April 2019 Safety Topic of the Month: Forklift Lift Chains

 Over the next few months, I will focus on specific components of equipment and my experiences with them. This month, I will discuss forklift lift chains.

Lift chains on vertical mast and some boom mast (telehandler) forklifts are the actual components that do all of the lifting, so maintaining chains is absolutely critical! Typical forklift lift chain is the multiple leaf style, which varies in size and individual leaf count with every forklift make and model (the larger the lift capacity, the larger the chain, usually). I have come across older (50's & 60's era) forklifts that used roller chain - units less than 3,000lb. capacity - just "putting that out there".

The basic inspection of any lift chain I would recommend, coinciding with the daily checklist:

• Visual inspection: note any excessive rust, corrosion, etc.
• Check for visible wear: over the sheaves/rollers, pins, and especially the master pins/links, and anchors. 
• With the forks fully lowered and mast positioned to create slack in the chains: grab the chain and push/pull - check for play in the pins, there should not be detectable play, move the chain side to side, looking for the same kind of play.
• Check for seized/ stiff links - depending on the amount of slack when you check, there should be proportionally a full range of play.

Be sure to document any of the conditions above.

Now to look at things in operation, forklift chains are always under tension when operating. They carry the full weight of the empty carriage: 500lb. or more and more as load increases, so we are fighting an uphill battle from the start in regard to chain preservation. Additional issues to consider, and prevent if possible:

• Bumpy paths: potholes and material in pathways should be avoided as much as possible, the bounce to the carriage will cause chain stretch, and increases under load.
• When unloading a pallet into a space above ground, racking for example, make sure the chain is holding tension on the carriage. The scenario: a pallet is unloaded onto a rack position above the operators line of sight, the operator lowers the carriage to place the pallet and continues to hold the lever in the down position. At this point, there is no detectable movement from the carriage, but the lift cylinder is still retracting. The operator pulls away from the rack, just as the forks clear the pallet/rack, the carriage slams down inches or a couple of feet causing stress on the chains and also the hoses.
• Overloading: do not exceed the lift rating, also make sure the load conforms to the load center rating of the truck. Even if the load is under the weight specification, exceeding the load center creates an unsafe situation and excess strain on the chains.
• Correct attachments: there are several types of attachments for specific jobs to be done, each has its own set of specifications to follow. Attachments can provide a safer way to complete tasks and prevent excessive wear, in chains as well as the rest of the machine.

Also to be considered, OSHA has set limits to chain stretch per chain pitch (the distance between pins in a single link of chain). If you handle your maintenance in house, make sure your mechanics are measuring chain stretch on a regular basis. Simple chain wear testers can be ordered from your parts provider or local dealership. If you outsource your maintenance, the chains should be measured and inspected every service.

Here is an example of chain and master pin wear. The master pin was located on the top part of the mast, 16 feet up! This was not visible from the ground, or standing on the step to the cab and engine (Hyster H350B) The pin was still in place, just about to give out completely. Notice the rust and pitting, several links had become stiff and would not bend by hand.

Thanks for reading!

Tom Kassen