In the forest of south Sweden, you will find the machine manufacturer Hypro. They have gained a good reputation in making processors and log-loaders for tractors. It´s a family business that we have written about before. Now, as they present a new type of drive for their largest processor model, the carrier mounted version of the 755 HB, we had to hit the forest to have a look. 
Photo: Per Jonsson
Get a grip – uphill is always a challenge
So far, the carrier mounted 755 HB has not had the option of drive on the carrier. The tractor had to do all the pulling and pushing. Now, however, the requested option is here. A new construction, it´s as simple as it is genius.
We revisited the forest owner and contractor Ronny Johansson. He is test- and demo operator for Hypro and all new products needs his approvement before entering the market.
Ronny experienced some problems when pushing the carrier uphill behind the tractor, especially on stony ground. When the carrier hit a stone there was a risk that the machine folded like a pocketknife because of the pushing force from the tractor. If the carrier could just have a little driving force, it would help a lot.
G-Drive and Hub-Drive – the two options
Hypro decided to have a look at this and came up with two different solutions: The G-Drive, that is presented in this article and in the film below. A simple gear drive that is meant to be used only when necessary. The Hub-Drive does the same thing but in this case one hydraulic motor is mounted directly on each wheel of the carrier.
G-Drive stands for gear drive, and that is exactly what it is. One open gear wheel is mounted on the wheel shaft. Open, so that dirt won´t fill the gap between the teeth and affect the grip. Another, smaller gear wheel is mounted on an arm that can move up and down. The smaller wheel is driven by a hydraulic motor, and the movement is controlled by a hydraulic cylinder. The cylinder pushes the smaller wheel on to the big wheel and creates a driving force. The operator decides when it´s needed. On flat terrain, downhill or when the machine stands still for processing trees, the system is disconnected.
Photo: Per Jonsson
Photo: Hypro
Uphill – no problems anymore
Ronny has been using the G-Drive for some time now and claims the difference is big. When driving into a single stone without the G-Drive, it could be like hitting a wall. With the G-Drive, the wheel climbs up on, and over the stone very easily. It takes very little driving force to make a difference. The G-Drive is exactly what was needed. Simple, reliable and efficient.
Hypro have already sold several new 755 HB processors with the G-Drive. Also, older 755 processors can be updated with the G-Drive, so you don´t have to buy a completely new processor just to get this function.
Film and more info
Find out more about Hypro’s processors and their whole range here.
And here is a short film from our visit in the forest:
