A Common Thread

When you’re young, it doesn’t get much better than digging holes in
the backyard — the bigger the better. But once you grow up and you have
a business to run, what might once have been your favorite activity
loses its novelty pretty fast. All of a sudden, digging holes starts to
look more like what it really is — a whole lot of hard work.

The bulk of landscaping, construction and even agricultural
applications involves digging rows and rows of holes in the ground on a
regular basis. As such an important part of their daily operations,
contractors long ago began looking for easier and quicker ways to
get the holes in the ground — without doing what used to be the best

For years now, operators have found that fitting an auger attachment to
their favorite piece of compact equipment is often the best solution.
These auger implements can do wonders for a crew’s productivity in a
variety of environments — from confined construction and landscaping
work to agricultural and nursery situations. The tools provide a
perfect solution to digging the right sized holes in rapid succession,
whether it’s a series of small, precise postholes to set fence posts or
larger holes to plant trees, bushes and shrubs.

Auger attachments range in price from $900 to about $2,600 and are
relatively straightforward in design. But there are still a few key
points that potential customers should be familiar with before they
start digging on their next job — and maybe more importantly, before
they start digging into their pockets.

Digging In

Depending on the market, auger attachments are linked to a piece of
compact equipment in one of two ways — via the hydraulic system of a
skid steer, mini excavator, compact backhoe loader or compact utility
loader, or through the PTO (power take-off) shaft on a compact tractor.
This is determined by the inner working of the auger drive — the
gearbox that holds the bit, also called the “power head.”

A variety of auger power heads are designed with different methods of
reduction to accommodate wide ranges of applications and ground
conditions. The three main types of power heads include direct drive,
chain reduction drive and planetary drive. The most basic and
inexpensive types of power heads are called direct drives or PTO-driven
units, which use hydraulic drives with no external reduction.

“A direct drive [power head] is essentially a three-point unit designed
to run on a 540-rpm PTO shaft located at the back of a standard
tractor,” explains Ron Grimstad, product manager for CEAttachments
Inc., an attachment distributor out of Cedarburg, Wis. “A PTO driveline
connects the tractor PTO shaft to a gearbox and the auger hangs from
the output shaft. Those drives are catered to agricultural
applications, or some landscaping — where you don’t really have a lot
of holes to drill.”

Hydraulic auger drives (chain drives and planetary drives) are used
more by customers who dig holes as a business, using them much more
frequently to drill a variety of different hole sizes. Chain reduction
drives incorporate a simple sprocket and chain leading into the output
shaft. While they are the most economic option for a hydraulic
attachment carrier, chain drives also have their drawbacks. They are
typically more prone to stretching and since the drives run dry, the
chain and sprockets are subject to substantial wear. Typically, these
factors lead to increased maintenance down the road.

Planetary auger drives, on the other hand, are smaller, more compact
units, with the hydraulic motor operating through hydraulic oil
contained in the gearbox. Also, the gears on a planetary drive
typically last longer than a chain and sprocket. And in contrast to the
rectangular design of a chain drive, planetary drives are made with a
cylindrical case that usually fits inside the hole being bored,
providing a slight advantage in digging depth. Planetary drives are
seen as the more durable of the two auger drives, but they are also
more expensive — so manufacturers say there is a legitimate market for
both designs.

“Chain drives are really
made for the less-frequent user,” Grimstad says. “They are a little
lower cost and it’s also a good option for rental houses, because
maintenance on them is not as exacting. If you break a chain, it’s easy
to fix, whereas if you break a planetary gearbox, it’s more expensive
and more difficult to fix.”

according to manufacturers, which type of auger drive you choose really
depends on what type of customer you are. “If you’re a contractor who
makes your living with it, then you probably are going to want a
heavy-service planetary drive,” notes Alan Jones, sales manager for
Belltec Industries Inc., an auger drive manufacturer based in Belton,
Texas. “But if you just need to pop a few holes every now and then —
and it’s not something you are going to use on a daily basis — cost
will typically become more of a factor and you might start looking at a
chain-driven auger.”

Customers are also faced with balancing the amount of torque they need
with the speed at which the bit turns, which is measured in rpm. Both
torque and speed depend on the amount of reduction, which differs
slightly with every manufacturer. Inherently, augers require a tradeoff
between torque and bit speed — which comes down to what type of work
you are doing and how fast you need to do it.

“If you are in hard, rocky soils conditions, the slower you can spin
that bit with more power and pressure, the better and easier it is
going to be to get through those harder, rockier conditions,” notes
Mike Amerman, attachment product specialist for Bobcat Co. “If you have
a fast bit and you are just trying to spin it real fast with low
torque, that drive is going to stall out instantly in those types of
situations. Then it’s the responsibility of the [dealer] to recommend
the appropriate attachment for each type of situation.”

