Mercedes-Benz first series automatic transmission
World's first 4-speed automatic from 1961
From Wikipedia, the free encyclopedia
The Mercedes-Benz first series of automatic transmission was produced from 1961 to 1983 in two 4-speed designs, at Mercedes-Benz later referred to as 1st and 2nd automatic transmission generation, and a 3-speed variant of the second design for passenger cars. In addition, transmissions with the second 4-speed design were offered for commercial vehicles until the mid-1990s.
| 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 | 4- and 3-speed longitudinal automatic transmission |
| Chronology | |
| Successor | 4G-Tronic |
All these designs are for cars with a longitudinal engine, rear-wheel-drive layout. 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.[citation needed]
Key data
| Model Design |
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 1st |
w/o 1st [c] |
1961 [1][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[d] | 4[b] | A | 25 kp⋅m (181 lb⋅ft) |
| K4B 050[e] 2nd |
w/o 2nd [f] |
1964[g] | −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[d] | 4[b] | B | 50 kp⋅m (362 lb⋅ft) |
| K4C 025 K4A 040 W4B 025 2nd |
722.2 722.2 722.1 2nd [f] |
1967[B] 1969 1972[B] |
−5.478 | 3.983 | 2.386 | 1.461 | 1.000 | 3.983 | 3.983 | 1.996 | 1.585 | K[d] K[d] W[h][3] |
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[i] 2nd |
720.1 2nd [f] |
1975 | −5.499 | 4.006 | 2.391 | 1.463 | 1.000 | 4.006 | 4.006 | 2.001 | 1.588 | W[h] | 4[b] | A | 18 kp⋅m (130 lb⋅ft) | ||
| W4B 035[j] 2nd |
TBD | 1975 | −5.881 | 4.176 | 2.412 | 1.462 | 1.000 | 4.176 | 4.176 | 2.043 | 1.610 | W[h] | 4[b] | B | 35 kp⋅m (253 lb⋅ft) | ||
| W3A 040 W3A 050 W3A 050 reinf.[k] 2nd |
720.0 722.0 722.0 2nd [f] |
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[h] | 3[b] | A | 40 kp⋅m (289 lb⋅ft) 50 kp⋅m (362 lb⋅ft) 56 kp⋅m (405 lb⋅ft) | |
| |||||||||||||||||
History
The K4A 025 was the first Mercedes automatic transmission developed in-house.[5] 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).
1st generation 1961: K4A 025 — first 4-speed design with 2 planetary gearsets —
Specifications
The K4A 025 is the first design, launched in April 1961 for the W 111 220 SEb, later replaced with the more reliable second design K4C 025 (type 722.2). It is a 4-speed unit and uses fluid coupling (also referred in some manuals as hydraulic/automatic clutch).
This first design did not work out. It 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—that is, all four of the relevant shift levers must be released or actuated.
Planetary gearset concept first design
For this 1st automatic transmission generation[a] 8 main components[b] are used. It is the only exemption which uses only 2 planetary gearsets for 4 speeds.
2nd generation 1964: K4B 050 and follow-up products — second 4-speed design with 3 planetary gearsets —
Specifications
The Mercedes-Benz 600, which was unveiled in September 1963 at the International Motor Show in Frankfurt, 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 1st automatic transmission generation was out of the question from the start. The introduction of the 600 was therefore taken as an opportunity to develop a completely new design for the automatic transmission, at Mercedes-Benz later referred to as 2nd automatic transmission generation.
Mercedes-Benz licensed a variant – featuring cross-coupled ring gears and carriers instead of coupled sun gears – of the Simpson planetary gearset in order to replace the original epicyclic gearset of the first design and thereby eliminate the need for group changes.
Models
1964: K4B 050
The first model with the new design 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 M 100.
1967: K4C 025
After the satisfactory experience with the new design, it was adopted with slightly different gear ratios in 1967 for the new core model K4C 025 (Type 722.2) of the 2nd automatic transmission generation from Mercedes-Benz.
1969: K4A 040
With the introduction of the small block V8 engine M 116, the K4A 040 (Type 722.2) was launched, 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).[3] 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 vehicles
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 is based on the same design and designated 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.
Planetary gearset concept second design
For this 2nd generation 4-speed variants[c] 8 main components[d] are used.[3]
2nd generation 1971: W3A 040 and follow-up products — 3-speed variant of the second design with 2 planetary gearsets —
Specifications
When the torque converter technique was fully established, 3-speed variants, the W3A 040 and W3B 050 (type 722.0) are combined with V8 engines, using torque converters instead of fluid couplings.[5][3] The transmission design saves 1 planetary gearset, so the Simpson planetary gearset is no longer necessary. Therefore this variant is not based on a Simpson gearset design, but on the Detroit Gear. Since the same housing as in the 4-speed versions is used, 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 variant 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 variant.
