Apparatus for controlled cutting down of trees

Claim 1

Apparatus for cutting down trees in a controlled manner, comprising: a base having an elongate anvil projecting therefrom, a cutter bar on the base opposed to the anvil and mounted for movement towards and away from said anvil, a saw chain operatively mounted on the cutter bar for cutting action thereon, a hydraulic motor carried by the base and operatively connected to the saw chain to move said chain in the cutting action, a first hydraulic circuit comprising said motor, a pump and a first pressure line between the pump and the motor, a hydraulic cylinder connected between the base and the cutter bar for moving said bar forward towards the anvil during the cutting action of the saw chain and away from the anvil, a second hydraulic circuit comprising said cylinder, a pump and a second pressure line between the cylinder and the pump, a by-pass valve separate from said second pressure line and connected thereto and operable during movement of the cutter bar and saw chain towards the anvil to selectively direct hydrauic fluid from the second circuit without restricting the flow of fluid through said second circuit, operating means for the valve to control the flow of fluid from the second pressure line between zero and sufficient to stop the hydraulic cylinder, and a third line from the first pressure line to said valve operating means to increase and decrease the flow of fluid through the by-pass valve in accordance with increases and decreases respectively in the pressure of fluid in said first line to control the pressure inversely in the feed line of the cylinder, whereby the rate of movement of the cutter bar with the saw chain is controlled by the load on the saw chain during the cutting action thereof.