Control system for booster type belt conveyor

In a booster type belt conveyor, a conveyor belt having conveying and return runs trained for orbital movement between driving and return end drums located respectively at head and tail ends of the belt conveyor, one or more intermediate booster belts having driving and return runs trained for orbital movement between driving and return end drums with the driving run of each booster belt in driving engagement with the conveying run, and a drum driving unit including electrical motor means for each driving drum, and improved electrical starting and control system comprising:

• engageable and disengageable coupling means in each drum driving unit between the corresponding motor means and driving drum;
• a plurality of control assemblies, one for each drum driving unit;
• means in each control assembly for sensing a running condition of the corresponding motor means and generating a running condition signal in response thereto;
• means for sequentially starting all of said motor means including means for starting a first one of said motor means and automatic means in said control assemblies for starting each of the remainder of said motor means in response to a running condition signal from a previously started motor means;
• a coupling-controlling electrical loop common to all of said control assemblies;
• a plurality of electrically energizable, coupling-actuating means in the loop, one in each said control assembly, each effective when energized to engage the corresponding coupling means;
• means responsive to said running condition signal from the last of said motor means started, to connect said electrical loop to an electrical power source and thereby condition said loop to engage all of said couplings;
• and
• a plurality of safety switch means in the loop, one in each said control assembly, each capable of responding to detection of an electrical or mechanical defect associated with the respective drum driving unit and control assembly to open the loop and disconnect all of said coupling-actuating means from the electrical power source, thereby simultaneously stopping said belt conveyor and all said booster conveyors on detection of such defect.