ZF 5HP transmission
Key data
Gear ratios
Model
First Deliv- ery
Gear
Total Span
Avg. Step
Components
Nomenclature
R
1
2
3
4
5
Nomi- nal
Effec- tive
Cen- ter
Total
per Gear
Gears Count
Cou- pling
Gear- sets
Input Shaft Diameter
Ravigneaux types
5
H
P
5HP 18 5HP 19
1990 1997
−4.096
3.665
1.995
1.407
1.000
0.742
4.936
4.936
1.650
1.491
3 Gearsets 3 Brakes 4 Clutches
2.000
18 mm 19 mm
Simpson types
5HP 30
1992
−3.684
3.553
2.244
1.545
1.000
0.787
4.517
4.517
1.672
1.458
3 Gearsets 3 Brakes 3 Clutches
1.800
30 mm
5HP 24
1996
−4.095
3.571
2.200
1.505
1.000
0.804
4.444
4.444
1.694
1.452
24 mm
↑ Differences in gear ratios have a measurable, direct impact on vehicle dynamics, performance, waste emissions as well as fuel mileage
1 2 Forward gears only
↑ Hydraulic torque converter · German : H ydraulischer Wandler oder Drehmomentwandler
↑ Planetary gearing · German : P lanetenradsätze
1990: 5HP 18 & 1997: 5HP 19— Ravigneaux planetary gearset types —
History
The Ravigneaux planetary gearset types were ZF's first 5-speed automatic transmission and introduced in 1990. They were produced through 2008 in different versions and were used in a wide range of vehicles. Since the successor model, the 6HP , could be manufactured at a significantly lower cost, most of the gearboxes were replaced shortly after its launch in 2000.
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.
Increased manufacturing complexity
The 5HP 18 and 19 are a transmission family with purely serial power flow: components were simply added to enable more gears. This makes these transmissions larger, heavier, and more expensive. With 10 main components, progress was unsatisfactory: an obvious transitional solution. It is therefore the last conventionally designed transmission from ZF. All subsequent transmissions from ZF including the 8-speed transmission 8HP require fewer main components.
Planetary gearset concept: manufacturing complexity
With Assessment
Output: Gear Ratios
InnovationElasticity Δ Output : Δ Input
Input: Main Components
Total
Gearsets
Brakes
Clutches
5HP 18/19 Ref. Object
n O 1 n O 2
Topic
n I = n G + n B + n C
n G 1 n G 2
n B 1 n B 2
n C 1 n C 2
Δ Number
n O 1 − n O 2
n I 1 − n I 2
n G 1 − n G 2
n B 1 − n B 2
n C 1 − n C 2
Relative Δ
Δ Outputn O 1 − n O 2 n O 2
n O 1 − n O 2 n O 2 : n I 1 − n I 2 n I 2 = n O 1 − n O 2 n O 2 ·n I 2 n I 1 − n I 2
Δ Inputn I 1 − n I 2 n I 2
n G 1 − n G 2 n G 2
n B 1 − n B 2 n B 2
n C 1 − n C 2 n C 2
5HP 18/194HP 14/16/18
5 4
Progress
10 7
3 2
3 2
4 3
Δ Number
1
3
1
1
1
Relative Δ
0.250 1 4
0.583 1 4 : 3 7 = 1 4 ·7 3 = 7 12
0.429 3 7
0.500 1 2
0.500 1 2
0.333 1 3
5HP 18/194HP 20/22/24
5 4
Progress
10 10
3 3
3 4
4 3
Δ Number
1
0
0
–1
1
Relative Δ
0.250 1 4
∞ 1 4 : 0 10 = 1 4 ·10 0 = 10 0
0.000 0 10
0.000 0 3
−0.250 − 1 4
0.333 1 3
5HP 18/19 3-Speed
5 3
Market Position
10 7
3 2
3 3
4 2
Δ Number
2
3
1
0
2
Relative Δ
0.667 2 3
1.556 2 3 : 3 7 = 2 3 ·7 3 = 14 9
0.429 3 7
0.500 1 2
0.000 0 3
1.000 2 2
↑ Progress increases cost-effectiveness and is reflected in the ratio of forward gears to main components. It depends on the power flow:
parallel: using the two degrees of freedom of planetary gearsets
to increase the number of gears
with unchanged number of components
serial: in-line combined planetary gearsets without using the two degrees of freedom
to increase the number of gears
a corresponding increase in the number of components is unavoidable
1 2 3 4 5 6 7 8 Innovation elasticity classifies progress and market position
