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Technical guidance note

Earthmoving equipment ― 

Burst protection on earthmovingequipment used as cranes

This technical guidance note clarifies therequirements for burst protection to be fitted toearthmoving equipment, when used in the crane

mode.

Background

 A catastrophic failure of a hydraulic hosesupplying the oil flow to raise or maintain a liftingboom at a specific height will cause a suddencollapse of the lifting system and injury to aperson if struck by a falling boom or load. The riskof hose failure increases significantly as hydraulicoperating pressures increase when the mass ofthe load increases.

For many years mobile cranes have been fittedwith burst protection on critical hydraulic cylindersto prevent crane or boom collapse. Thesedevices lock cylinders in the event of sudden lossof hydraulic fluid pressure (i.e. when a flexiblehydraulic hose ruptures). One type of burstprotection device is shown in photographs 1 and2.

Photograph 1: Burst protection fitted to boomcylinders.

Photograph 2: Burst protection fitted to dipper armcylinder.

The Mobile Crane Code of Practice 2006 discusses the need for burst protection to be fitted

to the boom and dipper arm of earthmovingequipment used as a crane (i.e. with a freelysuspended load).

Section 5.4 of International Standard ISO 8643describes the distance a test load is allowed tofall from a stationary position will not exceed100 mm during the first 10 seconds after a hoseburst.

Determination

Burst protection is to be fitted on all earthmoving

equipment used as a crane, where the ratedcapacity exceeds 1 tonne. The burst protection isto be fitted to both the boom and dipper arm ofthe equipment. Burst protection is to comply withthe performance requirements of ISO 8643:Earthmoving machinery – Hydraulic excavatorand backhoe loader boom-lowering control device – Requirements and tests. 

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The following additional conditions are to beapplied:

  The maximum rated capacity is to be inaccordance with the manufacturer’sspecifications for the equipment. Equipmentmust not be de-rated to avoid fitting burstprotection.

  Single rated capacity  Where the decisionis made to rate the lifting capacity of theequipment at its maximum lifting radius, thisbecomes the rated capacity1 and is to bemarked on the boom or dipper arm. The ratedcapacity must then be strictly observed at alltimes, irrespective of the radius of the load.Information should be available on site toconfirm that the rated capacity marked on theunit is the same as that specified by themanufacturer.

  Variable rated capacities 

 Where theequipment has variable lifting capacities, themanufacturer’s rated capacity chart (i.e. loadchart) is to be fixed to the inside of theoperator’s cabin. For equipment with variablerated capacity, the lifting capacity at minimumradius is to be used to decide whether burstprotection is required.

  The burst protection device should not beprovided with the ability for the operator toswitch the device on and off (in case theoperator forgets to switch the burst protection

on when the equipment is operated as acrane).

  Where the rated capacity of the equipment is1 tonne or less, and the decision is made notto fit burst protection, the equipment must notbe used to lift loads in close vicinity toworkers.

Earthmoving equipment owners should seekadvice on fitting of burst protection from originalequipment manufacturers, to help avoid fittingfaulty or unsafe systems.

ImplementationThe following scenarios provide guidance ontypical enforcement action that can be expectedfrom WHSQ:

  Scenario 1   An inspector observes a 40tonne excavator 2, with a rated capacity of 7.1tonnes at maximum radius, being used incrane mode to lift a storm water pipe with aworker partially underneath one end of thepipe. The excavator is not fitted with burst

protection. The inspector will issue aProhibition Notice that totally prohibits theexcavator from lifting any suspended loaduntil it is fitted with burst protection on boththe boom and dipper arm hydraulic cylinders.

  Scenario 2  An inspector observes a 20tonne excavator lifting loads in crane modeand the load is approximately 2.5 tonnes. Theexcavator was manufactured in 2008 and isnot fitted with burst protection. The dipper armis marked with the letters “SWL 1 Tonne”. Theoperator claims that because the excavator is

rated at 1 tonne it does not require burstprotection. The inspector checks themanufacturer’s specifications and notes theexcavator has a rated capacity of 3.6 tonnesat maximum radius. The inspector will issue aProhibition Notice that totally prohibits theexcavator from lifting any suspended loaduntil it is fitted with burst protection on boththe boom and dipper arm hydraulic cylinders.

  Scenario 3  An inspector observes a 5 tonneexcavator lifting a storm water pipe thatweighs approximately 500 kg. The dipper armis marked with the letters “SWL 700 kg” inaccordance with the manufacturer’s ratedcapacity at its maximum radius. The inspectorobserves workers walking under the load.The operator claims that it is okay to lift loadsover workers and the excavator doesn’trequire burst protection because theexcavator’s maximum rating doesn’t exceed 1

tonne. Enforcement action  The inspectorwill issue a Prohibition Notice that totallyprohibits the excavator from lifting any

suspended load over workers. The inspectortells the operator that the excavator can onlybe used to lift suspended loads if workers areexcluded from the lifting zone.

For more information1Safe working load abbreviated to “SWL” can also be used to indicate

the rated capacity.2 Earthmoving equipment is usually described by its operating weight

and not its rated lifting capacity, as is the case with a mobile crane. 

For more information about mobile plant, visitwww.worksafe.qld.gov.au or call the WorkplaceHealth and Safety Infoline on 1300 369 915.

© The State of Queensland (Department of Justice and Attorney-General) 2010

Copyright protects this document. The State of Queensland has no objection to this material being reproduced, but asserts its right to be recognised as author of theoriginal material and the right to have the material unaltered.

The material presented in this publication is distributed by the Queensland Government as an information source only. The State of Queensland makes no statements,representations, or warranties about the accuracy or completeness of the information contained in this publication, and the reader should not rely on it. The QueenslandGovernment disclaims all responsibility and all liability (including, without limitation, liability in negligence) for all expenses, losses, damages and costs you might incur asa result of the information being inaccurate or incomplete in any way, and for any reason.

Workplace Health and Safety Queensland, Department of Justice and Attorney-General 

Earthmoving equipment – Burst protection on earthmoving equipment used as cranes

PN10002 Version 2. Last updated July 2010.