# Unimog 421

The Unimog 421 is a vehicle of the Mercedes-Benz Unimog series, made by Daimler-Benz. In total, 18,995 units of the Unimog 421 were built from 1966 to 1989 in the Mercedes-Benz Gaggenau plant. It is a medium-sized vehicle bigger than the traditional Unimog 411, but smaller than the Unimog 406. Introduction of new heavy models and Unimog 411 production ceasing in the mid-1970s changed the Unimog 421's role in the Unimog lineup; it became the predecessor of the light Unimog series and thus succeeded the Unimog 411.
Both short and long wheelbase versions, as well as "front half only" OEM part versions, were made. Technically, the Unimog 421 is based on the Unimog 406 and Unimog 411. The plane ladder frame and axles are Unimog 411 parts, and the engines used for the 421-series are also passenger car engines. Cab and gearbox are Unimog 406-related. The 421 closed cab version looks almost exactly like a 406-series cab, but the cabrio version is a bit more narrow and "squat". A 406-series can be differentiated from a 421-series by the position of the air-intake: A 421-series has the air-intake on the right-hand side of the bonnet, and a 406-series on the left-hand side.
In Argentina, a copy of the Unimog 421, the 431-series, was produced under licence. From 1969 to 1971, 601 cabrios and 152 closed cab units of the Unimog 431 were made. Daimler-Benz produced CKD-kits in Gaggenau, which were then shipped to Argentina for manufacture. The 431-series was fitted with a 44 kW (59 hp; 60 PS) engine, but has the short wheelbase – this combination was not available for the original 421-series.

## Engines

The 421-series was made with straight-four precombustion chamber Diesel engines. Prototypes included, four different engines were used, which are all passenger car engines.
| Engine | Displacement | Rated power | Years |
| OM 636 | 1.767 L (107.8 in$^3$) | 40 PS (29 kW; 39 hp) | 1964–1965 (Prototypes only) |
| OM 621 | 1.988 L (121.3 in$^3$) | 40 PS (29 kW; 39 hp) | 1966–1968 |
| OM 615 | 2.197 L (134.1 in$^3$) | 45 PS (33 kW; 44 hp) | 1968–1970 |
| OM 616 | 2.404 L (146.7 in$^3$) | 52 PS (38 kW; 51 hp) – 60 PS (44 kW; 59 hp) | 1970–1989 |

## Types of the 421-series

In total 20 different types of the 421-series were made, out of which four were made as OEM parts for other manufacturers.

### Mercedes-Benz types

| Type | Model | Cab | Wheelbase | Rated power | Number manufactured | Notes |
| 421.122 | U40, U45 | Cabrio | 2,250 mm (88+5⁄8 in) | 29 kW (39 hp; 39 PS), 33 kW (44 hp; 45 PS) | 2.647 | |
| 421.123 | U40, U45 | Closed cab | 2,250 mm (88+5⁄8 in) | 29 kW (39 hp; 39 PS), 33 kW (44 hp; 45 PS) | 3.215 | |
| 421.124 | U52 | Cabrio | 2,250 mm (88+5⁄8 in) | 38 kW (51 hp; 52 PS) | 1.145 | |
| 421.125 | U52 | Closed cab | 2,250 mm (88+5⁄8 in) | 38 kW (51 hp; 52 PS) | 1.995 | |
| 421.126 | U60, U600L | Cabrio | 2,605 mm (102+1⁄2 in) | 44 kW (59 hp; 60 PS) | 4 | U 600 L: Crew cab |
| 421.128 | U60, U600L | Cabrio | 2,605 mm (102+1⁄2 in) | 44 kW (59 hp; 60 PS) | 3.252 | U 600 L: Crew cab |
| 421.129 | U60, U600L | Closed cab | 2,605 mm (102+1⁄2 in) | 44 kW (59 hp; 60 PS) | 599 | U 600 L: Crew cab |
| 421.130 | U40T, U45T, U55T | Cabrio | – | 29 kW (39 hp; 39 PS), 33 kW (44 hp; 45 PS), 40 kW (54 hp; 54 PS) | 6 | OEM part |
| 421.131 | U40T, U45T, U55T | Closed cab | – | 29 kW (39 hp; 39 PS), 33 kW (44 hp; 45 PS), 40 kW (54 hp; 54 PS) | 210 | OEM part |
| 421.132 | U60T, U600T | Cabrio | – | 44 kW (59 hp; 60 PS) | 35 | OEM part |
| 421.133 | U60T, U600T | Closed cab | – | 44 kW (59 hp; 60 PS) | 372 | OEM part |
| 421.140 | U52, U600 | Cabrio | 2,250 mm (88+5⁄8 in) | 38 kW (51 hp; 52 PS) | 1.805 | |
| 421.141 | U52, U600 | Closed cab | 2,250 mm (88+5⁄8 in) | 38 kW (51 hp; 52 PS) | 3.368 | |
| 421.162 | U60 | Cabrio | 2,605 mm (102+1⁄2 in) | 44 kW (59 hp; 60 PS) | 13 | |
| 421.163 | U60 | Closed cab | 2,605 mm (102+1⁄2 in) | 44 kW (59 hp; 60 PS) | 25 | |
| 421.310 | U421 | Cabrio | 2,250 mm (88+5⁄8 in) | 41 kW (55 hp; 56 PS) | 304 | |

