Mercedes-Benz first series automatic transmission

Motor vehicle

Mercedes-Benz K4A 025 K4B 050 · K4C 025 · K4A 040 W3A 040 · W3B 050 · W4B 025 W4A 018 · W4B 035
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 four- and three-speed variants for Mercedes-Benz passenger cars. In addition, variants for commercial vehicles were offered.

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 BorgWarner.

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 sixteen bolts.

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

Layout

The K4A 025^[a] (without type designation) is the first of the series, launched in April 1961 for the W111 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 four-speed model^[b] eight main components^[c] are used. It is the only exemption which uses only two planetary gearsets for four speeds.

In-Depth Gear Ratios^[d]
Gear Teeth and Ratios		Planetary Gearset Teeth Simple^[e]		Count	Total	Avg.

Model Type	Version First Delivery	$S_{1}$ ^[f] $R_{1}$ ^[g]	$S_{2}$ ^[h] $R_{2}$ ^[i]	Brakes Clutches	Ratio Span	Gear Step
Gear $n$		R	1	2	3	4
Step $i_{n-1}/i_{n}$		–R : 1		1 : 2	2 : 3	3 : 4

K4A 025 N/A	25 kp⋅m (181 lb⋅ft) 1961^[2]^[3]	50 76	44 76	3 3	3.9789	1.5846
Ratio $i_{n}$		−4.1455 $-{\tfrac {228}{55}}$	3.9789 ${\tfrac {378}{95}}$	2.5200 ${\tfrac {63}{25}}$	1.5789 ${\tfrac {30}{19}}$	1.0000 ${\tfrac {1}{1}}$
Step		1.0418		1.5789	1.5960	1.5789

Ratio	$-{\tfrac {R_{1}(S_{2}+R_{2})}{S_{1}S_{2}}}$	${\tfrac {(S_{1}+R_{1})(S_{2}+R_{2})}{S_{1}R_{2}}}$		${\tfrac {S_{1}+R_{1}}{S_{1}}}$	${\tfrac {S_{2}+R_{2}}{R_{2}}}$	${\tfrac {1}{1}}$

^ Kupplungs-4-Gang-Automatik bis 25 kpm Eingangsdrehmoment
(clutch-4-gear-automatic with 25 kp⋅m (181 lb⋅ft) maximum input torque
^ plus 1 reverse gear
^ 2 simple planetary gearsets, 3 brakes, 3 clutches
^ Differences in gear ratios have a measurable, direct impact on vehicle dynamics, performance, waste emissions as well as fuel mileage
^ Layout
(1) Planetary gearset 1 is on the input (turbine) side
(2) Output shaft is carrier 2 (the planetary gear carrier of gearset 2)
^ Sun gear of gearset 1
^ Ring gear of gearset 1
^ Sun gear of gearset 2
^ Ring gear of gearset 2

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

Layout

The Mercedes-Benz 600 from April 1964, the first post-war "Grand Mercedes", is 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.

The first model with this new layout was the K4B 050 (without type designation). Beside the new layout the number of pinions is doubled from three to six to handle the much higher torque of the big block V8 engine.

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 more powerful version of the same design.

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^[5] or if L position is selected in gear selector.

The W4A 018 (type 720.1) was derived from the W4B 025 (type 722.1) for vans up to 5,600 kg (12,350 lb) and off road vehicles, the W4B 035 from the W4B 025 (type 722.1) and K4A 040 (type 722.2) for light trucks up to 13,000 kg (28,660 lb).^[6] The main difference is the use of straight toothed planetary gearsets instead of skew toothed ones for better fuel efficiency at the price of lower noise comfort.

Specifications

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

In-Depth Gear Ratios^[c]
Gear Teeth and Ratios		Planetary Gearset Teeth Simple^[d]			Count	Total	Avg.
Gear Teeth and Ratios		Simpson		Simple	Count	Total	Avg.

Model Type	Version First Delivery	$S_{1}$ ^[e] $R_{1}$ ^[f]	$S_{2}$ ^[g] $R_{2}$ ^[h]	$S_{3}$ ^[i] $R_{2}$ ^[j]	Brakes Clutches	Ratio Span	Gear Step
Gear $n$		R		1	2	3	4
Step $i_{n-1}/i_{n}$		–R : 1			1 : 2	2 : 3	3 : 4

K4B 050 N/A	51 kp⋅m (369 lb⋅ft) 1964	50 76	44 76	44 76	3 2	3.9789	1.5846
Ratio $i_{n}$		−4.1455 $-{\tfrac {228}{55}}$		3.9789 ${\tfrac {378}{95}}$	2.4589 ${\tfrac {1,168}{475}}$	1.5789 ${\tfrac {30}{19}}$	1.0000 ${\tfrac {1}{1}}$
Step		1.0418			1.6182	1.5573	1.5789

K4C 025 722.2	25 kp⋅m (181 lb⋅ft) 1967^[7]	44 76	44 76	35 76	3 2	3.9833	1.5852
Ratio $i_{n}$		−5.4779 $-{\tfrac {228}{55}}$		3.9833 ${\tfrac {1,665}{418}}$	2.3855 ${\tfrac {5,439}{2280}}$	1.4605 ${\tfrac {111}{76}}$	1.0000 ${\tfrac {1}{1}}$
Step		1.3752			1.6698	1.6333	1.4605

