NATIONAL CRANE 800 SERIES
                        TRUCK-MOUNTED MOBILE CRANES


Produced by:  Occupational Health and Safety Branch
              Ontario Ministry of Labour


A recent accident investigated by officials of the Ministry of Labour 
involved the failure of a 17-ton Series 800B truck-mounted crane 
manufactured by National Crane.

The failure appears to have originated at the weld metal of the mounting 
plates closest to the cabin of the vehicle.  The failure progressed by 
shearing the mounting bolts and welds of the remaining plates and resulted 
in the overturning of the crane.

The investigation revealed that the welding of the mounting plates to the 
vehicle frame was not carried out in accordance with the installation 
instructions of the manufacturer.  The manufacturer's specification 
requires a bevel groove weld with an additional 3/16" fillet weld.  
Deviations from this specification will seriously affect the structural 
integrity of the crane.

Operators of these cranes should ensure that the mounting plates are 
inspected by a welding inspector certified by the Canadian Welding Bureau.  
If a complete penetration groove weld cannot be detected, repairs or 
replacement must be carried out in accordance with the procedures specified 
by the manufacturer.

For further information or assistance, please contact an engineering 
representative of the Ministry of Labour.