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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.

1. Differences in gear ratios have a measurable, direct impact on vehicle dynamics, performance, waste emissions as well as fuel mileage

Specifications

Basic Concept

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. ZF claims that it is able to save an average of 16% in fuel compared with current 6-speed automatic transmissions. The gear ratio spread is 9.81:1. The transmission has a torque range between 207 lb⋅ft (280 N⋅m) and 354 lb⋅ft (480 N⋅m).

Gear Ratios

With Assessment				Planetary Gearset: Teeth				Count	Total Center	Avg.
Model Type	Version First Delivery · Weight			S4 R4	S3 R3	S2 R2	S1 R1	Brakes Clutches	Ratio Span	Gear Step
Gear Ratio	R ${\displaystyle {i_{R}}}$	1 ${\displaystyle {i_{1}}}$	2 ${\displaystyle {i_{2}}}$	3 ${\displaystyle {i_{3}}}$	4 ${\displaystyle {i_{4}}}$	5 ${\displaystyle {i_{5}}}$	6 ${\displaystyle {i_{6}}}$	7 ${\displaystyle {i_{7}}}$	8 ${\displaystyle {i_{8}}}$	9 ${\displaystyle {i_{9}}}$
Step	${\displaystyle -{\tfrac {i_{R}}{i_{1}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{1}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{2}}}}$	${\displaystyle {\tfrac {i_{2}}{i_{3}}}}$	${\displaystyle {\tfrac {i_{3}}{i_{4}}}}$	${\displaystyle {\tfrac {i_{4}}{i_{5}}}}$	${\displaystyle {\tfrac {i_{5}}{i_{6}}}}$	${\displaystyle {\tfrac {i_{6}}{i_{7}}}}$	${\displaystyle {\tfrac {i_{7}}{i_{8}}}}$	${\displaystyle {\tfrac {i_{8}}{i_{9}}}}$
Δ Step			${\displaystyle {\tfrac {i_{1}}{i_{2}}}:{\tfrac {i_{2}}{i_{3}}}}$	${\displaystyle {\tfrac {i_{2}}{i_{3}}}:{\tfrac {i_{3}}{i_{4}}}}$	${\displaystyle {\tfrac {i_{3}}{i_{4}}}:{\tfrac {i_{4}}{i_{5}}}}$	${\displaystyle {\tfrac {i_{4}}{i_{5}}}:{\tfrac {i_{5}}{i_{6}}}}$	${\displaystyle {\tfrac {i_{5}}{i_{6}}}:{\tfrac {i_{6}}{i_{7}}}}$	${\displaystyle {\tfrac {i_{6}}{i_{7}}}:{\tfrac {i_{7}}{i_{8}}}}$	${\displaystyle {\tfrac {i_{7}}{i_{8}}}:{\tfrac {i_{8}}{i_{9}}}}$
Shaft Speed	${\displaystyle {\tfrac {i_{1}}{i_{R}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{1}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{2}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{3}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{4}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{5}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{6}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{7}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{8}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{9}}}}$
Δ Shaft Speed	${\displaystyle 0-{\tfrac {i_{1}}{i_{R}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{1}}}-0}$	${\displaystyle {\tfrac {i_{1}}{i_{2}}}-{\tfrac {i_{1}}{i_{1}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{3}}}-{\tfrac {i_{1}}{i_{2}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{4}}}-{\tfrac {i_{1}}{i_{3}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{5}}}-{\tfrac {i_{1}}{i_{4}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{6}}}-{\tfrac {i_{1}}{i_{5}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{7}}}-{\tfrac {i_{1}}{i_{6}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{8}}}-{\tfrac {i_{1}}{i_{7}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{9}}}-{\tfrac {i_{1}}{i_{8}}}}$
