Left Hand or Right Hand? Here’s How to Tell, Every Time
If you’ve ever stood in front of a parts diagram, or if you’ve been on the phone with our team trying to figure out whether you need a left-hand or right-hand part, you’re in good company. It’s one of the most common questions we get, and it even trips up people who have worked in this industry for decades.
The good news: there’s one rule to help you get it right. Once you’ve got it down, it works the same way for every wear part we sell, from Terminator teeth and Cup Cutters to augers.
The Rule: Always Look From the Operator’s Seat
Left and right depend entirely on where you’re standing when you look at the part. Stand on the ground facing the machine, and your left is the machine’s right. Sit in the operator’s seat and look out over the boom toward the chain, and now your left matches the machine’s left.
That second view, sitting on the machine and looking forward over the boom toward the cutting assembly, is how we identify every part we sell. It’s the same convention we’ve used for more than 60 years, and it applies the same way whether you’re holding a tooth or an auger.
Not everyone in this industry uses that same convention, which is a big part of why mix-ups happen so often. We’ve even seen manufacturers inadvertently label the exact same part “left” on one order and “right” on the next. Needless to say, it’s hard to keep things straight.
Just remember, when you’re ordering from us, the operator’s seat view is the perspective to use every time.
Identifying Left and Right on Teeth
Our two most commonly ordered teeth, the Terminator tooth and the Cup Cutter, both follow this exact same logic.
Picture yourself sitting on the machine, looking out over the boom at the back of the chain. The cutting edge (the carbide bit on a Terminator, the scoop on a Cup Cutter) faces away from you, out toward the dirt. From that view:
- If the tooth tilts or tapers to your right, it’s a right-hand tooth, and it bolts to the right side of the chain.
- If it tilts to your left, it’s a left-hand tooth, and it bolts to the left side.
It’s a little like picking up a pair of scissors: there’s a side that’s sharp and a side that isn’t, and you have to know which is which before you use them. Hold your tooth or cutter the way it would sit on the machine, cutting edge pointing away from you, and the taper tells you everything you need to know.
One thing to watch for: if you set a left-hand and right-hand tooth side by side on a table, they can look backwards from what you would expect. That’s completely normal. Trust the operator’s-seat view, not how they look sitting next to each other.
Identifying Left and Right on Augers
Augers are a little harder to picture, but the rule doesn’t change. An auger isn’t a separate drill attachment, it’s part of the trencher itself, mounted at the bottom of the chain assembly near the machine. As the chain cuts down into the ground, the auger pulls the excavated dirt sideways, away from the trench, so the cut stays clear.
To tell whether an auger is left hand or right hand, look at either flat end and watch which way the flighting (the metal spiral) coils:
- If it coils clockwise, wrapping to the right as it moves away from you, it’s a right-hand auger.
- If it coils counterclockwise, wrapping to the left, it’s a left-hand auger.
Mounting follows the same logic as teeth: a right-hand auger goes on the right side of the machine, from the operator’s seat, and pulls material out to the right. A left-hand auger goes on the left and pulls material to the left.
This one matters more than it might seem. An auger on the wrong side doesn’t clear material away from the trench, it pushes material back into it. If a machine seems to be filling its own hole instead of digging it, a wrong-side auger is usually the culprit.
Still Not Sure?
Once you have the operator’s-seat rule down, it works for anything you order from us. But if you’re ever holding a part and second-guessing yourself, give us a call at 800-328-2424. We would rather help you get it right the first time than have you send a part back.