K4A 040 722.2	40 kp⋅m (289 lb⋅ft) 1969	44 76	44 76	35 76	3 2	3.9833	1.5852
Ratio		−5.4779		3.9833	2.3855	1.4605	1.0000
Step		1.3752			1.6698	1.6333	1.4605

W4B 025 722.1	25 kp⋅m (181 lb⋅ft) 1972^[7]	44 76	44 76	35 76	3 2	3.9833	1.5852
Ratio		−5.4779		3.9833	2.3855	1.4605	1.0000
Step		1.3752			1.6698	1.6333	1.4605

W4A 018^[k] 720.1	18 kp⋅m (130 lb⋅ft) 1975	46 80	46 80	37 80	3 2	4.0060	1.5882
Ratio $i_{n}$		−5.4994 $-{\tfrac {4,680}{851}}$		4.0060 ${\tfrac {7,371}{1,840}}$	2.3911 ${\tfrac {1,339}{560}}$	1.4625 ${\tfrac {117}{80}}$	1.0000 ${\tfrac {1}{1}}$
Step		1.3728			1.6754	1.6349	1.4625

W4B 035^[l] N/A	35 kp⋅m (253 lb⋅ft) 1975	42 78	42 78	36 78	3 2	4.1758	1.6103
Ratio $i_{n}$		−5.8810 $-{\tfrac {2,223}{378}}$		4.1758 ${\tfrac {3,420}{819}}$	2.4115 ${\tfrac {627}{260}}$	1.4615 ${\tfrac {57}{39}}$	1.0000 ${\tfrac {1}{1}}$
Step		1.4083			1.7316	1.6500	1.4615

Ratio R & Even		$-{\tfrac {R_{1}(S_{3}+R_{3})}{S_{1}S_{3}}}$		${\tfrac {(S_{1}(S_{2}+R_{2})+R_{1}S_{2})(S_{3}+R_{3})}{S_{1}(S_{2}+R_{2})R_{3}}}$			${\tfrac {1}{1}}$
Ratio Odd			${\tfrac {(S_{1}+R_{1})(S_{3}+R_{3})}{S_{1}R_{3}}}$			${\tfrac {S_{3}+R_{3}}{R_{3}}}$

^ plus 1 reverse gear
^ 3 simple planetary gearsets, 3 brakes, 2 clutches
^ Differences in gear ratios have a measurable, direct impact on vehicle dynamics, performance, waste emissions as well as fuel mileage
^ Layout
(1) Planetary gearset 1 is on the input (turbine) side
(2) Output shaft is carrier 3 (the planetary gear carrier of gearset 3)
^ Sun gear of gearset 1
^ Ring gear of gearset 1
^ Sun gear of gearset 2
^ Ring gear of gearset 2
^ Sun gear of gearset 3
^ Ring gear of gearset 3
^ for light duty trucks up to 5,600 kg (12,350 lb)^[8]^[6]
^ for medium duty trucks up to 13,000 kg (28,660 lb)^[6]^[9]

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

Layout

When the torque converter technique was fully established, three-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 one planetary gearset and uses the same housing as the four-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 Mercedes-Benz W108 and W109 in 1971. The second in the series is the W3B 050, which was released initially for the W116 450 SE and SEL in 1973. At that time the four-speed transmission for the 350 SE and SEL was replaced by this three-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 Mercedes-Benz M100 engine, the biggest Mercedes-Benz engine in post-war history,^[10] exclusively used in the W116 450 SEL 6.9.

Specifications

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

In-Depth Gear Ratios^[c]
Gear Teeth and Ratios		Planetary Gearset Teeth Simple^[d]		Count	Total	Avg.

Model Type	Version First Delivery	$S_{1}$ ^[e] $R_{1}$ ^[f]	$S_{2}$ ^[g] $R_{2}$ ^[h]	Brakes Clutches	Ratio Span	Gear Step
Gear $n$		R		1	2	3
Step $i_{n-1}/i_{n}$		–R : 1			1 : 2	2 : 3

W3A 040 722.0	40 kp⋅m (289 lb⋅ft) 1971^[11]	44 76	35 76	3 2	2.3061	1.5186
Ratio $i_{n}$		−1.8361 $-{\tfrac {1,221}{665}}$		2.3061 ${\tfrac {1,665}{722}}$	1.4605 ${\tfrac {111}{76}}$	1.0000 ${\tfrac {1}{1}}$
Step		0.7962			1.5789	1.4605

W3B 050 722.0	50 kp⋅m (362 lb⋅ft) 1973^[11]	44 76	35 76	3 2	2.3061	1.5186
Ratio		−1.8361		2.3061	1.4605	1.0000
Step		0.7962			1.5789	1.4605

W3B 050 reinf. 722.0	56 kp⋅m (405 lb⋅ft) 1975^[11]	44 76	35 76	3 2	2.3061	1.5186
Ratio		−1.8361		2.3061	1.4605	1.0000
Step		0.7962			1.5789	1.4605

