a homemade utility vehicle with hydraulic dump

[dfkrug]

Most recent automotive PS pumps, as well as other accessories, use multi-rib belts
instead of V-belts. This has been true since about 1990, and adapting my new pump
to the old Samurai required a dual-belt crank pulley. I decided it was a bit easier
to make a hybrid pulley, versus changing my pump over from multi-rib to V-belt.

So, I cut and welded a mult-rib pulley to the V-belt crank pully. I used a lathe to
make sure they welded up accurately (photo #1).

Making the bracket for this small pump was the toughest part of the whole project.
Photos #2 and #3 are the mounted result.

For a reservoir, I could have purchased numerous PS units, but I wanted a bit more
volume, so I made one from a 4-inch pipe. The breather is a filter sold for valve
covers, and the fill cap is a leftover Stihl chainsaw fuel cap (photo #4).

 

[dfkrug]

You got that right... I'm kind of spoiled because in a wet year there are
many places I just can't go.

This year not once has rain or wet ground been an issue...

Yeah, normal rainfall here is 60+ inches, measured July 1 to June 30. Last season we
got only 36 inches total, which is the lowest I have ever measured (in 18 y).

I don't like to dig dry dirt if I don't have to. Much harder to dig with the rocks I have,
and it blows all over when you dump loads out of the FEL or hoe bkt. To add to
the problems, the placed dirt does not compact properly when too dry.

So I wait for the first significant rains in the fall, or dig in the spring when the ground
is still damp, but no longer saturated (winter).

Thx for looking.

 

[dfkrug]

Here's my Weber carb and manifold. It has a water-heated auto choke. I got
it used and one part was bad, but the new part was cheap and readily available.

Ignore the sloppy redneck wiring....it's temporary. It starts and charges; that's
all I need now. The original alternator got "borrowed" away for a JD tractor....a
perfect fit, BTW.

 

[Xfaxman]

What size cylinder will you use? With your small dump bed pressure may not be a problem, but the 3 gpm flow rate will make it a slow dumper.

 

[dfkrug]

For a valve, I used a monoblock open-center single spool unit I had lying
around (photo# 1).

The cylinder was another recycle. It's a long stroke single-acting cylinder that
came with my PTO mixer, and I later converted to double-acting. I definitely
wanted a DA cylinder for positive down force. I also did not want to buy another
cylinder if I did not have to. So, in designing around this cylinder, I did not
pick an ideal one. Stroke is near-perfect, but I would not mind a little slower
action. ID is 1.55", which puts out plenty of force. A 2" ID would have slowed
things a bit. A telescoping cylinder would have been great.

Reinforcements were made to the box's cross-beams, and the Samurai frame.
A may add more stiffness to the crossmember.

Calculations and a video to follow.

 

[David Devuono]

Interesting and timely thread. I never got a reasonable offer for my `1999 Grand Vitara so I halled it to camp last weekend. Its fully running with a V6 and auto tranny + plus I have a parts GV. Anyway I am planning the same thing. Only I have more wheelbase on the GV and body mounts behind the front doors so I will leave it alone from the door pillars forward and cut the back off. I may initially use an electric winch to dump and with the dump bed extending past the rear a bit it should not require as much to dump the box.

 

[dfkrug]

I may initially use an electric winch to dump and with the dump bed
extending past the rear a bit it should not require as much to dump the box.

Yes, extending the box past the rear will reduce lifting force requirements significantly. I will show
the calcs I used soon.

As for using an electric winch, as often used on quads for a snow plow, that can work, if you
can live with gravity down. I have a cheapo $50 HF winch on the trailer that I transported the dead
Samurai in. With a pulley to double the winch force, that could be a viable option, and the force
reduction will slow things down nicely. It will also reduce the collossal current these winches draw.

Here are some pix of the dump box pivot I made. I used 0.750" ID DOM tubing and 3/4" pins. I
beefed up the rear of the frame by closing off the open end. Clevis-type mounts and fully-wrapped
weldments will allow this to handle a lot of force. The long rod (pipe) was used to align the
pivots before they were welded.

 

[dfkrug]

Here is a drawing of the dump bed and cylinder.

'z' is the overhang distance from the PIVOT. I need to figure out what upward
force (Fi) my cylinder can exert when the bed is down. This is the position where
the greatest force is required.

I am designing the hydraulics backwards, since I have a cylinder that I want to
use. Normal engineering design would call for figuring the reactive force (Fn) first,
then designing the hydraulics (pump and cylinder) to meet the forces required
to lift the load I specify.

Geometrically, I can simplify the model of the dump box weight by concentrating
the equivalent downward force on the center-of-gravity (c.g.) where shown. The
overhang is balanced by and equal and opposite weight, which cancel out. I am
left with the forward, unbalanced weight. The c.g. point is halfway between the
front of the box and a position 'z' distance from the pivot. The drawing is not
to scale; 2z is more than 2/3 of my overall box length. I ignored the additional
weights of the gate and front panel of the box.

 

[dfkrug]

Next, I needed to find the angle (theta) of the cylinder when the bed is down, so
I can calculate the induced upward force, Fi.

With a little trig, and the measured horizontal and vertical distances, Dh and Dv, I
can now get the angle, and calculate Fi.

Once I have the angle theta, and the cylinder force, Fc, I can get the induced upward
force, Fi.

For my cylinder with 1.55" ID, and an estimated pressure, P, of 1500psi, I get
Fc = pi x (r-sqd) x P = 2830#. Fi = Fc x sin(theta) = 1240#

 

[dfkrug]

I am not done yet.

Here is a "free-body diagram" of the forces involved, and how they act. The cylinder
exerts upward force on its pin (Fi), and that exerts a moment about the bed PIVOT.

The dump box and materials it contains exert downward (normal) force equivalent to Fn
thru the c.g., causing a downward moment about the bed PIVOT.

The design goal is for the upward moment (Fi x d2) to be greater than the downward
moment, (Fn x d1).

Using the calculated induced upward force, Fi, and measuring the distances, d2 and d1,
I find that my cylinder can lift as much as Fi x d2/d1 = 774#.

Since my goal was to be able to handle as much as a ton with my dump box, and the
overhang distance 'z' is greater than 1/3 of the total length of the box, I should easily
exceed that capability.

I have posted a video on Youtube, but I have yet to try a full load of damp dirt/rocks.
Suzuki Samurai dumptruck - YouTube