| August 01, 2010
How to inspect a used rubber-tire trencher
Rubber-tired trencher inspections are straightforward affairs, with little of the complications seen in other machine types.
By Marcia Gruver Doyle
“We usually see 200 to 250 hours a year on a machine this size,” says Steve Howard, used equipment manager, Vermeer Southeast Sales & Service, Birmingham, Alabama. Our inspection machine, a 1999 Vermeer V-5750, was low on that scale, clocking in at 855 hours. “Utility users tend to put fewer hours on a machine than contractors,” Howard explains.
Contractors typically interested in this size and age of trencher do short runs and small jobs, such as plumbing or irrigation work. “They can get good value – this machine would cost about $7,500 compared to a $40,000 new trencher – and it will last them a long time,” Howard says.
Key inspections points include:
Engine: Perhaps because our 57-horsepower inspection machine had such low hours, Howard didn’t see anything in this area that concerned him. He looks for paint discoloration, especially on the engine head, which could tell the story of an engine overheating. If the engine is water cooled, he also suggests inspecting the radiator fins for damage. In addition, he highly recommends pulling an oil sample. “It’s inexpensive and it will give you a good idea of what’s been happening,” he says.
Hydraulics: Most of today’s trenchers are hydrostatic, with hydraulic pumps running the motors for both the ground and trencher drives. Howard recommends cranking the machine up and checking hydraulic pressures by putting a test gauge on the hydraulic test ports, then deadheading each system. And pull another oil sample. “You can’t just look at the trencher motor, for example, and determine the condition,” Howard says. “You’ve got to do the oil sample and pressure test.”
Operational checks: While the machine is running, make sure the hour meter is running properly and the alternator’s charging. Put it in forward and reverse to observe how it tracks and steers. Operate the trencher, and see if you can trench with it. Engage the chain, observe how it runs on the sprockets and idlers and make sure it’s not loose. Listen for any skips – the chain should run smoothly and a skip could indicate a sprocket problem or bad chain link. Run the chain in forward and reverse. Lower the boom and pick up the back end of the trencher about 6 inches, looking for play in the pivot rings as they take on the weight of the machine.
If you don’t have the time to check out a machine in question, Howard suggests hiring a local mechanic to thoroughly put a machine through its paces. Also check with your dealer buddies and other contractors – because of reported problems, certain makes and models may not have the resale value the buyer is asking.
Trencher: This is what Howard calls “the money end.” Look at the drive sprocket, noting any wear that would require replacement. The chain on our inspection machine had more age than wear – the teeth were badly pitted, and the rollers had a great deal of rust and corrosion. “I would plan on replacing this chain sometime in the near future,” Howard says.
Since it’s in the ground during trenching work, examine the end roller bearing looking for regular greasing, and the absence of excessive wear or damage. Check the auger drive and chain drive sprocket: are they tight and in good shape, with no hydraulic oil leaks visible? Sprocket teeth should have smooth edges – when they start to sharpen, it’s a sign of wear.
Frame: Trenchers this size usually don’t show stress fractures. Adverse digging conditions, however, could shear off bolts, and cause cracks. These stresses are more typical in plowing applications, which require the machine’s tractive effort to pull the heavy weight. A trencher plow attachment’s shaker – which vibrates to help pull it through the ground – also puts additional stress on the rear mounting. Another potential stress area to note is where the backhoe mounts at the front of the machine.
Backfill blade: Most trenchers of this size come with a 6-way backfill blade. Since operators sometime use the blade to push more than it’s designed for, look for stress fractures where the blade mounts to the tractor frame. Inspect the grader – or bottom edge – of the blade. Also note any dings and dents – since trenchers this size are typically equipped with a front-end backhoe, the blade sometimes takes a lot of abuse from too-quick swings. Even a badly banged up blade, though, will still be useful and is usually repaired instead of replaced.
Backhoe: (Note: Since our Vermeer inspection machine did not have a backhoe, we used a slightly smaller 2000 Case 460 trencher with 1,200 hours to go over backhoe inspection items.) Get into the backhoe operator seat and lower the boom to the ground, checking the center pivot by slowly touching the bucket to the ground and observing how much slack you get when it actually starts lifting the tractor off the ground. Run the backhoe through all basic functions – swing left and right, move the boom up and down, and the stick in and out, etc. Look for slack at any pivot or pin point, including the center pivot, and whether there’s any sway in the backhoe after it stops. Check the bucket and note if any teeth need replacing. Lower the stabilizers, observing the degree of movement once each one reaches the ground, which will indicate how tightly the backhoe is mounted to the frame.
Cosmetics: Scrapes, dents and dings are all part of a trencher’s workaday world. It’s up to you whether it’s important the used machine you buy resembles a just-off-the-assembly-line unit. Because of the amount of shielding on a trencher, a paint job can be a time consuming and moderately expensive wish list item – perhaps worth it on a two- or three-year-old model, but questionable in older units such as our inspection machine. EW
Go along with Howard as he points out critical inspection areas on our digital edition, EquipmentWorldDigital.com.
Serial number: _________________________________________
Tire/Track condition (percent of life left):
Hydraulic/hydrostatic system condition:___________________________
Transmission/gearbox condition: ___________________________________
Ground drive condition: ____________________________________________
Paint and shielding condition:________________________________________
Digging depth: ______________________________________
End idler diameter: _________________________________________
Chain style and size:___________________________________________
Cutter style and width:___________________________________________
Trencher drive motor/gearbox condition: _________________________________
Digging chain condition:__________________________________________
Sprockets, bearings and wearstrips condition:_______________________________
Bucket condition: ________________________________________________
Pins and bushings condition:__________________________________________
Condition of any other attachments:________________________________________