}}\eta _{0}}}}}}

Illustration

In the illustrations, the Ravigneaux gearset is shown vertically mirrored, contrary to actual practice, for the sake of clarity.

  • Reverse gear
  • Neutral
  • 1st gear
  • 2nd gear
  • 3rd gear
  • 4th gear
  • 5th gear: not used in actual existing gearboxes
  • 6th gear: 5th gear in actual existing gearboxes
  • 7th gear: 6th gear in actual existing gearboxes

Limitations

The limitations of the Lepelletier gearset mechanism lie in the number of gear ratios provided and in the efficiency issues that Ravigneaux gearsets always contend with. Therefore, starting in 2008 with the ZF 8HP, the Lepelletier gearset mechanism was replaced by gearset concepts with even more gears and largely dispensing with the use of Ravigneaux gearsets. This was followed later by the GM 8L, Aisin-Toyota 8-speed transmission, and the Ford-GM 10-speed transmission, for example.

Applications

The gearset was used in a wide range of automatic vehicle transmissions.

See also