Ratio	$-{\tfrac {S_{1}(S_{2}+R_{2})}{R_{1}S_{2}}}$		${\tfrac {(S_{1}+R_{1})(S_{2}+R_{2})}{R_{1}R_{2}}}$		${\tfrac {S_{2}+R_{2}}{R_{2}}}$	${\tfrac {1}{1}}$

^ plus 1 reverse gear
^ 2 simple planetary gearsets,^[4] 3 brakes, 2 clutches
^ Differences in gear ratios have a measurable, direct impact on vehicle dynamics, performance, waste emissions as well as fuel mileage
^ Layout
(1) Planetary gearset 1 is on the input (turbine) side
(2) Output shaft is carrier 2 (the planetary gear carrier of gearset 2)
^ Sun gear of gearset 1
^ Ring gear of gearset 1
^ Sun gear of gearset 2
^ Ring gear of gearset 2

Applications

K4C 025

W114 and W115
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	180.954	722.203
114.011 and 114.611	250	130.923	722.204
114.023 and 114.623	250 C	130.923	722.204
114.060 and 114.660	280	110.921	722.202
114.073 and 114.673	280 C	110.921	722.202
114.062 and 114.662	280 E	110.981	722.200
114.072 and 114.672	280 CE	110.981	722.200
115.015 and 115.615	200	115.923	722.205
115.010	220	115.920	722.205
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	615.912

K4A 040

W109 and W108
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

R107 and C107
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	116.982 (D-Jet) 116.984 (K-Jet)	722.201

W3A 040

W109 and W108
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

R107 and C107
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	116.982 (D-Jet) 116.984 (K-Jet)	722.002
107.044	450 SL	117.982 (D-Jet) 117.985 (K-Jet)	722.004	USA and Japan only
107.024	450 SLC	117.982 (D-Jet) 117.985 (K-Jet)	722.004	USA and Japan only

W116
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	116.983 (D-Jet) 116.985 (K-Jet)	722.002
116.032	450 SE	117.983 (D-Jet) 117.986 (K-Jet)	722.004	USA and Japan only
116.033	450 SEL	117.983 (D-Jet) 117.986 (K-Jet)	722.004	USA and Japan only

W3B 050

R107 and C107
Chassis code	Car model	Engine code	Transmission code	Notes
107.044	450 SL	117.982 (D-Jet) 117.985 (K-Jet)	722.004	worldwide except USA and Japan
107.024	450 SLC	117.982 (D-Jet) 117.985 (K-Jet)	722.004	worldwide except USA and Japan

W116
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	117.983 (D-Jet) 117.986 (K-Jet)	722.001	worldwide except USA and Japan
116.036	450 SEL 6.9	100.985	722.003	722.003 W3B 050 reinforced^[12]

W4B 025

R107 and C107
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	722.103 · 722.112

W114 and W115
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	180.954	722.105
114.011 and 114.611	250	130.923	722.104
114.023 and 114.623	250 C	130.923	722.104
114.060 and 114.660	280	110.921	722.102
114.073 and 114.673	280 C	110.921	722.102
114.062 and 114.662	280 E	110.981	722.103
114.072 and 114.672	280 CE	110.981	722.103
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	615.912
115.117	240 D	616.916	722.108
115.119	240 D Lang	616.916	722.108
115.114	240 D 3.0	617.910	722.109

W116
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	110.983 (D-Jet) 110.985 (K-Jet)	722.101 · 722.103 · 722.112
116.120	300 SD	617.950	722.120	USA only

W123
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	102.920 · 102.939	722.121
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	110.923	722.111
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	722.116
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

References

^ ^a ^b "50 years of automatic transmissions from Mercedes-Benz".
^ Johannes Looman · Zahnradgetriebe · pp. 133 ff · Berlin and Heidelberg 1970 · Print ISBN 978-3-540-04894-7
^ 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 (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) · pp. 6 · 20
^ ^a ^b ^c ^d "MB Passenger Car Series 116, PDF p. 10" (PDF).
^ "MB Passenger Car Series 116, PDF p. 11" (PDF).
^ ^a ^b ^c 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 (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) · pp. 9 · 22
^ ^a ^b 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 (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) · pp. 7 · 20
^ Hans Joachim Foerster · Automatische Fahrzeuggetriebe · p. 487 · Berlin and Heidelberg 1991 · Print ISBN 978-3-642-84119-4 · Online ISBN 978-3-642-84118-7
^ Hans Joachim Foerster · Automatische Fahrzeuggetriebe · p. 489 · Berlin and Heidelberg 1991 · Print ISBN 978-3-642-84119-4 · Online ISBN 978-3-642-84118-7
^ Only surpassed by the Mercedes-Benz 770, built from 1930 to 1943
^ ^a ^b ^c Hans Joachim Foerster · Automatische Fahrzeuggetriebe · p. 452 · Berlin and Heidelberg 1991 · Print ISBN 978-3-642-84119-4 · Online ISBN 978-3-642-84118-7
^ "MB AUS 1979, PDF p. 57" (PDF).