Automobile manufacturers drive forward technical developments primarily in order to remain competitive or to achieve or defend technological leadership. This technical progress has therefore always been subject to economic constraints
Only innovations whose relative additional benefit is greater than the relative additional resource input, i.e. whose economic elasticity is greater than 1, are considered for realization
The required innovation elasticity of an automobile manufacturer depends on its expected return on investment. The basic assumption that the relative additional benefit must be at least twice as high as the relative additional resource input helps with orientation
negative, if the output increases and the input decreases, is perfect
2 or above is good
1 or above is acceptable (red)
below this is unsatisfactory (bold)
1 2 Direct predecessor
To reflect the progress of the specific model change
1 2 3 4 5 6 plus 1 reverse gear
1 2 3 4 5 of which 2 gearsets are combined as a compound Ravigneaux gearset
↑ Reference standard (benchmark)
3-speed transmissions with torque converters have established the modern market for automatic transmissions and thus made it possible in the first place, as this design proved to be a particularly successful compromise between cost and performance
It became the archetype and dominated the world market for around 3 decades, setting the standard for automatic transmissions. It was only when fuel consumption became the focus of interest that this design reached its limits, which is why it has now completely disappeared from the market
What has remained is the orientation that it offers as a reference standard (point of reference, benchmark) for this market for determining progressiveness and thus the market position of all other, later designs
All transmission variants consist of 7 main components
Typical examples are
Quality
Planetary gearset concept: gear ratio quality
In-Depth Analysis With Assessment And Torque Ratio And Efficiency Calculation
Planetary Gearset: Teeth
Count
Nomi- nal Effec- tive
Cen- ter
Ravigneaux
Simple
Avg.
Model Type
Version First Delivery
S1 R1
S2 R2
S3 R3
Brakes Clutches
Ratio Span
Gear Step
Gear
R
1
2
3
4
5
Gear Ratio
i R
i 1
i 2
i 3
i 4
i 5
Step
− i R i 1
i 1 i 1
i 1 i 2
i 2 i 3
i 3 i 4
i 4 i 5
Δ Step
i 1 i 2 : i 2 i 3
i 2 i 3 : i 3 i 4
i 3 i 4 : i 4 i 5
Shaft Speed
i 1 i R
i 1 i 1
i 1 i 2
i 1 i 3
i 1 i 4
i 1 i 5
Δ Shaft Speed
0 − i 1 i R
i 1 i 1 − 0
i 1 i 2 − i 1 i 1
i 1 i 3 − i 1 i 2
i 1 i 4 − i 1 i 3
i 1 i 5 − i 1 i 4
Torque Ratio
μ R
μ 1
μ 2
μ 3
μ 4
μ 5
Efficiencyη n
μ R i R
μ 1 i 1
μ 2 i 2
μ 3 i 3
μ 4 i 4
μ 5 i 5
5HP 18
310 N⋅m (229 lb⋅ft ) 1990
3834
34 98
32 76
3 4
4.9363 4.9363
1.6495
1.4906
Gear
R
1
2
3
4
5
Gear Ratio
−4.0960− 1 , 323 323
3.6648 1 , 323 361
1.9990 7 , 938 3 , 971
1.4067 294 209
1.00001 1
0.7424 49 66
Step
1.1176
1.0000
1.8333
1.4211
1.4067
1.3469
Δ Step
1.2901
1.0102
1.0444
Speed
–0.8947
1.0000
1.8333
2.6053
3.6648
4.9363
Δ Speed
0.8947
1.0000
0.8333
0.7719
1.0596
1.2715
Torque Ratio
–3.9903 –3.9378
3.5344 3.4700
1.9581 1.9377
1.3861 1.3758
1.0000
0.7385 0.7366
Efficiencyη n
0.9742 0.9614
0.9644 0.9468
0.9795 0.9693
0.9854 0.9780
1.0000
0.9948 0.9921
5HP 19
325 N⋅m (240 lb⋅ft ) 1997
3834
34 98
32 76
3 4
4.9363 4.9363
1.6495
1.4906
Gear
R
1
2
3
4
5
Gear Ratio
−4.0960
3.6648
1.9990
1.4067
1.0000
0.7424
Actuated shift elements
Brake A
❶
❶
❶
Brake B
❶
❶
Brake C
❶
❶
❶
Clutch D
❶
❶
❶
❶
Clutch E
❶
Clutch F
❶
❶
Clutch G
❶
❶
❶
Geometric ratios: speed conversion
Gear Ratio R & 1 Ordinary Elementary Noted
i R = − R 2 ( S 3 + R 3 ) S 2 R 3
i 1 = R 1 R 2 ( S 3 + R 3 ) S 1 S 2 R 3
i R = − R 2 S 2 ( 1 + S 3 R 3 )
i 1 = R 1 R 2 S 1 S 2 ( 1 + S 3 R 3 )
