ZF 9HP transmission

9HP is the trademark name for the ZF Friedrichshafen 9-speed automatic transmission models (9-speed transmission with Hydraulic converter and Planetary gearsets) for transverse engine applications, designed by ZF's subsidiary in Saarbrücken and built in Gray Court, South Carolina. It is used in front-wheel drive and all-wheel drive vehicles.

The 9HP is the world's first 9-speed automatic transmission for passenger cars. Land Rover and Jeep launched it at the 2013 Geneva Motor Show. The 2014 Jeep Cherokee then was the first car with this transmission delivered to customers.

Key data

Gear ratiosTemplate:Efn

Model	First Deliv- ery	Gear										Total Span			Avg. Step	Components		Nomenclature
		R	1	2	3	4	5	6	7	8	9	Nomi- nal	Effec- tive	Cen- ter		Total	per GearTemplate:Efn	Gears Count	Cou- pling	Gear- sets	Maximum Input Torque
9HP 28 9HP 48	2013	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	Template:Round	4 Gearsets 3 Brakes 3 Clutches	Template:Round	9Template:Efn	HTemplate:Efn	PTemplate:Efn	Template:ConvertTemplate:Efn Template:ConvertTemplate:Efn Template:ConvertTemplate:Efn
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History

Production of the 9HP started in 2013 at ZF's Gray Court facility in Laurens, South Carolina. 400,000 units are produced per year.

Production of the 9HP for Fiat and Chrysler vehicles began in May 2013 at Indiana Transmission Plant I (ITPI), followed by Tipton Transmission Plant in Tipton County, Indiana in May 2014.

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. ZF claims that it is able to save an average of 16% in fuel compared with current 6-speed automatic transmissions.

Reduced manufacturing complexity

In order to avoid a further increase in manufacturing complexity while expanding the number of gear ratios, ZF 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. The 8HP has become the new reference standard (benchmark) for automatic transmissions.

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
9HP 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 $\frac{n_{O1}-n_{O2}}{n_{O2}}$	$\frac{n_{O1}-n_{O2}}{n_{O2}}:\frac{n_{I1}-n_{I2}}{n_{I2}}$ $=\frac{n_{O1}-n_{O2}}{n_{O2}}\cdot \frac{n_{I2}}{n_{I1}-n_{I2}}$	Δ Input $\frac{n_{I1}-n_{I2}}{n_{I2}}$	$\frac{n_{G1}-n_{G2}}{n_{G2}}$	$\frac{n_{B1}-n_{B2}}{n_{B2}}$	$\frac{n_{C1}-n_{C2}}{n_{C2}}$
9HP 4HPTemplate:Efn	9Template:Efn 4Template:Efn	ProgressTemplate:Efn	10 7	4 2Template:Efn	3 2	3 3
Δ Number	5		3	2	1	0
Relative Δ	Template:Round $\frac{5}{4}$	Template:RoundTemplate:Efn $\frac{5}{4}:\frac{3}{7}=\frac{5}{4}\cdot \frac{7}{3}=\frac{35}{12}$	Template:Round $\frac{3}{7}$	Template:Round $\frac{2}{2}$	Template:Round $\frac{1}{2}$	Template:Round $\frac{0}{3}$
9HP AisinTemplate:Efn	9Template:Efn 4Template:Efn	ProgressTemplate:Efn	10 8	4 3Template:Efn	3 2	3 3
Δ Number	3		2	1	1	0
Relative Δ	Template:Round $\frac{3}{6}$	Template:RoundTemplate:Efn $\frac{3}{6}:\frac{2}{8}=\frac{1}{2}\cdot \frac{4}{1}=\frac{2}{1}$	Template:Round $\frac{2}{8}$	Template:Round $\frac{1}{3}$	Template:Round $\frac{-1}{3}$	Template:Round $\frac{0}{3}$
9HP 8HPTemplate:Efn	9Template:Efn 8Template:Efn	Current Market PositionTemplate:Efn	10 9	4 4	3 2	3 3
Δ Number	1		1	0	1	0
Relative Δ	Template:Round $\frac{1}{8}$	Template:Font color	Template:Round $\frac{1}{9}$	Template:Round $\frac{0}{4}$	Template:Round $\frac{1}{2}$	Template:Round $\frac{0}{3}$
W9A 3-SpeedTemplate:Efn	9Template:Efn 3Template:Efn	Historical Market PositionTemplate:Efn	10 7	4 2	3 3	3 2
Δ Number	6		3	2	0	1
Relative Δ	Template:Round $\frac{6}{3}$	Template:RoundTemplate:Efn $\frac{6}{3}:\frac{3}{7}=\frac{2}{1}\cdot \frac{7}{3}=\frac{14}{3}$	Template:Round $\frac{3}{7}$	Template:Round $\frac{1}{1}$	Template:Round $\frac{0}{3}$	Template:Round $\frac{1}{2}$
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Quality

