Emergency brake control for hoists

A method of controlling the operation of an emergency brake and a drive means for a hoist conveyance, comprising:

• generating a first signal indicative of ascent or descent of said conveyance;
• generating a second signal indicative of the presence or absence of an emergency condition, including any of over-speed, over-travel, or manual emergency stop, requiring the emergency stopping of the conveyance;
• when said first signal indicates descent and said second signal indicates the occurrence of said emergency condition, applying said brakes immediately;
• and
• when said first signal indicates ascent and said second signal indicates over-speed or manual emergency stop signal, deenergizing said conveyance drive means and allowing said conveyance to coast to a stop, thereupon applying said brake.

A control system for a hoist having a conveyance, a brake for stopping said conveyance, and a drive means for selectively moving said conveyance upwardly and downwardly, said control system being operative to control the operation of said brake and said drive means in response to the direction of motion of said conveyance and the existence of an emergency situation, comprising:

• first means for indicating the direction of motion of said conveyance;
• second means for indicating the presence of an emergency situation;
• control means for immediately actuating said braking means responsive to the first means when it indicates descent of conveyance, and responsive to the second means when it simultaneously indicates the presence of an emergency situation;
• said control means additionally deenergizing said conveyance drive means and permitting said conveyance to coast to a stop, and thereupon actuating said braking means responsive to said first means when it indicates ascent of said conveyance, and when said second means simultaneously indicates an emergency condition.

In a hoisting system of the type including a rotating drum, a conveyance, a cable attaching the conveyance to the drum, driving means for driving said drum, and an emergency braking means for stopping the motor;

• the improvement comprising an emergency brake control system for controlling said emergency braking means responsive to the direction of motion of said conveyance, including:
• means for generating a first signal indicative of the direction of motion of said conveyance;
• means for deenergizing said driving means and automatically generating a second signal in the event of an emergency situation;
• and
• control circuit means responsive to said first and second signals, when said signals are respectively indicative of descending motion and an emergency situation, for immediately actuating said braking means;
• said control circuit means additionally being responsive to said first and second signals, when said signals are respectively indicative of ascending motion and an emergency situation, for actuating said braking means after said driving means has been deenergized and when said first signal generating means indicates that the ascending conveyance has coated to a halt.