The present invention relates to an improvement in wood chippers or vegetation grinders, herein referred to as wood chippers for convenience.

Wood chippers are used on site to grind, cut or crush vegetation, particularly trees, into small manageable chunks or chips which are much easier to transport away from the site than trees themselves. Such devices are usually mounted on a trailer and comprise a first or in- feed chute, one or more feed rollers, cutting or crushing means, motor means to drive the cutting means and the rollers, and a second chute out of which the chips are expelled, and control means.

There are several possible configurations for the feed rollers, which may include one or more horizontal rollers and/or one or more vertical rollers, each of which may be either fixed or movable along the vertical or horizontal axis. The direction of rotation of the rollers is controlled by a direction control bar which allows the rollers to be controlled so that they feed material into or out of the throat of the wood chipper.

To further describe the operation of current wood chippers it is sufficient to consider a wood chipper which has a pair of feed rollers one of which is a fixed bottom roller and the other of which is a movable top roller, which rests initially, just above the bottom roller.

In operation, the operator uses a direction control bar to cause the rollers to rotate in the infeed direction as branches are presented to the feed rollers. If the branches are small enough, the feed rollers will engage the material which is presented to them and feed it into the cutting area of the machine. Once the rollers

have engaged material, the top feed roller will rise and the gap between the rollers will widen allowing the rollers to engage material of a larger diameter. The operator will often have the machine accept larger diameter material by initially presenting it with small diameter material to cause the top feed rollers to rise and then presenting it with larger diameter material whilst the gap between the rollers is wider.

When the material is oversize and the rollers won't engage it, we provide a lift bar, which is typically located on the top of the chute, and by pulling the bar towards the opening of the chute the operator causes the top feed roller to rise and the gap between the rollers and/or the bed plate to widen or open. Once in position, the operator releases the lift bar allowing the top feed roller to lower onto the branch, thus engaging it and feeding it into the cutting area of the machine. Typically the top feed roller may be resiliently biased by one or more springs which operate to force the top feed roller down onto the material being fed into the machine, thus enhancing the engagement of the rollers.

The problem with prior art wood chippers is that if the operator is handling a large branch or tree trunk, he may require both hands in order to manipulate the branch into position. If the operator does not have assistance he may either not be able to operate the machine efficiently or may injure himself by trying to hold a large branch with one hand or by catching his hand in the branch and having it dragged with the branch into the rollers.

Once the feed rollers have taken hold of the material it is difficult if not impossible for the operator to stop this ingress. If he becomes caught by the material he can only stop and reverse the feed rollers by pushing the direction control bar located around the outer edge of the infeed chute. This bar could be difficult to reach, particularly if the operator is caught on his glove or gloves by the material being fed into the machine.

Also when feeding short, medium to large diameter material, the prior art engagement of the feed wheel often caused the material to flick up with great speed and power potentially crushing the operator's hand between the wood and the infeed chute.

Furthermore, the strength of the springs used to provide the resilient bias on the top-feed roller is restricted for convenient operation to that which can readily be forced apart by the presentation of thin materials. If the strength of the springs can be increased the crushing power on side limbs and branches that the top feed roller engages is much higher giving improved infeed performance.

It is hence an object of the present invention to provide means which allow the operator of a wood chipper to raise and lower the top roller without using his or her hands and/or be able to raise and lower the top roller from either side of the machine.

It is a further object that the operator be able to provide control means which allow the operator to raise the top roller if he is entangled in the material being fed to the wood chipper.

It is another object that the resilient bias

applied to a top-feed roller of this kind, be capable, if desired, of providing a greater engagement force than current wood-chippers.

Accordingly, there is provided by the present invention, a wood chipper having at least one feed roller which in use operates to feed material into a cutting area of said wood chipper, characterized by control means so arranged on said chipper as to enable an operator to disengage said feed roller by the application of pressure on a control bar at or adjacent an infeed chute of said chipper and/or by pressure on a lift bar accessible from the front or either side of said chute, thereby preventing the feeding of material to the cutting area.

Preferably, said one or more infeed rollers includes a top feed roller, said control means being so arranged as to enable an operator to raise or lower said top feed roller.

The leg actuated control bar of the present invention allows the operator to lift the top feed roller by pressing his knee or leg against the knee control bar thereby allowing him to maintain a two-handed grip on the large branch he wishes to feed into the mouth of the wood chipper or to throw short stout material into the throat of the chipper, or to push bulky tangled material into the throat of the chipper. When the operator removes his or her leg the top roller will lower due to gravity and the action of springs which act as a resilient bias means and feed the branch into the cutting area of the machine. A further advantage of this invention is that if, for example the operator's hand becomes trapped or caught by a branch which the rollers are feeding into the machine, he is able to lift the top roller and stop it from feeding the branch into the machine by applying pressure with his leg to the knee control bar. When the roller disengages the operator

is able to extricate himself from his entanglement.

