Depth detector systems

A clamping assembly, comprising:

• a mounting plate capable of being removably coupled to a load-carrying vehicle;
• a plurality of guide bars extending horizontally from the mounting plate;
• a plurality of slide arms slidably supported on the plurality of guide bars;
• first and second opposing clamp arms each attached to corresponding slide arms of the plurality of slide arms, the first and second clamp arms being movable towards and away from each other to contact and exert a clamping force on a load sufficient for lifting and transporting the load;
• an ultrasonic sensor attached to one or more of the guide bars and directed toward a space defined between the first and second opposing clamp arms, wherein the ultrasonic sensor is a diffuse mode sensor;
• a controller attached to one or more of the guide bars and capable of receiving signals from the at least one ultrasonic sensor;
• and
• a light display capable of being selectively illuminated by the controller to indicate depth of a load relative to the material handling attachment based on the received signals from the at least one ultrasonic sensor, wherein the light display is capable of being selectively illuminated by the controller to indicate only the depth of the load relative to the material handling attachment based on the received signals from the at least one ultrasonic sensor, and wherein the light display is mounted on one or more of the guide bars facing away from the clamp arms.