Brake circuit apparatus for hydraulic motor

Brake circuit apparatus for a hydraulic motor in a hydraulic circuit system including at least one main hydraulic pump, a hydraulic motor driven by a hydraulic fluid supplied from said main pump and having a rotary shaft, and a directional control valve actuated by operation means for control of flow rate and flow direction of the hydraulic fluid supplied to said hydraulic motor from said main hydraulic pump, said hydraulic motor being provided with mechanical brake means having a brake release cylinder adapted to release the rotary shaft of the motor from the braking by the mechanical brake means by supply of a hydraulic fluid to the brake release chamber, wherein:

• said apparatus comprises an auxiliary pump, and control circuit means connected to said auxiliary pump, said brake release cylinder and a reservoir for control of fluid communication therebetween, said control circuit means having a hydraulic fluid supply line for receiving a hydraulic fluid supplied from said auxiliary hydraulic pump, a first line connected between said hydraulic fluid supply line and said brake release cylinder, and a second line connected between said hydraulic fluid supply line and said reservoir, said second line being associated with said directional control valve such that when the control valve is in a neutral position, said hydraulic fluid supply line is brought into communication with said reservoir to thereby disable a hydraulic fluid from said hydraulic fluid supply line from being supplied to said brake release cylinder through said first line, while when said directional control valve is actuated, said communication is interrupted to thereby enable the hydraulic fluid from said hydraulic fluid supply line to be supplied to said brake release cylinder through said first line.