Darfield Earthship

Reflections on our tire press

Posted on 13. Jan, 2010 by Chris in Construction, Earthship, Tires

We’ve been getting emailed questions about our tire press, so I thought I would attempt to recap our experiences with it.

As described in an earlier posting we built the press out of materials we had on hand. The press design is quite simple.  The unit consists of:

• a stubby hydraulic cylinder, 
• two rounded steel plates welded at either end of the cylinder, 
• a control valve to extend and retract the cylinder, 
• hydraulic hose plus fittings,
• and a portable hydraulic pump that plugs into a standard 120 volt wall outlet.

The hydraulic cylinder is approximately 1′ retracted length (including the attached steel plates) and extends out another 3-4″ at full extension. The steel plates are 5/16″ thick and were cut from steel pipe that was approximately 16 inches in diameter.  The photo shows the initial plates that I used that came close to packing an entire tire in one pass.  These plates were impractical … it was too hard to place the packer in a tire, and it simply did not pack well.  We settled on much smaller plates that were only about 6″ wide.

As shown in the video (below this paragraph) the size of the packer is dictated by the inside diameter of the tires being filled.  The packer is dropped into a previously hand packed tire that is still hollow in the middle.  With the packer fully retracted, dirt is then shoveled into the tire so that when the packer cylinder is extended the new and existing dirt is packed into the tire.  The packer is rotated and this process is repeated until the tire is sufficiently packed.

After the tire is sufficiently packed, the packer is removed.  The tamper is then used to fill and compact the centre of the tire.
 Our tamper was simply an old sprocket welded to a five foot length of steel pipe.  The whole 
unit weighs significantly more and has a much wider packing head (approximately 8″ diameter) than a sledge hammer.  It was very effective at packing the centre of the tires.
Many thanks to Mike Casey for building and lending this packer to us!

Tamping requires a person to straddle the tire and compact the dirt by pounding the tamper up and down while periodically adding dirt until the tire is filled and compacted.
Care needs to be taken to not stand on the edges of the tire being tamped initially, as you run the risk of reducing the compaction of the tire by collapsing the dirt in the rim.  You also do no want to strike the side walls of the tire with the packer as this will also reduce the compaction of the tire.

Our packer was fairly small and portable.  We mounted the hydraulic pump and electric motor combination on a wheel barrow so that it could be moved easily from tire to tire.  We ran a 50′ extension cord to an available electrical outlet.  (We also ran the unit off of a 3500 watt gas generator during a power failure.)  The hoses were long enough such that the packer could be used at the top of an eight foot wall with the packer at the base of the wall.
As the walls got higher the packer stayed inside the building, and we brought dirt to the tires from the outside of the building and backfilled as we went.  This meant that moving the dirt was done at ground level and the operator of the packer stood on a ladder as the walls got higher.  We had to extend the lever controlling the cylinder so that the person operating it could still extend and retract the ram.

I guess the important question is was it worth it?  Was the packer effective? Did we save time, money or labour?

In terms of cost our packer was essentially free.  I had all of the parts needed to make this unit, although I did cannibalize one piece of equipment that will have to be put back together.  Also, I did all of the welding and assembly, and it went together surprisingly quickly.  So, there was very little cost in building this unit. I suspect you could pay a few thousand dollars buying and scrounging the parts needed.

The packer proved to be very effective in packing the tires, it did a very consistent job of filling and compacting the rims of the tires.  I can only compare the effectiveness of the packer to tires we filled with sledge hammers on our first tier and tires I have seen in finished buildings.  Both methods seem equally effective at compacting dirt in a tire.  One advantage of the packer is that it did not get tired, and loose oomph as the day went on.  Quality control was critical regardless of the method used, and we were careful to consistently inspect finished tires.

We definitely saved a lot of hard labour using the packer.  We were exhausted after a day of hand packing the tires.  The hydraulic press eliminated the physically demanding effort of packing with the sledge hammer.  The tamping was still done by hand (and generated lots of complaints) but was far easier than the alternative.

I also think that the packer saved us time.  A crew of three was very efficient when filling tires; one to operate the packer, one to shovel dirt and one to tamp tires and supply dirt to the shoveler.  I am estimating (guessing?) that we could easily have done half a row of tires a day (approximately 40) and finished the main tire wall in under a month with a dedicated crew of three to four people.  It took us three months, we did not work steadily, and our crew of volunteers changed constantly.  I suspect that either method can be very efficient.  The bigger issue with either method is keeping people busy packing tires.  A lot of time and effort goes into moving, supplying and preparing material (dirt, tires, water and cardboard).  More than once we stopped working to scrounge tires, move dirt or cut cardboard!

Ultimately, at the end of the day using a hydraulic packer meant that the crew was as happy at the end of the day as at the beginning!