ZF 3HP transmission

3HP 12 · 3HP 22
3HP 12 · 3HP 22
Overview
Manufacturer	ZF Friedrichshafen
Production	1963–1975 · 1973–1990
Model years	1963–1975 · 1973–1990
Body and chassis
Class	3-Speed Automatic Transmission for Longitudinal and Transverse Engines
Chronology
Successor	ZF 4HP transmission Family

Last updated January 06, 2026

The 3HP is a 3-speed Automatic transmission family with a hydrodynamic Torque converter with hydraulic control for passenger cars from ZF Friedrichshafen AG. In selector level position "P", the output is locked mechanically. The Ravigneaux planetary gearset types were first introduced in 1963 and produced through the mid seventies. The Simpson planetary gearset types were launched in 1973 and produced through 1990. Both were used in different versions in a large number of cars.

Gear Ratios^[a]
Model	Version	Gear				Total Span			Avg. Step	Components
Model	Version	R	1	2	3	Nomi- nal	Effec- tive	Cen- ter	Avg. Step	Total	per Gear^[b]

3HP 12	Small Engines	−2.000	2.560	1.520	1.000	2.560	2.000	1.600	1.600	2 Gearsets 3 Brakes 2 Clutches	2.333
3HP 12	Big Engines	−2.000	2.286	1.429	1.000	2.286	2.000	1.512	1.512	2 Gearsets 3 Brakes 2 Clutches	2.333

3HP 22	Big Engines	−2.086	2.479	1.479	1.000	2.479	2.086	1.575	1.575	2 Gearsets 3 Brakes 2 Clutches	2.333
3HP 22	Small Engines	−2.086	2.733	1.562	1.000	2.733	2.086	1.653	1.653
3HP 22	Porsche 944	−2.429	2.714	1.500	1.000	2.714	2.429	1.648	1.648

↑ Differences in gear ratios have a measurable, direct impact on vehicle dynamics, performance, waste emissions as well as fuel mileage ↑ Forward gears only

1963: 3HP 12 · Ravigneaux Planetary Gearset Types

Introduction

The 3HP 12 was produced through the mid-seventies and has been used in a variety of cars. There are versions for longitudinal and transverse engines.

Gear Ratio Analysis
In-Depth Analysis With Assessment^[a]		Planetary Gearset:^[b] Teeth		Count	Nomi- nal^[c] Effec- tive^[d]	Cen- ter^[e]
In-Depth Analysis With Assessment^[a]		Ravigneaux		Count	Nomi- nal^[c] Effec- tive^[d]	Avg.^[f]

Model Type	Version First Delivery	S₁^[g] R₁^[h]	S₂^[i] R₂^[j]	Brakes Clutches	Ratio Span	Gear Step^[k]
Gear Ratio		R ${i_{R}}$		1 ${i_{1}}$	2 ${i_{2}}$	3 ${i_{3}}$
Step^[k]		$-{\frac {i_{R}}{i_{1}}}$ ^[l]		${\frac {i_{1}}{i_{1}}}$	${\frac {i_{1}}{i_{2}}}$ ^[m]	${\frac {i_{2}}{i_{3}}}$
Δ Step^[n]^[o]					${\tfrac {i_{1}}{i_{2}}}:{\tfrac {i_{2}}{i_{3}}}$
Shaft Speed		${\frac {i_{1}}{i_{R}}}$		${\frac {i_{1}}{i_{1}}}$	${\frac {i_{1}}{i_{2}}}$	${\frac {i_{1}}{i_{3}}}$
Δ Shaft Speed^[p]		$0-{\tfrac {i_{1}}{i_{R}}}$		${\tfrac {i_{1}}{i_{1}}}-0$	${\tfrac {i_{1}}{i_{2}}}-{\tfrac {i_{1}}{i_{1}}}$	${\tfrac {i_{1}}{i_{3}}}-{\tfrac {i_{1}}{i_{2}}}$
Specific Torque^[q]		${\tfrac {T_{2;R}}{T_{1;R}}}$ ^[r]		${\tfrac {T_{2;1}}{T_{1;1}}}$ ^[r]	${\tfrac {T_{2;2}}{T_{1;2}}}$ ^[r]	${\tfrac {T_{2;3}}{T_{1;3}}}$ ^[r]
Efficiency $\eta _{n}$ ^[q]		${\tfrac {T_{2;R}}{T_{1;R}}}:{i_{R}}$		${\tfrac {T_{2;1}}{T_{1;1}}}:{i_{1}}$	${\tfrac {T_{2;2}}{T_{1;2}}}:{i_{2}}$	${\tfrac {T_{2;3}}{T_{1;3}}}:{i_{3}}$

