Dick Roosenberg, April 2016
To encourage sustainability and soil improvement, Tillers is working on tools to facilitate the use of compost/manure. Distributing manure with a calabash or old wash basin is hard, slow, and undignified. Working out options in tools to ease the task is a design challenge that Tillers is taking on. We are working on this in Michigan, Mozambique, and Uganda. It is a current theme on our FaceBook page.
Ox carts are on a number of farms and are a good starting point. Dumping manure from the cart is a fast way to unload in the field but the piles leave a lot of hand distribution to do with a fork or shovel later. Distributing the compost directly from the cart by fork gives elevation for more distant throwing and better spreading.
Using a fabric in the cart’s bottom can unload more rapidly and evenly. It pulls the compost or manure back as it is rolled up on a bar across the back. The compost incrementally spills on the ground as the fabric is wound back. In our first tests, a hand crank was used to power the roller. While the video on FaceBook (LINK) attracted comments about making it easier for the person on the crank, John Sarge says none of the people in the test field raised such a concern. They were pleased to see how much their carts could be improved by such a small investment. Nonetheless, it will be good to continue the search for design improvements that are low-cost and effective.
Most of the farmers with whom Tillers is working do not have the funds or materials to buy or build what in the USA know as a manure spreader. These great machines are dedicated to a single purpose and are fairly complex and expensive. Our design challenge is some of that function without much of the cost.
We have posted some photos and video to draw ideas. Rick Boeson took a lead on FB to suggest sprockets and a bicycle chain to transfer power from the cart wheel to the apron roller. I hope my attached sketch is a fair description of his suggestion. In addition to the question of whether the bicycle chain is heavy enough to transfer the load, two other design issues need simple and elegant solutions.
The direction of revolution of the cart wheel is opposite from the desired turning direction of the roller. A couple quick and imaginative suggestions were tossed onto the table:
- Unloading out of the front of the cart rather than the back so the direction of revolution of the wheel would be appropriate, Bill Brislen
- Adding a bar behind the roller bar around which the fabric will be drawn before being rolled, Rob Burdick.
- Twisting a V-belt instead of roller chain
- These are great out of the box ideas that can be captured from a group and then tested in the field.
The transfer of power from the wheel to the roller needs to be disconnected for transport to the field and at other times:
- A slip clutch was suggested, Rick Boesen
- A simple air pin through a sleeve on the roller bar sprocket could
The strength of the transfer system needs to be sufficient for fairly heavy loads. A cart load of moist manure could easily weigh 1,000 pounds. With an estimated friction coefficient of 40%, the load at the roller would be about 400 pounds, not insignificant.
- We can nearly half that load by folding the fabric so only part of the load is moved while the slack in the folds is being released.
- Alternatively, loading and spreading well composted and friable material as in the Moz video will make loads fairly light and reduce strains.
This spreader design project is important. In addition to a flow of ideas, we need funds to buy materials for prototypes. Tillers’ Innovation Workshops can quickly fabricate new designs. Going through the testing and trials develops their skills and stimulates their creative responses. We would appreciate your help underwriting these prototype developments. By underwriting some of these prototype tests, you can have some creative fun and push development ahead. Small distributed field trials assure that development is locally appropriate to the needs of farmers.