Torque Ratio	${\displaystyle {\tfrac {T_{2;R}}{T_{1;R}}}}$	${\displaystyle {\tfrac {T_{2;1}}{T_{1;1}}}}$	${\displaystyle {\tfrac {T_{2;2}}{T_{1;2}}}}$	${\displaystyle {\tfrac {T_{2;3}}{T_{1;3}}}}$	${\displaystyle {\tfrac {T_{2;4}}{T_{1;4}}}}$	${\displaystyle {\tfrac {T_{2;5}}{T_{1;5}}}}$	${\displaystyle {\tfrac {T_{2;6}}{T_{1;6}}}}$	${\displaystyle {\tfrac {T_{2;7}}{T_{1;7}}}}$	${\displaystyle {\tfrac {T_{2;8}}{T_{1;8}}}}$	${\displaystyle {\tfrac {T_{2;9}}{T_{1;9}}}}$
Efficiency	ηR	η1	η2	η3	η4	η5	η6	η7	η8	η9
9HP 28 9HP 48	280 Nm · 2013 · 78 kg (172 lb) 480 Nm · 2013 · 86 kg (190 lb)			42 110	42 110	91 133	42 86	3 3	9.8085 1.5007	1.3303
Gear Ratio	−3.8049 ${\displaystyle -{\tfrac {3,142,144}{825,825}}}$	4.7001 ${\displaystyle {\tfrac {184,832}{39,325}}}$	2.8419 ${\displaystyle {\tfrac {369,664}{130,075}}}$	1.9094 ${\displaystyle {\tfrac {5,776}{3,025}}}$	1.3818 ${\displaystyle {\tfrac {76}{55}}}$	1.0000 ${\displaystyle {\tfrac {1}{1}}}$	0.8081 ${\displaystyle {\tfrac {34,048}{42,133}}}$	0.6995 ${\displaystyle {\tfrac {6,272}{8,967}}}$	0.5802 ${\displaystyle {\tfrac {76}{131}}}$	0.4792 ${\displaystyle {\tfrac {2,176}{4,541}}}$
Step	0.8095	1.0000	1.6538	1.4884	1.3818	1.3818	1.2375	1.1553	1.2056	1.2107
Δ Step			1.1112	1.0771	1.0000	1.1167	1.0711	0.9583	0.9958
Speed	-1.2353	1.0000	1.6538	2.4615	3.4014	4.7001	5.5816	6.7197	8.1015	9.8085
Δ Speed	1.2353	1.0000	0.6538	0.8077	0.9399	1.2987	1.1161	0.9035	1.3818	1.7066
Torque	–3.4099	4.5402	2.7675	1.8779	1.3704	1.0000	0.7966	0.6857	0.5673	0.4582
Efficiency	0.8962	0.9660	0.9738	0.9835	0.9917	1.0000	0.9857	0.9803	0.9779	0.9561
Ratio R & Even	${\displaystyle {\tfrac {(S_{1}S_{2}-R_{1}R_{2})(S_{3}+R_{3})(S_{4}+R_{4})}{S_{1}S_{2}R_{3}R_{4}}}}$		${\displaystyle {\tfrac {(S_{1}+R_{1})(S_{3}+R_{3})(S_{4}+R_{4})}{R_{1}R_{3}R_{4}}}}$		${\displaystyle {\tfrac {S_{4}+R_{4}}{R_{4}}}}$	${\displaystyle {\tfrac {S_{3}(S_{1}+R_{1})(S_{4}+R_{4})}{S_{3}(S_{1}+R_{1})(S_{4}+R_{4})+S_{1}R_{3}S_{4}}}}$		${\displaystyle i_{8}={\tfrac {S_{3}(S_{4}+R_{4})}{S_{4}(S_{3}+R_{3})+S_{3}R_{4}}}}$
Ratio Odd	${\displaystyle {\tfrac {(S_{2}+R_{2})(S_{3}+R_{3})(S_{4}+R_{4})}{S_{2}R_{3}R_{4}}}}$		${\displaystyle i_{3}={\tfrac {(S_{3}+R_{3})(S_{4}+R_{4})}{R_{3}R_{4}}}}$		${\displaystyle i_{5}={\tfrac {1}{1}}}$	${\displaystyle {\tfrac {S_{3}(S_{2}+R_{2})(S_{4}+R_{4})}{S_{3}(S_{2}+R_{2})(S_{4}+R_{4})+R_{2}R_{3}S_{4}}}}$		${\displaystyle {\tfrac {S_{3}(R_{1}R_{2}-S_{1}S_{2})(S4+R_{4})}{S_{3}(R_{1}R_{2}-S_{1}S_{2})(S_{4}+R_{4})+R_{1}R_{2}R_{3}S_{4}}}}$
Algebra And Actuated Shift Elements
Brake A	❶	❶	❶	❶	❶
Brake C			❶				❶		❶
Brake D	❶	❶						❶	❶	❶
Clutch B	❶			❶		❶				❶
Clutch E					❶	❶	❶	❶	❶	❶
Clutch F		❶	❶	❶	❶	❶	❶	❶
Layout Input and output are on the same side Planetary gearset 4 is on the input (turbine) side Input shafts are, if actuated, S1, R1 + S3, and C3 (planetary gear carrier of gearset 1) + R4 Output shaft is C4 (planetary gear carrier of gearset 4) Total Ratio Span (Total Ratio Spread · Total Gear Ratio) ${\displaystyle {\tfrac {i_{n}}{i_{1}}}}$ A wider span enables the downspeeding when driving outside the city limits increase the climbing ability when driving over mountain passes or off-road or when towing a trailer Ratio Span's Center ${\displaystyle (i_{n}i_{1})^{\tfrac {1}{2}}}$ The center indicates the speed level of the transmission Together with