Mercedes-Benz first series automatic transmission

Mercedes-Benz K4A 025 K4B 050 · K4C 025 · K4A 040 W3A 040 · W3B 050 · W4B 025 W4A 018 · W4B 035
K4A 025
Overview
Manufacturer	Daimler AG
Production	1961–1983
Body and chassis
Class	3 and 4-speed longitudinal automatic transmission
Chronology
Successor	4G-Tronic

The Mercedes-Benz first series of automatic transmission was produced from 1961 to 1983 in 4- and 3-speed variants for Mercedes-Benz passenger cars. In addition, variants for commercial vehicles were offered until the mid-1990s.

This transmission was the first Mercedes-Benz automatic transmission in-house developing. ^[1] Before this, the company used semi-automatic systems like a vacuum-powered shifting for overdrive or the "Hydrak" hydraulic automatic clutch system. Alternatively, they bought automatic transmissions of other vendors, such as the Detroit gear 3-speed automatic transmission from BorgWarner for the 300 c and 300 d (not to be confused with the later 300 D and its successors).

The automatic transmissions are for engines with longitudinal layout for rear-wheel-drive layout passenger cars. The control of the fully automatic system is fully hydraulic and it uses electrical wire only for the kickdown solenoid valve and the neutral safety switch.

Physically, it can be recognized for its pan which uses 16 bolts.

Key Data

Gear Ratios ^[a]

Model	Type	First Deliv- ery	Gear					Total Span			Avg. Step	Components		Nomenclature
			R	1	2	3	4	Nomi- nal	Effec- tive	Cen- ter		Total	per Gear [b]	Cou- pling	Gears Count	Ver- sion	Maximum Input Torque
K4A 025	w/o	1961 [2] [A]	−4.145	3.979	2.520	1.579	1.000	3.979	3.979	1.995	1.585	2  Gearsets 3 Brakes 3 Clutches	2.000	K [c]	4 [b]	A	25  kp⋅m (181  lb⋅ft )
K4B 050	w/o	1964 [d]	−4.145	3.979	2.459	1.579	1.000	3.979	3.979	1.995	1.585	3 Gearsets 3 Brakes 2 Clutches	2.000	K [c]	4 [b]	B	50  kp⋅m (362  lb⋅ft )
K4C 025 K4A 040 W4B 025	722.2 722.2 722.1	1967 [B] 1969 1972 [B]	−5.478	3.983	2.386	1.461	1.000	3.983	3.983	1.996	1.585			K [c] K [c] W [e] [4]	4 [b]	C A B	25  kp⋅m (181  lb⋅ft ) 40  kp⋅m (289  lb⋅ft ) 25  kp⋅m (181  lb⋅ft )
W4A 018 [f]	720.1	1975	−5.499	4.006	2.391	1.463	1.000	4.006	4.006	2.001	1.588			W [e]	4 [b]	A	18  kp⋅m (130  lb⋅ft )
W4B 035 [g]	TBD	1975	−5.881	4.176	2.412	1.462	1.000	4.176	4.176	2.043	1.610			W [e]	4 [b]	B	35  kp⋅m (253  lb⋅ft )
W3A 040 W3A 050 W3A 050 reinf.	720.0 722.0 722.0	1971 1973 1975	−1.836	2.306	1.461	1.000		2.306	1.836	1.519	1.519	2  Gearsets 3 Brakes 2 Clutches	2.333	W [e]	3 [b]	A	40  kp⋅m (289  lb⋅ft ) 50  kp⋅m (362  lb⋅ft ) 56  kp⋅m (405  lb⋅ft )
Differences in gear ratios have a measurable, direct impact on vehicle dynamics, performance, waste emissions as well as fuel mileage Forward gears only Fluid coupling · German: Kupplung or Flüssigkeitskupplung Unveiled in September 1963 at the International Motor Show in Frankfurt, it went into production in September 1964 Torque converter · German: Wandler or Drehmomentwandler for light-duty trucks and vans up to 5,600  kg (12,350  lb) and off-road vehicles [B] [C] for medium-duty trucks up to 13,000  kg (28,660  lb) [D] [E]

1961: K4A 025
— 4-Speed Transmission With 2 Planetary Gearsets —

K4A 025 transmission left hand side view

K4A 025 transmission right hand side view

Layout

The K4A 025 is the first of the series, launched in April 1961 for the W 111 220 SEb, later replaced with the more reliable K4C 025 (type 722.2). It is a 4-speed unit and uses fluid coupling (also referred in some manuals as hydraulic/automatic clutch).

The design of the transmission results in poor shifting comfort, which does not meet Mercedes-Benz standards. This applies in particular to the change from 2nd to 3rd gear (and vice versa), which requires a group change, i.e. affects all shift elements.

Specifications

For this first 4-speed model ^[a] 8 main components ^[b] are used. It is the only exemption which uses only 2 planetary gearsets for 4 speeds.

Gear Ratio Analysis ^[c]

