For off-road ability and high speed agricultural transport there is little to challenge a Unimog, but manufacturer Mercedes-Benz is keen to promote its ability to perform a multitude of other farm tasks too. David Williams tried out the latest models.
“The best way to look at the Unimog is that it’s a commercial transport vehicle which can also perform tractor tasks,” explained Mercedes-Benz area sales manager for southern England, Michael Bateman. “It’s not going to be the first choice for heavy cultivations, but if an additional tractor is needed in busy periods, it can be called in to get the work done.”
Mercedes-Benz sees considerable potential to increase sales of the Unimog to agricultural users and a demonstration day at its commercial vehicle UK headquarters allowed current and prospective users and their dealers the opportunity to try out the latest models in a variety of work situations from off-roading to pulling agricultural and commercial trailers, and grass harvesting to cultivations.
“The Unimog’s strength is its ability to travel across terrain impassable by other vehicles, and to carry and tow heavy loads fast and safely. It’s incredibly fuel efficient, almost totally reliable and has resale values much better than commercial vehicles or tractors, making it an extremely competitive package to own and run,” Michael added.
Kent contractor view
Most Unimogs produced since the concept was launched in 1951 remain in use, which doesn’t surprise Sevenoaks, Kent-based contractor Peter Duke. His U1600 High Power has worked almost 15,000 hours and remains almost totally reliable having suffered no major breakdowns. “I had used other Unimogs previously and was always impressed by their ability,” said Peter whose contracting business is mainly agricultural spraying but also includes other general farm field tasks within 30 miles of Sevenoaks. “We use the Unimog as a pick-up truck to move the team around, to transport equipment and to move the spray bowsers. We are this Unimog’s second owners and have had it for four years.
“Main dealer Arthur Ibbett looks after us exceptionally well when we need anything, and the team there is very efficient and always helpful. Fuel consumption is surprisingly low, it’s safe and easy to use and we have it available as a back-up for cultivations too when needed. It handles our trailed equipment easily, including a 6.5m Vaderstad Carrier cultivator and we use it for tasks such as rolling. A conventional tractor is more capable in the field as it gets the power to the ground more efficiently, but the Unimog will do it and that is one of the reasons we like it.”
Peter was at the demonstration day to compare the latest models and see how the range is developing. “I have been concerned in recent years that the priority has been towards special applications and commercial haulage so wanted to find out what has been done to improve their suitability for farming. It’s reassuring to see the company focussing on agricultural use again and that recent developments in terms of specification and options available reflect this.
“Ours is popular with our team and customers like it too. When we travel on the road it tends to receive a more positive reaction from other road users than our tractors, which is another advantage.”
Engine and transmission
The current range includes models from 156–299hp, and payload capacity up to 25t depending on model. There are two basic vehicle types including an implement carrier designed to accommodate hydraulics and PTO, and an extreme off-road version which is more basic, but provides increased mobility in extreme situations.
Transmission options include a manual 8-speed, with button-selected high and low ranges and a crawler option reduces speed to 4.5kph maximum in 8th gear. Automatic shifting is an option and for added flexibility hydrostatic drive is available. This allows the user to switch drive to the clutch and transmission from the engine to an oil-driven motor. Stepless speed control from 0–45kph is available in hydrostatic mode and standard direct drive from the engine is resumed at the touch of a button allowing conventional operation. Return to mechanical drive also resumes immediately if the accelerator pedal is depressed quickly, for faster acceleration.
Permanent 4wd is standard, with traction assistance through three differential locks.
Portal axles provide ground clearance greater than most tractors, allowing the Unimog to carry out tasks such as crop spraying, and baling.
Air brakes with ABS are standard, and engine exhaust braking is also provided, selected by pulling back the right hand control stick beside the steering wheel, and includes three levels of braking aggression.
Built-in tyre inflation is a popular option with agricultural users allowing tyres to be inflated to carry heavy loads at high speeds during road travel, then to be dropped for low speed field work on arrival at the work site, maximising grip and reducing ground damage.
