5HP isZF Friedrichshafen AG'strademark name for its 5-speedautomatic transmission models (5-speed transmission withHydraulic converter andPlanetary gearsets) forlongitudinal engine applications, designed and built byZF's subsidiary inSaarbrücken.

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 transmission8HP require fewer main components.

Gearset Concept: Cost-Effectiveness^[a]

With Assessment	Output: Gear Ratios	Innovation Elasticity[b] Δ Output : Δ Input	Input: Main Components
			Total	Gearsets	Brakes	Clutches
5HP 18/19 Ref. Object	${\displaystyle n_{O1}}$ ${\displaystyle n_{O2}}$	Topic[b]	${\displaystyle n_I=n_G+}$ ${\displaystyle n_B+n_C}$	${\displaystyle n_{G1}}$ ${\displaystyle n_{G2}}$	${\displaystyle n_{B1}}$ ${\displaystyle n_{B2}}$	${\displaystyle n_{C1}}$ ${\displaystyle n_{C2}}$
Δ Number	${\displaystyle n_{O1}-n_{O2}}$		${\displaystyle n_{I1}-n_{I2}}$	${\displaystyle n_{G1}-n_{G2}}$	${\displaystyle n_{B1}-n_{B2}}$	${\displaystyle n_{C1}-n_{C2}}$
Relative Δ	Δ Output ${\displaystyle \frac{n_{O1}-n_{O2}}{n_{O2}}}$	${\displaystyle \frac{n_{O1}-n_{O2}}{n_{O2}}:\frac{n_{I1}-n_{I2}}{n_{I2}}}$ ${\displaystyle =\frac{n_{O1}-n_{O2}}{n_{O2}}}$·${\displaystyle \frac{n_{I2}}{n_{I1}-n_{I2}}}$	Δ Input ${\displaystyle \frac{n_{I1}-n_{I2}}{n_{I2}}}$	${\displaystyle \frac{n_{G1}-n_{G2}}{n_{G2}}}$	${\displaystyle \frac{n_{B1}-n_{B2}}{n_{B2}}}$	${\displaystyle \frac{n_{C1}-n_{C2}}{n_{C2}}}$
5HP 18/19 4HP 14/16/18[c]	5[d] 4[d]	Progress[b]	10 7	3[e] 2[e]	3 2	4 3
Δ Number	1		3	1	1	1
Relative Δ	0.250 ${\displaystyle \frac{1}{4}}$	0.583[b] ${\displaystyle \frac{1}{4}:\frac{3}{7}=\frac{1}{4}}$·${\displaystyle \frac{7}{3}=\frac{7}{12}}$	0.429 ${\displaystyle \frac{3}{7}}$	0.500 ${\displaystyle \frac{1}{2}}$	0.500 ${\displaystyle \frac{1}{2}}$	0.333 ${\displaystyle \frac{1}{3}}$
5HP 18/19 4HP 20/22/24[c]	5[d] 4[d]	Progress[b]	10 10	3[e] 3	3 4	4 3
Δ Number	1		0	0	-1	1
Relative Δ	0.250 ${\displaystyle \frac{1}{4}}$	∞[b] ${\displaystyle \frac{1}{4}:\frac{0}{10}=\frac{1}{4}}$·${\displaystyle \frac{10}{0}=\frac{10}{0}}$	0.000 ${\displaystyle \frac{0}{10}}$	0.000 ${\displaystyle \frac{0}{3}}$	−0.250 ${\displaystyle \frac{-1}{4}}$	0.333 ${\displaystyle \frac{1}{3}}$
5HP 18/19 3-Speed[f]	5[d] 3[d]	Market Position[b]	10 7	3[e] 2[e]	3 3	4 2
Δ Number	2		3	1	0	2
Relative Δ	0.667 ${\displaystyle \frac{2}{3}}$	1.556[b] ${\displaystyle \frac{2}{3}:\frac{3}{7}=\frac{2}{3}}$·${\displaystyle \frac{7}{3}=\frac{14}{9}}$	0.429 ${\displaystyle \frac{3}{7}}$	0.500 ${\displaystyle \frac{1}{2}}$	0.000 ${\displaystyle \frac{0}{3}}$	1.000 ${\displaystyle \frac{2}{2}}$
^Progress increases cost-effectiveness and is reflected in theratio of forward gears to main components. It depends on thepower flow: parallel: using the two degrees of freedom ofplanetary gearsets to increase the number of gears with unchanged number of components serial: in-line combinedplanetary gearsets without using the two degrees of freedom to increase the number of gears a corresponding increase in the number of components is unavoidable ^abcdefghInnovationElasticity 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. whoseeconomicelasticity is greater than 1, are considered for realization Therequired innovationelasticity of an automobile manufacturer depends on its expected return on investment. The basic assumption that the relative additional benefit must beat 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) ^abDirect Predecessor To reflect the progress of the specific model change ^abcdefplus 1 reverse gear ^abcdeof which 2 gearsets are combined as a compoundRavigneaux 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 Turbo-Hydramatic fromGM Cruise-O-Matic fromFord TorqueFlite fromChrysler Detroit Gear fromBorgWarner forStudebaker BW-35 fromBorgWarner and asT35 fromAisin 3N 71 fromNissan/Jatco 3 HP fromZF Friedrichshafen W3A 040 and W3B 050 fromMercedes-Benz

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).

