If trenching is a significant part of your business, you understand the benefits — and challenges — associated with purchasing a used trencher. A quality, low-hour used machine has definite advantages over the cost of a new model.
“A used trencher can have plenty of useful life even if it doesn’t look brand new,” says Matt Collins, trencher product manager, the Ditch Witch organization. “There are used trenchers working very effectively in the field with dings, dents, scratches and bad paint. The success of these used machines is due to a strong engine and a properly maintained working end.”
However, when purchasing a used trencher, there are precautions you should take to ensure the machine you buy has sufficient life to last well into the future.
Start with a Working End Walk-around
“There is a long checklist of items to inspect when evaluating a used trencher for purchase,” says Jon Kuyers, global product manager for the underground business segment of Vermeer Corp. “It’s always wise to start at the tip of the trencher boom and work through to the engine.”
Looking at the boom tip, Kuyers recommends moving the end idler from side to side to assess any wear on the bearings. The end idler can often be tightened, but if not, it’s time to replace the bearings.
From there, check the main part of the boom. Look at the wear strips on both ends. (Many are reversible, depending on the size of the trencher.) If wear strips show significant wear, they will need to be replaced. If the wear strips are worn through, Kuyers says there will be bigger problems down the road.
Check the boom itself. If there is significant wear on one side of the boom or the other, the entire boom assembly could be bent. This happens when operators engage in a tight radial turn while digging in hard material at shallow depths, Kuyers explains.
Digging in rocky ground or frost with a trencher that has not been properly maintained can cause the head shaft pivot to wear out. Inspect the bushing in the pivot. If it needs to be replaced or if the bushing has worn through, it will lead to greater problems with the pivot area in the future.
Moving closer to the tractor, inspect the auger sprocket and bearings. The auger sprocket teeth are typically square shaped. If the auger teeth are worn to a fine point, the sprocket could be damaging the digging chain and will need to be replaced.
Look to see if the augers are rolled over. Do they show excessive wear? Can you run the chain smoothly? Is there any oblong movement? If so, the auger shaft could be bent, which could lead to bearing failure.
With the machine turned off, move the auger in a side-to-side motion. If there is a lot of play when you pull or push the auger, the bearings are worn significantly and will need to be replaced, says Kuyers.
From the auger point, evaluate the main head shaft sprocket. If it shows wear, it will need to be replaced.
Check the Chain and Teeth
The next area to inspect is the digging chain. Inspect the teeth for excessive wear.
“There is no doubt that all the ground-engaging parts of a trencher are a large expense of the machine,” says Bob Wren, Toro trencher product specialist. “Digging teeth need to be replaced from time to time. It takes horsepower to run the digging chain. Working with worn teeth slows production and is not cost effective.”
Move the chain from side to side (not front to back) and watch for snaking in the chain. If the boom is at maximum chain adjustment and the chain still sags significantly, replacement will be required.
Also inspect the chain rollers. “A good indicator of the wear on a chain can be found by inspecting the condition of the rollers on the chain and any wear to the side bars of the chain,” Wren points out.
“Check for significant wear on the sidebars of the chain where it pivots around the end roller and the sprocket,” says Kuyers. “If more of a radius appears than a straight edge on the bottom of the chain, there has been significant wear on that chain. The rollers should be round and cylindrical. If they show wear like an hour glass, it’s only a matter of time before the chain fails.”