INTERFERENCE WARNING DEVICE

摘要

An interference warning device for an oil well drilling rig having a derrick, traveling equipment, a racker arm, and a block retractor. Fluid activated sensors provide electric signals when the traveling equipment is within a selected vertical distance from the racker arm, when the racker arm is within a selected horizontal distance from the vertical axis of the derrick, or when the block retractor has extended the traveling equipment to within a selected distance from the fully extended position. The operator is informed when any one of the sensors is activated, cautioned when any two of the sensors are activated, and warned when all three sensors are activated. The drawworks may be braked when all three sensors are activated.