Gear Ratio 2 & 3 Ordinary Elementary Noted
i 2 = R 2 ( S 1 + R 1 ) ( S 3 + R 3 ) S 1 R 3 ( S 2 + R 2 )
i 3 = R 2 ( S 1 + R 1 ) S 1 ( S 2 + R 2 )
i 2 = ( 1 + R 1 S 1 ) ( 1 + S 3 R 3 ) 1 + S 2 R 2
i 3 = 1 + R 1 S 1 1 + S 2 R 2
Gear Ratio 4 & 5 Ordinary Elementary Noted
i 4 = 1 1
i 5 = R 2 S 2 + R 2
i 5 = 1 1 + S 2 R 2
Kinetic ratios: torque conversion
Torque Ratio R & 1
μ R = − R 2 S 2 η 0 ( 1 + S 3 R 3 η 0 )
μ 1 = R 1 R 2 S 1 S 2 η 0 3 2 ( 1 + S 3 R 3 η 0 )
Torque Ratio 2 & 3
μ 2 = ( 1 + R 1 S 1 η 0 ) ( 1 + S 3 R 3 η 0 ) 1 + S 2 R 2 ⋅ 1 η 0
μ 3 = 1 + R 1 S 1 η 0 1 + S 2 R 2 ⋅ 1 η 0
Torque Ratio 4 & 5
μ 4 = 1 1
μ 5 = 1 1 + S 2 R 2 ⋅ 1 η 0
↑ Revised 14 January 2026Nomenclature
S n = sun gear: number of teeth
R n = ring gear: number of teeth
C n = carrier or planetary gear carrier (not needed)
s n = sun gear: shaft speed
r n = ring gear: shaft speed
c n = carrier or planetary gear carrier: shaft speed
With n = gear is
i n = gear ratio or transmission ratio
ω 1 ; n = ω t = shaft speed shaft 1: input (turbine) shaft
ω 2 ; n = shaft speed shaft 2: output shaft
T 1 ; n = T t = torque shaft 1: input (turbine) shaft
T 2 ; n = torque shaft 2: output shaft
μ n = torque ratio or torque conversion ratio
η n = efficiency
i 0 = stationary gear ratio
η 0 = (assumed) stationary gear efficiency
1 2 3 4 5 6 7 8 9 10 11 12 13 Gear ratio (transmission ratio) i n — speed conversion —
The gear ratio i n is the ratio of
input shaft speed ω 1 ; n
to output shaft speed ω 2 ; n
and therefore corresponds to the reciprocal of the shaft speeds
i n = 1 ω 2 ; n ω 1 ; n = ω 1 ; n ω 2 ; n = ω t ω 2 ; n
1 2 3 4 5 6 7 8 9 10 11 12 Torque ratio (torque conversion ratio) μ n — torque conversion —
The torque ratio μ n is the ratio of
output torque T 2 ; n
to input torque T 1 ; n
minus efficiency losses
and therefore corresponds (apart from the efficiency losses) to the reciprocal of the shaft speeds too
μ n = i n η n ; η 0 = ω 1 ; n η n ; η 0 ω 2 ; n = T 2 ; n η n ; η 0 T 1 ; n
whereby η n ; η 0 may vary from gear to gear according to the formulas listed in this table and 0 ≤ η n ; η 0 ≤ 1
1 2 3 4 5 6 7 8 9 Efficiency
The efficiency η n is calculated
from the torque ratio
in relation to the gear ratio (transmission ratio)
η n = μ n i n
Power loss for single meshing gears
is in the range of 1 % to 1.5 %
helical gear pairs, which are used to reduce noise in passenger cars, are in the upper part of the loss range
spur gear pairs, which are limited to commercial vehicles due to their poorer noise comfort, are in the lower part of the loss range
Corridor for torque ratio and efficiency
in planetary gearsets, the stationary gear ratio i 0 is formed via the planetary gears and thus by two meshes
for reasons of simplification, the efficiency for both meshes together is commonly specified there
the efficiencies η 0 specified here are based on assumed efficiencies for the stationary ratio i 0
of η 0 = 0.9800 (upper value)
and η 0 = 0.9700 (lower value)
for both interventions together
The corresponding efficiency
for single-meshing gear pairs is η 0 1 2
at 0.980 0 1 2 = 0.98995 (upper value)
and 0.970 0 1 2 = 0.98489 (lower value)
↑ Layout
Input and output are on opposite sides
Planetary gearset 2 (the outer Ravigneaux gearset) is on the input (turbine) side
Input (turbine) shafts are, if actuated, S1 , C1 /C2 (the common carrier of the compound Ravigneaux gearset), and R1 /S2
Output shaft is C3
↑ Total ratio span (total gear ratio/total transmission ratio) nominal
ω 2 ; n ω 2 ; 1 = ω 2 ; n ω 2 ; 1 ω 2 ; n ω 2 ; 1 ω 2 ; 1 ω 2 ; n = 1 ω 2 ; 1 1 ω 2 ; n = ω t ω 2 ; 1 ω t ω 2 ; n = i 1 i n