the final drive ratio it gives the shaft speed level of the vehicle Average Gear Step ${\displaystyle ({\tfrac {i_{n}}{i_{1}}})^{\tfrac {1}{n-1}}}$ With decreasing step width the gears connect better to each other shifting comfort increases Sun 4: sun gear of gearset 4 Ring 4: ring gear of gearset 4 Sun 3: sun gear of gearset 3 Ring 3: ring gear of gearset 3 Sun 2: sun gear of gearset 2 Ring 2: ring gear of gearset 2 Sun 1: sun gear of gearset 1 Ring 1: ring gear of gearset 1 ^ Standard 50:50 — 50 % Is Above And 50 % Is Below The Average Gear Step — With steadily decreasing gear steps (yellow highlighted line Step) and a particularly large step from 1st to 2nd gear the lower half of the gear steps (between the small gears; rounded down, here the first 4) is always larger and the upper half of the gear steps (between the large gears; rounded up, here the last 4) is always smaller than the average gear step (cell highlighted yellow two rows above on the far right) lower half: smaller gear steps are a waste of possible ratios (red bold) upper half: larger gear steps are unsatisfactory (red bold) ^ Standard R:1 — Reverse And 1st Gear Have The Same Ratio — The ideal reverse gear has the same transmission ratio as 1st gear no impairment when maneuvering especially when towing a trailer a torque converter can only partially compensate for this deficiency Plus 11.11 % minus 10 % compared to 1st gear is good Plus 25 % minus 20 % is acceptable (red) Above this is unsatisfactory (bold) Standard 1:2 — Gear Step 1st To 2nd Gear As Small As Possible — With continuously decreasing gear steps (yellow marked line Step) the largest gear step is the one from 1st to 2nd gear, which for a good speed connection and a smooth gear shift must be as small as possible A gear ratio of up to 1.6667:1 (5:3) is good Up to 1.7500:1 (7:4) is acceptable (red) Above is unsatisfactory (bold) ^ From large to small gears (from right to left) ^ Standard STEP — From Large To Small Gears: Steady And Progressive Increase In Gear Steps — Gear steps should increase: Δ Step (first green highlighted line Δ Step) is always greater than 1 As progressive as possible: Δ Step is always greater than the previous step Not progressively increasing is acceptable (red) Not increasing is unsatisfactory (bold) ^ Standard SPEED — From Small To Large Gears: Steady Increase In Shaft Speed Difference — Shaft speed differences should increase: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one 1 difference smaller than the previous one is acceptable (red) 2 consecutive ones are a waste of possible ratios (bold) ^ Torque Ratio And Efficiency Ratio of output torque ${\displaystyle T_{2;Gear}}$ to input torque ${\displaystyle T_{1;Gear}}$ Assumed efficiency η0 of the combined epicyclic meshing for ${\displaystyle i_{0}=0.9700}$ Assumed efficiency η0 of a single meshing: ${\displaystyle 0.9700^{\tfrac {1}{2}}=0.9849}$ 280 N⋅m (207 lb⋅ft) for both gasoline and diesel 450 N⋅m (332 lb⋅ft) for gasoline 480 N⋅m (354 lb⋅ft) for diesel Thereof 1 dog break Thereof 1 dog clutch Permanently coupled elements C1, C2, and R3 S3 and S4 C3 and R4 Dog brake blocks S3 and S4 Blocks S1 Blocks R2 Couples S1 with input shaft Couples C3 (carrier 3) and R4 with input shaft Dog clutch couples R1 and S2 with input shaft

