Project: Build trailer to haul the GL1200 ASPY

[DaveKamp]

So... a little progress today... after tackling this... it's a J.A. Fay & Co bandsaw.

Identified as Pt, June 16 1868
Spe. 19, & Nov. 14, 1871
May 21 1872 & May 19 1874
Reissued, Aug 25 1865.

Rescued from the scrapper's path late last fall, my son and I had to disassemble and carry it out of the building which it was installed... it's been waiting reassembly, so my buddy and I did just that.

 

[DaveKamp]

Look at the Victorian spoke and finial!

The wheels are 35" diameter. Originally lineshaft driven, family sources say it was originally built and sold to the Rock Island Arsenal, and shortly after WW1, acquired by the John Deere facility less than a quarter mile away, where it was converted to electric motor drive. The motor drive system fitted to it when I dismantled, was vintage late 1970's or so.

After pressure-washing off lots of loose paint, I decided to give it a rolled-on coat of machinery primer for protection. I did NOT strip off any original paint layers that was still hanging on... because there's original turn-of-the-century paint under there... someday, when someone gives it a really 'deep' restoration, they'll need to see what that color looked like IN PERSON, to understand how it should've looked. I'm just preserving it, and returning it to operation.

 

[DaveKamp]

Okay, so back to the trailer. I had just a little time to do some basic butchery to the axle. I snipped the center out of the (too long) drop axle, using Lucifer's Toothpick. After which, I placed the shortened half-axles into a 'general' position, to see what it looked like... and this is what I see...

Approximate length being... enough material for me to cut it clean with a bandsaw and fit a proper suspension pivot. it's leaning against the backbone for the moment, and my spring hangars and shackle hangers are just 'resting' there, so if you wonder why the shackle is in the 'halfway loaded' position, it's because gravity liked it there 'best'. In final, it'll be more vertical, and the tires will be higher, the axle angle will present more negative caster.

From this angle, it's easy to see the amount of clearance between axle tube and frame rail. Measured max travel with this spring set comes out to about 6 inches. I do NOT know the spring rate for these leaves, but I'm guessing this to be a 2500lb axle, so it's probably around 250lbs per inch or so... when it's fully loaded... 2500lbs /2 = 1200lbs /6" = 200. At no load, it's probably 150lbs for the first inch or so... so between the frame's weight and that guess, my 'gut' tells me that with trailer empty, it'll have an insignificant amount... mebbie a quarter-inch of loading tops, and once loaded with an 800lb motorcycle, there'll be 4.75 of 'real' travel left to modulate on the road.

Looking at a lower position, it's easy to see just-how-much camber was integrated into the axle's centerpoint BEFORE I cut it out. When loaded, the tires should exhibit about 1.5 degrees of negative camber... that means the tops are farther away than the bottoms... but not by much.

The 'gotcha' here, is that as the suspension compresses and extends, the swinging arc of the axle will cause wheel camber to change. Using trigonometry, I calculated that 5" of travel over the length of the swinging arm will result in a total of 12 degrees' angle change at the hub. My general plan is to assemble the suspension, but come up with a way to adjust the positioning of the axle's swing point AND it's elevation, so that once the bike is ON, I can set the wheel camber to suit the bike's weight.

Of course, as the axle articulates with bumps, the camber angle will change, but it'll return to proper in short order.

Another thing that one must keep in mind with a leaf-spring, is that ONE end (in this case, the FRONT end) of the spring is on a fixed eyelet, while the rear is on a swinging shackle. The fact that the shackle swings, means the axle beam will swing rearward. Now, I have not yet measured and calculated the amount of rearward swing, but I've concluded that my swing axle's pivot point needs to be adjustable to properly align it UNDER LOAD... so I'll measure and approximate, but when all is said and done, it'll be adjusted according to real-life circumstances.

 

[DaveKamp]

And an aside-note:

Many people have problems with trailers being unstable. There's plenty of geometric reasons WHY, and once you understand them, it's actually difficult for you to 'feel comfortable' with an improper setup.

Trailers steer. It is ineveitable that, because a trailer has a suspension system, and a hitching point, that motion between the two causes a change in how the trailer WANTS to go. A simple example falls in line with the note about leaf springs: when the spring compresses, ONE side of the spring moves one way, while the other stays fixed. As a result, the axle has to swing in the direction of the shackle. Let's say you have a trailer that is leaning to one side... this causes ONE spring to be more loaded than the other... this causes the more-loaded-spring to pull the axle rearward, steering the trailer to one side.

Let's say the trailer has a load with a high center-of-gravity. The load sways to one side, and then the trailer 'steers' that way, righting the load... but a little bit past 'center', forcing the springs into the opposite loading, causing the trailer to steer the opposite way. This oscillation is pretty scary.