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
1 2 3 4 5 Total ratio span (total gear ratio/total transmission ratio) effective
ω 2 ; n m a x ( ω 2 ; 1 ; | ω 2 ; R | ) = m i n ( i 1 ; | i R | ) i n
The span is only effective to the extent that
the reverse gear ratio
matches that of 1st gear
see also Standard R:1
Digression Reverse gear
is usually longer than 1st gear
the effective span is therefore of central importance for describing the suitability of a transmission
because in these cases, the nominal spread conveys a misleading picture
which is only unproblematic for vehicles with high specific power
Market participants
Manufacturers naturally have no interest in specifying the effective span
Users have not yet formulated the practical benefits that the effective span has for them
The effective span has not yet played a role in research and teaching
Contrary to its significance
the effective span has therefore not yet been able to establish itself
either in theory
or in practice.
End of digression
↑ Ratio span's center
( i 1 i n ) 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
( ω 2 ; n ω 2 ; 1 ) 1 n − 1 = ( i 1 i n ) 1 n − 1
There are n − 1 gear steps between n gears
with decreasing step width
the gears connect better to each other
shifting comfort increases
↑ Sun 1: sun gear of gearset 1: inner Ravigneaux gearset
↑ Ring 1: ring gear of gearset 1: inner Ravigneaux gearset
↑ Sun 2: sun gear of gearset 2: outer Ravigneaux gearset
↑ Ring 2: ring gear of gearset 2: outer Ravigneaux gearset
↑ Sun 3: sun gear of gearset 3
↑ Ring 3: ring gear of gearset 3
1 2 3 4 5 6 7 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 2) is always larger
and the upper half of the gear steps (between the large gears; rounded up, here the last 2) 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)
1 2 3 4 5 6 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)
see also Total ratio span (total gear ratio/total transmission ratio) effective
1 2 3 4 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)
1 2 From large to small gears (from right to left)
1 2 3 4 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)
1 2 3 4 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)
1 2 inner and outer sun gears of the Ravigneaux planetary gearset are inverted
↑ Blocks R1 (ring gear of the inner Ravigneaux gearset) and S2 (sun gear of the outer Ravigneaux gearset)
↑ Blocks C1 /C2 (the common carrier of the compound Ravigneaux gearset)
↑ Blocks S3
↑ Couples S1 (sun of the inner Ravigneaux gearset) with the input (turbine)
↑ Couples R1 (ring gear of the inner Ravigneaux gearset) and S2 (sun gear of the outer Ravigneaux gearset) with the input (turbine)
↑ Connects C1 /C2 (the common carrier of the compound Ravigneaux gearset) with the input (turbine)
↑ Couples S3 with R3
1 2 3 Ordinary noted
For direct determination of the gear ratio
1 2 3 Elementary noted
Alternative representation for determining the transmission ratio
Contains only operands
With simple fractions of both central gears of a planetary gearset
Or with the value 1
As a basis
For reliable
And traceable
Determination of torque conversion ratio and efficiency
1992: 5HP 30 & 1996: 5HP 24— Simpson planetary gearset types —
History
The Simpson planetary gearset types were ZF's second 5-speed automatic transmission and introduced in 1992. They were produced through 2000 in different versions and were used in a wide range of vehicles. Since the successor model, the 6HP , could be manufactured at a significantly lower cost, most of the gearboxes were replaced shortly after its launch in 2000.
