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#1
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Trailer Axel / Physics Puzzler
So the axels that we have are torsion axels (no springs). They will just attach directly to the underside of our trailer. The thing is, it's not just a straight across axel. Well, the axel goes straight across, but coming from the center of the axel is a 6" arm that goes back to the spindle. In other words, the tires are off-set 6" behind where the axel is. For a picture go to this web sire (really an Adobe PDF document) and see page 5 (the 2,300 lb to 3,500 lb Torflex axel). http://www.redneck-trailer.com/pdf/A/810torflex.pdf PUZZLER: Does the axel "balance" the weight over the axel or over the wheels? . Put another way: Say we had a rectangular frame 20 feel long and it was perfectly balanced at the 10 point. (No boat or anything on it yet.) So a straight across axel put at the 10' point, it'd basically balance. But with our axels, where the wheels are off-set 6"....do we put the AXEL at that 10' point or do we have the WHEELS at that 10' point. Our current thinking is that it's the wheels. It's pretty hard to test because of the weights involved and we have to weld the axels on (not bolt 'em) so we'ld like to get it right the first time. Gary |
#2
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Trailer Axel / Physics Puzzler
I've never built a trailer using torsion axels but I like the concept. I
wonder how to design a 2 axle system to achieve equalization? I'm thinking a rotating sub-frame would be required. I have built several single axle trailers with trailing arms and coil over springs that worked well but were a lot of work to build. IMHO, the balance point will be over the CL of the wheels. "Gary Warner" wrote in message ... So the axels that we have are torsion axels (no springs). They will just attach directly to the underside of our trailer. The thing is, it's not just a straight across axel. Well, the axel goes straight across, but coming from the center of the axel is a 6" arm that goes back to the spindle. In other words, the tires are off-set 6" behind where the axel is. For a picture go to this web sire (really an Adobe PDF document) and see page 5 (the 2,300 lb to 3,500 lb Torflex axel). http://www.redneck-trailer.com/pdf/A/810torflex.pdf PUZZLER: Does the axel "balance" the weight over the axel or over the wheels? . Put another way: Say we had a rectangular frame 20 feel long and it was perfectly balanced at the 10 point. (No boat or anything on it yet.) So a straight across axel put at the 10' point, it'd basically balance. But with our axels, where the wheels are off-set 6"....do we put the AXEL at that 10' point or do we have the WHEELS at that 10' point. Our current thinking is that it's the wheels. It's pretty hard to test because of the weights involved and we have to weld the axels on (not bolt 'em) so we'ld like to get it right the first time. Gary |
#3
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Trailer Axel / Physics Puzzler
QLW wrote:
I've never built a trailer using torsion axels but I like the concept. I wonder how to design a 2 axle system to achieve equalization? I'm thinking a rotating sub-frame would be required. I have built several single axle trailers with trailing arms and coil over springs that worked well but were a lot of work to build. IMHO, the balance point will be over the CL of the wheels. "Gary Warner" wrote in message ... So the axels that we have are torsion axels (no springs). They will just attach directly to the underside of our trailer. The thing is, it's not just a straight across axel. Well, the axel goes straight across, but coming from the center of the axel is a 6" arm that goes back to the spindle. In other words, the tires are off-set 6" behind where the axel is. For a picture go to this web sire (really an Adobe PDF document) and see page 5 (the 2,300 lb to 3,500 lb Torflex axel). http://www.redneck-trailer.com/pdf/A/810torflex.pdf PUZZLER: Does the axel "balance" the weight over the axel or over the wheels? . Put another way: Say we had a rectangular frame 20 feel long and it was perfectly balanced at the 10 point. (No boat or anything on it yet.) So a straight across axel put at the 10' point, it'd basically balance. But with our axels, where the wheels are off-set 6"....do we put the AXEL at that 10' point or do we have the WHEELS at that 10' point. Our current thinking is that it's the wheels. It's pretty hard to test because of the weights involved and we have to weld the axels on (not bolt 'em) so we'ld like to get it right the first time. Gary Yes you are correct, the wheels are the pivot point, not the rubberised section & cross beam (it's sorta like the spring hanger, if you had them:-)) It wouldn't matter if the torsion fittings attached just behind the coupling or just ahead of the extreme rear, the trailer & it's load still pivot around the wheels. K |
#4
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Trailer Axel / Physics Puzzler
QLW wrote:
