Lepelletier planetary gearset

The Lepelletier planetary gearset or Lepelletier gear mechanisms is an epicyclic gear system with seven forward gears, six of which are usable. It has three degrees of freedom and is based on a concept by Pierre A. G. Lepelletier from 1992. It is a combination of a planetary gearset and a compound Ravigneaux gearset.

History

The combination of serial and parallel power flow offers additional gear ratios without increasing the complexity of the design. This transmission is the first of its kind to take advantage of this benefit.

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 complexityTemplate:Efn

With Assessment	Output: Gear Ratios	Innovation ElasticityTemplate:Efn Δ Output : Δ Input	Input: Main Components
			Total	Gearsets	Brakes	Clutches
6HP Ref. Object	$n_{O1}$ $n_{O2}$	TopicTemplate:Efn	$n_I=n_G+$ $n_B+n_C$	$n_{G1}$ $n_{G2}$	$n_{B1}$ $n_{B2}$	$n_{C1}$ $n_{C2}$
Δ Number	$n_{O1}-n_{O2}$		$n_{I1}-n_{I2}$	$n_{G1}-n_{G2}$	$n_{B1}-n_{B2}$	$n_{C1}-n_{C2}$
Relative Δ	Δ Output $\frac{n_{O1}-n_{O2}}{n_{O2}}$	$\frac{n_{O1}-n_{O2}}{n_{O2}}:\frac{n_{I1}-n_{I2}}{n_{I2}}$ $=\frac{n_{O1}-n_{O2}}{n_{O2}}$·$\frac{n_{I2}}{n_{I1}-n_{I2}}$	Δ Input $\frac{n_{I1}-n_{I2}}{n_{I2}}$	$\frac{n_{G1}-n_{G2}}{n_{G2}}$	$\frac{n_{B1}-n_{B2}}{n_{B2}}$	$\frac{n_{C1}-n_{C2}}{n_{C2}}$
6HP 5HP 24/30Template:Efn	6Template:Efn 5Template:Efn	ProgressTemplate:Efn	8 9	3Template:Efn 3	2 3	3 3
Δ Number	1		-1	0	-1	0
Relative Δ	Template:Round $\frac{1}{5}$	Template:RoundTemplate:Efn $\frac{1}{5}:\frac{-1}{9}=\frac{1}{5}$·$\frac{-9}{1}=\frac{-9}{5}$	Template:Round $\frac{-1}{9}$	Template:Round $\frac{0}{3}$	Template:Round $\frac{-1}{3}$	Template:Round $\frac{0}{3}$
6HP 5HP 18/19Template:Efn	6Template:Efn 5Template:Efn	ProgressTemplate:Efn	8 10	3Template:Efn 3Template:Efn	2 3	3 4
Δ Number	1		-2	0	-1	-1
Relative Δ	Template:Round $\frac{1}{5}$	Template:RoundTemplate:Efn $\frac{1}{5}:\frac{-1}{5}=\frac{1}{5}$·$\frac{-5}{1}=\frac{-1}{1}$	Template:Round $\frac{-1}{5}$	Template:Round $\frac{0}{3}$	Template:Round $\frac{-1}{3}$	Template:Round $\frac{-1}{4}$
6HP 3-SpeedTemplate:Efn	6Template:Efn 3Template:Efn	Market PositionTemplate:Efn	8 7	3Template:Efn 2	2 3	3 2
Δ Number	3		1	1	-1	1
Relative Δ	Template:Round $\frac{1}{1}$	Template:RoundTemplate:Efn $\frac{1}{1}:\frac{1}{7}=\frac{1}{1}$·$\frac{7}{1}=\frac{7}{1}$	Template:Round $\frac{1}{7}$	Template:Round $\frac{1}{2}$	Template:Round $\frac{-1}{3}$	Template:Round $\frac{1}{2}$
Template:Notelist

No use of 5th (direct) 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 qualityTemplate:EfnTemplate:Efn