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.
Reduced manufacturing complexity
The 5HP 30 and 24 are the first transmission family with combined parallel and serial power flow to prevent these transmission from becoming larger, heavier, and more expensive. 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 complexity
With Assessment
Output: Gear Ratios
InnovationElasticity Δ Output : Δ Input
Input: Main Components
Total
Gearsets
Brakes
Clutches
5HP 30/24 Ref. Object
n O 1 n O 2
Topic
n I = n G + n B + n C
n G 1 n G 2
n B 1 n B 2
n C 1 n C 2
Δ Number
n O 1 − n O 2
n I 1 − n I 2
n G 1 − n G 2
n B 1 − n B 2
n C 1 − n C 2
Relative Δ
Δ Outputn O 1 − n O 2 n O 2
n O 1 − n O 2 n O 2 : n I 1 − n I 2 n I 2 = n O 1 − n O 2 n O 2 ·n I 2 n I 1 − n I 2
Δ Inputn I 1 − n I 2 n I 2
n G 1 − n G 2 n G 2
n B 1 − n B 2 n B 2
n C 1 − n C 2 n C 2
5HP 30/244HP 14/16/18
5 4
Progress
9 7
3 2
3 2
3 3
Δ Number
1
2
1
1
0
Relative Δ
0.250 1 4
0.875 1 4 : 2 7 = 1 4 ·7 2 = 7 8
0.286 2 7
0.500 1 2
0.500 1 2
0.000 0 3
5HP 30/244HP 20/22/24
5 4
Progress
9 10
3 3
3 4
3 3
Δ Number
1
–1
0
–1
0
Relative Δ
0.250 1 4
−2.500 1 4 : − 1 10 = 1 4 ·10 − 1 = 10 − 4
−0.100 − 1 10
0.000 0 3
−0.250 − 1 4
0.000 0 3
5HP 30/24 3-Speed
5 3
Market Position
9 7
3 2
3 3
3 2
Δ Number
2
2
1
0
1
Relative Δ
0.667 2 3
2.333 2 3 : 2 7 = 2 3 ·7 2 = 7 3
0.286 2 7
0.500 1 2
0.000 0 3
0.500 1 2
↑ Progress increases cost-effectiveness and is reflected in the ratio of forward gears to main components. It depends on the power flow:
parallel: using the two degrees of freedom of planetary gearsets
to increase the number of gears
with unchanged number of components
serial: in-line combined planetary gearsets without using the two degrees of freedom
to increase the number of gears
a corresponding increase in the number of components is unavoidable
1 2 3 4 5 6 7 8 Innovation elasticity classifies progress and market position
Automobile manufacturers drive forward technical developments primarily in order to remain competitive or to achieve or defend technological leadership. This technical progress has therefore always been subject to economic constraints
Only innovations whose relative additional benefit is greater than the relative additional resource input, i.e. whose economic elasticity is greater than 1, are considered for realization
The required innovation elasticity of an automobile manufacturer depends on its expected return on investment. The basic assumption that the relative additional benefit must be at least twice as high as the relative additional resource input helps with orientation
negative, if the output increases and the input decreases, is perfect
2 or above is good
1 or above is acceptable (red)
below this is unsatisfactory (bold)
1 2 Direct predecessor
To reflect the progress of the specific model change
1 2 3 4 5 6 plus 1 reverse gear
1 2 of which 2 gearsets are combined as a compound Ravigneaux gearset
↑ Reference standard (benchmark)
3-speed transmissions with torque converters have established the modern market for automatic transmissions and thus made it possible in the first place, as this design proved to be a particularly successful compromise between cost and performance
It became the archetype and dominated the world market for around 3 decades, setting the standard for automatic transmissions. It was only when fuel consumption became the focus of interest that this design reached its limits, which is why it has now completely disappeared from the market
What has remained is the orientation that it offers as a reference standard (point of reference, benchmark) for this market for determining progressiveness and thus the market position of all other, later designs
All transmission variants consist of 7 main components
Typical examples are
Quality
Planetary gearset concept: gear ratio quality
In-Depth Analysis With Assessment And Torque Ratio And Efficiency Calculation
Planetary Gearset: Teeth
Count
Nomi- nal Effec- tive
Cen- ter
Simpson
Simple
Avg.