3HP 12	160 N⋅m (118 lb⋅ft ) 1963	25 32	32 64	3 2	2.5600 2.0000^[d]^[l]	1.6000
3HP 12	160 N⋅m (118 lb⋅ft ) 1963	25 32	32 64	3 2	2.5600 2.0000^[d]^[l]	1.6000^[k]
Gear Ratio		−2.0000^[l]^[d] $-{\tfrac {2}{1}}$		2.5600 ${\tfrac {64}{25}}$	1.5200^[m] ${\tfrac {38}{25}}$	1.0000 ${\tfrac {1}{1}}$
Step		0.7825^[l]		1.0000	1.6842^[m]	1.5200
Δ Step^[n]					1.1080
Speed		-1.2800		1.0000	1.6842	2.5600
Δ Speed		1.2800		1.0000	0.6842	0.8758
Specific Torque^[q]		–1.9600 –1.9400		2.4836 2.4457	1.4928 1.4792	1.0000
Efficiency $\eta _{n}$ ^[q]		0.9800 0.9700		0.9702 0.9553	0.9821 0.9731	1.0000

3HP 12	Big Engines 1963	28 32	32 64	3 2	2.2857 2.0000^[d]^[l]	1.5119
3HP 12	Big Engines 1963	28 32	32 64	3 2	2.2857 2.0000^[d]^[l]	1.5119^[k]
Gear Ratio		−2.0000^[l]^[d] $-{\tfrac {2}{1}}$		2.2857 ${\tfrac {16}{7}}$	1.4286 ${\tfrac {10}{7}}$	1.0000 ${\tfrac {1}{1}}$
Step		0.8750^[l]		1.0000	1.6000	1.4286
Δ Step^[n]					1.1280
Speed		-1.1429		1.0000	1.6000	2.2857
Δ Speed		1.1429		1.0000	0.6000	0.6842
Specific Torque^[q]		–1.9600 –1.9400		2.2175 2.1836	1.4038 1.3914	1.0000
Efficiency $\eta _{n}$ ^[q]		0.9800 0.9700		0.9702 0.9553	0.9826 0.9740	1.0000

Actuated Shift Elements
Brake A^[s]					❶
Brake B^[t]					❶
Brake C^[u]		❶		❶
Clutch D^[v]				❶	❶	❶
Clutch E^[w]		❶				❶
Geometric Ratios
Ratios Ordinary^[x] Elementary Noted^[y]	$i_{R}=-{\frac {R_{2}}{S_{2}}}$	$i_{1}={\frac {R_{2}}{S_{1}}}$		$i_{2}={\frac {R_{2}(S_{1}+R_{1})}{S_{1}(S_{2}+R_{2})}}$		$i_{3}={\frac {1}{1}}$
Ratios Ordinary^[x] Elementary Noted^[y]	$i_{R}=-{\tfrac {R_{2}}{S_{2}}}$	$i_{1}={\tfrac {R_{2}}{S_{1}}}$		$i_{2}={\tfrac {1+{\tfrac {S_{2}}{S_{1}}}}{1+{\tfrac {S_{2}}{R_{2}}}}}$		$i_{3}={\frac {1}{1}}$
Kinetic Ratios
Specific Torque^[q]	${\tfrac {T_{2;R}}{T_{1;R}}}=-{\tfrac {R_{2}}{S_{2}}}\eta _{0}$	${\tfrac {T_{2;1}}{T_{1;1}}}={\tfrac {R_{2}}{S_{1}}}{\eta _{0}}^{\tfrac {3}{2}}$		${\tfrac {T_{2;2}}{T_{1;2}}}={\tfrac {1+{\tfrac {S_{2}}{S_{1}}}\eta _{0}}{1+{\tfrac {S_{2}}{R_{2}}}\cdot {\tfrac {1}{\eta _{0}}}}}$		${\tfrac {T_{2;3}}{T_{1;3}}}={\tfrac {1}{1}}$

↑ Revised 5 January 2026 ↑ Gearset Components: Nomenclature S $=$ sun gear R $=$ ring gear C $=$ carrier or planetary gear carrier Layout Input and output are on opposite sides Planetary gearset 2 (the outer Ravigneaux gearset) is on the input (turbine) side Input (turbine) shafts is, if actuated S₁ or S₂ Output shaft is R₂ (ring gear of the outer Ravigneaux gearset) ↑ Total Ratio Span (Total Gear/Transmission Ratio) Nominal ${\frac {i_{1}}{i_{n}}}$ 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/Transmission Ratio) Effective ${\frac {min(i_{1};\|i_{R}\|)}{i_{n}}}$ The span is only effective to the extent that the reverse gear ratio matches that of 1st gear see also Standard R:1 ↑ Ratio Span's Center $(i_{1}i_{n})^{\frac {1}{2}}$ 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 $\left({\frac {i_{1}}{i_{n}}}\right)^{\frac {1}{n-1}}$ 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 1 2 3 4 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 1) is always larger and the upper half of the gear steps (between the large gears; rounded up, here the last 1) 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 7 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/Transmission Ratio) Effective 1 2 3 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) ↑ 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) 1 2 3 4 5 6 7 Specific Torque Ratio And Efficiency The specific torque is the Ratio of output torque $T_{2;n}$ to input torque $T_{1;n}$ with $n=gear$ The efficiency is calculated from the specific torque in relation to the transmission ratio 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 1 2 3 4 Corridor for specific torque 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 $\eta _{0}$ specified here are based on assumed efficiencies for the stationary ratio $i_{0}$ of $\eta _{0}=0.9800$ (upper value) and $\eta _{0}=0.9700$ (lower value) for both interventions together The corresponding efficiency for single-meshing gear pairs is ${\eta _{0}}^{\frac {1}{2}}$ at $0.9800^{\frac {1}{2}}=0.98995$ (upper value) and $0.9700^{\frac {1}{2}}=0.98489$ (lower value) ↑ Blocks R₁ (ring gear of the inner Ravigneaux gearset) and S₂ (sun gear of the outer Ravigneaux gearset) ↑ Supports link with freewheel · blocks R₁ (ring gear of the inner Ravigneaux gearset) and S₂ (sun gear of the outer Ravigneaux gearset) in one direction ↑ Blocks C₁ and C₂ (the common carrier of the compound Ravigneaux gearset) ↑ Couples S₁ (sun gear of the inner Ravigneaux gearset) with the input (turbine) ↑ Couples S₂ (sun gear of the outer Ravigneaux gearset) with the input (turbine) ↑ Ordinary Noted For direct determination of the ratio ↑ 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 specific torque and efficiency