Gear Ratio Analysis^[a]

In-Depth Analysis[b] With Assessment And Torque Ratio[c] And Efficiency Calculation[d]		Planetary Gearset: Teeth[e]			Count	Nomi- nal[f] Effec- tive[g]	Cen- ter[h]
		Ravigneaux		Simple			Avg.[i]
Model Type	Version First Delivery	S1[j] R1[k]	S2[l] R2[m]	S3[n] R3[o]	Brakes Clutches	Ratio Span	Gear Step[p]
Gear	R		1	2	3	4	5
Gear Ratio[b]	${\displaystyle i_R}$[b]		${\displaystyle i_1}$[b]	${\displaystyle i_2}$[b]	${\displaystyle i_3}$[b]	${\displaystyle i_4}$[b]	${\displaystyle i_5}$[b]
Step[p]	${\displaystyle -\frac{i_R}{i_1}}$[q]		${\displaystyle \frac{i_1}{i_1}}$	${\displaystyle \frac{i_1}{i_2}}$[r]	${\displaystyle \frac{i_2}{i_3}}$	${\displaystyle \frac{i_3}{i_4}}$	${\displaystyle \frac{i_4}{i_5}}$
Δ Step[s][t]				${\displaystyle \frac{i_1}{i_2}:\frac{i_2}{i_3}}$	${\displaystyle \frac{i_2}{i_3}:\frac{i_3}{i_4}}$	${\displaystyle \frac{i_3}{i_4}:\frac{i_4}{i_5}}$
Shaft Speed	${\displaystyle \frac{i_1}{i_R}}$		${\displaystyle \frac{i_1}{i_1}}$	${\displaystyle \frac{i_1}{i_2}}$	${\displaystyle \frac{i_1}{i_3}}$	${\displaystyle \frac{i_1}{i_4}}$	${\displaystyle \frac{i_1}{i_5}}$
Δ Shaft Speed[u]	${\displaystyle 0-\frac{i_1}{i_R}}$		${\displaystyle \frac{i_1}{i_1}-0}$	${\displaystyle \frac{i_1}{i_2}-\frac{i_1}{i_1}}$	${\displaystyle \frac{i_1}{i_3}-\frac{i_1}{i_2}}$	${\displaystyle \frac{i_1}{i_4}-\frac{i_1}{i_3}}$	${\displaystyle \frac{i_1}{i_5}-\frac{i_1}{i_4}}$
Torque Ratio[c]	${\displaystyle {\mu }_R}$[c]		${\displaystyle {\mu }_1}$[c]	${\displaystyle {\mu }_2}$[c]	${\displaystyle {\mu }_3}$[c]	${\displaystyle {\mu }_4}$[c]	${\displaystyle {\mu }_5}$[c]
Efficiency ${\displaystyle {\eta }_n}$[d]	${\displaystyle \frac{{\mu }_R}{i_R}}$[d]		${\displaystyle \frac{{\mu }_1}{i_1}}$[d]	${\displaystyle \frac{{\mu }_2}{i_2}}$[d]	${\displaystyle \frac{{\mu }_3}{i_3}}$[d]	${\displaystyle \frac{{\mu }_4}{i_4}}$[d]	${\displaystyle \frac{{\mu }_5}{i_5}}$[d]
5HP 18	310 N⋅m (229 lb⋅ft) 1990	38 34[v]	34 98	32 76	3 4	4.9363 4.9363 [g][q]	1.6495
							1.4906 [p]
Gear	R		1	2	3	4	5
Gear Ratio[b]	−4.0960[q][g] ${\displaystyle -\frac{1,323}{323}}$		3.6648 ${\displaystyle \frac{1,323}{361}}$	1.9990[r] ${\displaystyle \frac{7,938}{3,971}}$	1.4067 [p][t][u] ${\displaystyle \frac{294}{209}}$	1.0000 ${\displaystyle \frac{1}{1}}$	0.7424 ${\displaystyle \frac{49}{66}}$
Step	1.1176[q]		1.0000	1.8333[r]	1.4211[p]	1.4067	1.3469
Δ Step[s]				1.2901	1.0102[t]	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[u]	1.0596	1.2715
Torque Ratio[c]	–3.9903 –3.9378		3.5344 3.4700	1.9581 1.9377	1.3861 1.3758	1.0000	0.7385 0.7366
Efficiency ${\displaystyle {\eta }_n}$[d]	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	38 34[v]	34 98	32 76	3 4	4.9363 4.9363 [g][q]	1.6495
							1.4906 [p]
Gear	R		1	2	3	4	5
Gear Ratio[b]	−4.0960[q][g]		3.6648	1.9990[r]	1.4067 [p][t][u]	1.0000	0.7424
Actuated Shift Elements
Brake A[w]				❶	❶		❶
Brake B[x]	❶		❶
Brake C[y]	❶		❶	❶
Clutch D[z]			❶	❶	❶	❶
Clutch E[aa]	❶
Clutch F[ab]						❶	❶
Clutch G[ac]					❶	❶	❶
Geometric Ratios: Speed Conversion
Gear Ratio[b] R & 1 Ordinary[ad] Elementary Noted[ae]	${\displaystyle i_R=-\frac{R_2(S_3+R_3)}{S_2{R}_3}}$			${\displaystyle i_1=\frac{R_1{R}_2(S_3+R_3)}{S_1{S}_2{R}_3}}$
	${\displaystyle i_R=-\frac{R_2}{S_2}\left(1+\frac{S_3}{R_3}\right)}$			${\displaystyle i_1=\frac{R_1{R}_2}{S_1{S}_2}\left(1+\frac{S_3}{R_3}\right)}$
Gear Ratio[b] 2 & 3 Ordinary[ad] Elementary Noted[ae]	${\displaystyle i_2=\frac{R_2(S_1+R_1)(S_3+R_3)}{S_1{R}_3(S_2+R_2)}}$				${\displaystyle i_3=\frac{R_2(S_1+R_1)}{S_1(S_2+R_2)}}$
	${\displaystyle i_2=\frac{\left(1+\frac{R_1}{S_1}\right)\left(1+\frac{S_3}{R_3}\right)}{1+\frac{S_2}{R_2}}}$				${\displaystyle i_3=\frac{1+\frac{R_1}{S_1}}{1+\frac{S_2}{R_2}}}$
Gear Ratio[b] 4 & 5 Ordinary[ad] Elementary Noted[ae]	${\displaystyle i_4=\frac{1}{1}}$			${\displaystyle i_5=\frac{R_2}{S_2+R_2}}$
				${\displaystyle i_5=\frac{1}{1+\frac{S_2}{R_2}}}$
Kinetic Ratios: Torque Conversion