Model Type
Version First Delivery
S1 R1
S2 R2
S3 R3
Brakes Clutches
Ratio Span
Gear Step
Gear
R
1
2
3
4
5
Gear Ratio
i R
i 1
i 2
i 3
i 4
i 5
Step
− i R i 1
i 1 i 1
i 1 i 2
i 2 i 3
i 3 i 4
i 4 i 5
Δ Step
i 1 i 2 : i 2 i 3
i 2 i 3 : i 3 i 4
i 3 i 4 : i 4 i 5
i 4 i 5 : i 5 i 6
Shaft Speed
i 1 i R
i 1 i 1
i 1 i 2
i 1 i 3
i 1 i 4
i 1 i 5
Δ Shaft Speed
0 − i 1 i R
i 1 i 1 − 0
i 1 i 2 − i 1 i 1
i 1 i 3 − i 1 i 2
i 1 i 4 − i 1 i 3
i 1 i 5 − i 1 i 4
Torque Ratio
μ R
μ 1
μ 2
μ 3
μ 4
μ 5
Efficiencyη n
μ R i R
μ 1 i 1
μ 2 i 2
μ 3 i 3
μ 4 i 4
μ 5 i 5
5HP 30
560 N⋅m (413 lb⋅ft ) 1992
40 100
32 108
38 97
3 3
4.5169 4.5169
1.6716
1.4578
Gear
R
1
2
3
4
5
Gear Ratio
−3.6842 − 70 19
3.5526 135 38
2.2436 175 78
1.5449 275 178
1.0000 1 1
0.786570 89
Step
1.0370
1.0000
1.5835
1.4522
1.5449
1.2714
Δ Step
1.0904
0.9400
1.2151
Speed
–0.9643
1.0000
1.5835
2.2995
3.5526
4.5169
Δ Speed
0.9643
1.0000
0.5835
0.7161
1.2531
0.9643
Torque Ratio
–3.5078 –3.4217
3.5016 3.4761
2.2059 2.1870
1.5272 1.5183
1.0000
0.7782 0.7738
Efficiencyη n
0.9521 0.9288
0.9856 0.9784
0.9832 0.9748
0.9885 0.9827
1.0000
0.9894 0.9839
5HP 24
440 N⋅m (325 lb⋅ft ) 1996
36 93
32 100
35 90
3 3
4.4435 4.4435
1.6943
1.4519
Gear
R
1
2
3
4
5
Gear Ratio
−4.0952− 86 21
3.5714 25 7
2.2000 11 5
1.5047 161 107
1.0000 1 1
0.803786 107
Step
1.1467
1.0000
1.6234
1.4621
1.5047
1.2419
Δ Step
1.1103
0.9717
1.2094
Speed
–0.8721
1.0000
1.6234
2.3736
3.5714
4.4435
Δ Speed
0.8721
1.0000
0.6234
0.7502
1.1979
0.8721
Torque Ratio
–3.8985 –3.8025
3.5200 3.4943
2.1630 2.1445
1.4880 1.4795
1.0000
0.7959 0.7918
Efficiencyη n
0.9520 0.9285
0.9856 0.9784
0.9832 0.9748
0.9889 0.9833
1.0000
0.9902 0.9851
Actuated shift elements
Brake A
❶
❶
Brake B
❶
Brake C
❶
❶
Clutch D
❶
❶
❶
❶
Clutch E
❶
❶
Clutch F
❶
Geometric ratios: speed conversion
Gear Ratio R & 2 Ordinary Elementary Noted
i R = − S 2 ( S 1 + R 1 ) ( S 3 + R 3 ) S 1 R 2 S 3
i 2 = ( S 2 + R 2 ) ( S 3 + R 3 ) S 2 R 3 + S 3 ( S 2 + R 2 )
i R = − S 2 R 2 ( 1 + R 1 S 1 ) ( 1 + R 3 S 3 )
i 2 = 1 1 1 + R 3 S 3 + 1 ( 1 + R 2 S 2 ) ( 1 + S 3 R 3 )
Gear Ratio 1 & 5 Ordinary Elementary Noted
i 1 = S 3 + R 3 S 3
i 5 = S 2 ( S 1 + R 1 ) ( S 3 + R 3 ) S 2 ( S 1 + R 1 ) ( S 3 + R 3 ) + S 1 R 2 S 3
i 1 = 1 + R 3 S 3
i 5 = 1 1 + R 2 S 2 ( 1 + R 1 S 1 ) ( 1 + R 3 S 3 )
Gear Ratio 3 & 4 Ordinary Elementary Noted
i 3 = ( S 1 ( S 2 + R 2 ) + R 1 S 2 ) ( S 3 + R 3 ) S 2 ( S 1 + R 1 ) ( S 3 + R 3 ) + S 1 R 2 S 3
i 4 = 1 1
i 3 = 1 1 1 1 + S 1 R 1 + 1 + R 2 S 2 1 + R 1 S 1 + 1 ( 1 + S 2 R 2 ( 1 + R 1 S 1 ) ) ( 1 + R 3 S 3 )
Kinetic ratios: torque conversion
Torque Ratio R & 1
μ R = − S 2 R 2 η 0 ( 1 + R 1 S 1 η 0 ) ( 1 + R 3 S 3 η 0 )
μ 1 = 1 + R 3 S 3 η 0
Torque Ratio 2 & 5
μ 2 = 1 1 1 + R 3 S 3 η 0 + 1 ( 1 + R 2 S 2 η 0 ) ( 1 + S 3 R 3 η 0 )
μ 5 = 1 1 + R 2 S 2 ⋅ 1 η 0 ( 1 + R 1 S 1 η 0 ) ( 1 + R 3 S 3 η 0 )
Torque Ratio 3 & 4
μ 3 = 1 1 1 1 + S 1 R 1 ⋅ 1 η 0 1 3 + 1 + R 2 S 2 η 0 1 2 1 + R 1 S 1 ⋅ 1 η 0 1 3 + 1 ( 1 + S 2 R 2 η 0 1 2 ( 1 + R 1 S 1 η 0 1 3 ) ) ( 1 + R 3 S 3 η 0 )
μ 4 = 1 1
↑ Revised 14 January 2026Nomenclature
