vertical feed rollers vs horizontal

[Rowden the cowboy]

just noticed that whilst the park range of tp chippers have horizontal feed rollers the forest range have vertical feed rollers. Why is this? What does it gain? Why are vertical feed rollers not normally available on domestic chippers?

[PeteB]

GreenMech started putting the vertical feed rollers on the Quad Chip over a year ago and with the geometry of blades and shear bars and the size of the infeed opening it makes feeding straight lengths of timber a lot easier and vibration free. When feeding brash into the QuadChip, the geometry of the vertical rollers can give greater crushing power and feed grip. This design could migrate onto other models as development goes on.

 

Horizontal feed rollers are easier to design and produce especially if you have a letterbox opening. But the downside is that the timber has more room to thrash about.

 

Turner/Gandini chippers from the 1980's had vertical rollers, some American made machines have vertical rollers, "extreme" forestry chippers have both horizontal and vertical.

 

With horizontal rollers, grip is also assisted by gravity and the weight of the roller. Vertical rollers require thought and ingenuity to get crushing power which, maybe, some designers see as a "development cost" and not a "customer benefit".