In-Depth AnalysisTemplate:Efn With Assessment And Torque RatioTemplate:Efn And Efficiency CalculationTemplate:Efn		Planetary Gearset: TeethTemplate:Efn Lepelletier Gear Mechanism			Count	Nomi- nalTemplate:Efn Effec- tiveTemplate:Efn	Cen- terTemplate:Efn
		Simple	Ravigneaux				Avg.Template:Efn
MakeTemplate:Efn Model	Version First Delivery	S1Template:Efn R1Template:Efn	S2Template:Efn R2Template:Efn	S3Template:Efn R3Template:Efn	Brakes Clutches	Ratio Span	Gear StepTemplate:Efn
Gear	R	1	2	3	4	5	6
Gear RatioTemplate:Efn	$i_R$Template:Efn	$i_1$Template:Efn	$i_2$Template:Efn	$i_3$Template:Efn	$i_4$Template:Efn	$i_5$Template:Efn	$i_6$Template:Efn
StepTemplate:Efn	$-\frac{i_R}{i_1}$Template:Efn	$\frac{i_1}{i_1}$	$\frac{i_1}{i_2}$Template:Efn	$\frac{i_2}{i_3}$	$\frac{i_3}{i_4}$	$\frac{i_4}{i_5}$	$\frac{i_5}{i_6}$
Δ StepTemplate:EfnTemplate:Efn			$\frac{i_1}{i_2}:\frac{i_2}{i_3}$	$\frac{i_2}{i_3}:\frac{i_3}{i_4}$	$\frac{i_3}{i_4}:\frac{i_4}{i_5}$	$\frac{i_4}{i_5}:\frac{i_5}{i_6}$
Shaft Speed	$\frac{i_1}{i_R}$	$\frac{i_1}{i_1}$	$\frac{i_1}{i_2}$	$\frac{i_1}{i_3}$	$\frac{i_1}{i_4}$	$\frac{i_1}{i_5}$	$\frac{i_1}{i_6}$
Δ Shaft SpeedTemplate:Efn	$0-\frac{i_1}{i_R}$	$\frac{i_1}{i_1}-0$	$\frac{i_1}{i_2}-\frac{i_1}{i_1}$	$\frac{i_1}{i_3}-\frac{i_1}{i_2}$	$\frac{i_1}{i_4}-\frac{i_1}{i_3}$	$\frac{i_1}{i_5}-\frac{i_1}{i_4}$	$\frac{i_1}{i_6}-\frac{i_1}{i_5}$
Torque RatioTemplate:Efn	${\mu }_R$Template:Efn	${\mu }_1$Template:Efn	${\mu }_2$Template:Efn	${\mu }_3$Template:Efn	${\mu }_4$Template:Efn	${\mu }_5$Template:Efn	${\mu }_6$Template:Efn
Efficiency ${\eta }_n$Template:Efn	$\frac{{\mu }_R}{i_R}$Template:Efn	$\frac{{\mu }_1}{i_1}$Template:Efn	$\frac{{\mu }_2}{i_2}$Template:Efn	$\frac{{\mu }_3}{i_3}$Template:Efn	$\frac{{\mu }_4}{i_4}$Template:Efn	$\frac{{\mu }_5}{i_5}$Template:Efn	$\frac{{\mu }_6}{i_6}$Template:Efn
2000: first manufacturer to use the Lepelletier gearset mechanism: ZF 6HP 1st generation
ZF 6HP 26Template:Efn ZF 6HP 19Template:Efn ZF 6HP 32Template:Efn	Template:Convert Template:ConvertTemplate:Efn Template:Convert 2000 (all)	37 71	31 38	38 85	2 3	Template:Round Template:Font color	Template:Round
							Template:RoundTemplate:Efn
Gear	R	1	2	3	4	5	6
Gear RatioTemplate:Efn	Template:Font color	Template:Round $\frac{9,180}{2,201}$	Template:Font color	Template:Round $\frac{108}{71}$	Template:Font color	Template:Round $\frac{4,590}{5,293}$	Template:Round $\frac{85}{123}$
Step	Template:Font colorTemplate:Efn	1.0000	Template:Font color	1.5382	Template:Font color	1.3178	1.2549