In-Depth Analysis [d] With Assessment And Torque Ratio [e] And Efficiency Calculation [f]		Planetary Gearset: Teeth [g]		Count	Nomi- nal [h] Effec- tive [i]	Cen- ter [j]
		Simple				Avg. [k]
Model Type	Version First Delivery	S1 [l] R1 [m]	S2 [n] R2 [o]	Brakes Clutches	Ratio Span	Gear Step [p]
Gear	R		1	2	3	4
Gear Ratio [d]	${\displaystyle {i_{R}}}$ [d]		${\displaystyle {i_{1}}}$ [d]	${\displaystyle {i_{2}}}$ [d]	${\displaystyle {i_{3}}}$ [d]	${\displaystyle {i_{4}}}$ [d]
Step [p]	${\displaystyle -{\frac {i_{R}}{i_{1}}}}$ [q]		${\displaystyle {\frac {i_{1}}{i_{1}}}}$	${\displaystyle {\frac {i_{1}}{i_{2}}}}$ [r]	${\displaystyle {\frac {i_{2}}{i_{3}}}}$	${\displaystyle {\frac {i_{3}}{i_{4}}}}$
Δ Step [s] [t]				${\displaystyle {\tfrac {i_{1}}{i_{2}}}:{\tfrac {i_{2}}{i_{3}}}}$	${\displaystyle {\tfrac {i_{2}}{i_{3}}}:{\tfrac {i_{3}}{i_{4}}}}$
Shaft Speed	${\displaystyle {\frac {i_{1}}{i_{R}}}}$		${\displaystyle {\frac {i_{1}}{i_{1}}}}$	${\displaystyle {\frac {i_{1}}{i_{2}}}}$	${\displaystyle {\frac {i_{1}}{i_{3}}}}$	${\displaystyle {\frac {i_{1}}{i_{4}}}}$
Δ Shaft Speed [u]	${\displaystyle 0-{\frac {i_{1}}{i_{R}}}}$		${\displaystyle {\tfrac {i_{1}}{i_{1}}}-0}$	${\displaystyle {\tfrac {i_{1}}{i_{2}}}-{\tfrac {i_{1}}{i_{1}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{3}}}-{\tfrac {i_{1}}{i_{2}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{4}}}-{\tfrac {i_{1}}{i_{3}}}}$
Efficiency ${\displaystyle \eta _{n}}$ [f]	${\displaystyle {\tfrac {T_{2;R}}{T_{1;R}}}:{i_{R}}}$		${\displaystyle {\tfrac {T_{2;1}}{T_{1;1}}}:{i_{1}}}$	${\displaystyle {\tfrac {T_{2;2}}{T_{1;2}}}:{i_{2}}}$	${\displaystyle {\tfrac {T_{2;3}}{T_{1;3}}}:{i_{3}}}$	${\displaystyle {\tfrac {T_{2;4}}{T_{1;4}}}:{i_{4}}}$
Torque Ratio [e]	${\displaystyle \mu _{R}}$ [e]		${\displaystyle \mu _{1}}$ [e]	${\displaystyle \mu _{2}}$ [e]	${\displaystyle \mu _{3}}$ [e]	${\displaystyle \mu _{4}}$ [e]
Efficiency ${\displaystyle \eta _{n}}$ [f]	${\displaystyle {\frac {\mu _{R}}{i_{R}}}}$ [f]		${\displaystyle {\frac {\mu _{1}}{i_{1}}}}$ [f]	${\displaystyle {\frac {\mu _{2}}{i_{2}}}}$ [f]	${\displaystyle {\frac {\mu _{3}}{i_{3}}}}$ [f]	${\displaystyle {\frac {\mu _{4}}{i_{4}}}}$ [f]
K4A 025 w/o	25  kp⋅m (245  N⋅m ; 181  lb⋅ft ) 1961 [2] [A]	50 76	44 76	3 3	3.9789 3.9789	1.9947
						1.5846 [p]
Gear	R		1	2	3	4
Gear Ratio [d]	−4.1455 ${\displaystyle -{\tfrac {228}{55}}}$		3.9789 ${\displaystyle {\tfrac {378}{95}}}$	2.5200 [p] [t] ${\displaystyle {\tfrac {63}{25}}}$	1.5789 [p] ${\displaystyle {\tfrac {30}{19}}}$	1.0000 ${\displaystyle {\tfrac {1}{1}}}$
Step	1.0418		1.0000	1.5789 [p]	1.5960 [p]	1.5789
Δ Step [s]				0.9893 [t]	1.0108
Speed	-0.9598		1.0000	1.5789	2.5200	3.9789
Δ Speed	0.9598		1.0000	0.5789	0.9411	1.4589
Torque Ratio [e]	–4.0111 –3.9447		3.9021 3.8640	2.4896 2.4744	1.5674 1.5616	1.0000
Efficiency ${\displaystyle \eta _{n}}$ [f]	0.9676 0.9516		0.9807 0.9711	0.9879 0.9819	0.9927 0.9890	1.0000
Actuated Shift Elements
Brake B1 [v]			❶	❶
Brake B2 [w]			❶		❶
Brake B3 [x]	❶
Clutch K1 [y]					❶	❶
Clutch K2 [z]				❶		❶
Clutch K3 [aa]	❶
Geometric Ratios: Speed Conversion
Gear Ratio [d] R & 2 & 4 Ordinary [ab] Elementary Noted [ac]	${\displaystyle i_{R}=-{\frac {R_{1}(S_{2}+R_{2})}{S_{1}S_{2}}}}$			${\displaystyle i_{2}={\frac {S_{1}+R_{1}}{S_{1}}}}$		${\displaystyle i_{4}={\frac {1}{1}}}$
	${\displaystyle i_{R}=-{\tfrac {R_{1}}{S_{1}}}\left(1+{\tfrac {R_{2}}{S_{2}}}\right)}$			${\displaystyle i_{2}=1+{\tfrac {R_{1}}{S_{1}}}}$
Gear Ratio [d] 1 & 3 Ordinary [ab] Elementary Noted [ac]	${\displaystyle i_{1}={\frac {(S_{1}+R_{1})(S_{2}+R_{2})}{S_{1}R_{2}}}}$				${\displaystyle i_{3}={\frac {S_{2}+R_{2}}{R_{2}}}}$
	${\displaystyle i_{1}=\left(1+{\tfrac {R_{1}}{S_{1}}}\right)\left(1+{\tfrac {S_{2}}{R_{2}}}\right)}$				${\displaystyle i_{3}=1+{\tfrac {S_{2}}{R_{2}}}}$
Kinetic Ratios: Torque Conversion
Torque Ratio [e] R & 2 & 4	${\displaystyle \mu _{R}=-{\tfrac {R_{1}}{S_{1}}}\eta _{0}\left(1+{\tfrac {R_{2}}{S_{2}}}\eta _{0}\right)}$			${\displaystyle \mu _{2}=1+{\tfrac {R_{1}}{S_{1}}}\eta _{0}}$		${\displaystyle \mu _{4}={\tfrac {1}{1}}}$
Torque Ratio [e] 1 & 3	${\displaystyle \mu _{1}=\left(1+{\tfrac {R_{1}}{S_{1}}}\eta _{0}\right)\left(1+{\tfrac {S_{2}}{R_{2}}}\eta _{0}\right)}$				${\displaystyle \mu _{3}=1+{\tfrac {S_{2}}{R_{2}}}\eta _{0}}$
plus 1 reverse gear 2 simple planetary gearsets, 3 brakes, 3  clutches Revised 14 January 2026 Nomenclature ${\displaystyle S_{n}=}$ sun gear: number of teeth ${\displaystyle R_{n}=}$ ring gear: number of teeth ${\displaystyle \color {gray}{C_{n}=}}$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 Gear Ratio (Transmission Ratio) ${\displaystyle i_{n}}$ — Speed Conversion — The gear 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 to the reciprocal of the shaft speeds ${\displaystyle i_{n}={\frac {1}{\frac {\omega _{2;n}}{\omega _{1;n}}}}={\frac {\omega _{1;n}}{\omega _{2;n}}}={\frac {\omega _{t}}{\omega _{2;n}}}}$ Torque Ratio (Torque Conversion Ratio) ${\displaystyle \mu _{n}}$ — Torque Conversion — The torque 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) to the 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 ${\displaystyle 0\leq \eta _{n;\eta _{0}}\leq 1}$ Efficiency The efficiency${\displaystyle \eta _{n}}$ 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, the stationary 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 the stationary 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 ${\displaystyle {\eta _{0}}^{\tfrac {1}{2}}}$ at ${\displaystyle 0.9800^{\tfrac {1}{2}}=0.98995}$ (upper value) and ${\displaystyle 0.9700^{\tfrac {1}{2}}=0.98489}$ (lower value) Layout Input and output are on opposite sides Planetary gearset 1 is on the input (turbine) side Input shafts is S1 and, if actuated, C1 Output shaft is C2 Total Ratio Span (Total Gear/Transmission Ratio) Nominal ${\displaystyle {\frac {i_{1}}{i_{n}}}}$ 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 Total Ratio Span (Total Gear Ratio/Total Transmission Ratio) Effective ${\displaystyle {\frac {min(i_{1};|i_{R}|)}{i_{n}}}}$ The span is only effective to the extent that the reverse gear ratio matches that of 1st gear see also Standard R:1 Digression Since reverse gear is usually longer than first gear, the effective span is of central importance for describing the suitability of a transmission. In these cases, the nominal span conveys a misleading picture that is only unproblematic for vehicles with high specific power. Manufacturers naturally have no interest in specifying the effective span Users have not yet formulated the practical benefits that effective span has for them Effective span has not yet played a role in research and teaching Contrary to its importance, effective span has therefore not been able to establish itself in either theory or practice: general acceptance and widespread application are still pending. 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 ${\displaystyle \left({\frac {i_{1}}{i_{n}}}\right)^{\frac {1}{n-1}}}$ With decreasing step width the gears connect better to each other shifting comfort increases Sun 1: sun gear of gearset 1 Ring 1: ring gear of gearset 1 Sun 2: sun gear of gearset 2 Ring 2: ring gear of gearset 2 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 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) 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) 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) 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) Blocks R1 Blocks S2 Also BR (brake for reverse gear · German: Bremse für Rückwärtsgang) · blocks C1 and R2 Couples C1 and R2 with the input (turbine) Couples C1 and R2 with S2 Also KR (clutch for reverse gear · German: Kupplung für Rückwärtsgang) · couples R1 with S2 Ordinary Noted For direct determination of the gear 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 the torque conversion ratio and efficiency

