Most operator manuals offer recommendations for chain tension. However, according to Kenkel, as a general rule proper tension for small pedestrian machines is a couple of fingers between the boom and chain when the boom is horizontal to the ground. For 30- to 80-hp ride-on trenchers, proper tension is about three fingers between the boom and chain. For 80- to 120-hp machines, it’s a solid three fingers.
Repair vs. Replacement
It’s also important to know when to replace worn teeth and chains.
“Continuing to run a trencher with worn teeth only puts wear and tear on the rest of the trencher and eventually leads to costly, yet avoidable, repairs,” says Whitaker.
While it’s virtually impossible to dictate the number of hours at which teeth need to be changed, it’s important that teeth be changed any time they are broken, or when you start to experience lost productivity. Teeth with excessive or uneven wear should also be replaced.
When you check the teeth, also check for loose bolts and replace as necessary. In the case of a rock and frost chain, be sure the carbide bits are turning freely so they won’t cause premature wear to the tooth or sprockets.
Monitor sprocket wear and replace as needed. “Never put a new chain on worn sprockets because this will wear out a new chain before its time,” says Whitaker. “And if you have sprockets with greasable bearings, lube them at the intervals suggested by the manufacturer.”
Also check channel and rock booms for wear and replace if necessary. You’ll know it’s time to replace channel bars when grooves begin to develop. Some manufacturers have wear bars on rock booms that are reversible, effectively doubling the bar’s life.
“The most important step is to be observant,” says Whitaker. “Monitor digging components on the machine and follow the maintenance and adjustment guides provided by the manufacturer. This will add life to components and the overall machine.”
The Need for Speed
Proper operation is also important to help achieve maximum life from a trencher and its digging components.
“Try to find the sweet spot between ground speed and chain speed,” says Brian Kenkel at Vermeer. “You want to get the most footage forward with the least amount of chain speed. That will extend chain life because every time the chain runs around, it wears. A lot of times you can actually slow down your chain and get better footage.”
“By adjusting the ground drive and chain line speeds you’ll get the most productivity out of the trencher, experience less downtime, prevent undue and potentially costly repairs and allow the trencher to perform in the most efficient manner,” adds George Whitaker at Case Construction.