### Types made for third party manufacturers

Several Unimog 421 types were custom-made as OEM parts for third party manufacturers.
| Type | Third party manufacturer | Model | Engine power | Number manufactured |
| 421.160 | Hoes | Knickschlepper | | |
| 421.164 | Werner Forst- und Industrietechnik | Uniknick UK52, UK60 | 38 kW (51 hp; 52 PS), 44 kW (59 hp; 60 PS) | 75 |
| 421.170 | Tractortecnic | Unitrac UT45 | 38 kW (51 hp; 52 PS) | 50 |
| 421.172 | Trenkle | Tremo | 38 kW (51 hp; 52 PS) | 250 |

## Technical specifications

| | U 40 | U 45 | U 52 | U 60 |
| Years | 1966–1971 | 1966–1971 | 1970–1988 | 1971–1988 |
| Mass | 2,450 kg (5,400 lb) | 2,470 kg (5,450 lb) | 2,850 kg (6,280 lb) | 2,850 kg (6,280 lb) |
| Permissible maximum mass | 3,700 kg (8,200 lb) | 4,000 kg (8,800 lb) | 4,100 kg (9,000 lb) | ? |
| Length | 4,005 mm (157+11⁄16 in) | 4,005 mm (157+11⁄16 in) | 4,020 mm (158+1⁄4 in) | 4,020 mm (158+1⁄4 in) |
| Width | 1,865 mm (73+7⁄16 in) | 1,865 mm (73+7⁄16 in) | 1,825 mm (71+7⁄8 in) | 1,800 mm (70+7⁄8 in) |
| Height | 2,180 mm (85+13⁄16 in) | 2,180 mm (85+13⁄16 in) | 2,230 mm (87+13⁄16 in) | 2,230 mm (87+13⁄16 in) |
| Wheelbase | 2,250 mm (88+9⁄16 in) | 2,250 mm (88+9⁄16 in) | 2,250 mm (88+9⁄16 in) | 2,605 mm (102+9⁄16 in) |
| Track width | 1,360 mm (53+9⁄16 in) | 1,360 mm (53+9⁄16 in) | 1,400 mm (55+1⁄8 in) | 1,400 mm (55+1⁄8 in) |
| Bed length | 1,475 mm (58+1⁄16 in) | 1,475 mm (58+1⁄16 in) | 1,750 mm (68+7⁄8 in) | 1,750 mm (68+7⁄8 in) |
| Bed width | 1,500 mm (59+1⁄16 in) | 1,500 mm (59+1⁄16 in) | 1,500 mm (59+1⁄16 in) | 1,500 mm (59+1⁄16 in) |
| Bed board wall height | 400 mm (15+3⁄4 in) | 400 mm (15+3⁄4 in) | 400 mm (15+3⁄4 in) | 400 mm (15+3⁄4 in) |
| Tyres | 10,5–18″ 6PR | 10,5–18″ 6PR | 10,5–18″ 6PR | 10,5–18″ 6PR |
| Engine type | OM 621 | OM 615 | OM 616 | OM 616 |
| Engine design | Water-cooled straight-four Diesel engine | Water-cooled straight-four Diesel engine | Water-cooled straight-four Diesel engine | Water-cooled straight-four Diesel engine |
| Fuel system | Precombustion chamber injection | Precombustion chamber injection | Precombustion chamber injection | Precombustion chamber injection |
| Displacement | 1.988 L (121.3 cu in) | 2.197 L (134.1 cu in) | 2.404 L (146.7 cu in) | 2.404 L (146.7 cu in) |
| Bore × Stroke | 87 mm × 83.6 mm (3.43 in × 3.29 in) | 87 mm × 92.4 mm (3.43 in × 3.64 in) | 91 mm × 92.4 mm (3.58 in × 3.64 in) | 91 mm × 92.4 mm (3.58 in × 3.64 in) |
| Rated power (DIN 70020) | 40 PS (29 kW; 39 hp) | 45 PS (33 kW; 44 hp) | 52 PS (38 kW; 51 hp) | 60 PS (44 kW; 59 hp) |
| Top speed | 54 km/h (34 mph) | 53 km/h (33 mph) | 67 km/h (42 mph) | 67 km/h (42 mph) |
| Source | | | | |

## Gallery

* Unimog 421 with closed cab and snorkel
* Unimog 421 with closed cab
* Unimog 421 with closed cab, 1971
* Unimog 421 Cabrio
* OM 616 engine