There are several smaller forest machines available in combi versions. That is machines that can be switched between being both harvesters and forwarders. The whole felling operation could be made by one machine. Malwa’s and Terri’s combi machines are based on the forwarders. Vimek has chosen another solution …
Vimek 404 T8 DUO
Vimek choose to use the harvester 404 T8 as the base for their combi machine. The Vimek 404 T8 DUO was presented already at the Elmia Wood show in 2017 and there are now several of them in operation around Sweden. However, there seems to be little information about it on social media, etc. so Torbjörn at the sister-site Skogsforum.se decided to track one down and make an article about it. This is a translation of that article (slightly adapted to an international target group).
A Vimek DUO delivered in December 2022
The machine he found in western Sweden was delivered to the contractor David Nygren by the end of December last year. By the time of the visit in March, the machine had 450 running hours on the meter. David has his own farming- and forestry estate, so some of the logging with the DUO is done there.
But most of the time he counts on working for other forest owners. Already before he bought the DUO several forest owners in line wanted a small machine to do young thinning. Now, that he is up and running with the Vimek DUO system, the rumor has spread, and the line gets longer. David calculates that he will work in the forest 75 percent of his time. The rest he needs for the farming business.
Davis is familiar with forestry and thinning as he used to operate both a John Deere 1070 and a Komatsu 911 in thinning.
Paid by the hour
So far Davis has only done thinning at an hourly rate. 900 SEK (Swedish Krona, approx. 80 USD) per hour for the harvester and 800 SEK (approx. 70 USD) for the forwarding. He keeps track of the cost per cubic meter as well and claims that the harvesting cost is like the cost for a larger harvester in thinning. As for forwarding, the Vimek DUO is approx. 30 percent more expensive compared to a larger forwarder. Thanks to the increased pulpwood prices, not many forest owners seem to see that as a problem.
Some forest owners prefer to forward the wood themselves with their log trailers. That means that the contractor, in this case, David, only does the harvesting. Something that could be a problem if he had both one harvester and one forwarder as the latter then might have to be parked. As David only has one machine, that is no problem.
If you wish to make your own calculation, the price for a Vimek 404 T8 DUO in Sweden is approx. 2,5 million SEK (221 000 USD). To be sure you will have to contact your local dealer. 
Vimek 404 T8 – the DUO version
The base unit of the DUO is almost identical to the harvester 404 T8. There are just a few exceptions:
The DUO has a longer crane than the normal harvester, a Mowi P25 with a reach of 5,2 meters (17 ft), the same as on the Vimek 610 forwarder. The original 404 harvester has a Mowi 2046 harvester crane with a reach of 4,6 meters (15 ft).
Another difference is that the DUO has a power take-off for the transmission of the log trailer and a ball joint for the trailer. Furthermore, it has quick couplings for hydraulic hoses for the brakes and boogies of the log trailer and controls in the cabin for both harvester and forwarder functions. 
Apart from this, it’s a similar machine to the normal 404 harvesters. David chose the band-fed Keto Supreme V4-head for his machine. It’s possible to upgrade to a Keto Xtreme head and for those who want feed rollers instead of band feeding Nisula 325H is also an option.
David’s DUO is equipped with 500-tires which gives a width of 2,05 meters (6,7 ft). If 400-tires are chosen the width is 1,8 meters (5,9 ft). However, the 500-tire option is the most common.
The base unit weighs 4,7 tons according to Vimek. The weight of tire chains and fluid in the tires under the crane should be added to that. 
The base unit/harvester has a double steering function. Waist steering plus normal steering on the wheels under the crane. This gives the machine extreme maneuverability. 
A long forwarder
It’s as a forwarder the DUO stands out compared to the competitors. A log trailer is attached to the base unit/harvester. The trailer has boogies and a roller drive that is powered by the power take-off. Altogether, this makes the machine an 8WD forwarder.