1973: 3HP 22 · Simpson Planetary Gearset Types

Introduction

The all new 3HP 22 was introduced in 1973 and was produced through 1990 and has been used in a variety of cars from Alfa Romeo, BMW,^[1] Citroën, Peugeot, and Fiat.^[2]

Specifications
Weight	45 kg (99 lb ) with converter
Control	mechanical · hydraulic

Gear Ratio Analysis
In-Depth Analysis With Assessment^[a]		Planetary Gearset:^[b] Teeth		Count	Nomi- nal^[c] Effec- tive^[d]	Cen- ter^[e]
In-Depth Analysis With Assessment^[a]		Simpson		Count	Nomi- nal^[c] Effec- tive^[d]	Avg.^[f]

Model Type	Version First Delivery	S₁^[g] R₁^[h]	S₂^[i] R₂^[j]	Brakes Clutches	Ratio Span	Gear Step^[k]
Gear Ratio		R ${i_{R}}$		1 ${i_{1}}$	2 ${i_{2}}$	3 ${i_{3}}$
Step^[k]		$-{\frac {i_{R}}{i_{1}}}$ ^[l]		${\frac {i_{1}}{i_{1}}}$	${\frac {i_{1}}{i_{2}}}$ ^[m]	${\frac {i_{2}}{i_{3}}}$
Δ Step^[n]^[o]					${\tfrac {i_{1}}{i_{2}}}:{\tfrac {i_{2}}{i_{3}}}$
Shaft Speed		${\frac {i_{1}}{i_{R}}}$		${\frac {i_{1}}{i_{1}}}$	${\frac {i_{1}}{i_{2}}}$	${\frac {i_{1}}{i_{3}}}$
Δ Shaft Speed^[p]		$0-{\tfrac {i_{1}}{i_{R}}}$		${\tfrac {i_{1}}{i_{1}}}-0$	${\tfrac {i_{1}}{i_{2}}}-{\tfrac {i_{1}}{i_{1}}}$	${\tfrac {i_{1}}{i_{3}}}-{\tfrac {i_{1}}{i_{2}}}$
Specific Torque^[q]		${\tfrac {T_{2;R}}{T_{1;R}}}$ ^[r]		${\tfrac {T_{2;1}}{T_{1;1}}}$ ^[r]	${\tfrac {T_{2;2}}{T_{1;2}}}$ ^[r]	${\tfrac {T_{2;3}}{T_{1;3}}}$ ^[r]
Efficiency $\eta _{n}$ ^[q]		${\tfrac {T_{2;R}}{T_{1;R}}}:{i_{R}}$		${\tfrac {T_{2;1}}{T_{1;1}}}:{i_{1}}$	${\tfrac {T_{2;2}}{T_{1;2}}}:{i_{2}}$	${\tfrac {T_{2;3}}{T_{1;3}}}:{i_{3}}$

3HP 22	320 N⋅m (236 lb⋅ft ) 1963	35 73	35 73	3 2	2.4795 2.0857^[d]^[l]	1.5746
3HP 22	320 N⋅m (236 lb⋅ft ) 1963	35 73	35 73	3 2	2.4795 2.0857^[d]^[l]	1.5746^[k]
Gear Ratio		−2.0857^[l]^[d] $-{\tfrac {2}{1}}$		2.4795 ${\tfrac {181}{73}}$	1.4795^[m] ${\tfrac {108}{73}}$	1.0000 ${\tfrac {1}{1}}$
Step		0.8412^[l]		1.0000	1.6759^[m]	1.4795
Δ Step^[n]					1.1328
Speed		-1.1888		1.0000	1.6759	2.4795
Δ Speed		1.1888		1.0000	0.6759	0.8035
Specific Torque^[q]		–2.0440 –2.0231		2.4303 2.4060	1.4699 1.4651	1.0000
Efficiency $\eta _{n}$ ^[q]		0.9800 0.9700		0.9802 0.9704	0.9935 0.9903	1.0000

