Black Posted May 22, 2019 Report Share Posted May 22, 2019 (edited) This is somewhat of a random question but has anyone seen a gooseneck/5th trailer hitch build that uses leaf springs instead of airbags? I found myself daydreaming at breakfast this morning and after thinking about it on the drive and during lunch, it seems like it would work with a few strength modifications. I'l likely never build it but since I dissect project ideas as my form of mental gymnastics and trying to stay sharp, has anyone seen such a thing or can point out why it wouldn't work? It wouldn't give you any front/back articulation but the side to side/compression articulation should be plenty. Actually, if you used 4 leaf springs you'd have some front/back articulation also... Edited May 22, 2019 by Black Quote Link to comment Share on other sites More sharing options...
Moresmoke Posted May 22, 2019 Report Share Posted May 22, 2019 Food for your thought... Quote Link to comment Share on other sites More sharing options...
Black Posted May 22, 2019 Author Report Share Posted May 22, 2019 1 hour ago, Moresmoke said: Food for your thought... Thanks, I was able to look your picture which led me find out that Silver Eagle tow dollys are pretty common and was even able to find a parts diagram online. My thought was to mount the leaf springs parallel with the frame rails but they went perpendicular....now the search is on to see if anyone’s already done that. Thanks a ton for this, I might end up messing around and building one just to play with and see what happens. Quote Link to comment Share on other sites More sharing options...
Black Posted May 22, 2019 Author Report Share Posted May 22, 2019 Quote Link to comment Share on other sites More sharing options...
Black Posted May 22, 2019 Author Report Share Posted May 22, 2019 Quote Link to comment Share on other sites More sharing options...
phoenix2013 Posted May 26, 2019 Report Share Posted May 26, 2019 Leaf springs behave in a very similar fashion as air springs and can be incorporated in a hitch suspensions, as shown above. The difference is that they do not operate over as wide a range as air springs (bags). That's why you see air bags almost exclusively in tractor trailers, which one day could be towed empty and next day loaded with 30,000 pounds of cargo. With air springs suspension all you do is vary the air pressure in the suspension to go from empty to fully loaded. In a spring suspension, like the one shown above, you'd have to be able to add or remove individual leafs to maintain the same response between running empty to fully loaded, not very practical. Leaf springs are designed to do their best in fully loaded configuration. That's why your one ton dually is not very "pleasant" (ride wise) when driving it empty and rides like a "sedan" when fully loaded. Conversion kits of air suspensions on pickups have been available for years and now are finally available as a factory option (on Dodge trucks). Again, with the stated "purpose" to maintain the ride quality whether empty or fully loaded. I would "venture a guess" that the hitches shown above don't do much for empty or lightly loaded trailers, but make a difference on fully loaded ones. Quote Link to comment Share on other sites More sharing options...
Black Posted May 26, 2019 Author Report Share Posted May 26, 2019 I agree with everything you said and yes, air bags are much more versatile than leafs. My thought with leafs was that it's an easy way (relatively) to achieve side to side articulation with a bit of up/down travel....if the springs were mounted front/back anyway. It's interesting you gave the air bag example for pickups, I was thinking for a 20K tongue weight (thinking along the lines of my gooseneck), two 8k leafs with backup air springs would give a decent loaded ride and still allow some side/side when off camber and the trailer's empty. This is based off a WAG and nothing factual, just spitballing. Quote Link to comment Share on other sites More sharing options...
DesertMiner Posted May 26, 2019 Report Share Posted May 26, 2019 What about this...... https://fifthwheelst.com/automated-safety-hitch-system.html Quote Link to comment Share on other sites More sharing options...
Black Posted May 27, 2019 Author Report Share Posted May 27, 2019 I don't see what you're getting at or where the parallels are... Quote Link to comment Share on other sites More sharing options...
phoenix2013 Posted May 27, 2019 Report Share Posted May 27, 2019 2 hours ago, Black said: I agree with everything you said and yes, air bags are much more versatile than leafs. My thought with leafs was that it's an easy way (relatively) to achieve side to side articulation with a bit of up/down travel....if the springs were mounted front/back anyway. It's interesting you gave the air bag example for pickups, I was thinking for a 20K tongue weight (thinking along the lines of my gooseneck), two 8k leafs with backup air springs would give a decent loaded ride and still allow some side/side when off camber and the trailer's empty. This is based off a WAG and nothing factual, just spitballing. You could actually design and build a leaf spring based fifth (or gooseneck) hitch with just the leaf spring, if you started with springs that closely support the load you are expecting. It would be a single purpose designed hitch for that pin weight. Side to side articulation is better achieved by having it built in into the head with one additional set of swivel pins, done in many examples of heads from different manufacturers. Conventional spring based suspensions provide for good lateral control and stiffness. Airbags have zero lateral stiffness and require additional components to achieve that, typically panhard bars or rods. Automated Safety Hitch is a totally different animal designed and built for a totally different purpose. I've seen it and spoke with the engineer and the designer of it at length. Lot of thought went into it and it works well in some very specific applications which typically are not in play for what we do on this forum. Quote Link to comment Share on other sites More sharing options...
jenandjon Posted May 27, 2019 Report Share Posted May 27, 2019 15 hours ago, DesertMiner said: What about this...... https://fifthwheelst.com/automated-safety-hitch-system.html I had the idea to make one of these out of a pickup box trailer when all I had was a suburban. But I thought thats too redneck even for me. Then I start seeing these pop up. I could have bee a millionaire. Quote Farmer, Trucker, Equipment operator, Mechanic Quando omni flunkus moritati-When all else fails, play dead I'm a man, but I can change, if I have to, I guess. Link to comment Share on other sites More sharing options...
phoenix2013 Posted May 27, 2019 Report Share Posted May 27, 2019 12 minutes ago, jenandjon said: I had the idea to make one of these out of a pickup box trailer when all I had was a suburban. But I thought thats too redneck even for me. Then I start seeing these pop up. I could have bee a millionaire. Yes, you could've, these are quite pricey. Pretty slick if you want to do this (the "specific applications" I mention above. Quote Link to comment Share on other sites More sharing options...
noteven Posted May 27, 2019 Report Share Posted May 27, 2019 What phoenix said ^ is why Class 8 tractors often have big looong correctly dampened taper leaf front suspensions - steer axle load is nearly constant especially on set back axles. Did I mention correctly dampened? Springs love to bounce back to “normal” as quick as they can. I’m not Joe Fast in the Dirt or Best Lap Time rider by any means but if you’ve ever ridden a bike with a basic suspension vs same configuration with a sophisticated suspension understanding comes quickly. Basic dampers (“shocks”) get hot and say to hell with it, the suspension forgets to travel and tires start to do the crow hop in the vertical vector. Rider discomfort and bizziness ensues. If not brought under control biting the dust can occur... Yer dishes in the cubbard and jars of spaghetti sauce can have the same experience in a trailer... phoenix can explain... Quote "Are we there yet?" asked no motorcycle rider, ever. Link to comment Share on other sites More sharing options...
phoenix2013 Posted May 31, 2019 Report Share Posted May 31, 2019 Sometimes it doesn't matter what the springs ratings or the dampening characteristics are! Quote Link to comment Share on other sites More sharing options...
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