The 9HP is only 0.24 inches (6 mm) longer than, and weighs 16.5 lbs (7.5 kg) less than, the outgoing six-speed transmission. The compact packaging is achieved by using a number of innovative design features: a new compact hydraulic vane-type pump, two patented dog clutches, which replace bulkier conventional clutch packs, and a nested gear set.

Planetary gearset concept: gear ratio qualityTemplate:Efn

In-Depth AnalysisTemplate:Efn With Assessment And Torque RatioTemplate:Efn And Efficiency CalculationTemplate:Efn				Planetary Gearset: TeethTemplate:Efn				Count	Nomi- nalTemplate:Efn Effec- tiveTemplate:Efn	Cen- terTemplate:Efn
										Avg.Template:Efn
Model Type	Version First Delivery · Weight			S4Template:Efn R4Template:Efn	S3Template:Efn R3Template:Efn	S2Template:Efn R2Template:Efn	S1Template:Efn R1Template:Efn	Brakes Clutches	Ratio Span	Gear StepTemplate:Efn
Gear	R	1	2	3	4	5	6	7	8	9
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	$i_7$Template:Efn	$i_8$Template:Efn	$i_9$Template:Efn
StepTemplate:Efn	$-\frac{i_R}{i_1}$Template:Efn	$\frac{i_1}{i_1}$	$\frac{i_1}{i_2}$Template:Efn	$\frac{i_2}{i_3}$	$\frac{i_3}{i_4}$	$\frac{i_4}{i_5}$	$\frac{i_5}{i_6}$	$\frac{i_6}{i_7}$	$\frac{i_7}{i_8}$	$\frac{i_8}{i_9}$
Δ StepTemplate:EfnTemplate:Efn			$\frac{i_1}{i_2}:\frac{i_2}{i_3}$	$\frac{i_2}{i_3}:\frac{i_3}{i_4}$	$\frac{i_3}{i_4}:\frac{i_4}{i_5}$	$\frac{i_4}{i_5}:\frac{i_5}{i_6}$	$\frac{i_5}{i_6}:\frac{i_6}{i_7}$	$\frac{i_6}{i_7}:\frac{i_7}{i_8}$	$\frac{i_7}{i_8}:\frac{i_8}{i_9}$
Shaft Speed	$\frac{i_1}{i_R}$	$\frac{i_1}{i_1}$	$\frac{i_1}{i_2}$	$\frac{i_1}{i_3}$	$\frac{i_1}{i_4}$	$\frac{i_1}{i_5}$	$\frac{i_1}{i_6}$	$\frac{i_1}{i_7}$	$\frac{i_1}{i_8}$	$\frac{i_1}{i_9}$
Δ Shaft SpeedTemplate:Efn	$0-\frac{i_1}{i_R}$	$\frac{i_1}{i_1}-0$	$\frac{i_1}{i_2}-\frac{i_1}{i_1}$	$\frac{i_1}{i_3}-\frac{i_1}{i_2}$	$\frac{i_1}{i_4}-\frac{i_1}{i_3}$	$\frac{i_1}{i_5}-\frac{i_1}{i_4}$	$\frac{i_1}{i_6}-\frac{i_1}{i_5}$	$\frac{i_1}{i_7}-\frac{i_1}{i_6}$	$\frac{i_1}{i_8}-\frac{i_1}{i_7}$	$\frac{i_1}{i_9}-\frac{i_1}{i_8}$
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	${\mu }_7$Template:Efn	${\mu }_8$Template:Efn	${\mu }_9$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	$\frac{{\mu }_7}{i_7}$Template:Efn	$\frac{{\mu }_8}{i_8}$Template:Efn	$\frac{{\mu }_9}{i_9}$Template:Efn