I've never built a trailer using torsion axels but I like the concept. I wonder how to design a 2 axle system to achieve equalization? I'm thinking a rotating sub-frame would be required. I have built several single axle trailers with trailing arms and coil over springs that worked well but were a lot of work to build. IMHO, the balance point will be over the CL of the wheels. "Gary Warner" wrote in message ... So the axels that we have are torsion axels (no springs). They will just attach directly to the underside of our trailer. The thing is, it's not just a straight across axel. Well, the axel goes straight across, but coming from the center of the axel is a 6" arm that goes back to the spindle. In other words, the tires are off-set 6" behind where the axel is. For a picture go to this web sire (really an Adobe PDF document) and see page 5 (the 2,300 lb to 3,500 lb Torflex axel). http://www.redneck-trailer.com/pdf/A/810torflex.pdf PUZZLER: Does the axel "balance" the weight over the axel or over the wheels? . Put another way: Say we had a rectangular frame 20 feel long and it was perfectly balanced at the 10 point. (No boat or anything on it yet.) So a straight across axel put at the 10' point, it'd basically balance. But with our axels, where the wheels are off-set 6"....do we put the AXEL at that 10' point or do we have the WHEELS at that 10' point. Our current thinking is that it's the wheels. It's pretty hard to test because of the weights involved and we have to weld the axels on (not bolt 'em) so we'ld like to get it right the first time. Gary Out of curiosity, how does one place the axle? Is it at the centerpoint? I think you'd want it a bit forward of the centerline. I built a box trailer some years ago, and was advised to have the axle forward of center under the box. I knew why at the time, but I've since forgotten. -- Email sent to is never read. |
#5
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Trailer Axel / Physics Puzzler
Harry Krause wrote in message ...
QLW wrote: I've never built a trailer using torsion axels but I like the concept. I wonder how to design a 2 axle system to achieve equalization? I'm thinking a rotating sub-frame would be required. I have built several single axle trailers with trailing arms and coil over springs that worked well but were a lot of work to build. IMHO, the balance point will be over the CL of the wheels. "Gary Warner" wrote in message ... So the axels that we have are torsion axels (no springs). They will just attach directly to the underside of our trailer. The thing is, it's not just a straight across axel. Well, the axel goes straight across, but coming from the center of the axel is a 6" arm that goes back to the spindle. In other words, the tires are off-set 6" behind where the axel is. For a picture go to this web sire (really an Adobe PDF document) and see page 5 (the 2,300 lb to 3,500 lb Torflex axel). http://www.redneck-trailer.com/pdf/A/810torflex.pdf PUZZLER: Does the axel "balance" the weight over the axel or over the wheels? . Put another way: Say we had a rectangular frame 20 feel long and it was perfectly balanced at the 10 point. (No boat or anything on it yet.) So a straight across axel put at the 10' point, it'd basically balance. But with our axels, where the wheels are off-set 6"....do we put the AXEL at that 10' point or do we have the WHEELS at that 10' point. Our current thinking is that it's the wheels. It's pretty hard to test because of the weights involved and we have to weld the axels on (not bolt 'em) so we'ld like to get it right the first time. Gary Out of curiosity, how does one place the axle? Is it at the centerpoint? I think you'd want it a bit forward of the centerline. I built a box trailer some years ago, and was advised to have the axle forward of center under the box. I knew why at the time, but I've since forgotten. If a standard type of axle, and if placed at the c.g. of the trailer, it would be in equalibrium, ie: balanced. If placed aft of the centerline, it would have tongue weight, if forward, when you unhooked the tongue, it would rise. Now, if using the torsion springed axle, where there is a lever arm all of this goes out the window, because the spring torsion, depending on which direction the wheel arm is pointing, will either try to raise the tongue, or lower the tongue. |
#6
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Trailer Axel / Physics Puzzler
"Harry Krause" wrote: Out of curiosity, how does one place the axle? Is it at the centerpoint? I think you'd want it a bit forward of the centerline. I built a box trailer some years ago, and was advised to have the axle forward of center under the box. I knew why at the time, but I've since forgotten. I'm not an expert (obviously) but our thinking is: We experimented with the trailer WITH the boat on it to find a point that is just BACK of the true center of gravity. A single axel placed right AT the center of gravity would give essentiall no tongue weight. Moving the single axel back just a little gives some tongue weight. In our case we are putting tandem axels. So one axel will go forward of the point we found and the other back of that point by the same distance. |
#7
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Trailer Axel / Physics Puzzler
Gary,
