college of engineering white

Project 8: Horse Therapy Model


The main goal of this project is to provide an interactive and instructional display of a horse’s digestive for Manna’s Hana riding center.  They are a non-profit organization that provides recreational riding for children with special needs.  They are wanting this display so that children of all ages can not only learn about riding horse’s, but also to learn about the horses and their bodily functions.

Wyatt Sauder, Brett Lingerfelt, Jacob Guy, and Bryce Duncan

Problem Statement

Manna’s Hana riding center does not have an interactive horse display to use for educational purposes and they are needing one to include in their learning experience.  They are wanting a display that is relatively life size, and works for all ages and shows each step of the digestive system while also allowing kids to move fake food and waste physically through the model/display.

Design Specifications

  • Lightweight
  • Weatherproof
  • Safe
  • Interactive
  • Detailed
  • Informative
  • Ability to be hung on a horse stall wall
  • Works easily
  • Transportable

Background Research

The owners of Manna’s Hana riding center were gracious enough to lend us a book that includes a detailed explanation of horse organs and their functions.  The book also includes photos of each organ.  We will primarily use the book to provide a detailed and informative model for the children.

Concept Design 1

The concept design shows all steps of horse digestion.  In this design chewing is shown by an interactive hinged jaw.  Then the fake food is dropped in from the top of the display where the one way valve is shown in the esophagus (rubber tube).  The food exits at the bottom so it can be reused.  The stomach is interactive by the use of a primer hand pump to show the digestion in the stomach taking place.  Then fake waste enters the display from the top and exits the model at the bottom through the rectum (rubber tube).  Both waste and food processes use gravity to show the steps of digestion.  The horse body will be made out of plywood and the organs will be protected by a clear hard plastic layer for weather proofing purposes.

Concept Design 2

This concept design shows all of a horse’s digestion system displayed by a pneumatic process.  The horse’s body will be built out of plywood for which can easily be hung on a barn stall.  There will be a Plexiglass panel on hinges which is see-through, for when the user operates the model.  Therefore, the model/display can be opened and closed.  As for the model being interactive, there will be a foot pump for both the food and waste.  The user will repeatedly step on the pump to watch the food/waste travel through a clear hose throughout the body.   Therefore, the food will be placed into the horse’s mouth for which it will travel through the esophagus, making its way into the stomach.  When the food goes through its final stage (small intestine), it will fall into the bottom of the model, hidden from the view of the user.  As for the waste, it will start at the large colon and will travel its way through the small colon and finally through the rectum.  Once at the end of the rectum state, it will fall onto the ground.  The process will be repeatable as long as the food/waste are placed back into their starting positions.  The food and waste will be fake, therefore they will have to be 3-D printed to match their appropriate applications.  The horse will have legs, because a horse with no legs is like a horse with a broke leg.

Concept Design 3

This concept design shows the steps of a horse’s digestive system with real life statistics of the organs used. All of the organs and other body parts will be attached to a flat, 2-D model of a horse that will be cut out of plywood. A frame will be made out of wood and placed around the outer borders of the horse to weather proof the design. A clear face plate will be attached to the frame with a hinge to allow for maintenance and clear visibility of the digestive process. The design will consist of an esophagus made out of a track powered by a hand crank. This will be the entrance of the “food” or small spherical object. Once the kids have “fed” the horse, the object will travel down the esophagus tubing into the stomach, which will be a 3-D model of an actual horses stomach. With appropriate sloping, the food will travel from the stomach to the small intestine, then to the cecum, then to both the small and large colon and finally landing on a small platform. Once on the platform, the kids will be able to perform an action, whether it be a lifting slider or another crank gear that will lift the food from the colon to the rectum where the food will be held stationary. Afterwards, the user will be able to lift the tail of the horse, which will be attached to a hinge mounted to the backplate plywood frame of the horse. Once the tail is lifted, the food will be dropped into a catch tray below the tail and rectum. The model will not consist of legs to save space and weight for mounting the model.

Selected Concept Design

Both concept design 2 and 3 are in consideration and aspects of both are going to be used in the final product. Either way the frame/overall body of the model will be the same.

Decision Matrix

Overview of Selected Design

We chose concept design 2 as our selected final design. We may incorporate parts from concept designs 1 and 3. We chose this design based off the score the design had in the decision matrix. We also chose it because of the functionality and practicality of the design.

Describe Design Details

The design has two pumps to achieve the pneumatic process of the model.  Therefore, we will be controlling the air pressure in a way that is very similar to how bicycle pumps work to achieve stable air pressure.  The main body of the horse will be made out of plywood which will provide a great support system for the internal organs.  The air will be traveling through two different rubber hoses, each connected to a pump. This will make the design a well interactive and learning model that has a two step process.  There will be a total of four organs inside of the “shadow box” shell, which will provide a safe place for the organs to be mounted whether that be glue or bolted down.  While, the entire model will be hung on a barn stall by two U-bolts.  The model will display a physical and visual process of how the horse digestion system works.

Engineering Analysis 1

Drew a free body diagram of the model hanging from the stall wall. Conducted a force balance analysis and found the reaction force on each hanger to be 25 lbs. One important assumption is the model is estimated to have a max weight of 50 lbs.

Engineering Analysis 3

The last analysis for the project was a mobility analysis for the pump. Since the pump only allowed translation, it had 1 DOF. See the image for Gruebler’s equation.

CAD Drawings

Bill of Materials

Document Fabrication Process

Lathe: Used the lathe to create the mock “food” to run through the tubing (insides) of the horse model.

Water Jet: Used the water jet to cut the pieces of the horse that were then screwed together to create a cross sectional 3-D view.

Additive Manufacturing: Used the 3-D printers in the fabrication lab to turn the 3-D modeled horse organs into actual pieces to be inserted into the cavity of the horse.

Miscellaneous: We went to Highland Hardware to create an adapter for the bicycle pump so the pump could pressurize the tubing system and therefore move the “food” through the organs in the cavity of the horse.

Note: Pictures of sanding and painting are also included

Testing Results

We conducted testing making sure that our adapter for the pump worked to build pressure in the tubing system so the “food” could be moved through the cavity. There was also trial and error testing done on the organs to see how they would fit in the cavity and how to move the tubing system through the cavity while the organs where in place to ensure that the “food” could move freely.

Completed Design Photos

Instructions for Safe Use

  • Ensure the horse is correctly hung to the stall wall so the model does not fall
  • When pumping the food make sure the food exits in a safe direction so no one gets hit by the projectile
  • Do not build up unnecessary pressure in the system as this will cause the food to exit the model in a violent fashion
  • Use care when touching the organs so that they are not damaged
  • Ensure the adapter and hose a firmly seated together so the hose does not disconnect from the adapter

Project Summary/Reflection

We thank Jeff Randolph, Chris Mills, Dr. Stephen Canfield, and the Department of Mechanical Engineering for their support on this project.


2023 Spring