S n = sun gear: number of teeth
R n = ring gear: number of teeth
C n = carrier or planetary gear carrier (not needed)
s n = sun gear: shaft speed
r n = ring gear: shaft speed
c n = carrier or planetary gear carrier: shaft speed
With n = gear is
i n = gear ratio or transmission ratio
ω 1 ; n = ω t = shaft speed shaft 1: input (turbine) shaft
ω 2 ; n = shaft speed shaft 2: output shaft
T 1 ; n = T t = torque shaft 1: input (turbine) shaft
T 2 ; n = torque shaft 2: output shaft
μ n = torque ratio or torque conversion ratio
η n = efficiency
i 0 = stationary gear ratio
η 0 = (assumed) stationary gear efficiency
1 2 3 4 5 6 7 8 9 10 11 12 13 Gear ratio (transmission ratio) i n — speed conversion —
The gear ratio i n is the ratio of
input shaft speed ω 1 ; n
to output shaft speed ω 2 ; n
and therefore corresponds to the reciprocal of the shaft speeds
i n = 1 ω 2 ; n ω 1 ; n = ω 1 ; n ω 2 ; n = ω t ω 2 ; n
1 2 3 4 5 6 7 8 9 10 11 12 13 Torque ratio (torque conversion ratio) μ n — torque conversion —
The torque ratio μ n is the ratio of
output torque T 2 ; n
to input torque T 1 ; n
minus efficiency losses
and therefore corresponds (apart from the efficiency losses) to the reciprocal of the shaft speeds too
μ n = i n η n ; η 0 = ω 1 ; n η n ; η 0 ω 2 ; n = T 2 ; n η n ; η 0 T 1 ; n
whereby η n ; η 0 may vary from gear to gear according to the formulas listed in this table and 0 ≤ η n ; η 0 ≤ 1
1 2 3 4 5 6 7 8 9 10 Efficiency
The efficiency η n is calculated
from the torque ratio
in relation to the gear ratio (transmission ratio)
η n = μ n i n
Power loss for single meshing gears
is in the range of 1 % to 1.5 %
helical gear pairs, which are used to reduce noise in passenger cars, are in the upper part of the loss range
spur gear pairs, which are limited to commercial vehicles due to their poorer noise comfort, are in the lower part of the loss range
Corridor for torque ratio and efficiency
in planetary gearsets, the stationary gear ratio i 0 is formed via the planetary gears and thus by two meshes
for reasons of simplification, the efficiency for both meshes together is commonly specified there
the efficiencies η 0 specified here are based on assumed efficiencies for the stationary ratio i 0
of η 0 = 0.9800 (upper value)
and η 0 = 0.9700 (lower value)
for both interventions together
The corresponding efficiency
for single-meshing gear pairs is η 0 1 2
at 0.980 0 1 2 = 0.98995 (upper value)
and 0.970 0 1 2 = 0.98489 (lower value)
↑ Layout
Input and output are on opposite sides
Planetary gearset 1 is on the input (turbine) side
Input shafts are, if actuated, S1 , C2 , S3 , and R1
Output shaft is C3
↑ Total ratio span (total gear ratio/total transmission ratio) nominal
ω 2 ; n ω 2 ; 1 = ω 2 ; n ω 2 ; 1 ω 2 ; n ω 2 ; 1 ω 2 ; 1 ω 2 ; n = 1 ω 2 ; 1 1 ω 2 ; n = ω t ω 2 ; 1 ω t ω 2 ; n = i 1 i n
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
1 2 3 4 Total ratio span (total gear ratio/total transmission ratio) effective
ω 2 ; n m a x ( ω 2 ; 1 ; | ω 2 ; R | ) = m i n ( i 1 ; | i R | ) i n