When using tandem axles some method of equalizing the weight must be used to keep one set of axles from being over loaded. The trailer will rarely be setting perfectly level and without an equalizer the tires will be unequally loaded as well. In the case of leaf springs, it's done using a common, rotating equalizer. In your case, I'm not sure. I'd ask the manufacturer of the axles. This catalog shows the normal axle setup and may show your's as well. http://www.championtrailers.com/catalog_pdf.htm "Gary Warner" wrote in message ... "Harry Krause" wrote: Out of curiosity, how does one place the axle? Is it at the centerpoint? I think you'd want it a bit forward of the centerline. I built a box trailer some years ago, and was advised to have the axle forward of center under the box. I knew why at the time, but I've since forgotten. I'm not an expert (obviously) but our thinking is: We experimented with the trailer WITH the boat on it to find a point that is just BACK of the true center of gravity. A single axel placed right AT the center of gravity would give essentiall no tongue weight. Moving the single axel back just a little gives some tongue weight. In our case we are putting tandem axels. So one axel will go forward of the point we found and the other back of that point by the same distance. |
#8
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Trailer Axel / Physics Puzzler
"QLW" wrote: Gary, When using tandem axles some method of equalizing the weight must be used to keep one set of axles from being over loaded. The trailer will rarely be setting perfectly level and without an equalizer the tires will be unequally loaded as well. In the case of leaf springs, it's done using a common, rotating equalizer. In your case, I'm not sure. I'd ask the manufacturer of the axles. This catalog shows the normal axle setup and may show your's as well. http://www.championtrailers.com/catalog_pdf.htm Question: On this axle each wheel has independent suspension. Would this take care of the situation you mentioned? Seems to me it might. For example, say the trailer was on totall level gound except for one wheel which was on a rock sticking up 3" above level. Hmmm, maybe not. I just don't know. |
#9
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Trailer Axel / Physics Puzzler
"QLW" wrote in message ...
I've never built a trailer using torsion axels but I like the concept. I wonder how to design a 2 axle system to achieve equalization? I'm thinking a rotating sub-frame would be required. I have built several single axle trailers with trailing arms and coil over springs that worked well but were a lot of work to build. IMHO, the balance point will be over the CL of the wheels. "Gary Warner" wrote in message ... So the axels that we have are torsion axels (no springs). They will just attach directly to the underside of our trailer. The thing is, it's not just a straight across axel. Well, the axel goes straight across, but coming from the center of the axel is a 6" arm that goes back to the spindle. In other words, the tires are off-set 6" behind where the axel is. For a picture go to this web sire (really an Adobe PDF document) and see page 5 (the 2,300 lb to 3,500 lb Torflex axel). http://www.redneck-trailer.com/pdf/A/810torflex.pdf PUZZLER: Does the axel "balance" the weight over the axel or over the wheels? . Put another way: Say we had a rectangular frame 20 feel long and it was perfectly balanced at the 10 point. (No boat or anything on it yet.) So a straight across axel put at the 10' point, it'd basically balance. But with our axels, where the wheels are off-set 6"....do we put the AXEL at that 10' point or do we have the WHEELS at that 10' point. Our current thinking is that it's the wheels. It's pretty hard to test because of the weights involved and we have to weld the axels on (not bolt 'em) so we'ld like to get it right the first time. Gary Your current thinking is correct, if all things equal, AND if you didn't consider the torsion of the spring. Again, if you put the wheel at the center of gravity of the boat, it will be balanced. Trouble is, when this is done, will the boat's C.G. be at the C.G. of the trailer? See, you could load the boat on the trailer, and the CG of the boat could be far enough behind that the tongue has a negative load. |
#10
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Trailer Axel / Physics Puzzler
"basskisser" wrote in message om... Your current thinking is correct, if all things equal, AND if you didn't consider the torsion of the spring. What????? The torsional forces can not have any effect on the trailer balace as long as the wheels are round or allowed to rotate. Again, if you put the wheel at the center of gravity of the boat, it will be balanced. No, it would need to be at the center of gravity of the boat + trailer. Trouble is, when this is done, will the boat's C.G. be at the C.G. of the trailer? Probably not. Which is why you would want to use the C.G. of boat + trailer for any calculations. See, you could load the boat on the trailer, and the CG of the boat could be far enough behind that the tongue has a negative load. A universally true statement. Take any boat and trailer, load the boat far enough back and the tongue weight will go negative. What's your point? Rod |
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