Speed control is by foot pedal or joystick and the user can swap between the two in work, and set and maintain constant speeds through a standard cruise control.
Precision farming options are available from after-market suppliers including the main brands, but not currently direct from the manufacturer.
Front PTO is standard and rear PTO is an option, along with front and rear hydraulic linkage. Hydraulic service options include load-sensing systems with up to 110-litres/min flow rate and 40 bar pressure.
Currently one in six UK users opt for rear hydraulic linkage, but most have a rear PTO as the Unimog lends itself well to tasks involving trailed implements such as slurry applicators, sprayers and spreaders.
Another popular option specified on almost all Unimogs is VarioPilot. This allows the steering wheel, instruments and pedals to be swapped for right- or left-hand drive in under a minute. For tasks such as verge or hedge cutting it allows the user an excellent view of the cutter head on the left, but ensures maximum visibility on the road with the controls back on the right. It’s also popular for harvest transport operations as, seated on the left, trailer filling progress is monitored easily at a glance, over the driver’s right shoulder.
A further benefit is improved residual value as VarioPilot makes the machine equally suited to use in the UK and abroad.
The cab layout is similar to a truck, with two seats standard and the option for a second passenger seat. There is plenty of space and legroom is generous with the driver’s seat fully back. Visibility all around is very good, and there has been no skimping on mirrors. Optional cameras can be added to further improve work monitoring or safety during manoeuvring, and they can be easily repositioned thanks to their magnetic bases.
Fuel consumption claims include considerably better economy than tractors or conventional commercial vehicles. Recent comparison tests in the UK demonstrated fuel consumption of 11.5mpg unladen and 7.4mpg with a 36t train weight, pulling a twin-axle trailer around a route consisting of public roads and tracks. For a user covering 32,000 miles annually this suggests potential fuel savings of £21,650 available, compared to conventional high-speed tractors, said the company.
East Yorkshire-based South Cave Tractors Ltd Unimog sales specialist Ben Middleton was at the demonstration day and he explained that demand for agricultural applications is growing. “It’s mainly for logistics tasks, such as transporting harvested crops from the field and delivering seed, fertiliser and water bowsers,” he said. “AD plants have created increased interest including transport of silage and digestate and users like the Unimog concept for the added efficiency resulting from faster travel speeds, and its extra safety. Cultivations aren’t a primary use but often rear linkage is specified so the Unimog can replace tractors if needed. They are reliable and economical, saving up to a third in diesel costs, and ideal for many tasks carried out by farmers and contractors.”
Notts farmers’ view
South Cave customer and Unimog user Tom Hawthorne runs Flawborough Farms in Nottinghamshire with his sister Tabs and their parents John and Emma. The 2,200ha arable farming business has operated Unimogs since 1980 and the current U500 model was purchased as an ex-demonstrator in 2008. Unimogs were selected primarily for their agri-logistics ability and a mixer bowser is mounted on the rear bed to supply two sprayers with pre-mixed agro-chemicals and liquid fertiliser. Tank capacity is matched to the sprayers so each tank fills one sprayer, with liquid transferred through high capacity pumps. Using the Unimog as a mobile bowser allows each sprayer to achieve an additional 100ha/day, according to Tom.
With the success of the spray bowser concept, Tom worked with a local engineering company to design and construct a Unimog-based filling system to keep the farm’s 12m drill supplied with the 3t of seed and 2,000 litres of liquid fertiliser it needs each hour. “Logistics is key to keeping the drill working efficiently, and the Unimog fits that role perfectly,” he said.
In the summer the Unimog assists with grain carting from the field, supplementing commercial trucks. Tom explained that using the Unimog allows the farm to maintain closer compliance with transport regulations than when tractors and trailers are used. The Unimog also moves a mobile workshop and service trailer between machines each morning during harvest.