9HP 28 9HP 48	280 NmTemplate:Efn · 2013 · Template:Convert 450 NmTemplate:Efn · 2013 · Template:Convert 480 NmTemplate:Efn · 2013 · Template:Convert			42 110	42 110	91Template:Efn 133	42 86	3Template:Efn 3Template:Efn	Template:Round Template:Font color	Template:Round
										Template:RoundTemplate:Efn
Gear	R	1	2	3	4	5	6	7	8	9
Gear RatioTemplate:Efn	Template:Font color	Template:Round $\frac{184,832}{39,325}$	Template:Round $\frac{369,664}{130,075}$	Template:Round $\frac{5,776}{3,025}$	Template:Font color	Template:Round $\frac{1}{1}$	Template:Font color	Template:Font color Template:EfnTemplate:Efn $\frac{6,272}{8,967}$	Template:Font color Template:Efn $\frac{76}{131}$	Template:Round $\frac{2,176}{4,541}$
Step	Template:Font color	1.0000	1.6538	1.4884	Template:Font color	1.3818	1.2375	Template:Font color	Template:Font color	1.2107
Δ StepTemplate:Efn			1.1112	1.0771	Template:Font colorTemplate:Efn	1.1167	1.0711	Template:Font colorTemplate:Efn	Template:Font colorTemplate:Efn
Speed	Template:Font color	1.0000	1.6538	2.4615	3.4014	4.7001	Template:Font color	Template:Font color	8.1015	9.8085
Δ Speed	Template:Font color	1.0000	0.6538	0.8077	0.9399	1.2987	Template:Font colorTemplate:Efn	Template:Font colorTemplate:Efn	1.3818	1.7066
Torque RatioTemplate:Efn	-3.5391 –3.4099	4.5931 4.5402	2.7922 2.7675	1.8884 1.8779	1.3742 1.3704	1.0000	0.8005 0.7966	0.6904 0.6857	0.5717 0.5673	0.4653 0.4582
Efficiency ${\eta }_n$Template:Efn	0.9302 0.8962	0.9772 0.9660	0.9825 0.9738	0.9890 0.9835	0.9945 0.9917	1.0000	0.9906 0.9857	0.9870 0.9803	0.9854 0.9779	0.9710 0.9561
Actuated shift elementsTemplate:Efn
Brake ATemplate:Efn	❶	❶	❶	❶	❶
Brake CTemplate:Efn			❶				❶		❶
Brake DTemplate:Efn	❶	❶						❶	❶	❶
Clutch BTemplate:Efn	❶			❶		❶				❶
Clutch ETemplate:Efn					❶	❶	❶	❶	❶	❶
Clutch FTemplate:Efn		❶	❶	❶	❶	❶	❶	❶
Geometric ratios: speed conversion
Gear RatioTemplate:Efn R & 1 OrdinaryTemplate:Efn Elementary NotedTemplate:Efn	$i_R=\frac{(S_1{S}_2-R_1{R}_2)(S_3+R_3)(S_4+R_4)}{S_1{S}_2{R}_3{R}_4}$					$i_1=\frac{(S_2+R_2)(S_3+R_3)(S_4+R_4)}{S_2{R}_3{R}_4}$
	$i_R=(1-\frac{R_1{R}_2}{S_1{S}_2})(1+\frac{S_3}{R_3})(1+\frac{S_4}{R_4})$					$i_1=(1+\frac{R_2}{S_2})(1+\frac{S_3}{R_3})(1+\frac{S_4}{R_4})$