1964: K4B 050 And Follow-Up Products
— 4-Speed Transmissions With 3 Planetary Gearsets —

Layout

The Mercedes-Benz 600, unveiled in September 1963 at the International Motor Show in Frankfurt, it went into production in September 1964 and was the first post-war "Grand Mercedes", powered by the Mercedes-Benz M100 engine. This made a gearbox for the highest demands of luxury vehicles necessary. The design of the gearbox in the range was out of the question from the outset. The introduction of the 600 was therefore taken as an opportunity to develop a completely new design for the automatic transmission.

Models

1964: K4B 050

The first model with this new layout was the K4B 050. Beside the new layout the number of pinions is doubled from 3 to 6 to handle the much higher torque of the big block V8 engine.

1967: K4C 025

After the satisfactory experience with the new design, it was adopted in 1967 for the new core model K4C 025 (Type 722.2) of the first automatic transmission series from Mercedes-Benz. With the small block V8 engine M 116, the K4A 040 (Type 722.2) was launched as a reinforced version of the same design.

1969: K4A 040

With the introduction of the V8 cylinder engines of the M 116 series with a displacement of 3.5 liters, the automatic transmission range was expanded to include the K4A 040 model, which is a reinforced version of the K4C 025 with the same gear ratios to accommodate the increased torque.

1972: W4B 025

When the torque converter technique was fully established, the fluid coupling was replaced by a torque converter for the smaller engines, which leads to the W4B 025 (type 722.1). ^[4] Used in L4, L5 and L6 engines due to its lower torque output. In normal situations, it rests stationary in 2nd gear, but it will use 1st gear when the vehicle starts moving and throttle is applied ^[6] or if L position is selected in gear selector.

Variants For Commercial Cars

The W4A 018 (type 720.1) was derived from the W4B 025 (type 722.1) for light-duty trucks and vans up to 5,600  kg (12,350  lb ) and off-road vehicles, ^{[B] [C]} the W4B 035 from the W4B 025 (type 722.1) and K4A 040 (type 722.2) for medium-duty trucks up to 13,000  kg (28,660  lb ). ^{[D] [E]} The main difference is the use of straight-cut planetary gearsets instead of helical-cut ones for better fuel efficiency at the price of lower noise comfort.

Specifications

For this second 4-speed models ^[a] 8 main components ^[b] are used. ^[4]

Gear Ratio Analysis ^[c]