Δ StepTemplate:Efn			1.1589	1.1559	Template:Font colorTemplate:Efn	1.0502
Speed	Template:Font color	1.0000	1.7826	2.7419	Template:Font color	4.8096	6.0354
Δ Speed	Template:Font color	1.0000	0.7826	0.9593	Template:Font colorTemplate:Efn	1.1599	1.2258
Torque RatioTemplate:Efn	–3.3116 –3.2665	4.0186 3.9436	2.2837 2.2559	1.5107 1.5055	1.1359 1.1325	0.8633 0.8613	0.6867 0.6845
Efficiency ${\eta }_n$Template:Efn	0.9733 0.9600	0.9635 0.9455	0.9761 0.9642	0.9931 0.9897	0.9939 0.9910	0.9955 0.9932	0.9937 0.9905
2007: ZF 6HP 2nd generation
ZF 6HP 28Template:Efn ZF 6HP 21Template:Efn ZF 6HP 34Template:Efn	Template:Convert Template:ConvertTemplate:Efn Template:ConvertTemplate:Efn 2007 (all)	37 71	31 38	38 85	2 3	Template:Round Template:Font color	Template:Round
							Template:RoundTemplate:Efn
Gear	R	1	2	3	4	5	6
Gear RatioTemplate:Efn	Template:Font color	Template:Round	Template:Font color	Template:Round	Template:Font color	Template:Round	Template:Round
Other manufacturer using the Lepelletier gear mechanism
Aisin AWTF-80 SC	Template:Convert 2005	50 90	36 44	44 96	2 3	Template:Round Template:Font color	Template:Round
							Template:RoundTemplate:Efn
Gear	R	1	2	3	4	5	6
Gear RatioTemplate:Efn	Template:Font color	Template:Round $\frac{112}{27}$	Template:Font color	Template:Round $\frac{14}{9}$	Template:Font color	Template:Round $\frac{336}{391}$	Template:Font color
Step	Template:Font colorTemplate:Efn	1.0000	Template:Font color	1.5238	Template:Font color	1.3436	1.2532
Δ StepTemplate:Efn			1.1484	1.1311	Template:Font colorTemplate:Efn	1.0722
Speed	Template:Font color	1.0000	1.7500	2.6667	3.5926	4.8272	Template:Font color
Δ Speed	Template:Font color	1.0000	0.7500	0.9167	0.9259	1.2346	Template:Font colorTemplate:Efn
Torque RatioTemplate:Efn	–3.3023 –3.2568	3.9956 3.9204	2.3127 2.2841	1.5444 1.5389	1.1471 1.1434	0.8553 0.8532	0.6813 0.6791
Efficiency ${\eta }_n$Template:Efn	0.9730 0.9596	0.9632 0.9451	0.9757 0.9636	0.9929 0.9893	0.9935 0.9903	0.9953 0.9928	0.9936 0.9904
Ford 6R 60 6R 80	Template:Convert Template:Convert 2005 (all)	37 71	31 38	38 85	2 3	Template:Round Template:Font color	Template:Round
							Template:RoundTemplate:Efn
Gear	R	1	2	3	4	5	6
Gear RatioTemplate:Efn	Template:Font color	Template:Round	Template:Font color	Template:Round	Template:Font color	Template:Round	Template:Round
Ford 6R 140	Template:Convert 2005	49 95	37 47	47 97	2 3	Template:Round Template:Font color	Template:Round
							Template:RoundTemplate:Efn
