The trailer looks very similar to the K1W1 Renegade here
http://www.renegadetrailers.co.nz/.
Renegade declare a "Patent Pending" on their "ground loading technology" on their web site. Design needs fundamental difference in order to avoid infringement.
gslender wrote:I'm located in Brisbane, and so probably a little too far to come to inspect before purchasing, but totally Ok for me to buy and come and collect.
In saying that, I'd need more photos and explanation on how the pivot is structurally sound and the engineering on how it keeps the axle solid/square - it looks like it floats the axle in a box section but has no cross beam to the other axle. So what stops the hubs from splaying out under heavy loads?
G
I declare I am a registered professional engineer (mechanical) with trailer design experience (helped my brother Richard design his Loadsafe Trailers
http://www.loadsafetrailers.com/)
Most car trailers are non engineered heavy designs which are tolerant to faults in design and workmanship. However when trailer weight is trimmed down to a minimum, 350kg in this case, the metal that is left may have to work that much harder. The trick is to move the metal to where it matters, particularly in respect of detail design to resist metal fatigue. Metal fatigue is the greatest challenge facing trailer designers wishing to dramatically reduce weight but maintain durability.
The proof of the pudding is how long the trailer lasts before it cracks and when/if it does so, how quickly the crack spreads before it is noticed and what are the consequences of the crack growing into ultimate failure. Proper "what if" or Failure Mode Effects Analysis during design captures faults before they fail so avoiding the finger pointing which could result from chasing light weight with fingers crossed.
The question about how the moment from wheel offset is dealt with is a good one. This offset moment is the most critical load from a fatigue point of view that a trailer experiences. It is normally dealt with by a small diameter solid axle clamped (not welded) to the trailer frame at its point of maximum bending moment and stress together with leaf spring suspension. Being unwelded where it matters, the traditional axle has proven itself quite durable over many years. When trailer designers depart from this design into cantilevered arm designs welded to something they usually introduce a welded joint at the point of highest bending moment and stress as well as torsion into the longitudinal members to which the cantilever arms attach. The lack of suspension serves to increase the magnitude of the fatigue loads, particularly those at the extreme end of the fatigue spectrum.
The trick is to lower the stress at the welded joint sufficiently for it to tolerate the fatigue and to provide stiff enough connections to be able to properly get the torsion into the longitudinal members in the first place. Establishing the right level of redundancy is not as easy as it seems. A detailed design review of the load paths and weld configurations used to handle this fatigue would be my recommendation in order to adequately answer the question asked.
