WorkSafe Victoria recently issued a safety alert reminding employers to check that safety pins are used on semi-automatic quick hitches, following an incident in which a worker’s leg was crushed when an excavator bucket unexpectedly detached from height during a house demolition.
Early indications are that the bucket was connected to an excavator via a semi-automatic quick hitch attachment when the incident occurred.
A quick hitch enables mounting and removal of attachments on machinery such as excavators.
It’s also called a quick adapter or quick coupler, and there are different types of quick hitches, including half-hitch, mechanical, semi-automatic and automatic.
Quick hitches have safety systems to prevent attachments from coming away if the hydraulics or excavator control system malfunctions or fails, and the alert said it’s important to ensure the safety system is always used.
In semi-automatic quick hitches, the safety system consists of a safety pin located where the attachment joins the machine. This pin has to be manually inserted and secured with a fastener such as a lynchpin.
The alert said quick hitch devices should comply with AS 4772 – 2008 or another equivalent standard (such as ISO13031 – 2016).
AS 4772 requires that a safety system is used to ensure the attachment does not unintentionally disconnect from the quick hitch in event of failure of the primary retention system.
Every time an attachment is changed, the safety system (safety pin) must first be removed to enable the attachment to be disconnected, then re-inserted and secured once the replacement attachment is engaged.
This usually requires the machine operator to get out of the machine and install the safety pin and fastener.
When attachments are being changed regularly, operators may not get out of the machine and install the safety pin and fastener every time.
This means that, if the primary retention system malfunctions or fails, the attachment can unexpectedly detach.
The alert recommended a number of ways to control risks.
If excavators, backhoes or similar items of plant are being used on your site, or if you operate excavators with quick hitches, ensure that any quick hitch devices are fitted with the safety system, and it is used in accordance with the manufacturer’s instructions
The safety system must be installed to prevent the uncontrolled release of buckets or other attachments when the machine is in operation.
This requirement must be reflected in documented site safety procedures and induction for plant operators.
Other measures to prevent accidental detachment include: