* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *  
*                                                                   *  
*                             HAZARD ALERT                          *  
*                                                                   *  
*  Produced by:  Saskatchewan Human Resources,                      *  
*                Labour and Employment                              *  
*  Provided by:  Canadian Centre for Occupational Health and Safety *  
*                                                                   *  
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *  
  
  
FARMER CRUSHED BY A HYDRAULIC HOIST  
  
  
  A Saskatechewan farmer met an untimely death recently, when he was  
  crushed by the hydraulic hoist of a grain truck.  In 2 seconds the  
  box dropped on him after he accidentally bumped the control lever.  
  In 2 seconds he had no chance to escape.  
  
  There have been other fatal accidents with truck hoists in the past  
  and no doubt there will be more.  It's possible that accidents have  
  resulted from the operator not knowing that the hydraulic system was  
  unsafe.  Perhaps the following information will help prevent such  
  an accident on your farm.  
  
  
*** CAUSE:  ***  
  
  In most cases when a person is crushed in the hoist of a grain  
  truck, the problem is a technical one.  The grain box, usually  
  loaded, suddenly falls onto it's victim -- too quickly to allow him  
  to escape.  A properly equipped hoist system would not allow the  
  box to drop quickly, even if the box is fully loaded.  
  
  A one-way flow restrictor valve, somethimes called a line throttle  
  valve, should always be mounted on the inlet port at the base end of  
  the hydraulic cylinder(s).  This device is called a one-way  
  restrictor valve because:  
  
      1)  to raise the load, oil is pumped unrestriced through the  
          valve into the base end of the cylinder;  and  
      2)  to lower the load, the flow of oil leaving the cylinder is  
          restricted -- causing the lowering of the box to slow down,  
          whether loaded or not.  
  
  The time it takes for the box to go from the fully raised to the  
  fully lowered postion is determined by the size  of the orifice in  
  the restrictor.  Common orifice sizes used on hoist systems are  
  .046 and .062 of an inch, however larger cylinders may require .093  
  or .125.  
  
  
*** TIME TEST:  ***  
  
  A test grain truch with approximately 150 bushels of wheat in the box,  
  engine running and with the PTO engaged, took 32 seconds to lower the  
  box.  The same hoist with no load to 34 seconds to lower.  
  
  The important point is that this test truck did have a restrictor  
  valve mounted on the base end of the cylinder.  If a hose broke, or if  
  the control valve was accidentally moved, anyone standing nearby would  
  have 30 seconds to get out of the way.  It would not be safe to have  
  this valve mounted anywhere else on the system, it must be mounted  
  directly onto the port at the base of the cylinder (see the diagram on  
  the reverse page).  
  
  
*** SAFETY CHECK YOUR HOIST:  ***  
  
  It should never be considered safe to work under a raised truck box  
  unless it is securely blocked.  Never bet your life on a hydraulic  
  system, remember:  
  
    - sometimes a farmer, not realizing it's importance, may leave the  
      restricotr valve off when replacing a hose;  
    - often this important restrictor valve is not installed when the  
      unit is new;  and  
    - sometimes an undersized restrictor valve is installed on the  
      unit and the farmer may remove the valve to speed up the  
      lowering of the box instead of replacing it with one which  
      is the correct size.  
  
  
*** COST:  ***  
  
  This valve retails for under $20.00 including the cost of a reducer  
  bushing.  It takes approximatelly 15 minutes to install.  FOR SAFETY  
  SAKE check the hydraulic hoist on your grain truck and make certain  
  that it has a restrictor valve.  
  
  
"DON'T RISK YOUR LIFE FOR $20.00"  
  
  
            * * * * * * * * * * * * * * * * * * * * * * * *