Locking system for a working machine

A working machine comprising:

• a working arm for mounting attachments thereto;
• and
• a locking system for securing an attachment to a working arm of a working machine, the locking system comprising:
• a latch member movable between an engaged position, where the attachment is secured to said working arm, and a disengaged position, where the attachment can be removed from said working arm;
• and
• a hydraulic circuit configured to lock the latch member in the engaged position;
• wherein the hydraulic circuit comprises a lock configured to open when the circuit reaches a predetermined pressure such that the latch member is released from the engaged position;
• a relief valve configured to activate below the predetermined pressure, such that the lock remains closed in normal operation;
• and
• an isolation arrangement configured to selectively isolate the relief valve from the circuit upon an operator input, to enable the circuit to reach the predetermined pressure such that the latch member is released.

A method of disengaging a latch member of a locking system for securing an attachment to a working arm of a working machine, the locking system comprising:

• a latch member movable between an engaged position, where the attachment is secured to said working arm, and a disengaged position, where the attachment can be removed from said working arm;
• and a hydraulic circuit configured to lock the latch member in the engaged position;
• wherein the hydraulic circuit comprises a lock configured to open when the circuit reaches a predetermined pressure such that the latch member is released from the engaged position;
• a relief valve configured to activate below the predetermined pressure, such that the lock remains closed in normal operation;
• and an isolation arrangement configured to selectively isolate the relief valve from the circuit upon an operator input, to enable the circuit to reach the predetermined pressure such that the latch member is released, the method comprising the steps of:
• a) isolating the relief valve from the circuit;
• and
• b) moving the latch member to a disengaged position.