Gear RatioTemplate:Efn 2 & 3 OrdinaryTemplate:Efn Elementary NotedTemplate:Efn	$i_2=\frac{(S_1+R_1)(S_3+R_3)(S_4+R_4)}{R_1{R}_3{R}_4}$					$i_3=\frac{(S_3+R_3)(S_4+R_4)}{R_3{R}_4}$
	$i_2=(1+\frac{S_1}{R_1})(1+\frac{S_3}{R_3})(1+\frac{S_4}{R_4})$					$i_3=(1+\frac{S_3}{R_3})(1+\frac{S_4}{R_4})$
Gear RatioTemplate:Efn 5–7 OrdinaryTemplate:Efn Elementary NotedTemplate:Efn	$i_5=\frac{1}{1}$	$i_6=\frac{S_3(S_1+R_1)(S_4+R_4)}{S_3(S_1+R_1)(S_4+R_4)+S_1{R}_3{S}_4}$					$i_7=\frac{S_3(S_2+R_2)(S_4+R_4)}{S_3(S_2+R_2)(S_4+R_4)+R_2{R}_3{S}_4}$
		$i_6=\frac{1}{1+\frac{\frac{R_3}{S_3}}{(1+\frac{R_1}{S_1})(1+\frac{R_4}{S_4})}}$					$i_7=\frac{1}{1+\frac{\frac{R_3}{S_3}}{(1+\frac{S_2}{R_2})(1+\frac{R_4}{S_4})}}$
Gear RatioTemplate:Efn 4 & 8 & 9 OrdinaryTemplate:Efn Elementary NotedTemplate:Efn	$i_4=\frac{S_4+R_4}{R_4}$		$i_8=\frac{S_3(S_4+R_4)}{S_4(S_3+R_3)+S_3{R}_4}$			$i_9=\frac{S_3(R_1{R}_2-S_1{S}_2)(S4+R_4)}{S_3(R_1{R}_2-S_1{S}_2)(S_4+R_4)+R_1{R}_2{R}_3{S}_4}$
	$i_4=1+\frac{S_4}{R_4}$		$i_8=\frac{1}{1+\frac{\frac{R_3}{S_3}}{1+\frac{R_4}{S_4}}}$			$i_9=\frac{1}{1+\frac{\frac{R_3}{S_3}}{(1-\frac{S_1{S}_2}{R_1{R}_2})(1+\frac{R_4}{S_4})}}$
Kinetic ratios: torque conversion
Torque RatioTemplate:Efn R & 1	${\mu }_R=(1-\frac{R_1{R}_2}{S_1{S}_2}{{\eta }_0}^2)(1+\frac{S_3}{R_3}{\eta }_0)(1+\frac{S_4}{R_4}{\eta }_0)$					${\mu }_1=(1+\frac{R_2}{S_2}{\eta }_0)(1+\frac{S_3}{R_3}{\eta }_0)(1+\frac{S_4}{R_4}{\eta }_0)$
Torque RatioTemplate:Efn 2 & 3	${\mu }_2=(1+\frac{S_1}{R_1}{\eta }_0)(1+\frac{S_3}{R_3}{\eta }_0)(1+\frac{S_4}{R_4}{\eta }_0)$					${\mu }_3=(1+\frac{S_3}{R_3}{\eta }_0)(1+\frac{S_4}{R_4}{\eta }_0)$
Torque RatioTemplate:Efn 5–7	${\mu }_5=\frac{1}{1}$	${\mu }_6=\frac{1}{1+\frac{\frac{R_3}{S_3}\cdot \frac{1}{{\eta }_0}}{(1+\frac{R_1}{S_1}{\eta }_0)(1+\frac{R_4}{S_4}{\eta }_0)}}$					${\mu }_7=\frac{1}{1+\frac{\frac{R_3}{S_3}\cdot \frac{1}{{\eta }_0}}{(1+\frac{S_2}{R_2}{\eta }_0)(1+\frac{R_4}{S_4}{\eta }_0)}}$
Torque RatioTemplate:Efn 4 & 8 & 9	${\mu }_4=1+\frac{S_4}{R_4}{\eta }_0$		${\mu }_8=\frac{1}{1+\frac{\frac{R_3}{S_3}\cdot \frac{1}{{\eta }_0}}{1+\frac{R_4}{S_4}{\eta }_0}}$			${\mu }_9=\frac{1}{1+\frac{\frac{R_3}{S_3}\cdot \frac{1}{{\eta }_0}}{(1-\frac{S_1{S}_2}{R_1{R}_2}\cdot \frac{1}{{{\eta }_0}^2})(1+\frac{R_4}{S_4}{\eta }_0)}}$
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How it works