In-Depth Analysis [d] With Assessment And Torque Ratio [e] And Efficiency Calculation [f]		Planetary Gearset: Teeth [g] Teeth			Count	Nomi- nal [h] Effec- tive [i]	Cen- ter [j]
		Simpson		Simple			Avg. [k]
Model Type	Version First Delivery	S1 [l] R1 [m]	S2 [n] R2 [o]	S3 [p] R3 [q]	Brakes Clutches	Ratio Span	Gear Step [r]
Gear		R		1	2	3	4
Gear Ratio [d]		${\displaystyle {i_{R}}}$ [d]		${\displaystyle {i_{1}}}$ [d]	${\displaystyle {i_{2}}}$ [d]	${\displaystyle {i_{3}}}$ [d]	${\displaystyle {i_{4}}}$ [d]
Step [r]		${\displaystyle -{\frac {i_{R}}{i_{1}}}}$ [s]		${\displaystyle {\frac {i_{1}}{i_{1}}}}$	${\displaystyle {\frac {i_{1}}{i_{2}}}}$ [t]	${\displaystyle {\frac {i_{2}}{i_{3}}}}$	${\displaystyle {\frac {i_{3}}{i_{4}}}}$
Δ Step [u] [v]					${\displaystyle {\tfrac {i_{1}}{i_{2}}}:{\tfrac {i_{2}}{i_{3}}}}$	${\displaystyle {\tfrac {i_{2}}{i_{3}}}:{\tfrac {i_{3}}{i_{4}}}}$
Shaft Speed		${\displaystyle {\frac {i_{1}}{i_{R}}}}$		${\displaystyle {\frac {i_{1}}{i_{1}}}}$	${\displaystyle {\frac {i_{1}}{i_{2}}}}$	${\displaystyle {\frac {i_{1}}{i_{3}}}}$	${\displaystyle {\frac {i_{1}}{i_{4}}}}$
Δ Shaft Speed [w]		${\displaystyle 0-{\tfrac {i_{1}}{i_{R}}}}$		${\displaystyle {\tfrac {i_{1}}{i_{1}}}-0}$	${\displaystyle {\tfrac {i_{1}}{i_{2}}}-{\tfrac {i_{1}}{i_{1}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{3}}}-{\tfrac {i_{1}}{i_{2}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{4}}}-{\tfrac {i_{1}}{i_{3}}}}$
Torque Ratio [e]		${\displaystyle \mu _{R}}$ [e]		${\displaystyle \mu _{1}}$ [e]	${\displaystyle \mu _{2}}$ [e]	${\displaystyle \mu _{3}}$ [e]	${\displaystyle \mu _{4}}$ [e]
Efficiency ${\displaystyle \eta _{n}}$ [f]		${\displaystyle {\frac {\mu _{R}}{i_{R}}}}$ [f]		${\displaystyle {\frac {\mu _{1}}{i_{1}}}}$ [f]	${\displaystyle {\frac {\mu _{2}}{i_{2}}}}$ [f]	${\displaystyle {\frac {\mu _{3}}{i_{3}}}}$ [f]	${\displaystyle {\frac {\mu _{4}}{i_{4}}}}$ [f]
K4B 050 w/o	51  kp⋅m (500  N⋅m ; 369  lb⋅ft ) 1964	50 76	44 76	44 76	3 2	3.9789 3.9789	1.9947
							1.5846 [r]
Gear		R		1	2	3	4
Gear Ratio [d]		−4.1455 ${\displaystyle -{\tfrac {228}{55}}}$		3.9789 ${\displaystyle {\tfrac {378}{95}}}$	2.4589 ${\displaystyle {\tfrac {1,168}{475}}}$	1.5789 [v]	1.0000 ${\displaystyle {\tfrac {1}{1}}}$
Step		1.0418		1.0000	1.6182	1.5573	1.5789
Δ Step [u]					1.0391	0.9863 [v]
Speed		-0.9598		1.0000	1.6182	2.5200	3.9789
Δ Speed		0.9598		1.0000	0.6182	0.9018	1.4589
Torque Ratio [e]		–4.0111 –3.9447		3.9021 3.8640	2.4125 2.3896	1.5674 1.5616	1.0000
Efficiency ${\displaystyle \eta _{n}}$ [f]		0.9676 0.9516		0.9807 0.9711	0.9811 0.9718	0.9927 0.9890	1.0000
K4C 025 722.2	25  kp⋅m (245  N⋅m ; 181  lb⋅ft ) 1967 [B]	44 76	44 76	35 76	3 2	3.9833 3.9833	1.9958
							1.5852 [r]
Gear		R		1	2	3	4
Gear Ratio [d]		−5.4779 [s] ${\displaystyle -{\tfrac {2,109}{385}}}$		3.9833 ${\displaystyle {\tfrac {1,665}{418}}}$	2.3855 [t] [v] ${\displaystyle {\tfrac {5,439}{2,280}}}$	1.4605 [r] ${\displaystyle {\tfrac {111}{76}}}$	1.0000 ${\displaystyle {\tfrac {1}{1}}}$
Step		1.3752 [s]		1.0000	1.6698 [t]	1.6333 [r]	1.4605
Δ Step [u]					1.0223 [v]	1.1183
Speed		-0.7271		1.0000	1.6696	2.7273	3.9833
Δ Speed		0.7271		1.0000	0.6696	1.0575	1.2560
Torque Ratio [e]		–5.2949 –5.2044		3.9080 3.8706	2.3406 2.3184	1.4513 1.4467	1.0000
Efficiency ${\displaystyle \eta _{n}}$ [f]		0.9666 0.9501		0.9811 0.9717	0.9812 0.9719	0.9937 0.9905	1.0000
K4A 040 722.2	40  kp⋅m (392  N⋅m ; 289  lb⋅ft ) 1969	44 76	44 76	35 76	3 2	3.9833 3.9833	1.9958
							1.5852 [r]
Gear		R		1	2	3	4
Gear Ratio [d]		−5.4779 [s]		3.9833	2.3855 [t] [v]	1.4605 [r]	1.0000
W4B 025 722.1	25  kp⋅m (245  N⋅m ; 181  lb⋅ft ) 1972 [B]	44 76	44 76	35 76	3 2	3.9833 3.9833	1.9958
							1.5852 [r]
Gear		R		1	2	3	4
Gear Ratio [d]		−5.4779 [s]		3.9833	2.3855 [t] [v]	1.4605 [r]	1.0000
W4A 018 [x] 720.1	18  kp⋅m (177  N⋅m ; 130  lb⋅ft ) 1975	46 80	46 80	37 80	3 2	4.0060 4.0060	2.0015
							1.5882 [r]
Gear		R		1	2	3	4
Gear Ratio [d]		−5.4994 [s] ${\displaystyle -{\tfrac {4,680}{851}}}$		4.0060 ${\displaystyle {\tfrac {7,371}{1840}}}$	2.3911 [t] [v] ${\displaystyle {\tfrac {1,339}{560}}}$	1.4625 [r] ${\displaystyle {\tfrac {117}{80}}}$	1.0000 ${\displaystyle {\tfrac {1}{1}}}$
Step		1.3728 [s]		1.0000	1.6754 [t]	1.6349 [r]	1.4625
Δ Step [u]					1.0248 [v]	1.1179
Speed		-0.7284		1.0000	1.6754	2.7391	4.0060
Δ Speed		0.7284		1.0000	0.6754	1.0637	1.2668
Torque Ratio [e]		–5.3157 –5.2250		3.9301 3.8924	2.3459 2.3236	1.4533 1.4486	1.0000
Efficiency ${\displaystyle \eta _{n}}$ [f]		0.9666 0.9501		0.9811 0.9716	0.9811 0.9718	0.9937 0.9905	1.0000
W4B 035 [y] TBD	35  kp⋅m (343  N⋅m ; 253  lb⋅ft ) 1975	42 78	42 78	36 78	3 2	4.1758 4.1758	2.0435
							1.6103 [r]
Gear		R		1	2	3	4
Gear Ratio [d]		−5.8810 [s] ${\displaystyle -{\tfrac {2,223}{378}}}$		4.1758 ${\displaystyle {\tfrac {3,420}{819}}}$	2.4115 [t] [v] ${\displaystyle {\tfrac {627}{260}}}$	1.4615 [r] ${\displaystyle {\tfrac {57}{39}}}$	1.0000 ${\displaystyle {\tfrac {1}{1}}}$
Step		1.4083 [s]		1.0000	1.7360 [t]	1.6500 [r]	1.4615
Δ Step [u]					1.0495 [v]	1.1289
Speed		-0.7101		1.0000	1.7316	2.8571	4.1758
Δ Speed		0.7101		1.0000	0.7316	1.1255	1.3187
Torque Ratio [e]		–5.6845 –5.5874		4.0955 4.0556	2.3653 2.3425	1.4523 1.4477	1.0000
Efficiency ${\displaystyle \eta _{n}}$ [f]		0.9666 0.9501		0.9808 0.9712	0.9808 0.9714	0.9937 0.9905	1.0000