Torque Ratio[c] R & 1	${\displaystyle {\mu }_R=-\frac{R_2}{S_2}{\eta }_0\left(1+\frac{S_3}{R_3}{\eta }_0\right)}$			${\displaystyle {\mu }_1=\frac{R_1{R}_2}{S_1{S}_2}{{\eta }_0}^{\frac{3}{2}}\left(1+\frac{S_3}{R_3}{\eta }_0\right)}$
Torque Ratio[c] 2 & 3	${\displaystyle {\mu }_2=\frac{\left(1+\frac{R_1}{S_1}{\eta }_0\right)\left(1+\frac{S_3}{R_3}{\eta }_0\right)}{1+\frac{S_2}{R_2}\cdot \frac{1}{{\eta }_0}}}$				${\displaystyle {\mu }_3=\frac{1+\frac{R_1}{S_1}{\eta }_0}{1+\frac{S_2}{R_2}\cdot \frac{1}{{\eta }_0}}}$
Torque Ratio[c] 4 & 5	${\displaystyle {\mu }_4=\frac{1}{1}}$			${\displaystyle {\mu }_5=\frac{1}{1+\frac{S_2}{R_2}\cdot \frac{1}{{\eta }_0}}}$
^Revised 14 January 2026 Nomenclature ${\displaystyle S_n=}$ sun gear: number of teeth ${\displaystyle R_n=}$ ring gear: number of teeth ${\displaystyle C_n=}$carrier or planetary gear carrier (not needed) ${\displaystyle s_n=}$ sun gear: shaft speed ${\displaystyle r_n=}$ ring gear: shaft speed ${\displaystyle c_n=}$ carrier or planetary gear carrier: shaft speed With${\displaystyle n=}$ gear is ${\displaystyle i_n=}$ gear ratio or transmission ratio ${\displaystyle {\omega }_{1;n}={\omega }_t=}$ shaft speed shaft 1: input (turbine) shaft ${\displaystyle {\omega }_{2;n}=}$ shaft speed shaft 2: output shaft ${\displaystyle T_{1;n}=T_t=}$ torque shaft 1: input (turbine) shaft ${\displaystyle T_{2;n}=}$ torque shaft 2: output shaft ${\displaystyle {\mu }_n=}$ torque ratio or torque conversion ratio ${\displaystyle {\eta }_n=}$ efficiency ${\displaystyle i_0=}$ stationary gear ratio ${\displaystyle {\eta }_0=}$ (assumed) stationary gear efficiency ^abcdefghijklmGear Ratio (Transmission Ratio)${\displaystyle i_n}$ — Speed Conversion — Thegear ratio${\displaystyle i_n}$ is the ratio of input shaft speed${\displaystyle {\omega }_{1;n}}$ to output shaft speed${\displaystyle {\omega }_{2;n}}$ and therefore corresponds tothe reciprocal of the shaft speeds ${\displaystyle i_n=\frac{1}{\frac{{\omega }_{2;n}}{{\omega }_{1;n}}}=\frac{{\omega }_{1;n}}{{\omega }_{2;n}}=\frac{{\omega }_t}{{\omega }_{2;n}}}$ ^abcdefghijklTorque Ratio (Torque Conversion Ratio)${\displaystyle {\mu }_n}$ — Torque Conversion — Thetorque ratio${\displaystyle {\mu }_n}$ is the ratio of output torque${\displaystyle T_{2;n}}$ to input torque${\displaystyle T_{1;n}}$ minus efficiency losses and therefore corresponds (apart from the efficiency losses) tothe reciprocal of the shaft speeds too ${\displaystyle {\mu }_n=i_n{\eta }_{n;{\eta }_0}=\frac{{\omega }_{1;n}{\eta }_{n;{\eta }_0}}{{\omega }_{2;n}}=\frac{T_{2;n}{\eta }_{n;{\eta }_0}}{T_{1;n}}}$ whereby${\displaystyle {\eta }_{n;{\eta }_0}}$ may vary from gear to gear according to the formulas listed in this table and${\displaystyle 0\le {\eta }_{n;{\eta }_0}\le 1}$ ^abcdefghiEfficiency Theefficiency${\displaystyle {\eta }_n}$ is calculated from the torque ratio in relation to the gear ratio (transmission ratio) ${\displaystyle {\eta }_n=\frac{{\mu }_n}{i_n}}$ 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, thestationary gear ratio${\displaystyle i_0}$ 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${\displaystyle {\eta }_0}$ specified here are based on assumed efficiencies for thestationary ratio${\displaystyle i_0}$ of${\displaystyle {\eta }_0=0.9800}$ (upper value) and${\displaystyle {\eta }_0=0.9700}$ (lower value) for both interventions together The corresponding efficiency for single-meshing gear pairs is${\displaystyle {{\eta }_0}^{\frac{1}{2}}}$ at${\displaystyle {0.9800}^{\frac{1}{2}}=0.98995}$ (upper value) and${\displaystyle {0.9700}^{\frac{1}{2}}=0.98489}$ (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), andR1/S2 Output shaft isC3 ^Total Ratio Span (Total Gear/Transmission Ratio) Nominal ${\displaystyle \frac{{\omega }_{2;n}}{{\omega }_{2;1}}=\frac{\frac{{\omega }_{2;n}}{{\omega }_{2;1}{\omega }_{2;n}}}{\frac{{\omega }_{2;1}}{{\omega }_{2;1}{\omega }_{2;n}}}=\frac{\frac{1}{{\omega }_{2;1}}}{\frac{1}{{\omega }_{2;n}}}=\frac{\frac{{\omega }_t}{{\omega }_{2;1}}}{\frac{{\omega }_t}{{\omega }_{2;n}}}=\frac{i_1}{i_n}}$ 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 ^abcdeTotal Ratio Span (Total Gear Ratio/Total Transmission Ratio) Effective ${\displaystyle \frac{{\omega }_{2;n}}{max({\omega }_{2;1};|{\omega }_{2;R}|)}=\frac{min(i_1;|i_R|)}{i_n}}$ The span is only effective to the extent that the reverse gear ratio matches that of 1st gear see alsoStandard R:1 Digression Reverse gear is usuallylonger than 1st gear theeffective span is therefore ofcentral importance for describing the suitability of a transmission because in these cases, thenominal 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 theeffective span has thereforenot yet been able to establish itself eitherin theory orin practice. End of digression ^Ratio Span's Center ${\displaystyle (i_1{i}_n{)}^{\frac{1}{2}}}$ 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 ${\displaystyle {\left(\frac{{\omega }_{2;n}}{{\omega }_{2;1}}\right)}^{\frac{1}{n-1}}={\left(\frac{i_1}{i_n}\right)}^{\frac{1}{n-1}}}$ There are${\displaystyle n-1}$ gear steps between${\displaystyle n}$ 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 ^abcdefgStandard 50:50 — 50 % Is Above And 50 % Is Below The Average Gear Step — With steadily decreasing gear steps (yellow highlighted lineStep) and a particularly large step from 1st to 2nd gear thelower half of the gear steps (between the small gears; rounded down, here the first 2)is always larger and theupper half of the gear steps (between the large gears; rounded up, here the last 2)is always smaller than the average gear step (cell highlightedyellow 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) ^abcdefStandard 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 alsoTotal Ratio Span (Total Gear/Transmission Ratio) Effective ^abcdStandard 1:2 — Gear Step 1st To 2nd Gear As Small As Possible — With continuously decreasing gear steps (yellow marked lineStep) thelargest 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) ^abFrom large to small gears (from right to left) ^abcdStandard STEP — From Large To Small Gears: Steady And Progressive Increase In Gear Steps — Gear steps should increase: Δ Step (firstgreen highlighted lineΔ Step) is always greater than 1 Asprogressive as possible: Δ Step is always greater than the previous step Not progressively increasing is acceptable (red) Not increasing is unsatisfactory (bold) ^abcdStandard SPEED — From Small To Large Gears: Steady Increase In Shaft Speed Difference — Shaft speed differences should increase: Δ Shaft Speed (second line marked ingreenΔ (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) ^abinner and outer sun gears of theRavigneaux planetary gearset are inverted ^ BlocksR1 (ring gear of the inner Ravigneaux gearset) andS2 (sun gear of the outer Ravigneaux gearset) ^ BlocksC1/C2 (the common carrier of the compound Ravigneaux gearset) ^ BlocksS3 ^ CouplesS1 (sun of the inner Ravigneaux gearset) with the input (turbine) ^ CouplesR1 (ring gear of the inner Ravigneaux gearset) andS2 (sun gear of the outer Ravigneaux gearset) with the input (turbine) ^ ConnectsC1/C2 (the common carrier of the compound Ravigneaux gearset) with the input (turbine) ^ CouplesS3 withR3 ^abcOrdinary Noted For direct determination of the gear ratio ^abcElementary 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

With planetary transmissions, the number of gears can be increased conventionally by adding additional gearsets as well as brakes and clutches, or conceptually by switching from serial to combined parallel and serial power flow. The conceptual way requires a computer-aided design. 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 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. With 9 main components, it saves 1 component compared to the 5HP 18 and 19 family. No subsequent transmissions from ZF including the 8-speed transmission8HP require more main components.