Gear	R	1	2	3	4	5	6
Gear RatioTemplate:Efn	Template:Font color	Template:Round $\frac{13,968}{3,515}$	Template:Font color	Template:Round $\frac{144}{95}$	Template:Font color	Template:Round $\frac{13,968}{16,271}$	Template:Round $\frac{97}{144}$
Step	Template:Font colorTemplate:Efn	1.0000	Template:Font colorTemplate:Efn	1.5293	Template:Font color	1.3389	1.2744
Δ StepTemplate:Efn			Template:Font colorTemplate:Efn	1.1594	Template:Font colorTemplate:Efn	1.0504
Speed	Template:Font color	1.0000	1.7143	2.6216	Template:Font color	4.6290	5.8993
Δ Speed	Template:Font color	1.0000	0.7143	0.9073	Template:Font colorTemplate:Efn	1.1710	1.2703
Torque RatioTemplate:Efn	–3.0449 –3.0035	3.8290 3.7576	2.2615 2.2333	1.5055 1.5003	1.1419 1.1383	0.8543 0.8522	0.6692 0.6669
Efficiency ${\eta }_n$Template:Efn	0.9733 0.9601	0.9635 0.9456	0.9756 0.9635	0.9932 0.9898	0.9937 0.9906	0.9952 0.9927	0.9934 0.9900
GM 6L 45 6L 50	Template:Convert 2006	49 89	37 47	47 97	2 3	Template:Round Template:Font color	Template:Round
							Template:RoundTemplate:Efn
Gear	R	1	2	3	4	5	6
Gear RatioTemplate:Efn	Template:Font color	Template:Round $\frac{13,386}{3,293}$	Template:Font color	Template:Round $\frac{138}{89}$	Template:Font color	Template:Round $\frac{13,386}{15,689}$	Template:Round $\frac{97}{144}$
Step	Template:Font colorTemplate:Efn	1.0000	Template:Font colorTemplate:Efn	1.5293	Template:Font color	1.3557	1.2662
Δ StepTemplate:Efn			Template:Font colorTemplate:Efn	1.1408	Template:Font colorTemplate:Efn	1.0703
Speed	Template:Font color	1.0000	1.7143	2.6216	Template:Font color	4.7643	6.0346
Δ Speed	Template:Font color	1.0000	0.7143	0.9073	Template:Font colorTemplate:Efn	1.2499	1.2703
Torque RatioTemplate:Efn	–3.1138 –3.0710	3.9156 3.8421	2.3127 2.2826	1.5396 1.5340	1.1490 1.1453	0.8490 0.8468	0.6692 0.6692
Efficiency ${\eta }_n$Template:Efn	0.9730 0.9597	0.9633 0.9452	0.9753 0.9630	0.9929 0.9893	0.9934 0.9902	0.9951 0.9925	0.9934 0.9900
GM 6L 80 6L 90	Template:Convert 2005	50 94	35 46	46 92	2 3	Template:Round Template:Font color	Template:Round
							Template:RoundTemplate:Efn
Gear	R	1	2	3	4	5	6
Gear RatioTemplate:Efn	Template:Font color	Template:Round $\frac{6,624}{1,645}$	Template:Font color	Template:Round $\frac{72}{47}$	Template:Font color	Template:Round $\frac{144}{169}$	Template:Round $\frac{2}{3}$
Step	Template:Font colorTemplate:Efn	1.0000	Template:Font colorTemplate:Efn	1.5429	Template:Font color	1.3522	1.2781
Δ StepTemplate:Efn			Template:Font colorTemplate:Efn	1.1604	Template:Font colorTemplate:Efn	1.0580
