Specialist Focus: Plant Hire - Quick Hitches

Quick hitches are to excavators what the internet is to a PC - a gateway to a whole new world. The ability to quickly swap buckets or to pick up a breaker, a vibrating plate, a piling attachment and so on has broadened the usefulness of excavators, transforming them into multi-purpose tool carriers.

Product handbooks:

Miller
Dromone

Watch the product in action:

www.youtube.com/contractjournal

However, four deaths within a year caused by items becoming detached from quick hitches have prompted the Health and Safety Executive (HSE) to issue an alert about the devices. It has identified semi-automatic quick hitches as a common theme with these accidents.

Yet this is not a new problem. This type of accident has been happening for some considerable time, and the HSE's figures show that 13% of all excavator accidents involve such unexpected detachments.

So why hasn't the HSE banned semi-automatic quick hitches? Because they are perfectly safe - provided they are used correctly.

Unlike the fully automatic hitch, which has a mechanical locking device built into the mechanism, the hydraulics on a semi-automatic only grab the pins - a locking pin is used to ensure absolute security of the attachment. Brendan McGreevy, engineering manager at hitch manufacturer Hill Engineering, sums up the situation by saying: "A semi-automatic without a safety pin is only as good as an O ring in the hydraulic system or an exposed hose."

Alan Rackstraw from quick hitch manufacturer Miller UK goes one step further. As quality engineering and improvements manager, he has attended accident sites to investigate accidents involving Miller couplers and attended meetings about incidents with other makes. His conclusion is that incidents don't usually happen just because a safety pin has been left out - there is usually another contributing factor.

In one incident, Rackstraw says not only was the safety pin unused, but the operator was grabbing a new bucket and instantly slewing over a trench. When the accident happened, the bucket had not properly attached before the slewing started.

All the manufacturers advise checking the bucket (or other tool) is firmly attached to the coupler and the safety pin is inserted before putting the machine to work.

Tom Gauhran, service and back-up manager with hitch producer Geith, echoes this theme. Before starting work, his firm recommends fully crowding and then opening the freshly picked up attachment and 'shaking' the dipper to expose an unsound connection.

Messages ignored

Clearly such messages are not getting through or are being ignored. Rackstraw recently attended an incident where an operator was sorting buckets by moving them from one position to another without making a full connection. Unfortunately a bucket fell off during slewing and rolled down a bank, hitting another site worker.

The HSE team investigating a fatality found that not only was the safety pin missing from the hitch of the machine involved in the accident, but there were no safety pins in the couplers on the other machines on the same site. It has advised its inspectors to check if safety pins are being used and consider prosecution if two or more safety pins are missing on a single site.

Pressures of the job

The question is: why there is such widespread misuse? Are operators unaware of the problem, untrained, just lazy or under intense pressure to get the job done? Most probably it is a mixture of all these factors. Certainly the HSE says the Construction Plant Competence Scheme (CPCS) card does not indicate competence in the use of quick hitches, and the advent of automatic quick hitches means the lack of a safety pin does not automatically sound alarm bells with operators.

So if a machine operator has taken the safety pin out and lost it or stowed it in the toolbox, any subsequent operator may not know the hitch even needs a safety pin.

To counter this, hitch manufacturer Lemac has recently altered the design of its quick hitches so the safety pin remains attached to the body at all times (as recommended by the HSE - see box below). Company owner Vic Feary says his firm is producing a kit of parts to convert existing hitches and safety pins to the new design.

Rackstraw says the only way to ensure the hitch is operated safely is for the operator to determine what type of coupler is fitted before putting that machine to work. He talks through the process: "First, look to see if there are hydraulic hoses running to the coupler - not the quick-release ones that power the attachment, but permanently connected to the coupler itself.

"If there are, then it is a hydraulic coupler and you need to determine whether it is a semi- or fully-automatic model. Where there is a safety pin already in place, it's problem solved. If not, look for a sticker in the cab with a diagram showing the coupling/uncoupling process."

Coupler body

"If you are still unclear, look at the body of the coupler. Holes in the coupler body are expensive to create and each has a reason to be there: some will be for access to the ram pins and pivots, but others could be for safety pins - and remember, not all safety pins are round. If there is an 'unused' hole (or holes), be aware that a safety pin may be missing and make further enquiries before starting to operate the machine.

"A hitch dedicated to a single bucket pin spacing will have a single safety pin location, while couplers that can pick up a range of buckets with various pin spacing can have two or three safety pin positions.

Usually the safety pin will only fit through one of the sets of holes depending on the pin spacing of the bucket being grabbed. If you are unsure, consult the manufacturer's handbook."

He concludes with what for many is the most crucial point: "No matter whether you are using a semi- or fully-automatic hitch of whatever make, complete the coupling procedure before slewing or moving the machine - even if you are only repositioning buckets."

HSE Alert

The Health and Safety Executive (HSE) says recent fatalities involve semi-automatic quick hitches where the retaining pin or bar was missing (although other incidents have involved both manual and automatic types). Its advice is to check and set up the following:

• Has the excavator operator been trained on the use of quick hitches?
• Has the operator been trained on the specific hitch being used?
• Is the manufacturer-specified retaining pin available on the machine?
• Has the pin been designed for this specific use?
• Is there a system for checking the pin is in place before starting the work and each time a new attachment is fitted?
• Operators must not to use the machine unless they are satisfied the bucket/attachment is secured in place - which could entail visual check from the ground rather than the cab.
• Managers undertake random checks to ensure the precautions are being implemented.

Further advice includes:

• Attaching easily lost pins or clips to the quick hitch.
• Painting the end of the pin (to make it more visible) and the area around safety pin insertion holes to make it clear where the pin should be inserted.
• Duty holders wishing to modify pins so they cannot be fully removed from the hitch should first check with the manufacturer.
• Forbidding the ad-hoc replacements of pins with large bolts, wire or other substitutes.
• Ensuring that others do not work below the bucket/attachment.