The hand operated control bar, hereinafter referred to as the lift bar allows the operator to raise and lower the top feed roller by pulling the bar towards the opening of the chute if the operator is in the area of the feed opening, or by lifting a short handle bar affixed to each of a pair of vertical side arms of said lift bar if the operator is at the side of the chipper. The combination of the arrangement of the lift bar and the leg actuated control bar enable a single operator to disengage the feed rollers without the danger of his hand becoming entangled in material being fed into the machine.

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which:

Fig. 1 shows a prior art wood chipper; Fig. 2 is a rear elevational view of the wood chipper; Fig. 3 is a left hand side view of the top in-feed roller lift and crush linkage; and

Fig. 4 is a right hand side view of the top in-feed roller lift and crush cable linkage to the hydraulic direction control valve;

Figure 1 shows a conventional wood chipper which includes a trailer 20, a first or infeed chute 21, a second or output chute 22, a motor 23, a cutting and crushing portion 24 which is hidden by the machine casing, and a direction control bar 36. The direction control bar 36 of the current machine is used to control the rotation direction of the rollers and extends around the top and sides of the infeed chute 21. Lift bar 7 is used to raise and lower the top feed roller which is resiliently biased by springs 40.

Turning now to Figures 2 to 4 which illustrate

the present invention.

Fig 2 shows the rear of a wood chipper, having a chute 31 which narrows to a throat 32 in which are housed a top feed roller 16 and in some models a bottom feed roller 17. There may also be provided additional rollers such as, for example vertical rollers. The top infeed roller is moveable along the path indicated by arrow 34 of Fig 3. This movement is achieved by riding on top of the material being fed and by the operation of hydraulic cylinder 15 which is mounted on frame 35.

The lift bar is a substantially inverted "U" shaped member having a horizontal bar 7 extending across the top of the machine and a pair of short substantially vertical side members pivotally mounted at 9 to vertical warning light posts 8 affixed to each side of said chipper. Each short vertical side member comprises a short handle bar 9a welded or otherwise securely affixed thereto thus permitting an operator to activate the hydraulic cylinder 15 from either side of the machine.

The top feed roller 16 may be lifted by pulling lift bar 7 from the front opening of the machine or by lifting either of the handle bars 9a from the sides of the machine. A integral link 7b is connected by rod end connector 10 to the inner of a cable 11 which has a captured outer. The other inner end of cable 11 is connected to a hydraulic valve 12 which activates the hydraulic cylinder 15 allowing it to raise or lower the top feed roller 16. When the top feed roller is raised it allows branches to be fed into the throat 32. When the lift bar 7 is subsequently released, the top feed roller 16 lowers onto the material to be fed into the wood chipper, and by its rotation feeds the material into the cutting area of the wood chipper.

The top feed roller 16 is also capable of being

lifted by a knee control bar 1 which may be pushed by the leg of the operator whilst a branch or the like is being supported by the hands of the operator. This bar is connected integrally with link 2 pivoting on pivot point 3 and actuates via rod end connection 4 an adjustable connecting rod 5, the top end of which 6 is connected to an integral link 7a on bar 7 which pivots on pivot point 9. A link 7b also connects with rod end connector 10 that joins this link with the inner of a cable 11 which has a captured outer. The other inner end of cable 11 is connected to a hydraulic valve 12. This valve 12 when activated in the lift direction allows hydraulic fluid to enter the hydraulic cylinder 15 causing this cylinder which supports the top feed roller 16 to rise. When the top feed roller is in the raised position the operator can feed large branches into the throat of the chipper or alternatively throw chunks of wood, which typically are not engaged efficiently by the rollers, directly into the cutting area of the wood chipper.

If the operator becomes entangled in the material he is feeding into the machine, he can press his leg against the knee control bar 1 which operates through the series of links to raise the top feed roller 16. When the roller is raised it no longer engages the material and the operator is able to drag the material out of the throat and extricate himself from his entanglement.

Knee control bar 1 also allows the strength of the springs used as a resilient bias means to be increased if desired, because the operator may easily raise the top feed roller 16 by using the knee control bar.

When the knee control bar 1 is released, the top feed roller 16 lowers due to gravity and due to the resilient bias provided by springs 40 and 41 (not shown) and engages the material fed into the machine. The springs

ensure that the top feed roller engages the material and doesn't rotate ineffectually.

It is also possible to move the knee control or the lift bar in the opposite direction to that required to lift the top feed roller 16 in order to increase the engagement of the rollers with the material being fed into the wood chipper.

When the wood chipper is feeding material into the wood chipper, the rollers rotate in order to drag the material into the machine. When viewed from the right hand side as in Fig. 4, the bottom infeed roller 17 rotates clockwise and the top infeed roller 16 rotates anti- clockwise. The operator is able to change the direction or stop the rotation of the rollers by operating direction control bar 36.

It will thus be seen that the present invention provides for the control of the space between the feed rollers whilst leaving the hands of the operator free to manipulate the feeding of material into the machine.