Actuated Shift Elements
Brake B1 [z]					❶
Brake B2 [aa]				❶	❶	❶
Brake B3 [ab]		❶
Clutch K1 [ac]						❶	❶
Clutch K2 [ad]		❶		❶			❶
Geometric Ratios: Speed Conversion
Gear Ratio [d] R & 1 Ordinary [ae] Elementary Noted [af]	${\displaystyle i_{R}=-{\frac {R_{1}(S_{3}+R_{3})}{S_{1}S_{3}}}}$			${\displaystyle i_{1}={\frac {(S_{1}+R_{1})(S_{3}+R_{3})}{S_{1}R_{3}}}}$
	${\displaystyle i_{R}=-{\tfrac {R_{1}}{S_{1}}}\left(1+{\tfrac {R_{3}}{S_{3}}}\right)}$			${\displaystyle i_{1}=\left(1+{\tfrac {R_{1}}{S_{1}}}\right)\left(1+{\tfrac {S_{3}}{R_{3}}}\right)}$
Gear Ratio [d] 2 & 3 & 4 Ordinary [ae] Elementary Noted [af]	${\displaystyle i_{2}={\frac {(S_{1}(S_{2}+R_{2})+R_{1}S_{2})(S_{3}+R_{3})}{S_{1}(S_{2}+R_{2})R_{3}}}}$					${\displaystyle i_{3}={\frac {S_{3}+R_{3}}{R_{3}}}}$
	${\displaystyle i_{2}=\left(1+{\tfrac {\tfrac {R_{1}}{S_{1}}}{1+{\tfrac {R_{2}}{S_{2}}}}}\right)\left(1+{\tfrac {S_{3}}{R_{3}}}\right)}$				${\displaystyle i_{3}=1+{\tfrac {S_{3}}{R_{3}}}}$		${\displaystyle i_{4}={\frac {1}{1}}}$
Kinetic Ratios: Torque Conversion
Torque Ratio [e] R & 1	${\displaystyle \mu _{R}=-{\tfrac {R_{1}}{S_{1}}}\eta _{0}\left(1+{\tfrac {R_{3}}{S_{3}}}\eta _{0}\right)}$			${\displaystyle \mu _{1}=\left(1+{\tfrac {R_{1}}{S_{1}}}\eta _{0}\right)\left(1+{\tfrac {S_{3}}{R_{3}}}\eta _{0}\right)}$
Torque Ratio [e] 2 & 3 & 4	${\displaystyle \mu _{2}=\left(1+{\tfrac {{\tfrac {R_{1}}{S_{1}}}\eta _{0}}{1+{\tfrac {R_{2}}{S_{2}}}\cdot {\tfrac {1}{\eta _{0}}}}}\right)\left(1+{\tfrac {S_{3}}{R_{3}}}\eta _{0}\right)}$				${\displaystyle \mu _{3}=1+{\tfrac {S_{3}}{R_{3}}}\eta _{0}}$		${\displaystyle \mu _{4}={\frac {1}{1}}}$
plus 1 reverse gear 3 simple planetary gearsets, 3 brakes, 2  clutches Revised 14 January 2026 Nomenclature ${\displaystyle S_{n}=}$ sun gear: number of teeth ${\displaystyle R_{n}=}$ ring gear: number of teeth ${\displaystyle \color {gray}{C_{n}=}}$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 Gear Ratio (Transmission Ratio) ${\displaystyle i_{n}}$ — Speed Conversion — The gear 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 to the reciprocal of the shaft speeds ${\displaystyle i_{n}={\frac {1}{\frac {\omega _{2;n}}{\omega _{1;n}}}}={\frac {\omega _{1;n}}{\omega _{2;n}}}={\frac {\omega _{t}}{\omega _{2;n}}}}$ Torque Ratio (Torque Conversion Ratio) ${\displaystyle \mu _{n}}$ — Torque Conversion — The torque 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) to the 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 ${\displaystyle 0\leq \eta _{n;\eta _{0}}\leq 1}$ Efficiency The efficiency${\displaystyle \eta _{n}}$ 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, the stationary 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 the stationary 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 ${\displaystyle {\eta _{0}}^{\tfrac {1}{2}}}$ at ${\displaystyle 0.9800^{\tfrac {1}{2}}=0.98995}$ (upper value) and ${\displaystyle 0.9700^{\tfrac {1}{2}}=0.98489}$ (lower value) Layout Input and output are on opposite sides Planetary gearset 1 is on the input (turbine) side Input (turbine) shaft is S1 Output shaft is C3 Total Ratio Span (Total Gear/Transmission Ratio) Nominal ${\displaystyle {\frac {i_{1}}{i_{n}}}}$ 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 Total Ratio Span (Total Gear Ratio/Total Transmission Ratio) Effective ${\displaystyle {\frac {min(i_{1};|i_{R}|)}{i_{n}}}}$ The span is only effective to the extent that the reverse gear ratio matches that of 1st gear see also Standard R:1 Digression Since reverse gear is usually longer than first gear, the effective span is of central importance for describing the suitability of a transmission. In these cases, the nominal span conveys a misleading picture that is only unproblematic for vehicles with high specific power. Manufacturers naturally have no interest in specifying the effective span Users have not yet formulated the practical benefits that effective span has for them Effective span has not yet played a role in research and teaching Contrary to its importance, effective span has therefore not been able to establish itself in either theory or practice: general acceptance and widespread application are still pending. 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 ${\displaystyle \left({\frac {i_{1}}{i_{n}}}\right)^{\frac {1}{n-1}}}$ With decreasing step width the gears connect better to each other shifting comfort increases Sun 1: sun gear of gearset 1 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 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 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) 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) 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) 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) for light-duty trucks and vans up to 5,600  kg (12,350  lb) and off-road vehicles [B] [C] for medium-duty trucks up to 13,000  kg (28,660  lb) [D] [E] Blocks S2 Blocks S3 Also BR (brake for reverse gear · German: Bremse für Rückwärtsgang) · Blocks C1 Couples S2 with C2 Couples R1 with S3 Ordinary Noted For direct determination of the gear 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 the torque conversion ratio and efficiency