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

▶️ Interactive Nomogram

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 (carrier 3) and R₄ with input shaft)
F: Dog clutch (couples R₁ and S₂ with input shaft)

Applications

Acura

• TLX (V6 models, 2015–2020)
• MDX (2016–2020, non-hybrid models)

Alfa Romeo

• Tonale 2.0T engine

Chrysler

• 200
• Pacifica minivan (gasoline version)
• Voyager

Dodge

• Hornet (2023–, 2.0L turbo)
• Rampage

FIAT

• Dobló/RAM Promaster City (2015–2022)
• 500C
• Toro
• Ducato (2020–)

MG

• MG 7 (2023–)

Opel/Vauxhall

• Astra (2020; Diesel Engine)
• Insignia (2020; Diesel Engine)

Honda

• CR-V (diesel, 2015–2022)
• Pilot (2016–2020 optional, 2021-2022 standard on all trims)
• Avancier/UR-V (2016–, 2.0L turbo)
• Odyssey (2018–19 )
• Passport (2019–2025)
• Ridgeline (2020–)
• Civic (diesel, 2018–2022)

Infiniti

• QX60 (2022–)

Jeep

• Cherokee (KL)
• Renegade
• Compass (MP)
• Gran Commander

Ram Trucks

• ProMaster City
• ProMaster (2022–)

Land Rover

• Range Rover Evoque
• Discovery Sport

Jaguar

• E-Pace

Nissan

• Pathfinder (2022–)

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.

Production

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.

See also

• List of Chrysler transmissions
• List of ZF transmissions

References

1. ^ "ZF Develops 9-Speed Automatic Transmission for Passenger Cars".
2. ^ "Land Rover uses the 9-speed automatic transmission by ZF".
3. ^ ZF’s 9-Speed 9HP Transmission Puts Dog Clutches On The Leash
4. Robert Willis (1841). "Principles of mechanism" (PDF). Retrieved 2024-11-04.
5. "HONDA British-built CR-V refreshed for 2015".
6. "World Premiere in Geneva: Land Rover installs the world's first 9-speed automatic passenger car transmission from ZF".
7. "2022 Nissan Pathfinder Adds New Features and Ditches the CVT". 4 February 2021.
8. "Holy Shift ZF 9 Speed Automatic Problems Mount Chrysler Releases Third Software Update for Jeep Cherokee". 4 February 2015.
9. "Short Shirt Jeep Cherokee 9 Speed Automatic Gets Second Update for Rough Shifting".
10. "Acura TLX Shifting Problems".
11. "Spotted: ZF testing the 9HP Hybrid transmission".
12. Chrysler Group Dedicates New Plant and Launches Nine-Speed Production in Tipton, Ind.

• ZF Friedrichshafen transmissions