1. Michael Schwerin
    June 18, 2020 @ 3:24 PM

    Yesterday I bought plans for your 4×6 torsion axle utility trailer. I have a couple of questions, but first I thought you might find my project interesting. The purpose for the trailer will be as a mobile test stand for an R2800 aircraft engine I own. Specs here: store.rotecaerosport.com/r2800-radial-engine-10-deposit

    The engine weighs about 250 lb, incl. oil and a bit of fuel. I intend to mount it facing the rear, so that the tow vehicle acts as an anchor during operation. It swings a 68″ long prop, so the choice is either mount the engine all the way in the rear of the trailer, such that the prop clears the tail and the deck height allows extra prop clearance from the ground, allowing the engine to be mounted somewhat lower, or mount the engine further forward and high enough such that the prop clears the deck.

    Here is a YouTube vid of this type of engine mounted at the rear of an ATV trailer: youtube.com/watch?v=iu2yYoIpEJc

    Unlike the YouTube example, I’d like my test stand (complete with mounted engine) to be roadable. Obviously, mounting all the way to the rear (such as in the video) creates challenges for load distribution and axle placement on the trailer. Alternatively, mounting the engine further forward requires the prop center to be at least 36″ (34″ + at least 2″ clearance) above the deck. The higher mounting is of course more top-heavy.
    Any thoughts?

    Also, 2000# is far more GVWR than I need, and the stiffer ride wouldn’t be as smooth as I would like. Your torsion axle commentary mentions 1,500# axle as being equally well suited to this trailer size, but I don’t see Dexter offering that size: nothing between 1,000# and 2,000#. 1,000# axle is probably sufficient for my purposes, but that begs the question if I can use lighter building materials?

    I recognize that it would be asking too much to look for a re-engineering of your plans to suit my project, but any comments you might offer would be most appreciated.


  2. Michael Schwerin
    June 18, 2020 @ 5:33 PM

    Oops, sorry!
    The prop length is 74″, so clearing the deck would require a stand with the hub about 39″ above the deck. This being a round engine, that is also roughly where its CG would be located. The weight of the stand itself would naturally lower the combined CG somewhat.

    Is 64″ hub face – to hub face likely to be a wide enough stance for this set up to be stable?


    • Mechanic
      June 19, 2020 @ 9:15 AM

      Sounds to me like the load is less weight than the trailer. I’d put the motor on the back and move the axle back using these equations to accommodate. Don’t forget other things that will be on the trailer — fuel, toolbox, etc..


  3. Michael Schwerin
    June 19, 2020 @ 1:29 PM

    The plans suggest that the axle can be moved forward or back 3″. Is this the limit, or given that the load is indeed less than the trailer, and ideally would be fixed close to the tail, can I move the axle more than 3″ back? Thanks


    • Mechanic
      June 19, 2020 @ 4:11 PM

      For a standard application, the point given in the plans is the way to go. For most people, a minor adjustment of 3″ fore or aft is a modification to meet typical needs. For yours, it’s totally different because of what you need to do. You can move the axle back to where the balance is correct using the calculations for where the axle should go on your trailer. You will need to measure loads and centers to figure it out, but it will be fine. Also, you may need to shorten the spring mount bar if you move it back a long way.


Leave a Reply

Your email address will not be published. Required fields are marked *