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,[3] which replace bulkier conventional clutch packs, and a nested gear set.[2] 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 9.8085:1. The transmission has a torque range between 280 and 480 Nm.[1]
Technical data
| Gear Teeth and Ratios | Planetary Gearset: Teeth | Count | Total | Avg. | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Model | Version | First Delivery |
Sun 4 Ring 4 |
Sun 3 Ring 3 |
Sun 2 Ring 2 |
Sun 1 Ring 1 |
Brakes Clutches |
Ratio Span |
Gear Step | |
| Gear | R | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| 9HP 28 | 280 N⋅m (207 lb⋅ft) | 2013 | 42 110 |
42 110 |
91 133 |
42 86 |
3[a] 3[b] |
9.8085 | 1.3303 | |
| Ratio | - 3.8049 | 4.7001 | 2.8419 | 1.9094 | 1.3818 | 1.0000 | 0.8081 | 0.6995 | 0.5802 | 0.4792 |
| 9HP 48 | 480 N⋅m (354 lb⋅ft) | 2013 | 42 110 |
42 110 |
91 133 |
42 86 |
3[a] 3[b] |
9.8085 | 1.3303 | |
| Ratio | - 3.8049 | 4.7001 | 2.8419 | 1.9094 | 1.3818 | 1.0000 | 0.8081 | 0.6995 | 0.5802 | 0.4792 |
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 the last planetary gearset RS4) follows closely to those of the actual transmission. Note that elements A and F are labelled interchanged (cf. legend below).
9HP 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 Clutch (couples r1+s2 with input shaft)
B : Clutch (couples s1 with input shaft)
C : Brake (blocks s1 sun gear)
D : Brake (blocks r2 ring gear)
E : Clutch (couples c3+r4 with input shaft)
F : Dog Brake (blocks s3+s4 sun gears)