The log trailer is equipped with brakes, but it has no frame steering. The trailer is basically the same as on the Vimek 610 forwarder but this one is a little wider and has a larger loading area. According to Vimek, the loading capacity is 5,5 tons. There is no information about the weight of the log trailer. 
Longer than the competition
The total length of the DUO as forwarder is 9,25 meters (30,3 ft). It’s in other words much longer than for example the Malwa forwarder which is 6,3 (20,7 ft) meters or the extended Terri forwarder which is 7,8 meters (25,6 ft). The forwarder mode of the DUO is more comparable in length to a tractor and log trailer. But only in length …
Despite the long length, the 404 T8 DUO is a surprisingly smooth and maneuverable forwarder. This is thanks to the double steering of the base unit, especially the steering of the wheels under the crane. David claims that this steering reacts much faster than a frame steering on the trailer. The double steering makes it possible for the trailer to follow the base unit smoothly in bends. 
The Vimek 404 T8 DUO is delivered with a tiltable grapple for forwarding. This grapple makes it easier to handle long logs without damaging standing trees in thinning.
David normally reverses along the strip roads but says that the machine can be driven in both directions as a forwarder just as easily. 
Both in the strip roads and between
The work methodology with Vimek DUO is the same as with the normal Vimek harvester. The harvester works both in and between the strip roads and makes sure the wood piles end up within reach of the strip roads. The forwarder then operates only on the strip roads.
This method assures that the distance between the strip roads could be large enough despite the short harvester crane. If the harvester makes two strokes between the strip roads, David claims he can reach a strip road distance of 30 meters (98 ft). In rocky terrain, it’s however difficult to keep such a long distance.
Forest owners do the forwarding themselves
Several of David’s clients are self-employed forest owners who prefer to do the forwarding themselves. It’s common for forest owners to have a log trailer and log loader for their tractors and find it amusing to do some forwarding occasionally. On the other hand, they often hand the harvesting to someone else, like David and his Vimek DUO.
In those cases, the DUO concept is suitable as it is only one machine. If it had been a normal harvester group, with one harvester one forwarder, and two operators the forwarder would have to be parked during such an assignment and the operator would be unemployed. With the DUO system, only the log trailer must be parked which it anyway is during harvesting. The “vacation” for the trailer will just be longer than normal and money will roll in through the harvester instead.
Easy to move
Even though the DUO concept contains more items than e.g., the corresponding Malwa- and Terri machines, it’s easy to move between sites. According to Vimek, many customers get a hook lift bed for transport. If the trailer is rolled on first, the harvester fits just behind it, and “everything” is loaded on the bed ready to go to the next site. All you need is a hook lift truck.
David has solved this problem with help of a friend who has a small truck. The harvester is loaded onto the truck and the trailer is attached behind with the drive rollers deactivated.
The switch between harvester and forwarder
The method is simple. First, the harvesting is done, then the machine is transformed into a forwarder and the job continues until it’s done. The switch takes about 30 minutes and is normally done only once for each site. If there is more than one site within short distances, David normally harvests all sites before he transforms the machine into a forwarder.
A number of solutions such as quick couplings make the switch simple. Vimek has prioritized simplicity and the environment in the design. No oil should be wasted, and the switch can be done with just a few simple tools. 
Satisfied but …
David is very satisfied with his Vimek 404 T8 DUO. The concept suits both him and his customers well. The only thing he’s missing is a crane tilt function. He often operates in slopes and that would be easier if there was a crane tilt on the machine, especially during harvesting.
Something for Vimek to consider?
“Swiss army knife”
The idea of the DUO system reminds me a bit of a Swiss army knife – a multi-tool that can do “everything”. Vimek offers a variety of equipment to the 404 harvesters: the clearing head C12, the felling head FG50, a grapple shovel, and a grapple for slash handling.
The DUO quick coupling system, combined with some attachments (or all of them), is probably a good tool for a versatile contractor or a private forest owner.
Photos: Torbjörn Johnsen