3HP 22	Small Engines 1973	35 73	41 73	3 2	2.7331 2.0857^[d]^[l]	1.6532
3HP 22	Small Engines 1973	35 73	41 73	3 2	2.7331 2.0857^[d]^[l]	1.6532^[k]
Gear Ratio		−2.0857^[l]^[d] $-{\tfrac {73}{35}}$		2.7331 ${\tfrac {6,983}{2,555}}$	1.5616^[m] ${\tfrac {114}{73}}$	1.0000 ${\tfrac {1}{1}}$
Step		0.7631^[l]		1.0000	1.7501^[m]	1.5616
Δ Step^[n]					1.1207
Speed		-1.3103		1.0000	1.7501	2.7331
Δ Speed		1.3103		1.0000	0.7501	0.9829
Specific Torque^[q]		–2.0440 –2.0231		2.6755 2.6470	1.5504 1.5448	1.0000
Efficiency $\eta _{n}$ ^[q]		0.9800 0.9700		0.9789 0.9685	0.9928 0.9892	1.0000

3HP 22	Porsche 944 1981	28 68	32 64	3 2	2.7143 2.4286^[d]^[l]	1.6475
3HP 22	Porsche 944 1981	28 68	32 64	3 2	2.7143 2.4286^[d]^[l]	1.6475^[k]
Gear Ratio		−2.4286^[l]^[d] $-{\tfrac {17}{7}}$		2.7143 ${\tfrac {19}{7}}$	1.5000^[m] ${\tfrac {3}{2}}$	1.0000 ${\tfrac {1}{1}}$
Step		0.8947^[l]		1.0000	1.8095^[m]	1.5000
Δ Step^[n]					1.2063
Speed		-1.1176		1.0000	1.8095	2.7143
Δ Speed		1.1176		1.0000	0.8095	0.9048
Specific Torque^[q]		–2.3800 –2.3557		2.6562 2.6275	1.4900 1.4850	1.0000
Efficiency $\eta _{n}$ ^[q]		0.9800 0.9700		0.9786 0.9680	0.9933 0.9900	1.0000

Actuated Shift Elements
Brake A^[s]					❶
Brake B^[t]					❶	❶
Brake C^[u]		❶		❶
Clutch D^[v]				❶	❶	❶
Clutch E^[w]		❶				❶
Geometric Ratios
Ratio R & 2 Ordinary^[x] Elementary Noted^[y]	$i_{R}=-{\frac {R_{1}}{S_{1}}}$		$i_{2}={\frac {S_{2}+R_{2}}{R_{2}}}$
Ratio R & 2 Ordinary^[x] Elementary Noted^[y]	$i_{R}=-{\tfrac {R_{1}}{S_{1}}}$		$i_{2}=1+{\tfrac {S_{2}}{R_{2}}}$

Ratio 1 & 3 Ordinary^[x] Elementary Noted^[y]	$i_{1}={\frac {S_{1}(S_{2}+R_{2})+R_{1}S_{2}}{S_{1}R_{2}}}$				$i_{3}={\frac {1}{1}}$
Ratio 1 & 3 Ordinary^[x] Elementary Noted^[y]	$i_{1}=1+{\tfrac {S_{2}}{R_{2}}}\left(1+{\tfrac {R_{1}}{S_{1}}}\right)$				$i_{3}={\frac {1}{1}}$
Kinetic Ratios
Specific Torque^[q] R & 2	${\tfrac {T_{2;R}}{T_{1;R}}}=-{\tfrac {R_{1}}{S_{1}}}\eta _{0}$		${\tfrac {T_{2;2}}{T_{1;2}}}=1+{\tfrac {S_{2}}{R_{2}}}\eta _{0}$
Specific Torque^[q] 1 & 3	${\tfrac {T_{2;1}}{T_{1;1}}}=1+{\tfrac {S_{2}}{R_{2}}}\eta _{0}\left(1+{\tfrac {R_{1}}{S_{1}}}\eta _{0}\right)$				${\tfrac {T_{2;3}}{T_{1;3}}}={\tfrac {1}{1}}$

↑ Revised 5 January 2026 ↑ Gearset Components: Nomenclature S $=$ sun gear R $=$ ring gear C $=$ carrier or planetary gear carrier Layout Input and output are on opposite sides Planetary gearset 1 is on the input (turbine) side Input (turbine) shaft is, if actuated, S₁ or R₂ Output shaft is R₁ ↑ Total Ratio Span (Total Gear/Transmission Ratio) Nominal ${\frac {i_{1}}{i_{n}}}$ 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 6 7 Total Ratio Span (Total Gear/Transmission Ratio) Effective ${\frac {min(i_{1};\|i_{R}\|)}{i_{n}}}$ The span is only effective to the extent that the reverse gear ratio matches that of 1st gear see also Standard R:1 ↑ Ratio Span's Center $(i_{1}i_{n})^{\frac {1}{2}}$ 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 $\left({\frac {i_{1}}{i_{n}}}\right)^{\frac {1}{n-1}}$ 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 1 2 3 4 5 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 1) is always larger and the upper half of the gear steps (between the large gears; rounded up, here the last 1) 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 7 8 9 10 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) 1 2 3 4 5 6 7 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 4 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) 1 2 3 4 5 6 7 8 9 10 Specific Torque Ratio And Efficiency The specific torque is the Ratio of output torque $T_{2;n}$ to input torque $T_{1;n}$ with $n=gear$ The efficiency is calculated from the specific torque in relation to the transmission ratio 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 1 2 3 4 Corridor for specific torque 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 $\eta _{0}$ specified here are based on assumed efficiencies for the stationary ratio $i_{0}$ of $\eta _{0}=0.9800$ (upper value) and $\eta _{0}=0.9700$ (lower value) for both interventions together The corresponding efficiency for single-meshing gear pairs is ${\eta _{0}}^{\frac {1}{2}}$ at $0.9800^{\frac {1}{2}}=0.98995$ (upper value) and $0.9700^{\frac {1}{2}}=0.98489$ (lower value) ↑ Blocks S₁ ↑ Supports link with freewheel · blocks S₁ in one direction ↑ Blocks C₁ ↑ Couples S₁ with the input (turbine) ↑ Couples R₂ with the input (turbine) 1 2 Ordinary Noted For direct determination of the ratio 1 2 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 specific torque and efficiency

