Wheel Grippers - Strength in Numbers

When pneumatic systems need to produce high force levels designers tend to think in terms of larger bores. While this approach works, sometimes the manufacturing aspects of a project play an important roll. Multiple standard units may be more cost and schedule effective than special big bore devices. After all, there is strength in numbers.

Wright Industries, Nashville, TN., was faced with a $8,000 to $12,000 price tag for a pneumatic wheel gripper that could handle 125 pound wheels when Accuride Corporation, North America’s largest producer of truck and trailer wheels, asked Wright to develop a robotic work cell. The robot cell is required to manage 19.5”, 22.5” and 24.5” wheels through a proprietary subassembly operation. Wright Industries is one of America’s largest integrator of robotic systems and after Brad Reed of Wright recovered from the sticker shock he knew that there had to be a more efficient solution.

Brad called ZAYTRAN with the idea of using XRAY-1250-200 Wheel Grippers with an intensifier. He required a parallel gripper with about 8” of stroke and approximately 500 pounds of holding force from each jaw. With 200 PSI the XRAY would give the required closing force but the bearing system would not tolerate the torque that a 125-pound wheel swung by a robot would apply to the gripper.

With a relatively tight budget and schedule ZAYTRAN’s application support specialist went to work with ZAYTRAN’s engineering department. The idea of a large bore gripper (SIGMA-6) had to be abandoned due to cost and schedule for a more innovative approach using multiple standard products. Two XRAY-1250-200s would provide the required force with shop air but more importantly having two 32mm guide bars would allow a pair of XRAYs to handle the torque that the 125-pound wheel would apply to the gripper. The TANDEM XRAY-1250-200 was born!

ZAYTRAN packaged the two XRAYs as a tandem Wheel Gripper using:
• A base plate, on which both grippers were mounted and robot mounting is accommodated
• A set of Jaw attachment plates, that connects the two XRAY jaws and provides a mounting surface for the customers jaws
• A manifold that connects the two grippers pneumatically

The TANDEM XRAY-1250-200 was designed, fabricated and tested in 5-weeks and is priced below $6000. Both the lead-time and price reflect the positive aspects of using standard components to make unique solutions. The Tandem project also proves that there is strength in number. Anyone need a triple?