Let's say the hitch is too low, or too high... now the trailer frame isn't running level, and the suspension, when it compresses, is not compressing vertically, but rather, at an angle... this means the deflection of the axle in a rearward direction, is actually acting like a more aggressive steering angle... it therefore 'steers' more aggressively (like changing the head tube angle on a motorcycle).

Getting the running dynamics of a loaded trailer, means getting control of all the variables that lead to instability.

Normally, having a 'swing axle' suspension would NOT be a first-choice for trailer suspension design. Why? Because that change-of-camber can do some strange things to handling, REGARDLESS of what type of suspension system design is employed.

In his book Unsafe At Any Speed, Ralph Nader attacked the Chevy Corvair, citing that the suspension system as being fundamentally dangerous... what he conveniently left out, is the host of other VEHICLES that were using exactly the same design, for over FIVE DECADES... and long after his adolescent tierade, the swing-axle design STILL appears on everything from tiny economy cars, to big luxury cars, and huge all-wheel-drive multi-axle trucks. The demonstrations Ralph fabricated, were seriously rigged (tire pressures, road modifications, and extreme misloading of vehicle) in order to allow the demonstration drivers to yield the dramatic-looking results HE wanted, but in real life, these things simply couldn't happen. For PR purposes, Chevrolet abandoned the swing-axle setup in lieu of a double-wishbone after 2nd year of production, but a dozen other manufacturers (everything Volkswagen, some Porsche, many Triumph, Mercedes-Benz) continued using them... but the one Ralph never touched on, was the most prolific, and least recognized swing-axle implementation by FORD... and it's still used today: Twin I-Beam (2wd) and Twin Traction Beam (4wd) on their light trucks. If the Corvair's Swing Axle was deemed 'unsafe', how could Ralph have overlooked it when Ford brought it to market in 1965 in the FRONT?

Basically, it's because he was a creep... a thug, and a bully. He had a fixation that drove him to attack something that was naturally different, but not wrong...

But I digress. back to this trailer:

Swing-axle is perfect for this application. Why?
First - Because, like the front end of a Ford F100, or the rear end of a Corvair, or a Beetle, or a 356 Porsche, I know WITH CLARITY how much the suspension's loaded height will vary... the bike will weigh 800lbs, plus or minus mebbie 50lbs... and with these axles, that constitutes less than a quarter-inch variation over range of 750 to 850lbs... probably same from 650 to 900lbs. I can calculate the degrees of camber change based on that.
Second- Because change in camber due to TRAILER LEAN will be very little with respect to the road surface. The motorcycle's center of gravity is very low... and... the trailer's load surface will ALSO be extremely low, so even IF the trailer leans to one side, it won't be able to lean very much, and it'll have basically no impact on camber when it does.
Third: when compressed, the wheel's camber will change, but the axle will also steer slightly rear, which will counteract the tire's natural deviation due to impact and camber. It will do what a motorcycle does on gravel- it will 'want' to steer itself in a stable direction...
Fourth: Because the tires are NOT linked, tire reaction to a bump on ONE side, will not destabilize or otherwise alter the camber or steering angle of the other side.

So now to prepare these axles, fabricate appropriate pivot parts, and get the springs mounted to an adjustable chassis bracket... Don't touch that dial!

 

[Ansimp]

:good:

 

[DaveKamp]

Okay, so aside from reassembling the saw (which I'll be brushing on a color coat tomorrow) and converting a detassling machine into a self-propelled all-wheel-drive off-road scaffold and work platform... I got a little bit done today.

First, you'll recall that when I cut the 8x8 steel post down the middle, that one half became the wheel tray. The other half had a pretty noticeable kink in it. Well, I snipped that part off, which left me with a shallower piece of channel about 5ft long. Today, I cut that down the center to reveal two fairly heavy pieces of L-bracket, which will recieve the spring hangers for right and left side suspension. I COULD weld the hangers direct to the frame, but I will not, and for two reasons- 1) the frame material is not thick enough to withstand the concentrated load and shock that spring hangers would apply. Using a heavier piece not only eliminates the heat-affected-zone of the lighter railing, it distributes the load over a larger area, which is a net stronger result. 2) The general balance point has been determined, but the exact position hasn't been determined yet. I want to be able to put the suspension in place, and then alter it's position based on real life operation, so having the siderails (and axle end brackets) adjustable gives me that option not only on initial testing, but if I someday decide to put some other 2-wheeler on there that has different characteristics, I can easily change it.