Current use amounts to approximately 800 hours each year, but Tom said he envisages this increasing in the future. Benefits of using the Unimog over other transport vehicles include the ability to meet transport regulations, the versatile load platform, very low depreciation costs, long service intervals and reliability. Very low fuel use is also highlighted as an advantage, as is the back-up and product knowledge from Tony Levett and the rest of the South Cave team.
The demonstration day provided an opportunity to operate Unimogs on- and off-road and with implements including mowers, rakes, forage wagons and a large cultivator. The off-road course included deeply rutted tracks which would have been impassable to any conventional 4×4, and deep water to prove the vehicles’ 1.2m fording capability.
Access to the cab is good, with large steps and decent grab handles on both sides of the door. The air-suspended seat is firm but comfortable with plenty of adjustment for legroom. The steering wheel and column-mounted controls also adjust to suit the driver.
Controls are well laid out and suitably chunky, making them easy to operate, even at speed on very bumpy ground, and the dashboard features large dials which are easy to read at a glance.
The 4- and 6-cylinder engines provide copious amounts of torque, making it easy to operate at any speed and pull away with heavy loads. Gears offer lots of overlap and the Unimog was easily capable of negotiating the deep ruts and slippery slopes of the off-road course with the engine at an idle, allowing the driver to ‘feel’ his way around tricky sections at low travel speeds and under full control.
Descending steeper slopes was made easier by the effective exhaust brake. This has three settings from gentle to firm retardation and, by pulling back on the stalk to the right of the steering column the exhaust brake could be set and left operative until it was no longer needed, allowing the driver to keep both hands on the steering wheel.
An on-road test track demonstrated the exhaust brake’s effectiveness at higher speeds and with heavily loaded trailers, as progressive deceleration was achieved without aggressive use of the foot brake, saving wear and tear.
In the field
There was also the opportunity to test the Unimog in the field with a wide range of farm implements. Visibility all-around was excellent, including down to the front tines of the cultivator or the baler pick-up, making it easy to monitor the implement and react quickly when needed.
Working conditions were good, but an Amazone Cenius 4m cultivator provided a fair test of the Unimog’s draft and traction capability. The 300hp U530 coped easily, with minimal wheelslip and plenty of power, even with the tines working deep.
There was little grass for the large Kuhn GA13131 4-rotor rake, but it allowed operators to try out hydrostatic drive, and to compare it to standard mechanical mode. The Unimog’s rear PTO is hydraulic-driven from the vehicle’s supply and rated to 120hp. Because it is hydraulic-driven, rather than direct-coupled to the engine and transmission, the operator has only to set adequate engine revs to achieve the minimum oil flow requirement. Even when the engine speed is altered during travel, the PTO speed remains constant.
In hydrostatic transmission mode, infinite speed adjustment allowed travel speed to be ideally matched to the operating conditions, whereas in mechanical drive mode speed was adjusted in steps through the gears with fine adjustment by engine revs, but in either mode the rake rotor speed remained constant.
Unimogs offer big advantages for those with long distances to travel between work areas and whose business relies on efficient logistics, such as keeping drills, sprayers and spreaders supplied in the field. They offer greater on-road comfort than most tractors, but less than conventional commercial vehicles where their heavy-duty suspension provides a somewhat firmer ride. But where a commercial vehicle stops at the field gateway and relies on tractors to take over, the Unimog offers an all-in-one, on- and off-road solution, capable of travelling across muddy work areas with the trailer behind.
Mercedes-Benz is keen to eat into the market share currently occupied by high-speed tractors for farm transport and the Unimog’s ability to carry out occasional field tasks during a busy drilling season will help those considering their first purchase to justify the investment.
Current agricultural users interviewed by Farmers Guide back up the manufacturer’s argument that significant fuel and time-savings can be achieved, and with growing attention to on-road safety and compliance with transport regulations, the Unimog offers reassurance and advantages.
A reputation for superb reliability, low running costs and strong resale values means that for many larger farms and contracting businesses, where time spent on transport tasks is considerable, swapping one tractor on the fleet for a Unimog might provide a solution.