References

↑ "BMWE21.net". BMWe21.net. Retrieved 24 November 2013.
↑ "ZF North America application chart (automatic)". ZF.com. Archived from the original on 22 February 2013. Retrieved 22 November 2013.

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

[2] Forward gears only

[3] Revised 5 January 2026

[4] Gearset Components: Nomenclature
S $=$ sun gear
R $=$ ring gear
C $=$ carrier or planetary gear carrier
Layout
Input and output are on opposite sides
Planetary gearset 2 (the outer Ravigneaux gearset) is on the input (turbine) side
Input (turbine) shafts is, if actuated S₁ or S₂
Output shaft is R₂ (ring gear of the outer Ravigneaux gearset)

[mwAz4] S $=$ sun gear

[mwA0k] R $=$ ring gear

[mwA1Q] C $=$ carrier or planetary gear carrier

[mwA2E] Input and output are on opposite sides

[mwA2I] Planetary gearset 2 (the outer Ravigneaux gearset) is on the input (turbine) side

[mwA2M] Input (turbine) shafts is, if actuated S₁ or S₂

[mwA2g] Output shaft is R₂ (ring gear of the outer Ravigneaux gearset)

[5] Total Ratio Span (Total Gear/Transmission Ratio) Nominal
${\frac {i_{1}}{i_{n}}}$
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

[mwA3A] ${\frac {i_{1}}{i_{n}}}$

[mwA4M] 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

[mwA4U] wnspeeding when driving outside the city limits

[mwA4Y] rease the climbing ability
when driving over mountain passes or off-road
or when towing a trailer

[mwA4g] when driving over mountain passes or off-road

[mwA4k] r when towing a trailer

[effective-6] 1 2 3 4 5 Total Ratio Span (Total Gear/Transmission Ratio) Effective
${\frac {min(i_{1};|i_{R}|)}{i_{n}}}$
The span is only effective to the extent that
the reverse gear ratio
matches that of 1st gear
see also Standard R:1

[mwA5c] ${\frac {min(i_{1};|i_{R}|)}{i_{n}}}$

[mwA7k] The span is only effective to the extent that
the reverse gear ratio
matches that of 1st gear

[mwA7s] the reverse gear ratio

[mwA7w] tches that of 1st gear

[mwA70] see also Standard R:1

[7] Ratio Span's Center
$(i_{1}i_{n})^{\frac {1}{2}}$
The center indicates the speed level of the transmission
Together with the final drive ratio
it gives the shaft speed level of the vehicle

[mwA8Q] $(i_{1}i_{n})^{\frac {1}{2}}$

[mwA9w] The center indicates the speed level of the transmission

[mwA90] Together with the final drive ratio

[mwA94] t gives the shaft speed level of the vehicle

[8] Average Gear Step
$\left({\frac {i_{1}}{i_{n}}}\right)^{\frac {1}{n-1}}$
With decreasing step width
the gears connect better to each other
shifting comfort increases

[mwA-Q] $\left({\frac {i_{1}}{i_{n}}}\right)^{\frac {1}{n-1}}$

[mwBAI] With decreasing step width
the gears connect better to each other
shifting comfort increases

[mwBAQ] the gears connect better to each other

[mwBAU] shifting comfort increases

[9] Sun 1: sun gear of gearset 1: inner Ravigneaux gearset

[10] Ring 1: ring gear of gearset 1: inner Ravigneaux gearset

[11] Sun 2: sun gear of gearset 2: outer Ravigneaux gearset

[12] Ring 2: ring gear of gearset 2: outer Ravigneaux gearset

[50:50-13] 1 2 3 4 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 1) is always larger
and the upper half of the gear steps (between the large gears; rounded up, here the last 1) 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)

[mwBCU] With steadily decreasing gear steps (yellow highlighted line Step)

[mwBCc] rticularly large step from 1st to 2nd gear
the lower half of the gear steps (between the small gears; rounded down, here the first 1) is always larger
and the upper half of the gear steps (between the large gears; rounded up, here the last 1) is always smaller

[mwBCk] the lower half of the gear steps (between the small gears; rounded down, here the first 1) is always larger

[mwBCw] the upper half of the gear steps (between the large gears; rounded up, here the last 1) is always smaller

[mwBC8] than the average gear step (cell highlighted yellow two rows above on the far right)

[mwBDE] wer half: smaller gear steps are a waste of possible ratios (red bold)

[mwBDU] upper half: larger gear steps are unsatisfactory (red bold)

[R:1-14] 1 2 3 4 5 6 7 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/Transmission Ratio) Effective

[mwBFA] 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

[mwBFI] rment when maneuvering

[mwBFM] specially when towing a trailer

[mwBFQ] torque converter can only partially compensate for this deficiency

[mwBFU] Plus 11.11 % minus 10 % compared to 1st gear is good

[mwBFg] Plus 25 % minus 20 % is acceptable (red)

[mwBFw] Above this is unsatisfactory (bold)

[mwBF8] see also Total Ratio Span (Total Gear/Transmission Ratio) Effective

[1:2-15] 1 2 3 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)

[mwBHA] With continuously decreasing gear steps (yellow marked line Step)

[mwBHI] the largest gear step is the one from 1st to 2nd gear, which
for a good speed connection and
a smooth gear shift

[mwBHU] r a good speed connection and

[mwBHY] smooth gear shift

[mwBHc] ust 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)

[mwBHk] A gear ratio of up to 1.6667 : 1 (5 : 3) is good

[mwBHw] Up to 1.7500 : 1 (7 : 4) is acceptable (red)

[mwBIA] Above is unsatisfactory (bold)

[LS-16] 1 2 3 From large to small gears (from right to left)

[step-17] 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)

[mwBJU] 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

[mwBJc] increase: Δ Step (first green highlighted line Δ Step) is always greater than 1

[mwBJw] As progressive as possible: Δ Step is always greater than the previous step

[mwBJ8] Not progressively increasing is acceptable (red)

[mwBKE] Not increasing is unsatisfactory (bold)

[speed-18] 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)

[mwBK8] Shaft speed differences should
increase: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one

[mwBLE] increase: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one

[mwBLY] 1 difference smaller than the previous one is acceptable (red)

[mwBLg] 2 consecutive ones are a waste of possible ratios (bold)

[Efficiency1-19] 1 2 3 4 5 6 7 Specific Torque Ratio And Efficiency
The specific torque is the Ratio of
output torque $T_{2;n}$
to input torque $T_{1;n}$
with $n=gear$
The efficiency is calculated from the specific torque in relation to the transmission ratio
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

[mwBMw] The specific torque is the Ratio of
output torque $T_{2;n}$
to input torque $T_{1;n}$
with $n=gear$

[mwBM4] utput torque $T_{2;n}$

[mwBN0] to input torque $T_{1;n}$

[mwBOw] with $n=gear$

[mwBPs] The efficiency is calculated from the specific torque in relation to the transmission ratio

[mwBP0] 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

[mwBQE] r pairs, which are used to reduce noise in passenger cars, are in the upper part of the loss range

[mwBQI] spur gear pairs, which are limited to commercial vehicles due to their poorer noise comfort, are in the lower part of the loss range

[Efficiency2-20] 1 2 3 4 Corridor for specific torque 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 $\eta _{0}$ specified here are based on assumed efficiencies for the stationary ratio $i_{0}$
of $\eta _{0}=0.9800$ (upper value)
and $\eta _{0}=0.9700$ (lower value)
for both interventions together
The corresponding efficiency for single-meshing gear pairs is ${\eta _{0}}^{\frac {1}{2}}$
at $0.9800^{\frac {1}{2}}=0.98995$ (upper value)
and $0.9700^{\frac {1}{2}}=0.98489$ (lower value)

[mwBQ4] tary gearsets, the stationary gear ratio $i_{0}$ is formed via the planetary gears and thus by two meshes

[mwBRs] r reasons of simplification, the efficiency for both meshes together is commonly specified there

[mwBRw] the efficiencies $\eta _{0}$ specified here are based on assumed efficiencies for the stationary ratio $i_{0}$
of $\eta _{0}=0.9800$ (upper value)
and $\eta _{0}=0.9700$ (lower value)

[mwBTY] $\eta _{0}=0.9800$ (upper value)

[mwBUU] $\eta _{0}=0.9700$ (lower value)

[mwBVQ] r both interventions together

[mwBVU] The corresponding efficiency for single-meshing gear pairs is ${\eta _{0}}^{\frac {1}{2}}$
at $0.9800^{\frac {1}{2}}=0.98995$ (upper value)
and $0.9700^{\frac {1}{2}}=0.98489$ (lower value)

[mwBWk] t $0.9800^{\frac {1}{2}}=0.98995$ (upper value)

[mwBXo] $0.9700^{\frac {1}{2}}=0.98489$ (lower value)

[21] Blocks R₁ (ring gear of the inner Ravigneaux gearset) and S₂ (sun gear of the outer Ravigneaux gearset)

[22] Supports link with freewheel · blocks R₁ (ring gear of the inner Ravigneaux gearset) and S₂ (sun gear of the outer Ravigneaux gearset) in one direction

[23] Blocks C₁ and C₂ (the common carrier of the compound Ravigneaux gearset)

[24] Couples S₁ (sun gear of the inner Ravigneaux gearset) with the input (turbine)

[25] Couples S₂ (sun gear of the outer Ravigneaux gearset) with the input (turbine)

