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*                             HAZARD ALERT                          *  
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*  Produced by:  Saskatchewan Human Resources,                      *  
*                Labour and Employment                              *  
*  Provided by:  Canadian Centre for Occupational Health and Safety *  
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HYDRAULIC CYLINDER OF OUTRIGGER JACK USED TO HOIST TRUCK FAILS,  
CAUSING TRUCK TO COLLAPSE ON WORKER  
  
  
*** INJURY:  ***  
  
  A Saskatchewan worker was killed when the hydraulic outrigger jack  
  cylinder failed, causing the digger truck unit it was supporting to  
  fall on him.  
  
  
*** CIRCUMSTANCES:  ***  
  
  Maintenance work on the rear suspension (passenger side) was required  
  on a hydraulic digger truck unit.  The unit had been stored outside  
  in -33C temperatures.  It was brought into the shop and parked under  
  the shop heater.  The vehicle was then hoisted (elevated) by fully  
  extending the hydraulic stabilizer outrigger jack.  The tandem rear  
  tires on the passenger side of the truck unit were removed.  Substantial  
  stands or blocks were not used to support the truck.  
  
  The worker situated himself under the rear truck frame and proceeded to  
  repair the rear suspension.  The cold hydraulic oil expanded within the  
  cylinder as it warmed up.  Full extension of the outrigger cylinder ram  
  allowed no room for the increased volume of oil.  Eventually the  
  pressure became so great that it ruptured the cylinder casing.  The  
  escaping fluid allowed the cylinder ram to retreat and the truck to fall.  
  
  
*** PREVENTION:  ***  
  
  Hydraulic outrigger jacks are designed only to stabilize the unit during  
  operations.  They are not to be used as an elevating or hoisting device  
  when performing work under elevated parts.  
  
  Hydraulic oil expands when exposed to increased temperature.  This should  
  be allowed for whenever hydraulic lifting or hoisting devices are used.  
  
  
*** REGULATIONS:  ***  
  
  Section 204(3) of the 'Occupational Health and Safety Regulations'  
  requires an employer to ensure that when work is being done on any  
  powered mobile equipment, the elevated part is securely blocked to prevent  
  its accidental movement.  Section 224(3)(b) requires the employer to  
  ensure that no worker is allowed to work under a load unless it is  
  supported by a vehicle hoist designed for that purpose or by substantial  
  stands or blocks.  
  
  
*** FOR MORE INFORMATION:  ***  
  
  The Occupational Health and Safety Branch, 1870 Albert Streeet, Regina,  
  S4P 3V7 (phone 787-4496).  Saskatoon office, 3130 - 8th St. East, S7K 2H6  
  (phone 933-5052).  
  
  
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