1971: W3A 040 And Follow-Up Products
— 3-Speed Transmissions With 2 Planetary Gearsets —

Layout

When the torque converter technique was fully established, 3-speed units, the W3A 040 and W3B 050 (type 722.0) is combined with V8 engines, and it uses torque converter instead of fluid coupling. ^{[1] [4]} The transmission saves 1 planetary gearset and uses the same housing as the 4-speed versions. The free space therefore is used to reinforce the shift elements (brakes and clutches) to handle the higher torque of the V8 engines.

First the W3A 040 was released for the all new M117 V8 engine of the W 108 and W 109 in 1971. The second in the series is the W3B 050, which was released initially for the W 116 450 SE/SEL in 1973. At that time the 4-speed transmission for the 350 SE/SEL was replaced by this 3-speed model. The reinforced W3B 050 reinforced (type 722.003) is the strongest of the series, able to handle the input of the enlarged version of the M 100, the biggest Mercedes-Benz engine in post-war history, ^[7] exclusively used in the W 116 450 SEL 6.9.

Specifications

For the 3-speed models ^[a] 7 main components ^[b] are used, which shows economic equivalence with the direct competitor.

Gear Ratio Analysis ^[c]

In-Depth Analysis [d] With Assessment And Torque Ratio [e] And Efficiency Calculation [f]		Planetary Gearset: Teeth [g]		Count	Nomi- nal [h] Effec- tive [i]	Cen- ter [j]
		Simple				Avg. [k]
Model Type	Version First Delivery	S1 [l] R1 [m]	S2 [n] R2 [o]	Brakes Clutches	Ratio Span	Gear Step [p]
Gear		R		1	2	3
Gear Ratio [d]		${\displaystyle {i_{R}}}$ [d]		${\displaystyle {i_{1}}}$ [d]	${\displaystyle {i_{2}}}$ [d]	${\displaystyle {i_{3}}}$ [d]
Step [p]		${\displaystyle -{\frac {i_{R}}{i_{1}}}}$ [q]		${\displaystyle {\frac {i_{1}}{i_{1}}}}$	${\displaystyle {\frac {i_{1}}{i_{2}}}}$ [r]	${\displaystyle {\frac {i_{2}}{i_{3}}}}$
Δ Step [s] [t]					${\displaystyle {\tfrac {i_{1}}{i_{2}}}:{\tfrac {i_{2}}{i_{3}}}}$
Shaft Speed		${\displaystyle {\frac {i_{1}}{i_{R}}}}$		${\displaystyle {\frac {i_{1}}{i_{1}}}}$	${\displaystyle {\frac {i_{1}}{i_{2}}}}$	${\displaystyle {\frac {i_{1}}{i_{3}}}}$
Δ Shaft Speed [u]		${\displaystyle 0-{\tfrac {i_{1}}{i_{R}}}}$		${\displaystyle {\tfrac {i_{1}}{i_{1}}}-0}$	${\displaystyle {\tfrac {i_{1}}{i_{2}}}-{\tfrac {i_{1}}{i_{1}}}}$	${\displaystyle {\tfrac {i_{1}}{i_{3}}}-{\tfrac {i_{1}}{i_{2}}}}$
Torque Ratio [e]		${\displaystyle \mu _{R}}$ [e]		${\displaystyle \mu _{1}}$ [e]	${\displaystyle \mu _{2}}$ [e]	${\displaystyle \mu _{3}}$ [e]
Efficiency ${\displaystyle \eta _{n}}$ [f]		${\displaystyle {\frac {\mu _{R}}{i_{R}}}}$ [f]		${\displaystyle {\frac {\mu _{1}}{i_{1}}}}$ [f]	${\displaystyle {\frac {\mu _{2}}{i_{2}}}}$ [f]	${\displaystyle {\frac {\mu _{3}}{i_{3}}}}$ [f]
W3A 040 722.0	40  kp⋅m (392  N⋅m ; 289  lb⋅ft ) 1971 [F]	44 76	35 76	3 2	2.3061 1.8361 [i] [q]	1.5186
						1.5186 [p]
Gear		R		1	2	3
Gear Ratio [d]		−1.8361 [q] [i] ${\displaystyle -{\tfrac {1,221}{665}}}$		2.3061 ${\displaystyle {\tfrac {1,665}{722}}}$	1.4605 ${\displaystyle {\tfrac {63}{25}}}$	1.0000 ${\displaystyle {\tfrac {1}{1}}}$
Step		0.7962 [q]		1.0000	1.5789	1.4605
Δ Step [s]					1.0811
Speed		-1.2560		1.0000	1.5789	2.3061
Δ Speed		1.2560		1.0000	0.5789	0.9411
Torque Ratio [e]		–1.7747 –1.7444		2.2747 2.2592	1.4513 1.4467	1.0000
Efficiency ${\displaystyle \eta _{n}}$ [f]		0.9666 0.9501		0.9864 0.9796	0.9937 0.9905	1.0000
W3A 050 722.0	50  kp⋅m (490  N⋅m ; 362  lb⋅ft ) 1973 [F]	44 76	35 76	3 2	2.3061 1.8361 [i] [q]	1.5186
						1.5186 [p]
Gear		R		1	2	3
Gear Ratio [d]		−1.8361 [q] [i]		2.3061	1.4605	1.0000
W3A 050 reinf. 722.0	56  kp⋅m (549  N⋅m ; 405  lb⋅ft ) 1975 [F]	44 76	35 76	3 2	2.3061 1.8361 [i] [q]	1.5186
						1.5186 [p]
Gear		R		1	2	3
Gear Ratio [d]		−1.8361 [q] [i]		2.3061	1.4605	1.0000
Actuated Shift Elements
Brake B1 [v]				❶
Brake B2 [w]				❶	❶
Brake B3 [x]		❶
Clutch K1 [y]					❶	❶
Clutch K2 [z]		❶				❶
Geometric Ratios: Speed Conversion
Gear Ratio [d] R & 2 Ordinary [aa] Elementary Noted [ab]	${\displaystyle i_{R}=-{\frac {S_{1}(S_{2}+R_{2})}{R_{1}S_{2}}}}$			${\displaystyle i_{2}={\frac {S_{2}+R_{2}}{R_{2}}}}$
	${\displaystyle i_{R}=-{\tfrac {S_{1}}{R_{1}}}(1+{\tfrac {R_{2}}{S_{2}}})}$			${\displaystyle i_{2}=1+{\tfrac {S_{2}}{R_{2}}}}$
