The GBB140 shown below is designed to operate with a tilt rotator coupler which has two auxillary circuits. This allows the grab to rotate continuously while at the same time tilting 40 degrees left or right. In addition the full crowd range of the excavator is available to provide fore and aft tilt.
This grab and its unique mounting was designed specifically for the placement of heavy steel beams in an underground mining operation. Because of the tunnel limitations, all beams had to placed from underneath as no slinging from a crane was possible. Using a fully proportional electro hydraulic control system to operate the grab functions, this Doherty design safely positioned all vertical, horizontal and diagonal beams to a +/- 5mm accuracy in record time and was awarded a Queensland Innovation in Safety Award.