In this design, the coupler can only be disengaged when the release command is given (by releasing a positive switch in the cab) and the coupler is positioned in its full curl position. It also uses the main hydraulic system on the excavator for a constant supply of high-pressure oil, which keeps the coupler's internal cylinder locked at all times during engagement. A two-position safety switch and an audible alarm that sounds during disengagement further enhance safety.
The Hendrix II coupler also includes redundancy features such as a double-acting cylinder with check valve, integrated compression spring and even a mechanical locking pin.
Maintain and train for safe operation
Even with physical safety features in place, manufacturers stress the importance of maintenance and training in improving safety when using quick couplers.
"The coupler is an attachment, and like any other attachment, it needs to be maintained," says Bramel.
Keep the coupler as clean as possible and grease any areas that require it. "And whenever the opportunity is available, clean the machine and run it through a cycle without anything hooked up to make sure it's still working," says Bell.
Bell also advises paying close attention to coupler operation. "Operators need to have the same sense of awareness about using a quick coupler as they have when operating the excavator," he states. "They need to be all hands and eyes, and pay attention to what they're doing to operate the equipment safely."
"There needs to be an increased awareness of the probability of danger," agrees MacKenzie. "Operators should never swing a bucket over workers and never let workers under the bucket. They also should never operate an unsafe coupler, and should report any unsafe couplers to their supervisors. And never operate a coupler without the supplemental safety device in place. It may sound intuitive, but in the highly accelerated pace of the jobsite, anything can happen."
"It's easy for operators to become complacent about how to use quick couplers," Bramel adds. "Many unintentional detachments are due to operator error and not getting it hooked up properly. We focus on training to minimize the potential, as well as stress the importance of maintenance." ¦
Tips for Safe Coupler Operation
OSHA offers these safety tips when using quick couplers on the jobsite:
Be sure to include positive locking pins and other devices that need to be manually installed.