An animated drive line schematic & a rotational speeds nomogram

These ordinates are positioned on the abscissa in strict accordance with the proportions of the sun gears' teeth numbers relative to those of their rings. Consequently, the output ratios on the ordinate C₄ (carrier of planetary gearset 4) follows closely to those of the actual transmission. Note that elements A and F are labelled swapped (cf. legend below).

Nomogram

Template:Center

▶️ Interactive nomogram Template:Webarchive

This interactive nomogram is a real geometric calculator exactly representing the rotational speeds of the transmission's 3x4 = 12 internal shafts for each of its 9 ratios (+ reverse), grouped according to their 5 permanent coupling on 4 joint ordinates and 3 independent ordinates. These ordinates are positioned on the abscissa in strict accordance with the proportions of the sun gears' teeth numbers relative to those of their rings. Consequently, the output ratios on the 6th ordinate (carrier of the fourth planetary gearset) follows closely those of the actual transmission. This advantageous geometric construction sets us free from Robert Willis' famous and tedious formula, because all calculations are exclusively determined by lengths ratios, respectively teeth numbers on the abscissa for the 4 epicyclic ratios, and of rotational speeds on the 6th ordinate for the 10 gear ratios.

Legend

A: Dog brake (blocks S₃ and S₄)
C: Brake (blocks S₁)
D: Brake (blocks R₂)
B: Clutch (couples S₁ with input shaft)
E: Clutch (couples C₃ and R₄ with input shaft)
F: Dog clutch (couples R₁ and S₂ with input shaft)

Technical imperfections

The transmission has been problematic, as customers of Jeep, Chrysler, and Acura models equipped with the transmission have experienced problems in their vehicles regarding slow shifting and noisy operation. ZF has said this is due to software problems, not mechanical issues.

Chrysler issued Technical Service Bulletins (TSB) for the 2014 Jeep Cherokee to "fix rough and delayed gearshifts", and Acura has issued transmission-related recalls for the 2015 Acura TLX.

Applications

Variants and applications

Make	Car ModelTemplate:Efn
Acura	Template:Div col TLX (2015–2020, V6 models) MDX (2016–2020, non-hybrid models)
Alfa Romeo	Template:Div col Tonale 2.0L turbo engine
Chrysler	Template:Div col 200 Pacifica minivan (petrol engine) Voyager
Dodge	Template:Div col Hornet (2023–2025, 2.0L turbo engine)
FIAT	Template:Div col Dobló/RAM Promaster City (2015–2022) 500C Toro Ducato (2020–)
MG	Template:Div col MG 7 (2023–)
Opel/Vauxhall	Template:Div col Astra (2020, diesel engine) Insignia (2020, diesel engine)
Honda	Template:Div col CR-V (2015–2022, diesel engine) Pilot (2016–2020 optional, 2021–2022 standard on all trims) Avancier/UR-V (2016–, 2.0L turbo engine) Odyssey (2018–2019 standard, 10-speed automatic optional) Passport (2019–2025) Ridgeline (2020–) Civic (2018–2022, diesel engine)
Infiniti	Template:Div col QX60 (2022–)
Jeep	Template:Div col Cherokee (KL) Renegade Compass (MP) Gran Commander
Ram Trucks	Template:Div col ProMaster City ProMaster (2022–) Rampage
Land Rover	Template:Div col Range Rover Evoque Discovery Sport
Jaguar	Template:Div col E-Pace
Nissan	Template:Div col Pathfinder (2022–)
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See also

• List of Chrysler transmissions
• List of ZF transmissions