Gearset Concept: Cost-Effectiveness^[a]

With Assessment	Output: Gear Ratios	Innovation Elasticity[b] Δ Output : Δ Input	Input: Main Components
			Total	Gearsets	Brakes	Clutches
5HP 30/24 Ref. Object	${\displaystyle n_{O1}}$ ${\displaystyle n_{O2}}$	Topic[b]	${\displaystyle n_I=n_G+}$ ${\displaystyle n_B+n_C}$	${\displaystyle n_{G1}}$ ${\displaystyle n_{G2}}$	${\displaystyle n_{B1}}$ ${\displaystyle n_{B2}}$	${\displaystyle n_{C1}}$ ${\displaystyle n_{C2}}$
Δ Number	${\displaystyle n_{O1}-n_{O2}}$		${\displaystyle n_{I1}-n_{I2}}$	${\displaystyle n_{G1}-n_{G2}}$	${\displaystyle n_{B1}-n_{B2}}$	${\displaystyle n_{C1}-n_{C2}}$
Relative Δ	Δ Output ${\displaystyle \frac{n_{O1}-n_{O2}}{n_{O2}}}$	${\displaystyle \frac{n_{O1}-n_{O2}}{n_{O2}}:\frac{n_{I1}-n_{I2}}{n_{I2}}}$ ${\displaystyle =\frac{n_{O1}-n_{O2}}{n_{O2}}}$·${\displaystyle \frac{n_{I2}}{n_{I1}-n_{I2}}}$	Δ Input ${\displaystyle \frac{n_{I1}-n_{I2}}{n_{I2}}}$	${\displaystyle \frac{n_{G1}-n_{G2}}{n_{G2}}}$	${\displaystyle \frac{n_{B1}-n_{B2}}{n_{B2}}}$	${\displaystyle \frac{n_{C1}-n_{C2}}{n_{C2}}}$
5HP 30/24 4HP 14/16/18[c]	5[d] 4[d]	Progress[b]	9 7	3 2[e]	3 2	3 3
Δ Number	1		2	1	1	0
Relative Δ	0.250 ${\displaystyle \frac{1}{4}}$	0.875[b] ${\displaystyle \frac{1}{4}:\frac{2}{7}=\frac{1}{4}}$·${\displaystyle \frac{7}{2}=\frac{7}{8}}$	0.286 ${\displaystyle \frac{2}{7}}$	0.500 ${\displaystyle \frac{1}{2}}$	0.500 ${\displaystyle \frac{1}{2}}$	0.000 ${\displaystyle \frac{0}{3}}$
5HP 30/24 4HP 20/22/24[c]	5[d] 4[d]	Progress[b]	9 10	3 3	3 4	3 3
Δ Number	1		-1	0	-1	0
Relative Δ	0.250 ${\displaystyle \frac{1}{4}}$	−2.500[b] ${\displaystyle \frac{1}{4}:\frac{-1}{10}=\frac{1}{4}}$·${\displaystyle \frac{10}{-1}=\frac{10}{-4}}$	−0.100 ${\displaystyle \frac{-1}{10}}$	0.000 ${\displaystyle \frac{0}{3}}$	−0.250 ${\displaystyle \frac{-1}{4}}$	0.000 ${\displaystyle \frac{0}{3}}$
5HP 30/24 3-Speed[f]	5[d] 3[d]	Market Position[b]	9 7	3 2[e]	3 3	3 2
Δ Number	2		2	1	0	1
Relative Δ	0.667 ${\displaystyle \frac{2}{3}}$	2.333[b] ${\displaystyle \frac{2}{3}:\frac{2}{7}=\frac{2}{3}}$·${\displaystyle \frac{7}{2}=\frac{7}{3}}$	0.286 ${\displaystyle \frac{2}{7}}$	0.500 ${\displaystyle \frac{1}{2}}$	0.000 ${\displaystyle \frac{0}{3}}$	0.500 ${\displaystyle \frac{1}{2}}$
^Progress increases cost-effectiveness and is reflected in theratio of forward gears to main components. It depends on thepower flow: parallel: using the two degrees of freedom ofplanetary gearsets to increase the number of gears with unchanged number of components serial: in-line combinedplanetary gearsets without using the two degrees of freedom to increase the number of gears a corresponding increase in the number of components is unavoidable ^abcdefghInnovationElasticity 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. whoseeconomicelasticity is greater than 1, are considered for realization Therequired innovationelasticity of an automobile manufacturer depends on its expected return on investment. The basic assumption that the relative additional benefit must beat 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) ^abDirect Predecessor To reflect the progress of the specific model change ^abcdefplus 1 reverse gear ^abof which 2 gearsets are combined as a compoundRavigneaux 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 Turbo-Hydramatic fromGM Cruise-O-Matic fromFord TorqueFlite fromChrysler Detroit Gear fromBorgWarner forStudebaker BW-35 fromBorgWarner and asT35 fromAisin 3N 71 fromNissan/Jatco 3 HP fromZF Friedrichshafen W3A 040 and W3B 050 fromMercedes-Benz

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).

