Operation of Fully Automatic Excavator Quick Hitches. (Disengaging the Bucket)

Following a recent incident, The Health and Safety Authority (HSA) is issuing an urgent warning to Construction Employers, SOLAS CSCS Trainers and Excavator Drivers of the dangers associated with how certain types of automatic excavator quick-hitches are operated. The concern arises from the bucket on the quick-hitch disengaging more rapidly than the operator expects. This in turn could lead to the bucket falling on personnel causing serious injury or death.

The HSA understands that many operators do not expect excavator buckets attached via quick-hitches to disengage unless the bucket is “crowded” inwards (See Fig 1).

However this is not necessarily the case since with some designs once the disengagement switch is activated, the bucket may disengage rapidly. This will happen if there is a small build-up of hydraulic pressure in the quick-hitch. Such a build-up can happen in matter of seconds. The risk appears to be particularly pronounced on certain types of “tilt-rotate” type excavator attachments.

Operators should NEVER press the disengagement switch of a quick-hitch before the bucket has been landed to a stable landing space (See Fig 2), preferably its transport position. This space should be level and should be such that the bucket is not in danger of rolling or falling further.

The HSA also advises that disengagement switches must be fully maintained. This includes maintenance of a lock to prevent inadvertent operation and an audible signal to warn of the activation of the disengagement switch.

In certain instances there may be two separate couplers each with its own separate set of controls. This might be the case where one controller controls the coupling of an attachment such as a tilt-rotate mechanism to the excavator arm while a second controller might control the attachment of an excavator bucket to the tilt rotate mechanism. In such instances the operator should be aware of which controls operates which mechanism.

The owner and operator should always refer to the instruction manual in order to operate these attachments in a safe manner.

Fig 1: Excavator Bucket “crowded” inward.

Note a bucket does not always need to be crowded to disengage.

Fig 2: Ensure that Bucket is on a flat level stable surface before pressing the disengagement switch

June 2015