ABSTRACT
The use of mobile woodchippers has gradually increased over the last ten years, and they are now widely used by arboriculturalists and conservation and landscaping contractors to convert unwanted wood and brush into woodchips for mulch. They are typically used at roadsides and in parks and gardens by local authorities and arboricultural businesses. It is estimated that there may be around 10000 in the UK. A mobile wood chipper is a trailer mounted machine consisting of a feed chute or hopper into which wood and brush
is fed. At the neck of the hopper are either one or two infeed rollers. These grip the material and draw it in against a fast spinning chipping blade(s). The cutting blades are usually powered by a diesel engine with the infeed roller(s) powered hydraulically. A typical pulling force has been calculated as 370 kg force, with quoted feed rates of 46 metres/minute (760mm/sec). The chipped material is blown out of a directable chute, usually into the back of a truck for removal. These machines are capable of chipping wood of around 230 mm in diameter. The operation of the wood chipper is usually controlled by a control bar which also acts as a safety device. The typical design has the bar extending around the sides and top of the front edge of the hopper and Pivoting at the base. The action of the feed rollers is controlled by the position of this bar, it having several positions for stop, feed, and reverse functions. The engine is usually controlled by other means as well as an emergency stop switch.
