ZF 9HP transmission explained

ZF 9HP
Production:2013–present
Manufacturer:ZF Friedrichshafen
Assembly:Gray Court, South Carolina, United States
Class:9-speed transverse automatic transmission
Predecessor:ZF 4HP (same ZF transverse transmission)

9HP is the trademark name for the ZF Friedrichshafen nine-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.[1] It is used in front-wheel drive and all-wheel drive vehicles.

Abstract

Land Rover and Jeep demonstrated the world's first nine-speed automatic transmissions for passenger cars at the 2013 Geneva Motor Show. The 2014 Jeep Cherokee featured the world's first nine-speed automatic transmission for a passenger vehicle to market.

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,[2] which replace bulkier conventional clutch packs, and a nested gear set.[3] 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 280Nm and 480Nm.

Technical data

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 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

Alfa Romeo

Chrysler

Dodge

FIAT

MG

Opel/Vauxhall

Honda

Infiniti

Jeep

Ram Trucks

Land Rover

Jaguar

Nissan

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.[7]

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.[8] [9]

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.[10]

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.[11]

See also

Notes and References

  1. Web site: ZF Develops 9-Speed Automatic Transmission for Passenger Cars.
  2. http://www.thetruthaboutcars.com/2014/02/zfs-9-speed-9hp-transmission-puts-dog-clutches-on-the-leash/ ZF’s 9-Speed 9HP Transmission Puts Dog Clutches On The Leash
  3. Web site: Land Rover uses the 9-speed automatic transmission by ZF.
  4. Web site: HONDA British-built CR-V refreshed for 2015.
  5. Web site: World Premiere in Geneva: Land Rover installs the world's first 9-speed automatic passenger car transmission from ZF.
  6. Web site: 2022 Nissan Pathfinder Adds New Features and Ditches the CVT. 4 February 2021.
  7. Web site: Holy Shift ZF 9 Speed Automatic Problems Mount Chrysler Releases Third Software Update for Jeep Cherokee. 4 February 2015.
  8. Web site: Short Shirt Jeep Cherokee 9 Speed Automatic Gets Second Update for Rough Shifting.
  9. Web site: Acura TLX Shifting Problems.
  10. Web site: Spotted: ZF testing the 9HP Hybrid transmission.
  11. http://media.chrysler.com/newsrelease.do;jsessionid=7C83DA28BCDDE8D399435FEC01D49F0A?&id=15636&mid=1 Chrysler Group Dedicates New Plant and Launches Nine-Speed Production in Tipton, Ind.