Speed	Template:Font color	1.0000	1.7037	2.6286	Template:Font color	4.7258	6.0401
Δ Speed	Template:Font color	1.0000	0.7037	0.9249	Template:Font colorTemplate:Efn	1.2310	1.3143
Torque RatioTemplate:Efn	–2.9817 –2.9410	3.8794 3.8068	2.3048 2.2756	1.5213 1.5160	1.1448 1.1412	0.8478 0.8456	0.6622 0.6599
Efficiency ${\eta }_n$Template:Efn	0.9732 0.9599	0.9634 0.9454	0.9751 0.9628	0.9931 0.9896	0.9936 0.9904	0.9950 0.9924	0.9932 0.9898
Actuated Shift ElementsTemplate:Efn
Brake ATemplate:Efn		❶	❶	❶	❶
Brake BTemplate:Efn	❶			❶		❶
Clutch CTemplate:Efn			❶				❶
Clutch DTemplate:Efn	❶	❶
Clutch ETemplate:Efn					❶	❶	❶
Geometric Ratios: Speed Conversion
Gear RatioTemplate:Efn R & 3 & 6 OrdinaryTemplate:Efn Elementary NotedTemplate:Efn	$i_R=-\frac{R_3(S_1+R_1)}{R_1{S}_3}$		$i_3=\frac{S_1+R_1}{R_1}$		$i_6=\frac{R_3}{S_3+R_3}$
	$i_R=-(1+\frac{S_1}{R_1})\frac{R_3}{S_3}$		$i_3=1+\frac{S_1}{R_1}$		$i_6=\frac{1}{1+\frac{S_3}{R_3}}$
Gear RatioTemplate:Efn 1 & 2 OrdinaryTemplate:Efn Elementary NotedTemplate:Efn	$i_1=\frac{R_2{R}_3(S_1+R_1)}{R_1{S}_2{S}_3}$			$i_2=\frac{R_3(S_1+R_1)(S_2+R_2)}{R_1{S}_2(S_3+R_3)}$
	$i_1=(1+\frac{S_1}{R_1})\frac{R_2{R}_3}{S_2{S}_3}$			$i_2=\frac{(1+\frac{S_1}{R_1})(1+\frac{R_2}{S_2})}{1+\frac{S_3}{R_3}}$
Gear RatioTemplate:Efn 4 & 5 OrdinaryTemplate:Efn Elementary NotedTemplate:Efn	$i_4=\frac{R_2{R}_3(S_1+R_1)}{R_2{R}_3(S_1+R_1)-S_1{S}_2{S}_3}$			$i_5=\frac{R_3(S_1+R_1)}{R_3(S_1+R_1)+S_1{S}_3}$
	$i_4=\frac{1}{1-\frac{\frac{S_2{S}_3}{R_2{R}_3}}{1+\frac{R_1}{S_1}}}$			$i_5=\frac{1}{1+\frac{\frac{S_3}{R_3}}{1+\frac{R_1}{S_1}}}$
Kinetic Ratios: Torque Conversion
Torque RatioTemplate:Efn R & 3 & 6	${\mu }_R=-(1+\frac{S_1}{R_1}{\eta }_0)\frac{R_3}{S_3}{\eta }_0$		${\mu }_3=1+\frac{S_1}{R_1}{\eta }_0$		${\mu }_6=\frac{1}{1+\frac{S_3}{R_3}\cdot \frac{1}{{\eta }_0}}$
Torque RatioTemplate:Efn 1 & 2	${\mu }_1=(1+\frac{S_1}{R_1}{\eta }_0)\frac{R_2{R}_3}{S_2{S}_3}{{\eta }_0}^{\frac{3}{2}}$			${\mu }_2=\frac{(1+\frac{S_1}{R_1}{\eta }_0)(1+\frac{R_2}{S_2}{\eta }_0)}{1+\frac{S_3}{R_3}\cdot \frac{1}{{\eta }_0}}$
Torque RatioTemplate:Efn 4 & 5	${\mu }_4=\frac{1}{1-\frac{\frac{S_2{S}_3}{R_2{R}_3}{{\eta }_0}^{\frac{3}{2}}}{1+\frac{R_1}{S_1}\cdot \frac{1}{{\eta }_0}}}$			${\mu }_5=\frac{1}{1+\frac{\frac{S_3}{R_3}\cdot \frac{1}{{\eta }_0}}{1+\frac{R_1}{S_1}{\eta }_0}}$
Template:Notelist

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

• ZF 6HP transmission
• Ford 6R transmission
• GM 6L transmission
• Aisin AWTF-80 SC