The span is only effective to the extent that
the reverse gear ratio
matches that of 1st gear
see also Standard R:1
Digression Reverse gear
is usually longer than 1st gear
the effective span is therefore of central importance for describing the suitability of a transmission
because in these cases, the nominal spread conveys a misleading picture
which is only unproblematic for vehicles with high specific power
Market participants
Manufacturers naturally have no interest in specifying the effective span
Users have not yet formulated the practical benefits that the effective span has for them
The effective span has not yet played a role in research and teaching
Contrary to its significance
the effective span has therefore not yet been able to establish itself
either in theory
or in practice.
End of digression
↑ Ratio span's center
( i 1 i n ) 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
( ω 2 ; n ω 2 ; 1 ) 1 n − 1 = ( i 1 i n ) 1 n − 1
There are n − 1 gear steps between n gears
with decreasing step width
the gears connect better to each other
shifting comfort increases
↑ Sun 1: sun gear of gearset 1
↑ Ring 1: ring gear of gearset 1
↑ Sun 2: sun gear of gearset 2
↑ Ring 2: ring gear of gearset 2
↑ Sun 3: sun gear of gearset 3
↑ Ring 3: ring gear of gearset 3
1 2 3 4 5 6 7 8 9 10 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 2) is always larger
and the upper half of the gear steps (between the large gears; rounded up, here the last 2) 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)
1 2 3 4 5 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)
see also Total ratio span (total gear ratio/total transmission ratio) effective
↑ 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)
1 2 3 From large to small gears (from right to left)
1 2 3 4 5 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)
1 2 3 4 5 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)
↑ Blocks S1
↑ Blocks C1
↑ Blocks R3
↑ Connects S2 and S3 with the input (turbine)
↑ Connects R1 with the input (turbine)
↑ Connects C1 with the input (turbine)
1 2 3 Ordinary Noted
For direct determination of the gear ratio
1 2 3 Elementary Noted
Alternative representation for determining the transmission ratio
Contains only operands
With simple fractions of both central gears of a planetary gearset
Or with the value 1
As a basis
For reliable
And traceable
Determination of the torque conversion ratio and efficiency
Applications
Variants and applications
Model
Car Model
1990: 5HP 18 · 1997: 5HP 19 · Ravigneaux planetary gearset types
5HP 18
5HP 19
5HP 19FL
5HP 19FLA
5HP 19HL
5HP 19HLA
1999–2003 Porsche 911 Carrera 996 3.6
1999–2003 Porsche 911 Carrera 4S 996 3.6
1997-2004 Porsche Boxster 986 2.5 6-cyl
1997-2004 Porsche Boxster 986 2.7 6-cyl
1997-2004 Porsche Boxster 986 3.2 6-cyl
2005–2008 Porsche Boxster 987 2.7 6-cyl
2005–2008 Porsche Boxster S 987 3.4 6-cyl
2005–2008 Porsche Cayman 987 2.7 6-cyl
2005–2008 Porsche Cayman S 987 3.4 6-cyl
1992: 5HP 30 · 1996: 5HP 24 · Simpson planetary gearset types
5HP 30
5HP 24
5HP 24A