Patent ID: 7621112

Claim:
A hydraulic rotary forestry machine, comprising a forestry vehicle including a hydraulic pump and hydraulic controls; a cutting apparatus hydraulically operated via hydraulic fluid from the hydraulic pump of the vehicle and including: a hydraulic motor operable to drive a rotor in a first direction and including a motor inlet and motor outlet; a cutting tool mounted on the rotor; a fluid circuit comprising at least one fluid supply line operable to supply hydraulic fluid to the hydraulic motor, and at least one fluid return line operable to return fluid from the hydraulic motor to a tank; and a hydraulic brake comprising: a counterbalance valve arranged in the fluid return line, wherein the counterbalance valve is operable to pressurize fluid at the motor outlet to a predetermined pressure level of between about 2000 psi and about 4000 psi when a flow of hydraulic fluid from the pump to the motor is discontinued, and wherein the counterbalance valve includes a pilot port hydraulically connected to the motor inlet, a valve port hydraulically connected to the tank and configured for supply of hydraulic fluid to the tank during operation of the motor, and a load port hydraulically connected to the motor outlet; and at least one valve hydraulically connected to the valve port and operable to direct the flow of fluid from the fluid return line to the at least one fluid supply line when the supply of hydraulic fluid from the pump to the motor is discontinued; wherein the hydraulic controls are operable to selectively supply hydraulic fluid to the at least one fluid supply line from the pump.