ZF 9HP transmission


9HP is the trademark name for the ZF Friedrichshafen 9-speed automatic transmission models 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



Specifications

Combined Parallel and Serial Coupled Gearset Concept For More Gears And Improved Cost-Effectiveness



Gearset Concept: Quality

The 9HP is only 0.24 inches longer than, and weighs 16.5 lbs 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.


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 follows closely to those of the actual transmission. Note that elements A and F are labelled swapped.

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, 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 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

C: Brake

D: Brake

B: Clutch

E: Clutch

F: Dog clutch

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.
Chrysler issued Technical Service Bulletins 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, followed by Tipton Transmission Plant in Tipton County, Indiana in May 2014.