Hazard summary

A recent incident at an automobile assembly plant revealed an area in the mast assemblies of Clark Model ECS and GCS Series Forklift trucks where cracking and failure may occur. The web of the channel in one or both masts was found to be cracking near the rear corner where the lower rail is welded to the mast channel. It is likely that the cracking occurs when the manufacturer's preventive maintenance requirements have not been strictly adhered to.

This resource does not replace the Occupational Health and Safety Act (OHSA) and its regulations, and should not be used as or considered legal advice. Health and safety inspectors apply the law based on the facts in the workplace.

Locations and sectors

Manufacturing; warehouses


It is extremely important with all models of forklift trucks that the manufacturer's maintenance and inspection procedures be rigorously followed.

Clark Model ECS and GCS Series Forklift Trucks should be examined for cracks, as follows:

  1. Elevate the forks to about 12 feet.
  2. Clean residual grease from the area of the mast channel where the lower rail is welded to it to about eight inches above the rail.
  3. With a flashlight, examine the area closely for cracking or any other sign of stress.

Any forklift that has cracks in this area should be taken out of service immediately. Complete failure in this section of the mast assembly can result in catastrophic loss of load.

The Occupational Health and Safety Act (s. 25(1)(b)) requires an employer to ensure that equipment is maintained in good condition. The Regulations for Industrial Establishments (R.R.O.1990, Reg. 851, s. 51(1)(b)) state that a lifting device shall

"be thoroughly examined by a competent person to determine its capability of handling the maximum load as rated,
  1. prior to being used the first time, and
  2. thereafter as often as necessary but not less frequently than recommended by the manufacturer and in any case, at least once a year and a permanent record shall be kept, signed by the competent person doing the examination."


Mast/mast channels

On a forklift truck, the forklift moves up and down inside the channels of the two masts, which are the vertical components that hold the forklift and its load above the rest of truck. The web (in this case) is the area of steel at the back of the channel.

Rails or crossties

These extend from the main body of the truck to the two front wheel assemblies. They are essential for stability, especially when the forklift is carrying a load. In these models, there are two on each side, upper and lower.