The other thing I did today, was fish out some parts to make pivots for the ends of the axles. They'll need to be durable, but simple, and allow motion not only on the vertical axis, but also on the horizontal path, because the front leaf eyelet is in a fixed position, but as the leaf spring compresses, it must move the axle point rearward, towards the SHACKLE. This isn't much motion, but enough so that a rigid pivot would put stress on the chassis and mounting points, and result in a bind that makes for harsh suspension.

I took some pieces of already-fairly-suitable stuff, and stuck rod-end joints in them with nuts to weld down, and it worked very nicely. I'm going to chuck these in the lathe and trim the OD down so that it slips INTO the axle tube for welding. It'll be self-explanatory when you see it.

Here's the assemblage before:

And after addition of 'hot glue':

 

[DaveKamp]

So got a little done tonight... Chucked the pivot inserts into the lathe and chewed back enough to make 'em slip into the axle tubes:

I usually start a process like this by taking a 'sizing cut'... that is, I cut a ledge into the end of the part that will give good indication of when to STOP my hogging (removal of lots of material) and then lighten up my cuts (to get precise fit). This ledge tells me I can take several thick cuts, but when I get to this point, stop, measure, and think, lest I take off too much.

So here's the first one getting 'carbide attention':

And then a test fit of a piece cut out of the (removed) center:

And now the second one:

 

[DaveKamp]

And now, both side-by-side, with one started into the 'test coupon':

Now, I'll add in that this particular operation doesn't require incredible precision. The inside of the axle tubes are not particularly precise. I made these inserts so that they'll start in, but I actually incorporated a little bit of taper in the last 3/4", so when I sink them into the ends of the tubes, it'll take a 4lb hammer to drive them home, then I'll weld around the circumference... but to assure that it has more than one plane of weldment (which is a key to fixing strength of a weldment), I'll drill some holes in the axle tubes about midway through the machined surface, and I'll fill from the welded insert, out to the surface of the tube. This is called a Rosette Weld. It doesn't take much to get incredible strength from this type of fitting, and it takes away no strength of either the tube or the insert., but between the rosette and a circumferencial weld, it certainly won't be weak.

 

[DaveKamp]

Oh, and I almost forgot to add this:

Now, you'll note from above that the measurements I noted are slightly different from here. I projected this on some arbitrary values of what I feel will be within 'real life' operation. Some engineers would consider this to be 'bad', but it's been my experience that I develop in concept around what my expected operational parameters will be within, and then I work outward.

The roll center that I identified... it's not an accurate measurement- it's an educated guess. It may be TOTALLY WRONG, but my gut feeling is that the engineers wanted a low center of gravity... and they did everything they could to get it as low as possible. Now, it's POSSIBLE that they could have gotten the roll center lower than the center of the wheel axles... but I'm pretty certain that they didn't... they probably didn't get quite there, but they probably got close, so I gave 'em about 2" higher as my wild guess. The reason why roll center is indicated, is basically so that I can get a rough idea of much camber-change will occur under lateral accelleration (a turn)...

I guess I should clarify that... the BIKE doesn't have a roll center... technically, it's roll center occurs where the tires contact the ground (if it didn't... well... there'd be some very interesting language, as well as sparks and road-rash)... The Roll Center as I've noted here, is a guesstimate for the motorcycle and trailer AS A UNIT... I'm estimating that when loaded, the trailer's roll center will occur around that point... and I won't go into the rest right now, but I'll reiterate that there's really only two things in life we can totally depend on... gravity, and triangles. Cats not so much.

And yes, there's supposed to be something in the bottom of the tray- it's a piece of 2" lumber. I could roll the tires up on steel, but steel is slippery, and the trough will be able to accumulate rain, snow, and ice. I'll have a plank in there to provide a little elevation, and a surface suitable for driving on and off of with better all-weather adhesion, than rusty steel. I'll sand the end to make a smooth approach once trailer is tilted.

 

[Ansimp]

:good: opcorn: opcorn:

 

[GTC@MSAC]

Not to throw another curve in here, but will the trailer wheels have any positive or negative toe? One or the other could give it good or bad "trailing" characteristics, but I can't remember which, lol!

 

[DaveKamp]

GTC@MSAC » Today, 6:19 pm[/url]":99yntqo6]
Not to throw another curve in here, but will the trailer wheels have any positive or negative toe? One or the other could give it good or bad "trailing" characteristics, but I can't remember which, lol!

Excellent question, and Yes... but the camber in a swing-axle design is a function of both compression (down) and roll (sideways) I've purposely left the pivot point out of the equation because it will be adjustable. Once I have the suspension and tongue installed, I'll be able to load the bike on, and then set the pivot location to yield what I feel is an approprate toe (1.5 degrees is a good starting point), and then I'll hitch it up, and pull it around, and make adjustments accordingly.

