Quick hitches: why there's no quick fix

The HSE is to ban new semi-automatic quick hitches after a spate of fatal accidents, but not existing ones.

What a pity somebody had to die and another go to jail to highlight the bad practice that is going on in industry," says Alan Rackstraw, quality systems manager with Miller UK.

And he should know. When a bucket fell off an excavator operating at the Drax power station in September last year fatally injuring a site worker, Rackstraw was dispatched to the site to investigate the operation of the Miller semi-automatic quick hitch that attached the bucket.

"When I arrived at the site the safety pin was in its correct position in the coupler, but there was no bucket attached. And when I withdrew the pin to check the coupler's functions it was immediately clear it hadn't been used from day one. The excavator was four years old and the pin didn't have a scratch on it."

The result was a double tragedy: site worker Alwyne Parkinson (59) died from his injuries three days after the accident and the digger driver Michael Ernest Roys from Doncaster pleaded guilty to the charge of manslaughter and is serving a year in prison.

A rare bout of action

Last year four people died in accidents related to semi-automatic quick hitches - from different manufacturers - prompting the Health and Safety Executive (HSE) into a rare bout of action as it issued a safety alert. It found that all the fatalities involved semi-automatic quick hitches where the retaining pin or bar was missing (although it notes other incidents with both manual and automatic hitches).

With the safety pin removed, a semi-automatic will pick up and drop a bucket or attachment without the operator leaving the cab. While this may appear to be perfectly satisfactory - and suit operators - the coupler is not designed to be used without the safety pin.

Brendon McGreevy, engineering manager with coupler manufacturer Hill Engineering, sums it up by saying: "A semi-automatic without a safety pin is only as good as an O ring in the hydraulic system."

Rackstraw says the situation is even worse as some operators don't check the bucket is properly connected before getting back to work. When sorting buckets some operators just hook the front pin without setting the hydraulics to the closed position. "If they then slew across a trench and the unsecured bucket falls off, anybody in the trench could be seriously injured - or worse," he says.

This boils down to lack of training, bad practice or laziness on the part of the excavator operator. Several firms have implemented training schemes for their operators others have moved to 'ban' semi- automatics from their sites. There have also been questions about the CPCS training requirements in respect of quick hitches. While the whole scheme is under review, there is currently no system of continued training for plant operators and therefore no way to trace card holders who need further training.

Earlier in the year, the HSE issued advice to its inspectors to check whether safety pins are being used and to consider prosecution if two or more safety pins are missing on a single site. It is also determined to stop new machines being fitted with semi-automatic couplers and aims to ban their use on new excavators by implementing a UK-only safeguard action, against the section of EN474 that covers quick hitches. This would modify EN474, which forms part of the machinery directive, as it applies to the UK, which could be enforced rapidly without waiting for the revised machinery directive to become law across the whole of the EU. This safeguard will then be superseded by changes to EN474, which are currently being drafted but will not come into force for at least 18 months.

Automatic safeguard

For new excavators the HSE is proposing that powered couplers have an automatic device that prevents the attachment from falling off in the event of a loss of hydraulic pressure. There must also be an indicator, viewable from inside the cab, to show the device is secure.

However, the HSE says it has no plans to ban existing semi-automatic quick hitches. Some argue that this could exacerbate the situation as fewer operators will be acquainted with semi-automatics, which could make accidents even more likely.

It seems there may be no quick fix for the quick hitch problem.

HSE advice - important checks

• Has the excavator operator been trained on the use of quick hitches and the specific hitch being used?
• Is the manufacturer-specified retaining pin available on the machine and 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 when attachments are exchanged?

Further HSE advice

• Operators must not use a machine unless they are satisfied the bucket/attachment is secured in place - which could entail a visual check from the ground rather than the cab, and managers must undertake random checks to ensure the precautions are being implemented.
• Attach easily lost pins or clips to the quick hitch - duty holders should check with the manufacturer before modifying pins.
• Paint the end of the pin (to make it more visible) and the area around safety pin holes to make it clear where the pin should be inserted.
• Forbid the ad-hoc replacement of pins with large bolts, wire or other substitutes and ensure nobody works below the bucket/attachment.