[ordinary-26] Ordinary Noted
For direct determination of the ratio

[mwBa8] For direct determination of the ratio

[elementary-27] 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 specific torque and efficiency

[mwBbU] Alternative representation for determining the transmission ratio

[mwBbY] Contains only operands
With simple fractions of both central gears of a planetary gearset
Or with the value 1

[mwBbg] With simple fractions of both central gears of a planetary gearset

[mwBbk] Or with the value 1

[mwBbo] As a basis
For reliable
And traceable

[mwBbw] For reliable

[mwBb0] And traceable

[mwBb4] Determination of specific torque and efficiency

[30] Revised 5 January 2026

[31] Gearset Components: Nomenclature
S $=$ sun gear
R $=$ ring gear
C $=$ carrier or planetary gear carrier
Layout
Input and output are on opposite sides
Planetary gearset 1 is on the input (turbine) side
Input (turbine) shaft is, if actuated, S₁ or R₂
Output shaft is R₁

[mwCRk] S $=$ sun gear

[mwCSQ] R $=$ ring gear

[mwCS8] C $=$ carrier or planetary gear carrier

[mwCTw] Input and output are on opposite sides

[mwCT0] Planetary gearset 1 is on the input (turbine) side

[mwCT4] Input (turbine) shaft is, if actuated, S₁ or R₂

[mwCUM] Output shaft is R₁

[32] Total Ratio Span (Total Gear/Transmission Ratio) Nominal
${\frac {i_{1}}{i_{n}}}$
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

[mwCUs] ${\frac {i_{1}}{i_{n}}}$

[mwCV4] 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

[mwCWA] wnspeeding when driving outside the city limits

[mwCWE] rease the climbing ability
when driving over mountain passes or off-road
or when towing a trailer

[mwCWM] when driving over mountain passes or off-road

[mwCWQ] r when towing a trailer

[effective-33] 1 2 3 4 5 6 7 Total Ratio Span (Total Gear/Transmission Ratio) Effective
${\frac {min(i_{1};|i_{R}|)}{i_{n}}}$
The span is only effective to the extent that
the reverse gear ratio
matches that of 1st gear
see also Standard R:1

[mwCXY] ${\frac {min(i_{1};|i_{R}|)}{i_{n}}}$

[mwCZg] The span is only effective to the extent that
the reverse gear ratio
matches that of 1st gear

[mwCZo] the reverse gear ratio

[mwCZs] tches that of 1st gear

[mwCZw] see also Standard R:1

[34] Ratio Span's Center
$(i_{1}i_{n})^{\frac {1}{2}}$
The center indicates the speed level of the transmission
Together with the final drive ratio
it gives the shaft speed level of the vehicle

[mwCaM] $(i_{1}i_{n})^{\frac {1}{2}}$

[mwCbs] The center indicates the speed level of the transmission

[mwCbw] Together with the final drive ratio

[mwCb0] t gives the shaft speed level of the vehicle

[35] Average Gear Step
$\left({\frac {i_{1}}{i_{n}}}\right)^{\frac {1}{n-1}}$
With decreasing step width
the gears connect better to each other
shifting comfort increases

[mwCcM] $\left({\frac {i_{1}}{i_{n}}}\right)^{\frac {1}{n-1}}$

[mwCeE] With decreasing step width
the gears connect better to each other
shifting comfort increases

[mwCeM] the gears connect better to each other

[mwCeQ] shifting comfort increases

[36] Sun 1: sun gear of gearset 1: inner Ravigneaux gearset

[37] Ring 1: ring gear of gearset 1: inner Ravigneaux gearset

[38] Sun 2: sun gear of gearset 2: outer Ravigneaux gearset

[39] Ring 2: ring gear of gearset 2: outer Ravigneaux gearset

[50:50-40] 1 2 3 4 5 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 1) is always larger
and the upper half of the gear steps (between the large gears; rounded up, here the last 1) 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)

[mwCgY] With steadily decreasing gear steps (yellow highlighted line Step)

[mwCgg] rticularly large step from 1st to 2nd gear
the lower half of the gear steps (between the small gears; rounded down, here the first 1) is always larger
and the upper half of the gear steps (between the large gears; rounded up, here the last 1) is always smaller

[mwCgo] the lower half of the gear steps (between the small gears; rounded down, here the first 1) is always larger

[mwCg0] the upper half of the gear steps (between the large gears; rounded up, here the last 1) is always smaller

[mwChA] than the average gear step (cell highlighted yellow two rows above on the far right)

[mwChI] wer half: smaller gear steps are a waste of possible ratios (red bold)

[mwChY] upper half: larger gear steps are unsatisfactory (red bold)

[R:1-41] 1 2 3 4 5 6 7 8 9 10 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)

[mwCjc] 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

[mwCjk] rment when maneuvering

[mwCjo] specially when towing a trailer

[mwCjs] torque converter can only partially compensate for this deficiency

[mwCjw] Plus 11.11 % minus 10 % compared to 1st gear is good

[mwCj8] Plus 25 % minus 20 % is acceptable (red)

[mwCkM] Above this is unsatisfactory (bold)

[1:2-42] 1 2 3 4 5 6 7 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)