 

[DaveKamp]

This afternoon's weld-fest:

First, cutting the tubes. My large tubing cutter lost a seemingly-more-significant-than-expected fastener, so I just put 'em in the bandsaw. Yeah, the guide is way back, I interrupted someone else's larger job to whack the ends clean. Not perfectly straight, but it's not a problem here...

Here's the end insert slapped into the hole, it took a few swings of a mallet to send them home. Also note the hole drilled in for aforementioned rosette weld. The seam around the insert is fairly strong, but the rosette welds give it an additional dimension, so it's not coming apart, even if my seam ain't great.

And yeah, that gap is a smidgen wide, the bandsaw guide bein' back caused a little drift, and the hub, spring, etc., on the far end didn't help, fortunately, it's insignificant once hot-glue is applied.

so that's done.

Now for the spring perches on steel angle. I didn't photo the making of these two rails, but the're cut from the other (bent up) side of that post that yielded the main backbone. I positioned one of the half-axles, and tacked the hangers in place, then finish welded, and used IT to replicate it's mirror-image partner.

and now a little finish:

It's not falling off anytime soon...

 

[Ansimp]

Nice welds. :salute:

 

[dan filipi]

Ansimp » 18 minutes ago[/url]":gjttyw81]
Nice welds. :salute:

:yes:

 

[DaveKamp]

Thanks for the complement, but some are better than others. I should do some things better...

So I sprayed the rod end threads with anti-seize, then slathered on some protection from the nearest rattle can, which happened to be blue, and closer to glue... but it covered it for now. This thing will get more appropriate finishing later, if it turns out well...

But heres some more in-situ so the concept is clearer:

Vise grips on each side are holding the suspension rails to the frame... if I didn't, the weight of the brake drums and spindles would flip them right up on end...

So as the spring compresses, it will move towards the rail, and rearward, rotating the shackle.

I had'ta prop up the spindle on this on this side, because it really wanted to lift.

Rest of the weekend might be a bit too busy to get more done, we shall see!

 

[joedrum]

Looking good

 

[DaveKamp]

So I got absolutely NOTHING done on the trailer tonight... but I did get some things done, so I'll share it for insanity's sake:

Several months ago, I came upon this old detassling machine. For those of you who don't know... corn doesn't magically grow in desired hybrids without humans actively choosing traits, and the way we get corn hybrids, is by... cross-breeding them... and there's two parts of corn that facilitate hybridization... the tassels (up on top) are the genome donors in pollination... and when breeding is done, that has to be controlled. Here's a link on it if you want a better definition: https://en.wikipedia.org/wiki/Detasseling but the short of it, is that SOME of the corn needs to have tassels removed in order for the hybridization to come out right.

A detassling machine of this type doesn't actually remove the tassels... instead, it serves as an elevated transport mechanism for highly sophisticated units with technologically advanced vision, autonomic motor control, and extremely fast processing that rapidly detect, then remove tassels from the rows predefined in the hybridization program. The machine is the transportation platform, and it has long booms that reach out to each side, wherin two baskets are suspended between rows, and as the machine creeps through the tall corn, a team of laborers riding in the baskets pull out the tassels as they pass by.

I'm not really certain how it came to be that this machine appeared within my reach, but it came to me on a trade. The booms were still present, but the baskets had been removed and scrapped. The engine is an Onan horizontally opposed twin, about 16hp or so, driving a Vickers hydrostatic pump whose swashplate is controlled by a hand lever to the left of the steering wheel. There's a hydraulic motor located in each of the four wheel hubs, and a selector valve that switches the drive motors from parallel, to a sequence where the two rear and two front motors are in parallel, but the front two are in series with the rear two. As a result, the first position is a slow speed arrangement, and the second is a high-speed arrangement... high being relative anyway... at full bore, it moves at a moderatly fast walking pace. In LOW, it moves at about half a walking pace.. The front two wheels are steered by a mechanical steering box and pitman arm/drag link arrangement.

I've removed the long booms, and cut off unnecessary bracketry on the sides, and in this picture, I'm fitting 'outrigger' tubes to support some convoluted steel grating.

 

[DaveKamp]

I started by measuring and mounting two of the four outrigger tubes... I just tack-welded them into position, in the event that I screwed it up and would have to knock them off. Murphy's Law says that if I glue them down tight, I'd have it all wrong, but if I tack weld 'em on first, they'll be in the correct position already... :roll:

And then I slid the walkway into place, checked the position and fitment... then used the walkway to get the position and inclination of the remaining two outriggers correct to the grating.

And here it is finally secured...

 

[DaveKamp]

And from above...

And from the side...ish...