Gear Ratio [d] 1 & 3 Ordinary [aa] Elementary Noted [ab]	${\displaystyle i_{1}={\frac {(S_{1}+R_{1})(S_{2}+R_{2})}{R_{1}R_{2}}}}$				${\displaystyle i_{3}={\frac {1}{1}}}$
	${\displaystyle i_{1}=\left(1+{\tfrac {S_{1}}{R_{1}}}\right)\left(1+{\tfrac {S_{2}}{R_{2}}}\right)}$				${\displaystyle i_{3}={\frac {1}{1}}}$
Kinetic Ratios: Torque Conversion
Torque Ratio [e] R & 2	${\displaystyle mu_{R}=-{\tfrac {S_{1}}{R_{1}}}\eta _{0}(1+{\tfrac {R_{2}}{S_{2}}}\eta _{0})}$			${\displaystyle mu_{2}=1+{\tfrac {S_{2}}{R_{2}}}\eta _{0}}$
Torque Ratio [e] 1 & 3	${\displaystyle mu_{1}=\left(1+{\tfrac {S_{1}}{R_{1}}}\eta _{0}\right)\left(1+{\tfrac {S_{2}}{R_{2}}}\eta _{0}\right)}$				${\displaystyle mu_{3}={\frac {1}{1}}}$
plus 1 reverse gear 2 simple planetary gearsets, [4] 3 brakes, 2  clutches Revised 14 January 2026 Nomenclature ${\displaystyle S_{n}=}$ sun gear: number of teeth ${\displaystyle R_{n}=}$ ring gear: number of teeth ${\displaystyle \color {gray}{C_{n}=}}$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 Gear Ratio (Transmission Ratio) ${\displaystyle i_{n}}$ — Speed Conversion — The gear 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 to the reciprocal of the shaft speeds ${\displaystyle i_{n}={\frac {1}{\frac {\omega _{2;n}}{\omega _{1;n}}}}={\frac {\omega _{1;n}}{\omega _{2;n}}}={\frac {\omega _{t}}{\omega _{2;n}}}}$ Torque Ratio (Torque Conversion Ratio) ${\displaystyle \mu _{n}}$ — Torque Conversion — The torque 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) to the 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 ${\displaystyle 0\leq \eta _{n;\eta _{0}}\leq 1}$ Efficiency The efficiency${\displaystyle \eta _{n}}$ 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, the stationary 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 the stationary 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 ${\displaystyle {\eta _{0}}^{\tfrac {1}{2}}}$ at ${\displaystyle 0.9800^{\tfrac {1}{2}}=0.98995}$ (upper value) and ${\displaystyle 0.9700^{\tfrac {1}{2}}=0.98489}$ (lower value) Layout Input and output are on opposite sides Planetary gearset 1 is on the input (turbine) side Input (turbine) shaft is R1 Output shaft is C2 Total Ratio Span (Total Gear/Transmission Ratio) Nominal ${\displaystyle {\frac {i_{1}}{i_{n}}}}$ 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 Total Ratio Span (Total Gear Ratio/Total Transmission Ratio) Effective ${\displaystyle {\frac {min(i_{1};|i_{R}|)}{i_{n}}}}$ The span is only effective to the extent that the reverse gear ratio matches that of 1st gear see also Standard R:1 Digression Since reverse gear is usually longer than first gear, the effective span is of central importance for describing the suitability of a transmission. In these cases, the nominal span conveys a misleading picture that is only unproblematic for vehicles with high specific power. Manufacturers naturally have no interest in specifying the effective span Users have not yet formulated the practical benefits that effective span has for them Effective span has not yet played a role in research and teaching Contrary to its importance, effective span has therefore not been able to establish itself in either theory or practice: general acceptance and widespread application are still pending. 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 ${\displaystyle \left({\frac {i_{1}}{i_{n}}}\right)^{\frac {1}{n-1}}}$ With decreasing step width the gears connect better to each other shifting comfort increases Sun 1: sun gear of gearset 1 Ring 1: ring gear of gearset 1 Sun 2: sun gear of gearset 2 Ring 2: ring gear of gearset 2 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) 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) 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) 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) Blocks S1 Blocks S2 Blocks C1 Couples S1 with C1 Couples S1 with S2 Ordinary Noted For direct determination of the gear 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 the torque conversoin ratio and efficiency

Applications

K4A 025

• 1961–1965 (saloon) · 1961–1968 (coupé/convertible) W 111
• 1961–1965 (saloon) · 1962–1968 (coupé/convertible) W 112
• 1961–1968 W 110
• 1963–1971 W 113
• 1965–1968 W 108/W 109

K4B 050

• 1964–1981 600 (W 100)
• 1968–1972 300 SEL 6.3 (W 109)

