This model is a functional miniature of a pumpjack, often referred to as a “nodding donkey”, commonly used in oil extraction.

The design focuses on clearly demonstrating the mechanical principle behind the system: converting rotational motion into an up-and-down movement using a crank and linkage mechanism. This makes it particularly suitable as an educational model for engineering students or anyone interested in mechanical systems.

The model is optimized for 3D printing and assembly:

• Designed with standard FDM printers in mind
• Minimal supports required
• Easy assembly with clear mechanical visibility
• Moving parts included for realistic motion

Required hardware:

• 10× M3x12 bolts (DIN 912)
• 12× M3 nuts
• 4× M3 washers
• 2× M3x20 bolts (DIN 912)
• 3× M4x16 pins
• 1× M4x20 pin
• 1× M4x32 pin
• 3x M4x8x6 bushing (optional but recommended) 

The M4 pins can optionally be replaced by a custom-cut wooden dowel of matching diameter.

Printing instructions:

• All parts can be printed without supports
• Use 2–3 walls
• 15% infill is sufficient

If your printer struggles with angled overhangs, the tower can be split into 5 separate parts and glued together after printing.

Assembly notes:

• M3x20 bolts (DIN 912) are used for the drive mechanism
• M3x12 bolts (DIN 912) are used for the handles and base connections
• The M4x32 pin connects the drive mechanism to the beam
• The M4x20 pin connects the beam to the tower
• The M4x16 pins are used for the remaining connections

For each nut, a dedicated hexagonal slot is provided in the model.
Washers are used where no spacer/leg is present and on the drive mechanism.
Bushings are used in the beam for better movement.

Use cases:

• Educational demonstrations (mechanics / kinematics)
• STEM projects
• Desk model or conversation piece

Tips:

• Use PLA for easy printing
• Ensure good tolerances for moving parts
• Light sanding may improve motion
• You can find seperate parts and print profiles for the tower and the Beam
  (Tower printed as 1 part instead of 5 parts / Beam without bushings)

Attention:

I am still working on improving this model, so any feedback, ideas, or suggestions are more than welcome and greatly appreciated.

This design was created as part of a school assignment, using the standard hardware components that were available to me. However, I am open to modifying the design to accommodate different types of hardware if needed.

In the future, I would also like to add a motor mount and possibly even make the pump functional by integrating a valve and a matching piston system.