[mwCl0] With continuously decreasing gear steps (yellow marked line Step)

[mwCl8] the largest gear step is the one from 1st to 2nd gear, which
for a good speed connection and
a smooth gear shift

[mwCmI] r a good speed connection and

[mwCmM] smooth gear shift

[mwCmQ] ust 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)

[mwCmY] A gear ratio of up to 1.6667 : 1 (5 : 3) is good

[mwCmk] Up to 1.7500 : 1 (7 : 4) is acceptable (red)

[mwCm0] Above is unsatisfactory (bold)

[LS-43] 1 2 3 4 From large to small gears (from right to left)

[step-44] 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)

[mwCoQ] 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

[mwCoY] increase: Δ Step (first green highlighted line Δ Step) is always greater than 1

[mwCos] As progressive as possible: Δ Step is always greater than the previous step

[mwCo4] Not progressively increasing is acceptable (red)

[mwCpA] Not increasing is unsatisfactory (bold)

[speed-45] 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)

[mwCp4] Shaft speed differences should
increase: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one

[mwCqA] increase: Δ Shaft Speed (second line marked in green Δ (Shaft) Speed) is always greater than the previous one

[mwCqU] 1 difference smaller than the previous one is acceptable (red)

[mwCqc] 2 consecutive ones are a waste of possible ratios (bold)

[Efficiency1-46] 1 2 3 4 5 6 7 8 9 10 Specific Torque Ratio And Efficiency
The specific torque is the Ratio of
output torque $T_{2;n}$
to input torque $T_{1;n}$
with $n=gear$
The efficiency is calculated from the specific torque in relation to the transmission ratio
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

[mwCsE] The specific torque is the Ratio of
output torque $T_{2;n}$
to input torque $T_{1;n}$
with $n=gear$

[mwCsM] utput torque $T_{2;n}$

[mwCtI] to input torque $T_{1;n}$

[mwCuE] with $n=gear$

[mwCvA] The efficiency is calculated from the specific torque in relation to the transmission ratio

[mwCvI] 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

[mwCvY] r pairs, which are used to reduce noise in passenger cars, are in the upper part of the loss range

[mwCvc] spur gear pairs, which are limited to commercial vehicles due to their poorer noise comfort, are in the lower part of the loss range

[Efficiency2-47] 1 2 3 4 Corridor for specific torque 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 $\eta _{0}$ specified here are based on assumed efficiencies for the stationary ratio $i_{0}$
of $\eta _{0}=0.9800$ (upper value)
and $\eta _{0}=0.9700$ (lower value)
for both interventions together
The corresponding efficiency for single-meshing gear pairs is ${\eta _{0}}^{\frac {1}{2}}$
at $0.9800^{\frac {1}{2}}=0.98995$ (upper value)
and $0.9700^{\frac {1}{2}}=0.98489$ (lower value)

[mwCwM] tary gearsets, the stationary gear ratio $i_{0}$ is formed via the planetary gears and thus by two meshes

[mwCxA] r reasons of simplification, the efficiency for both meshes together is commonly specified there

[mwCxE] the efficiencies $\eta _{0}$ specified here are based on assumed efficiencies for the stationary ratio $i_{0}$
of $\eta _{0}=0.9800$ (upper value)
and $\eta _{0}=0.9700$ (lower value)

[mwCys] $\eta _{0}=0.9800$ (upper value)

[mwCzo] $\eta _{0}=0.9700$ (lower value)

[mwC0k] r both interventions together

[mwC0o] The corresponding efficiency for single-meshing gear pairs is ${\eta _{0}}^{\frac {1}{2}}$
at $0.9800^{\frac {1}{2}}=0.98995$ (upper value)
and $0.9700^{\frac {1}{2}}=0.98489$ (lower value)

[mwC14] t $0.9800^{\frac {1}{2}}=0.98995$ (upper value)

[mwC28] $0.9700^{\frac {1}{2}}=0.98489$ (lower value)

[48] Blocks S₁

[49] Supports link with freewheel · blocks S₁ in one direction

[50] Blocks C₁

[51] Couples S₁ with the input (turbine)

[52] Couples R₂ with the input (turbine)

[ordinary-53] 1 2 Ordinary Noted
For direct determination of the ratio

[mwC6A] For direct determination of the ratio

[elementary-54] 1 2 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 specific torque and efficiency

[mwC6g] Alternative representation for determining the transmission ratio

[mwC6k] Contains only operands
With simple fractions of both central gears of a planetary gearset
Or with the value 1

[mwC6s] With simple fractions of both central gears of a planetary gearset

[mwC6w] Or with the value 1

[mwC60] As a basis
For reliable
And traceable

[mwC68] For reliable

[mwC7A] And traceable

[mwC7E] Determination of specific torque and efficiency

[28] "BMWE21.net". BMWe21.net. Retrieved 24 November 2013.

[29] "ZF North America application chart (automatic)". ZF.com. Archived from the original on 22 February 2013. Retrieved 22 November 2013.

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ZF 3HP transmission

Contents

1963: 3HP 12 · Ravigneaux Planetary Gearset Types

Introduction

1973: 3HP 22 · Simpson Planetary Gearset Types

Introduction

See also

References