K4C 025

• 1968–1971 (coupé/convertible) W 111
• 1968–1972 W 108/W 109

W 114/W 115

Chassis code	Car model	Engine code	Transmission code
114.015 and 114.615	230.6	180.954	722.203
114.017 and 114.617	230.6 Lang
114.011 and 114.611	250	130.923	722.204
114.023 and 114.623	250 C
114.060 and 114.660	280	110.921	722.202
114.073 and 114.673	280 C
114.062 and 114.662	280 E	110.981	722.200
114.072 and 114.672	280 CE
115.015 and 115.615	200	115.923	722.205
115.010	220	115.920
115.115 and 115.715	200 D	615.913	722.206
115.110 and 115.710	220 D	615.912
115.112	220 D Lang

K4A 040

W 108/W 109

Chassis code	Car model	Engine code	Transmission code	Notes
109.057	300 SEL 3.5	3.5 L M 116 V8	722.201	worldwide except USA
108.067	280 SE 3.5
108.068	280 SEL 3.5

R 107/C 107

Chassis code	Car model	Engine code	Transmission code
107.043	350 SL	116.982 (D-Jet) 116.984 (K-Jet)	722.201
107.023	350 SLC

W3A 040

W 108/W 109

Chassis code	Car model	Engine code	Transmission code	Notes
109.056	300 SEL 4.5	4.5 L M 117 V8	722.000	USA only
108.057	280 SE 4.5
108.058	280 SEL 4.5

R 107/C 107

Chassis code	Car model	Engine code	Transmission code	Notes
107.043	350 SL	116.982 (D-Jet) 116.984 (K-Jet)	722.002
107.023	350 SLC
107.044	450 SL	117.982 (D-Jet) 117.985 (K-Jet)	722.004	USA and Japan only
107.024	450 SLC

W 116

Chassis code	Car model	Engine code	Transmission code	Notes
116.028	350 SE	116.983 (D-Jet) 116.985 (K-Jet)	722.002
116.029	350 SEL
116.032	450 SE	117.983 (D-Jet) 117.986 (K-Jet)	722.004	USA and Japan only
116.033	450 SEL

W3B 050

R 107/C 107

Chassis code	Car model	Engine code	Transmission code	Notes
107.044	450 SL	117.982 (D-Jet) 117.985 (K-Jet)	722.001	worldwide except USA and Japan
107.024	450 SLC

W 116

Chassis code	Car model	Engine code	Transmission code	Notes
116.032	450 SE	117.983 (D-Jet) 117.986 (K-Jet)	722.001	worldwide except USA and Japan
116.033	450 SEL
116.036	450 SEL 6.9	100.985	722.003	722.003 W3B 050 reinforced [8]

• 1977 – 1984 Porsche 928

W4B 025

R 107/C 107

Chassis code	Car model	Engine code	Transmission code
107.042	280 SL	110.982 110.986 110.990	722.103 722.112
107.022	280 SLC	110.982 110.986

W 114/W 115

Chassis code	Car model	Engine code	Transmission code
114.015 and 114.615	230.6	180.954	722.105
114.017 and 114.617	230.6 Lang
114.011 and 114.611	250	130.923	722.104
114.023 and 114.623	250 C
114.060 and 114.660	280	110.921	722.102
114.073 and 114.673	280 C
114.062 and 114.662	280 E	110.981	722.103
114.072 and 114.672	280 CE
115.015 and 115.615	200	115.923	722.106
115.017	230.4	115.951	722.110
115.115 and 115.715	200 D	615.913	722.107
115.110 and 115.710	220 D	615.912
115.112	220 D Lang
115.117	240 D	616.916	722.108
115.119	240 D Lang
115.114	240 D 3.0	617.910	722.109

W 116

Chassis code	Car model	Engine code	Transmission code	Notes
116.020	280 S	110.922	722.100 722.102 722.111
116.024	280 SE	110.983 (D-Jet) 110.985 (K-Jet)	722.101 722.103 722.112
116.025	280 SEL
116.120	300 SD	617.950	722.120	USA only

W 123

Chassis code	Car model	Engine code	Transmission code	Notes
123.020	200	115.938 115.939	722.115
123.220	200	102.920 102.939	722.121
123.280	200 T
123.023	230	115.954	722.119
123.083	230 T
123.043	230 C
123.223	230 E	102.980	722.122
123.283	230 TE
123.243	230 CE
123.026	250	123.920 123.921	722.113
123.086	250 T
123.028	250 Lang
123.030	280	110.923	722.111
123.050	280 C
123.033	280 E	110.984 110.988	722.112
123.093	280 TE
123.053	280 CE
123.120	200 D	615.940	722.116
123.126	220 D	615.941
123.123	240 D	616.912	722.117
123.183	240 TD
123.125	240 D Lang
123.130	300 D	617.912	722.118
123.190	300 TD
123.132	300 D Lang
123.150	300 CD			USA only

See also

• Cars portal

• List of Daimler AG transmissions

Notes

1. pp. 6 & 20 ^[3]
2. pp. 7 & 20 ^[3]
3. p. 487 ^[5]
4. pp. 9 & 22 ^[3]
5. p. 489 ^[5]
6. p. 452 ^[5]

References

1. "50 years of automatic transmissions from Mercedes-Benz".
2. Johannes Looman · Gear Transmissions · pp. 133 ff · German : Johannes Looman · Zahnradgetriebe · Berlin und Heidelberg 1970 · Print ISBN   978-3-540-04894-7 · S. 133 ff
3. Result And Outlook · commemorative publication for Prof. Dr. Hans-Joachim Foerster on the occasion of leaving as director from active duty at Daimler-Benz AG · November 1982 · German: Ergebnis und Ausblick · Festschrift für Herrn Prof. Dr. Hans-Joachim Förster zum Ausscheiden als Direktor aus dem aktiven Dienst der Daimler-Benz AG · November 1982
4. "MB Passenger Car Series 116" (PDF). · p. 10
5. Hans-Joachim Foerster · Automatic Vehicle Transmissions · German: Hans-Joachim Förster · Automatische Fahrzeuggetriebe · Berlin und Heidelberg 1991 · Print ISBN   978-3-642-84119-4 · eBook ISBN   978-3-642-84118-7
6. "MB Passenger Car Series 116" (PDF). p. 11
7. Only surpassed by the Mercedes-Benz 770, built from 1930 to 1943
8. "MB AUS 1979" (PDF). · p. 57