Gear Ratio Analysis^[a]

In-Depth Analysis[b] With Assessment And Torque Ratio[c] And Efficiency Calculation[d]		Planetary Gearset: Teeth[e]			Count	Nomi- nal[f] Effec- tive[g]	Cen- ter[h]
		Simpson		Simple			Avg.[i]
Model Type	Version First Delivery	S1[j] R1[k]	S2[l] R2[m]	S3[n] R3[o]	Brakes Clutches	Ratio Span	Gear Step[p]
Gear	R		1	2	3	4	5
Gear Ratio[b]	${\displaystyle i_R}$[b]		${\displaystyle i_1}$[b]	${\displaystyle i_2}$[b]	${\displaystyle i_3}$[b]	${\displaystyle i_4}$[b]	${\displaystyle i_5}$[b]
Step[p]	${\displaystyle -\frac{i_R}{i_1}}$[q]		${\displaystyle \frac{i_1}{i_1}}$	${\displaystyle \frac{i_1}{i_2}}$[r]	${\displaystyle \frac{i_2}{i_3}}$	${\displaystyle \frac{i_3}{i_4}}$	${\displaystyle \frac{i_4}{i_5}}$
Δ Step[s][t]				${\displaystyle \frac{i_1}{i_2}:\frac{i_2}{i_3}}$	${\displaystyle \frac{i_2}{i_3}:\frac{i_3}{i_4}}$	${\displaystyle \frac{i_3}{i_4}:\frac{i_4}{i_5}}$	${\displaystyle \frac{i_4}{i_5}:\frac{i_5}{i_6}}$
Shaft Speed	${\displaystyle \frac{i_1}{i_R}}$		${\displaystyle \frac{i_1}{i_1}}$	${\displaystyle \frac{i_1}{i_2}}$	${\displaystyle \frac{i_1}{i_3}}$	${\displaystyle \frac{i_1}{i_4}}$	${\displaystyle \frac{i_1}{i_5}}$
Δ Shaft Speed[u]	${\displaystyle 0-\frac{i_1}{i_R}}$		${\displaystyle \frac{i_1}{i_1}-0}$	${\displaystyle \frac{i_1}{i_2}-\frac{i_1}{i_1}}$	${\displaystyle \frac{i_1}{i_3}-\frac{i_1}{i_2}}$	${\displaystyle \frac{i_1}{i_4}-\frac{i_1}{i_3}}$	${\displaystyle \frac{i_1}{i_5}-\frac{i_1}{i_4}}$
Torque Ratio[c]	${\displaystyle {\mu }_R}$[c]		${\displaystyle {\mu }_1}$[c]	${\displaystyle {\mu }_2}$[c]	${\displaystyle {\mu }_3}$[c]	${\displaystyle {\mu }_4}$[c]	${\displaystyle {\mu }_5}$[c]
Efficiency ${\displaystyle {\eta }_n}$[d]	${\displaystyle \frac{{\mu }_R}{i_R}}$[d]		${\displaystyle \frac{{\mu }_1}{i_1}}$[d]	${\displaystyle \frac{{\mu }_2}{i_2}}$[d]	${\displaystyle \frac{{\mu }_3}{i_3}}$[d]	${\displaystyle \frac{{\mu }_4}{i_4}}$[d]	${\displaystyle \frac{{\mu }_5}{i_5}}$[d]
5HP 30	560 N⋅m (413 lb⋅ft) 1992	40 100	32 108	38 97	3 3	4.5169 4.5169 [g][q]	1.6716
							1.4578 [p]
Gear	R		1	2	3	4	5
Gear Ratio[b]	−3.6842 ${\displaystyle -\frac{70}{19}}$		3.5526 ${\displaystyle \frac{135}{38}}$	2.2436 ${\displaystyle \frac{175}{78}}$	1.5449[p][t] ${\displaystyle \frac{275}{178}}$	1.0000[p] ${\displaystyle \frac{1}{1}}$	0.7865[u] ${\displaystyle \frac{70}{89}}$
Step	1.0370		1.0000	1.5835	1.4522[p]	1.5449[p]	1.2714
Δ Step[s]				1.0904	0.9400[t]	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[u]
Torque Ratio[c]	–3.5078 –3.4217		3.5016 3.4761	2.2059 2.1870	1.5272 1.5183	1.0000	0.7782 0.7738
Efficiency ${\displaystyle {\eta }_n}$[d]	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 [g][q]	1.6943
							1.4519[p]
Gear	R		1	2	3	4	5
Gear Ratio[b]	−4.0952[q][g] ${\displaystyle -\frac{86}{21}}$		3.5714 ${\displaystyle \frac{25}{7}}$	2.2000 ${\displaystyle \frac{11}{5}}$	1.5047[t] ${\displaystyle \frac{161}{107}}$	1.0000[p] ${\displaystyle \frac{1}{1}}$	0.8037[u] ${\displaystyle \frac{86}{107}}$
Step	1.1467[q]		1.0000	1.6234	1.4621	1.5047[p]	1.2419
Δ Step[s]				1.1103	0.9717[t]	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[u]
Torque Ratio[c]	–3.8985 –3.8025		3.5200 3.4943	2.1630 2.1445	1.4880 1.4795	1.0000	0.7959 0.7918
Efficiency ${\displaystyle {\eta }_n}$[d]	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[v]					❶		❶
Brake B[w]				❶
Brake C[x]	❶		❶
Clutch D[y]			❶	❶	❶	❶
Clutch E[z]						❶	❶
Clutch F[aa]	❶
Geometric Ratios: Speed Conversion
Gear Ratio[b] R & 2 Ordinary[ab] Elementary Noted[ac]	${\displaystyle i_R=-\frac{S_2(S_1+R_1)(S_3+R_3)}{S_1{R}_2{S}_3}}$			${\displaystyle i_2=\frac{(S_2+R_2)(S_3+R_3)}{S_2{R}_3+S_3(S_2+R_2)}}$
	${\displaystyle i_R=-\frac{S_2}{R_2}\left(1+\frac{R_1}{S_1}\right)\left(1+\frac{R_3}{S_3}\right)}$			${\displaystyle i_2=\frac{1}{\frac{1}{1+\frac{R_3}{S_3}}+\frac{1}{\left(1+\frac{R_2}{S_2}\right)\left(1+\frac{S_3}{R_3}\right)}}}$
Gear Ratio[b] 1 & 5 Ordinary[ab] Elementary Noted[ac]	${\displaystyle i_1=\frac{S_3+R_3}{S_3}}$		${\displaystyle i_5=\frac{S_2(S_1+R_1)(S_3+R_3)}{S_2(S_1+R_1)(S_3+R_3)+S_1{R}_2{S}_3}}$