Auger Bits

Just as important as choosing the appropriate type of power head to fit
your needs, there is also a wide variety of auger bits available on the
market today. Auger bits range in size from 4 to 36 in. and in price
from $170 up to $900 for a standard auger bit, while prices can range
higher for heavy-duty carbide teeth, rock bits, etc.

“A standard auger bit will be a dual-flighted bit and will have
essentially flat cutting teeth with what is called a fishtail center
point, which are primarily used for removing soils,” explains Grimstad.
“Then if you have stratified rock — whether it’s shale or limestone —
you move to a rock and frost bit, which actually has carbide rock
teeth. The other obvious bit selection would be the tree and shrub —
which is usually a tapered, cone-shaped bit used for making sink holes
for plants.”

In tougher ground
conditions, most auger manufacturers supply two or three earth-style
bits, depending on the type of soil conditions. Rock bits are
essentially the same, but the teeth and the thickness of the flighting
vary. A standard rock bit has flighting that is 3/16- or 1/4-in. thick,
whereas heavier bits use flighting up to 3/8- to 1/2-in. Like anything
else, making sure you use the right tool for your application is
critical for success.

“The flighting is really the main difference between auger bits,
referring to how the angle or pitch of the flight changes to help drive
the auger into the earth,” explains Amerman. “For the most part, the
type of material and the thickness of the metal stays the same, whether
you have a light-duty bit or a rock bit. In addition, rock bits will
typically have carbide teeth on the bottom on the auger bit, which
allows them to get through different fragmented rock, softer asphalts
or harder soils.”

Manufacturers suggest you get a good idea of the ground conditions you
will be digging in, then ask your equipment dealer what types of bits
work best in those conditions. Oftentimes, an experienced dealer should
be able to match up the right bit specifications just by their
knowledge of the ground in your area.

“When a customer calls up from Louisiana, he’s not going to need the
heaviest-duty unit in the line,” notes Jones. “Bit-wise, you’re always
going to direct that

customer to a dirt auger, because a rock
auger is not what he needs. Now if someone calls in from west Texas,
Kansas or somewhere else that has a lot of rock, you immediately know
they are going to need the heavier-duty bit, because a light-duty unit
is not going to do the job or might not hold up.”

In addition to flighting, auger shoppers also need to know what kind of
shaft their auger drive unit accepts — round, hex or both. They also
need to determine the output shaft diameter, because there are a
multitude of diameters available on the market. Some manufacturers
offer 2- or 2 1/2-in. round or 2-in. hex. Hex bits make the auger ride
on the output shaft, rather than just the bolt. Round bolts place all
the torque directly onto the bolt, so some manufacturers say hex bits
can withstand more arduous use than a round-shafted bit.

“Typically, round drive bits tend to be less expensive” notes Grimstad.
“The hex drive tends to be for the guy who is going to be sinking a lot
more holes and is willing to pay a 10 or 15 percent premium for the
bits. The only thing keeping the bit from spinning on the shaft of a
round drive is a cross bolt. A hex drive functions like an Allen head
wrench stuck in a socket head screw, so it’s the hex that is making the
drive — not the cross bolt. The cross bolt is there just to hold the
bit onto the shaft, as opposed to transferring torque.”

Know Your Needs

When it comes down to it, choosing the right auger attachment is no
different than picking out any other tool for your business. “Determine
what areas you are going to be using the auger attachment — your
possible environments and surroundings,” suggests Amerman. “Today, you
might need a standard-duty bit, but down the road you might need more
torque, more speed or a completely different style of bit. So, just
knowing your potential uses and ground conditions can really pay off.”

And just as with any work tool, the most important part is matching
the auger attachment to the intended carrier machine and to the job
conditions. Manufacturers cannot stress enough the importance of
matching the hydraulic flow of your auger attachment with the intended
tool carrier. On the outside, many auger drives are essentially
identical. And it doesn’t matter whether you want to use a skid steer,
backhoe loader, excavator, compact track loader or tractor — the volume
of the motor must match up with the available flow of the machine.

Auger attachments are grouped by flow range to correspond to the
appropriate carrier — from 15 up to 35 or 40 gallons per minute (gpm).
According to manufacturers, operators should never try to get more out
of a 10-gpm power head, for example, by hooking it up to a skid steer
that produces a 35-gpm flow. While this might be an exaggerated
hypothetical, it does demonstrate the importance of knowing your
equipment, your application and your environment.

“In certain
instances, customers are going to need high torque and low speed —
especially if they are going to have a large auger in very hard digging
applications,” says Jones. “But if you are looking at smaller diameter
holes in easy-digging dirt, then speed becomes a more valuable tool
than torque. Overall, the best advice you can give a customer is to get
the right tool for the job. If a guy is only going to dig five
postholes, then he really doesn’t need to buy anything too heavy-duty.”


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