Incident

A farm employee was critically injured after a blow to the forehead from a crank handle used to raise the wheels on a Prattley trailer unit, see Image 1. This incident is in the interest of anyone who has the same or similar type of unit as remedial action is required.

IMAGE 1 Example of an early model Prattley Portable Yard, manufactured 30 years ago, similar to the one involved in a recent incident. (Arrow: Cranking the handle raises the wheel arms, through pivot system.) Click image to see larger copy

IMAGE 2 Detail of sole means to secure the crank system. The end of the handle does not show in this photo but the crank is hanging down alongside the fences. (Arrow: Locking pin and safety clip.) Click image to see larger copy

Circumstances

The employee had wound the unit's wheels up, which takes the weight of the unit, in preparation for towing by a farm vehicle. The employee attempted to insert the locking pin into the holes on the cranking unit and it is believed he lost control over the crank handle. At this point, the handle quickly unwound, hitting the victim in the forehead with great force.

Investigation

• The yard's wheels are raised by turning a crank handle attached to a shaft that winds two wire ropes to raises the wheel arm (and the two wheels to the travelling position.
• The travelling position of the wheels is maintained by locking the cranking mechanism at the correct height for towing. This is done by aligning respective holes in the cranking disk with the fixed plate and placing an "L" shaped locking pin through both aligned holes. This pin is then secured by a spring safety clip as shown in the photo below. The unit is now set for towing with the weight taken by the wire ropes and spring mechanism.
• Once the full weight of the unit, along with the weight of the portable gates is taken by the cranking mechanism, considerable strength and concentration is required to wind to the correct height and maintain steady pressure on the crank while the holes in the two disks are aligned to allow the locking pin to be inserted.
• In order to maintain the correct leverage on the crank and hold it in position, the operator may need to move their body and head into the area where the crank is turned, placing the operator at serious risk of injury.
• If the crank freely unwinds under the weight of the whole unit, the crank handle will turn at great speed, putting anyone in its path at risk of a very serious injury.
• Several hundred of the original units still in use. The manufacturer has subsequently made key improvements on the current unit's winder and the upgrade winder kits are considered to be a very safe design and significant improvement over the original.

Recommendations

If you use a Prattley Trailer unit such as described, it is recommended you;

• Contact the manufacturer or supplier of your Prattley equipment to find out how your portable yard can be modified and made safe. The early model's crank handle can be improved by replacing the locking pin system with a safety winch and secondary friction device to prevent the handle from spinning out of control. An upgrade kit is available from Prattley Industries Limited, call Prattley Industries on 0800 45 00 00.
• Enter this hazard and any similar ones into your hazard register along with your means of hazard control.

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Issued by the Department of Labour, New Zealand
http://www.osh.dol.govt.nz

No. 29 - January 2008