	${\displaystyle i_1=1+\frac{R_3}{S_3}}$		${\displaystyle i_5=\frac{1}{1+\frac{\frac{R_2}{S_2}}{\left(1+\frac{R_1}{S_1}\right)\left(1+\frac{R_3}{S_3}\right)}}}$
Gear Ratio[b] 3 & 4 Ordinary[ab] Elementary Noted[ac]	${\displaystyle i_3=\frac{(S_1(S_2+R_2)+R_1{S}_2)(S_3+R_3)}{S_2(S_1+R_1)(S_3+R_3)+S_1{R}_2{S}_3}}$					${\displaystyle i_4=\frac{1}{1}}$
	${\displaystyle i_3=\frac{1}{\frac{1}{\frac{1}{1+\frac{S_1}{R_1}}+\frac{1+\frac{R_2}{S_2}}{1+\frac{R_1}{S_1}}}+\frac{1}{\left(1+\frac{S_2}{R_2}\left(1+\frac{R_1}{S_1}\right)\right)\left(1+\frac{R_3}{S_3}\right)}}}$
Kinetic Ratios: Torque Conversion
Torque Ratio[c] R & 1	${\displaystyle {\mu }_R=-\frac{S_2}{R_2}{\eta }_0\left(1+\frac{R_1}{S_1}{\eta }_0\right)\left(1+\frac{R_3}{S_3}{\eta }_0\right)}$				${\displaystyle {\mu }_1=1+\frac{R_3}{S_3}{\eta }_0}$
Torque Ratio[c] 2 & 5	${\displaystyle {\mu }_2=\frac{1}{\frac{1}{1+\frac{R_3}{S_3}{\eta }_0}+\frac{1}{\left(1+\frac{R_2}{S_2}{\eta }_0\right)\left(1+\frac{S_3}{R_3}{\eta }_0\right)}}}$				${\displaystyle {\mu }_5=\frac{1}{1+\frac{\frac{R_2}{S_2}\cdot \frac{1}{{\eta }_0}}{\left(1+\frac{R_1}{S_1}{\eta }_0\right)\left(1+\frac{R_3}{S_3}{\eta }_0\right)}}}$
Torque Ratio[c] 3 & 4	${\displaystyle {\mu }_3=\frac{1}{\frac{1}{\frac{1}{1+\frac{S_1}{R_1}\cdot \frac{1}{{{\eta }_0}^{\frac{1}{3}}}}+\frac{1+\frac{R_2}{S_2}{{\eta }_0}^{\frac{1}{2}}}{1+\frac{R_1}{S_1}\cdot \frac{1}{{{\eta }_0}^{\frac{1}{3}}}}}+\frac{1}{\left(1+\frac{S_2}{R_2}{{\eta }_0}^{\frac{1}{2}}\left(1+\frac{R_1}{S_1}{{\eta }_0}^{\frac{1}{3}}\right)\right)\left(1+\frac{R_3}{S_3}{\eta }_0\right)}}}$						${\displaystyle {\mu }_4=\frac{1}{1}}$
^Revised 14 January 2026 Nomenclature ${\displaystyle S_n=}$ sun gear: number of teeth ${\displaystyle R_n=}$ ring gear: number of teeth ${\displaystyle C_n=}$carrier or planetary gear carrier (not needed) ${\displaystyle s_n=}$ sun gear: shaft speed ${\displaystyle r_n=}$ ring gear: shaft speed ${\displaystyle c_n=}$ carrier or planetary gear carrier: shaft speed With${\displaystyle n=}$ gear is ${\displaystyle i_n=}$ gear ratio or transmission ratio ${\displaystyle {\omega }_{1;n}={\omega }_t=}$ shaft speed shaft 1: input (turbine) shaft ${\displaystyle {\omega }_{2;n}=}$ shaft speed shaft 2: output shaft ${\displaystyle T_{1;n}=T_t=}$ torque shaft 1: input (turbine) shaft ${\displaystyle T_{2;n}=}$ torque shaft 2: output shaft ${\displaystyle {\mu }_n=}$ torque ratio or torque conversion ratio ${\displaystyle {\eta }_n=}$ efficiency ${\displaystyle i_0=}$ stationary gear ratio ${\displaystyle {\eta }_0=}$ (assumed) stationary gear efficiency ^abcdefghijklmGear Ratio (Transmission Ratio)${\displaystyle i_n}$ — Speed Conversion — Thegear ratio${\displaystyle i_n}$ is the ratio of input shaft speed${\displaystyle {\omega }_{1;n}}$ to output shaft speed${\displaystyle {\omega }_{2;n}}$ and therefore corresponds tothe reciprocal of the shaft speeds ${\displaystyle i_n=\frac{1}{\frac{{\omega }_{2;n}}{{\omega }_{1;n}}}=\frac{{\omega }_{1;n}}{{\omega }_{2;n}}=\frac{{\omega }_t}{{\omega }_{2;n}}}$ ^abcdefghijklmTorque Ratio (Torque Conversion Ratio)${\displaystyle {\mu }_n}$ — Torque Conversion — Thetorque ratio${\displaystyle {\mu }_n}$ is the ratio of output torque${\displaystyle T_{2;n}}$ to input torque${\displaystyle T_{1;n}}$ minus efficiency losses and therefore corresponds (apart from the efficiency losses) tothe reciprocal of the shaft speeds too ${\displaystyle {\mu }_n=i_n{\eta }_{n;{\eta }_0}=\frac{{\omega }_{1;n}{\eta }_{n;{\eta }_0}}{{\omega }_{2;n}}=\frac{T_{2;n}{\eta }_{n;{\eta }_0}}{T_{1;n}}}$ whereby${\displaystyle {\eta }_{n;{\eta }_0}}$ may vary from gear to gear according to the formulas listed in this table and${\displaystyle 0\le {\eta }_{n;{\eta }_0}\le 1}$ ^abcdefghijEfficiency Theefficiency${\displaystyle {\eta }_n}$ is calculated from the torque ratio in relation to the gear ratio (transmission ratio) ${\displaystyle {\eta }_n=\frac{{\mu }_n}{i_n}}$ 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, thestationary gear ratio${\displaystyle i_0}$ 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${\displaystyle {\eta }_0}$ specified here are based on assumed efficiencies for thestationary ratio${\displaystyle i_0}$ of${\displaystyle {\eta }_0=0.9800}$ (upper value) and${\displaystyle {\eta }_0=0.9700}$ (lower value) for both interventions together The corresponding efficiency for single-meshing gear pairs is${\displaystyle {{\eta }_0}^{\frac{1}{2}}}$ at${\displaystyle {0.9800}^{\frac{1}{2}}=0.98995}$ (upper value) and${\displaystyle {0.9700}^{\frac{1}{2}}=0.98489}$ (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, andR1 Output shaft isC3 ^Total Ratio Span (Total Gear/Transmission Ratio) Nominal ${\displaystyle \frac{{\omega }_{2;n}}{{\omega }_{2;1}}=\frac{\frac{{\omega }_{2;n}}{{\omega }_{2;1}{\omega }_{2;n}}}{\frac{{\omega }_{2;1}}{{\omega }_{2;1}{\omega }_{2;n}}}=\frac{\frac{1}{{\omega }_{2;1}}}{\frac{1}{{\omega }_{2;n}}}=\frac{\frac{{\omega }_t}{{\omega }_{2;1}}}{\frac{{\omega }_t}{{\omega }_{2;n}}}=\frac{i_1}{i_n}}$ 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 ^abcdTotal Ratio Span (Total Gear Ratio/Total Transmission Ratio) Effective ${\displaystyle \frac{{\omega }_{2;n}}{max({\omega }_{2;1};|{\omega }_{2;R}|)}=\frac{min(i_1;|i_R|)}{i_n}}$ The span is only effective to the extent that the reverse gear ratio matches that of 1st gear see alsoStandard R:1 Digression Reverse gear is usuallylonger than 1st gear theeffective span is therefore ofcentral importance for describing the suitability of a transmission because in these cases, thenominal 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 theeffective span has thereforenot yet been able to establish itself eitherin theory orin practice. End of digression ^Ratio Span's Center ${\displaystyle (i_1{i}_n{)}^{\frac{1}{2}}}$ 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 ${\displaystyle {\left(\frac{{\omega }_{2;n}}{{\omega }_{2;1}}\right)}^{\frac{1}{n-1}}={\left(\frac{i_1}{i_n}\right)}^{\frac{1}{n-1}}}$ There are${\displaystyle n-1}$ gear steps between${\displaystyle n}$ 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 ^abcdefghijStandard 50:50 — 50 % Is Above And 50 % Is Below The Average Gear Step — With steadily decreasing gear steps (yellow highlighted lineStep) and a particularly large step from 1st to 2nd gear thelower half of the gear steps (between the small gears; rounded down, here the first 2)is always larger and theupper half of the gear steps (between the large gears; rounded up, here the last 2)is always smaller than the average gear step (cell highlightedyellow 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) ^abcdeStandard 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 alsoTotal Ratio Span (Total Gear/Transmission Ratio) Effective ^Standard 1:2 — Gear Step 1st To 2nd Gear As Small As Possible — With continuously decreasing gear steps (yellow marked lineStep) thelargest 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) ^abcFrom large to small gears (from right to left) ^abcdeStandard STEP — From Large To Small Gears: Steady And Progressive Increase In Gear Steps — Gear steps should increase: Δ Step (firstgreen highlighted lineΔ Step) is always greater than 1 Asprogressive as possible: Δ Step is always greater than the previous step Not progressively increasing is acceptable (red) Not increasing is unsatisfactory (bold) ^abcdeStandard SPEED — From Small To Large Gears: Steady Increase In Shaft Speed Difference — Shaft speed differences should increase: Δ Shaft Speed (second line marked ingreenΔ (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) ^ BlocksS1 ^ BlocksC1 ^BlocksR3 ^ConnectsS2 andS3 with the input (turbine) ^ConnectsR1 with the input (turbine) ^ConnectsC1 with the input (turbine) ^abcOrdinary Noted For direct determination of the gear ratio ^abcElementary 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