PhysicsGuy
Fascinating Ideas, Tried and True
Harbor Freight Backhoe
The Harbor Freight backhoe/trencher is a great technology that has evolved over time. It doesn't have the weight that traditional backhoes
have, so the force the bucket exerts on the ground depends on
it's two front black stabilizers. Once these are planted firmly
with the teeth planted in the ground as shown below, the backhoe works
amazingly well. The
basic modifications discussed here further improve its performance.
Towing
this baby backhoe requires removing the front stabilizers and moving
the back wheels to the front. Unfortunately there is no good place to
store the four somewhat heavy components of the stabilizers on the
backhoe. Alternatively, one can move the backhoe with the stabilizers
in place by using the bucket and boom to lift the stabilizers off the
ground and inching the backhoe forward or backward. While this does
work, the distance of the stabilizers to the ground requires short
steps and the sharp points at the ends of the stabilizers can damage
parking lots and garage floors. One solution is to flip the
stabilizers so that the points face upward. Retracting the stabilizers
backwards through the square tubes also allows bigger steps to be made.
Another solution is to add wheels as
shown below. This has the additional advantages of
being able to move the baby backhoe by hand in a garage or parking lot,
and allows it to be loaded easily onto a trailer for transport on
public roads. Although the backhoe has a towing hitch, it is not
adequate for towing the backhoe on public roadways since the wheels are not rated for high speed roads. So a trailer is needed
along with some way of loading and unloading the backhoe.
So
I added two 2X10 ramps to my Glastron Boat trailer as shown above. I also added four
front wheels. Each wheel is rated at 300 lbs for a total allowable load
of 1200 lbs. The backhoe without stabilizers weighs about 1000 pounds.The wheels are spaced to match the distance between
the ramps on my trailer. Note the upper part of the stabilizers remains in place and
are used to support the wheels. The wheels are mounted on short
4X4 pressure treated post wood and attached with four threaded rods
and brackets. For this prototype no permanent changes like welded
joints were made or needed. If the prototype didn't work, I wanted to
be able to revert the backhoe back to its original condition. The wheel
height is just enough to allow the stabilizers to ride above ground
when fully retracted and with the points facing upward. That way the
stabilizers can be moved with the backhoe. To minimize the weight and
due to clearance issues, I did remove the stabilizers in the above
picture and placed them in the back of my SUV for towing. I also
removed the seat and placed it in the SUV.
Note the added ramps on this trailer
have no effect on using the trailer for loading, unloading and towing
my boat. My boat sits in the middle of the trailer without touching the
ramps. Note also that the wheel distance on the backhoe might have to
be adjusted to match the distance between the ramps. This is not a
major issue because both the front and back wheels can slide in or out
on their square steel tubes.
The above picture also shows the
thumb, the two long steel shank teeth near the bucket, I added to the backhoe. I've used this thumb to pick up timbers and
logs, stumps and even medium size rocks. It has almost no effect on the
backhoe's ability to dig, so I just leave it in place. It is made with
two pieces of 3/4" plywood, a short piece of a 4X4 post, four large
bolts, two half-inch steel brackets, two turnbuckles, and two 18" box blade shanks. The total cost was about $65. For this prototype no permanent changes like welded joints were made or needed.
Securing the backhoe to the trailer:
A
unique design advantage of this approach is the center of gravity of the backhoe on
the trailer is low and slightly in front of the trailer wheels. It rides very smoothly since the boom is
low and nothing is bouncing. I sometimes forget it is there when I am towing it with my Ford Escape. I would take this backhoe on this trailer to California
and back to Maine if needed. By the way, don't forget to turn off the gas to the
carburetor when towing the backhoe or any tractor on a trailer. The float valve in the carburetor will
bounce on the road and could flood the engine. I learned that the hard way.
The bucket above rests
nicely on the winch post. I also tie the bucket down with a rope as a safety precaution. I
drilled two 3/4" holes straight through the two 4X4 posts used for the
front wheels, and directly through the bottom ramp. I pass two long bolts
through these holes to tightly anchor down the backhoe. I also use two
tie-downs straps as shown to secure the back of the backhoe. You can see the 4X4 with a bolt in it in the above picture, just to the right of the left trailer wheel.
Unloading the backhoe:
The
center of gravity of the backhoe is controllable by moving the boom and
bucket forward or backward. At the right position, the four front
wheels are holding all of
the weight of the backhoe. This allows the backhoe to be tipped easily
forward or backward, and allows it to be moved on a flat surface like
that of a garage floor or a parking lot. The back of the 4X4 acts as a
brake on the ramps as can be seen in the picture above. To move the
backhoe on the trailer, the back of the backhoe has to lifted slightly
so that the 4X4
does not touch the ramp. The boat winch strap is
used to safely control the position of the backhoe.
A simple 2X10
board in the center of the trailer placed in the middle of the trailer is used for pushing the front wheels off the trailer and
inching them off of the trailer with the bucket. You can see the 2X10 tied down to two boat struts with a white rope in the third picture on this page. The above picture shows the bucket
resting on this board, and pushing down so that the front wheels are
off of the ramps. Extending the boom and bucket slides the backhoe
backwards on its two back wheels. When the front wheels are completely
off the trailer, raising the boom and bucket will lower the front
wheels onto the ground. Loading the backhoe onto the trailer is
basically the reverse of these unloading steps.