The reinforced W3B 050 reinforced (type 722.003) is the strongest variant 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.
The W3B 050 was available as an optional extra for the Porsche 928 from 1977 to 1984.
Planetary gearset concept second design, 3-speed variant
For the 3-speed variants[e] 7 main components[f] are used, which shows economic equivalence with the direct competitor.
Applications
| Model | Car Model[g] | ||||
|---|---|---|---|---|---|
| Chassis code | Car model | Engine code |
Transmission code |
Notes | |
| K4A 025[h] (1st generation[i]) | |||||
| E-Class |
| ||||
| S-Class | |||||
| SL-Class |
| ||||
| K4B 050[h] (2nd generation[j]) | |||||
| S-Class |
| ||||
| K4C 025 (Type 722.2, 2nd generation[j]) | |||||
| E-Class | 114.015 | 230.6 | 180.954 | 722.203 | |
| 114.017 | 230.6 Lang | ||||
| 114.011 | 250 | 130.923 | 722.204 | ||
| 114.023 | 250 C | ||||
| 114.060 | 280 | 110.921 | 722.202 | ||
| 114.073 | 280 C | ||||
| 114.062 | 280 E | 110.981 | 722.200 | ||
| 114.072 | 280 CE | ||||
| 115.015 | 200 | 115.923 | 722.205 | ||
| 115.010 | 220 | 115.920 | |||
| 115.115 | 200 D | 615.913 | 722.206 | ||
| 115.110 | 220 D | 615.912 | |||
| 115.112 | 220 D Lang | ||||
| S-Class | |||||
| K4A 040 (Type 722.2, 2nd generation[j]) | |||||
| S-Class | 109.056 | 300 SEL 3.5 | 116.981 (D-Jet) | 722.201 | worldwide except USA |
| 108.057 | 280 SE 3.5 | 116.980 (D-Jet) | |||
| 108.058 | 280 SEL 3.5 | ||||
| SL-Class | 107.043 | 350 SL | 116.982 (D-Jet) 116.984 (K-Jet) |
722.201 | |
| 107.023 | 350 SLC | ||||
| W3A 040 (Type 722.0, 2nd generation[j]) | |||||
| S-Class | 109.057 | 300 SEL 4.5 | 117.981 (D-Jet) | 722.000 | USA only |
| 108.067 | 280 SE 4.5 | 117.984 (D-Jet) | |||
| 108.068 | 280 SEL 4.5 | ||||
| S-Class | 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 | ||||
| SL-Class | 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 | ||||
| W3B 050[k] (Type 722.0, 2nd generation[j]) | |||||
| S-Class | 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 (K-Jet) | 722.003 W3B 050[k] |
||
| SL-Class | 107.044 | 450 SL | 117.982 (D-Jet) 117.985 (K-Jet) |
722.001 | worldwide except USA and Japan |
| 107.024 | 450 SLC | ||||
| 107.026 | 450 SLC 5.0[l] | 117.960 (K-Jet) | |||
| Porsche |
| ||||
| W4B 025 (Type 722.1, 2nd generation[j]) | |||||
| E-Class | 114.615 | 230.6 | 180.954 | 722.105 | |
| 114.617 | 230.6 Lang | ||||
| 114.611 | 250 | 130.923 | 722.104 | ||
| 114.623 | 250 C | ||||
| 114.660 | 280 | 110.921 | 722.102 | ||
| 114.673 | 280 C | ||||
| 114.662 | 280 E | 110.981 | 722.103 | ||
| 114.672 | 280 CE | ||||
| 115.615 | 200 | 115.923 | 722.106 | ||
| 115.017 | 230.4 | 115.951 | 722.110 | ||
| 115.715 | 200 D | 615.913 | 722.107 | ||
| 115.710 | 220 D | 615.912 | |||
| 115.117 | 240 D | 616.916 | 722.108 | ||
| 115.119 | 240 D Lang | ||||
| 115.114 | 240 D 3.0 | 617.910 | 722.109 | ||
| E-Class | 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 | |||
| S-Class | 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 | |
| SL-Class | 107.042 | 280 SL | 110.982 (D-Jet) 110.986 (K-Jet) |
722.103 722.112 |
|
| 107.022 | 280 SLC | ||||
| |||||
