STEM Education Series
Pump Jack
A working model of an oil pump jack. A motor turns a crank, the crank nods a beam, and the beam drives a syringe pump with two one-way valves that lifts water out of a cup and up a tube. It keeps pumping as long as the switch is on.
Real wells cannot be drunk through a straw -- atmospheric pressure gives out at about thirty feet and the oil is thousands of feet down. So the nodding beam sends a rod to the bottom and lifts the oil in stages, one valve letting it in and another refusing to let it fall back. These machines are called nodding donkeys, some stand ninety feet tall, and some have run without stopping for fifty years.
Pump Jack
The Big Idea
A motor turns a crank, the crank nods a beam, and the beam works a syringe pump that lifts real water out of a cup. It is an oil well with the dirt taken away.
- Ages
- 10+10+ with an adult, and the adult has a specific job: the wiring step calls for a lighter to shrink the tubing over a joint. Everything after that is screws and fitting tubes.
- Build time
- About an hour and a half
- Engineering
- Mechanical Design
- Circuitry
- Problem Solving
Safety
- Contains small parts. Not suitable for children under 6. Adult supervision is recommended.
- The build requires a lighter to shrink tubing over a wire joint. That step belongs to an adult, not a child.
- It pumps water, so build and run it somewhere a spill will not matter.
What’s in the Kit
- Numbered laser-cut plates for the base, frame and beam
- TT motor with a crank plate
- Syringe pump with a tee fitting
- Two one-way check valves
- Transparent tubing, cut to length during the build
- Iron shafts, fixing rings and a punch shaft
- Battery box with a rocker switch and heat-shrink tubing
- Plastic cup and cable ties
- Illustrated instruction guide
What you add
- AA batteries
- A small Phillips screwdriver
- Scissors
- A lighter, for the heat-shrink tubing, to be used by an adult
- Water
Real-world connection
How do you get oil out of the ground?
You do not suck it up. A straw only works because the air above pushes the liquid into the space you make, and atmospheric pressure runs out of strength at about thirty feet. Oil wells are thousands of feet deep. So nothing drinks the oil out of the ground; something has to go down and lift it.
That is what the nodding beam is doing. A motor turns a crank, the crank converts turning into rocking, and the rocking drives a rod straight down the well to a plunger at the bottom. The plunger goes down past the oil, a one-way valve lets oil in above it, and then the plunger rises and carries that column up while the valve holds it from falling back. Nod after nod, the oil climbs in stages. The two check valves in this kit are doing exactly that job: one lets water in, the other refuses to let it back out, and between them the syringe can only move water one direction no matter which way it is being pushed.
The machines themselves are called nodding donkeys and they have been doing this for over a century. Some stand ninety feet tall, some have run continuously for fifty years, and they persist not because they are efficient but because they are simple enough to keep running in a field with almost no attention. Newer ones are wired into monitoring systems that watch load and pressure and call for maintenance before something breaks, which is a very modern answer bolted onto a very old machine.
The build
-
Wire the switch
Battery box wires join the rocker switch, heat-shrink tubing slides over the joint, and an adult shrinks it down with a lighter.
-
Mount the motor
The TT motor clamps between two numbered plates, and the guide warns that reversing the wires reverses the rotation.
-
Build the frame and beam
Plates stack into a base and a support frame, then iron shafts and fixing rings carry the beam, each ring left about a millimeter clear so nothing binds.
-
Plumb the pump
Tubing is cut to length, the tee goes on the syringe, and the two check valves fit on either side, facing the right way or no water moves at all.
-
Fill and run
The cup goes in its slot, the inlet valve goes in the cup, batteries in, switch on, and the beam starts nodding water up the tube.
For classrooms
One kit builds one pump jack and this is a long build, close to the Sorting Machine and the Remote Solar Car at the top of the range. Plan two sessions, and plan who holds the lighter. There is exactly one step that needs a flame and it belongs to an adult; everything else is screws, shafts and tubing.
Running it is wet, so set it up on a tray or near a sink and keep a towel per table. The payoff is that this is the only kit in the series that moves a real material rather than just moving itself. It lifts water out of a cup and keeps lifting it, and that is a more convincing demonstration of what a machine does for a living than a thing that drives across the floor. Nothing is consumed but the batteries.
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