Hi, I am not (get) into tilting trikes, but I would suggest to consider a lever instead. Something like in the picture. Also, I would consider not to use knots but to sew the required loops. Br Gerald -----Ursprüngliche Nachricht----- Von: Ronald Hongsermeier <rwhongser@xxxxxx> An: python@xxxxxxxxxxxxx Gesendet: Di., 20. Sep 2011, 03:05:43 GMT+00:00 Betreff: [python] Re: Pythonjetrike My two cents on this one is to use flat parachute chord and backpack type adjustment. Run the chord through appropriated sized and deburred slots instead of bending a chord around a bolt. The point load on the round chord is very high unless you go to a larger bolt cross-section. regards, Ron On 20.09.2011 04:38, UH-13P wrote: > Have you considered wire rope witha thimble end at the attachment > point? > It is low cost and easily obtainable at hardware stores. > Another option > would be hardened steel wire such as clothes line wire > or the wire used in > vineyards for trellis construction. > > *From:* Patrick van Gompel <patrick_van_gompel@xxxxxxxxxxx> > *To:* python@xxxxxxxxxxxxx > *Sent:* Monday, September 19, 2011 2:56 PM > *Subject:* [python] Re: Pythonjetrike > > Thanks guys for the tips and help! > Jaculus, can you please clearify so I am sure I understand it > correctly. > Are you saying that when I put a line around a bolt whitout > a knot or > anything and I hold both ends, that I can't multiply the > line strenght by > two? Of course the bolt does give some friction, but > aren't the forces on > both ends roughly the same? Isn't that how > pulleys work? If you pull one > end, the other end will move and have > the same force to it, or am I > completely wrong here? > Is a M6 bolt to sharp a bend for a 3 or 7mm thick rope? Please advice. > > Yes, as you can see in the pictures, the safety line goes through a > hole in > the tube and is of course sharp. But the primary line goes > over a > unthreaded bolt part, otherwise I would indeed have much more > wear. Wear on > the piece of string around the bolts was not the reason > for snapping. > Of course 150kg is about 1500N. But kg is what they use for kitelines, > and > probably Newton is for climbing ropes (donno why though). I used > kiting > knots for attaching both ends, so that the lenght was easy to > adjust. Don't > know what they are called, but it looks a bit like your > example: Clove > hitch combined with a figure of eight knot on the lose > end. Though, it was > the end knot that snapped off. The safety line was > of course snapped at the > sharp edge of the metal. > Now I use a /Square or Reef Knot/ for joining the line ends. Is this a > good > knot or can I better use your suggested Double fishermans knot? > The latter > seems more complicated and harder to adjust, but if it > gives more > strenght... > > Henry, I checked your dimensions for the swing arm again. Mine are a > bit > larger, but I have about the same relation: 1:3 for the arms > (about 30cm > for pivot point to axle and 10cm for pivot point to the > link connection > point). So 10kg load on the wheel will be 30 kg load > on the link going to > the rockerarm. Not sure why I have problems with > this connection and you > don't. My M6 economy rod ends where worn out > very quickly (without using > the trailer). My double M8 rod ends on the > rocker arm have signs of wear > too and the 15x15x1mm square tube is > deformed by the pulling load. I did > buy new M8 PTFE rod ends for the > links and M10 for the rocker arm, but I > haven't installed them because > I was testing the strings. But I am in doubt > now whether they are > strong enough. This M8 PTFE rod end has a 5.85kN > dynamic load rating > which is only about double the amount of my worn out M6 > rod ends. > > Thanks for the help, > Patrick > > > > Subject: [python] Re: (No From: Jaculus <jaculusbent@xxxxxxxxx> > > To: python@xxxxxxxxxxxxx > > Date: Mon, 19 Sep 2011 04:32:05 -0400 > > From: python-bounce@xxxxxxxxxxxxx > > > > Being a bit into rope climbing I see some design flaws in your rope > set > > up. > > > > First of all your rope goes over some pretty sharp metal edges, and a > > threaded bolt. Both of these increase wear and tear a lot (especialy > > when there is a lot of movement on those spots as I assume there is, > > judging from the photo’s). > > > > Then there is the issue of weakening a rope with knots and alike. As a > > rule of thumb you can say the tighter the bend of the rope in a knot > > is the more it weakens the rope. This does also apply for places where > > the is no knot, but only a bend or an angle, like at the metal edges > > in your pictures. > > > > An other point, two "150 kg lines" (I suppose you mean two 1500 N > > lines) do not ad up to a "300 kg connection" it will still be a "150 > > kg connection", because the changing loads will be on just 1 of the > > two lines in certain moments. > > > > Then the knot used: please keep it simple, improvising in knots rarely > > ever helps. There are plenty of good knots, but to avoiid confusion > > stick to simple ones. I would advise you to keep to the following 4 > > knots: > > - (Double)figure of eight knot. (to thicken rope or make loops at the > > end of rope) > > - Alpine butterfly. (for loops in the middle of rope) > > - Double fishermans knot. (to join two ropes) > > - Clove hitch combined with a figure of eight knot on the lose end. > > (to attach rope to a piece of wood/metal etc.) > > Never have a knot in another knot or in a bend of the rope. And > > remember the rule: Keep It Simple Stupid! > > > > Jaculus > > > > > > 2011/9/19 dirk@xxxxxxxxxx <dirk@xxxxxxxxxx>: > > > Hi Patrick, > > > > > > unfortunately, i don't have a link i can point to, but paragliders > have > > > the > > > "knot issue" as well. There are certains knots that introduce far > less > > > strain > > > into the strings than others do. Some can be reopened while others > > > > cannot. > > > > > > Greetings, > > > DirkS > > > > > > > > > Patrick van Gompel <patrick_van_gompel@xxxxxxxxxxx> hat am 18. > > > > September 2011 um > > > 17:44 geschrieben: > > > > > >> > > >> Wow Henry, that looks like a nasty slide... > > >> > > >> I did cycle quite a bit the last few days and although everything > > > >> seemed to go > > >> fine, I must warn people for the big loads going from swing arm > to > > >> rocker arm > > >> for the jetrike. Today I snapped a double 150kg line! I did have > the > > >> trailer > > >> behind the trike, but it was only loaded for maybe 50kg and not > really > > >> pushing > > >> much on the hook (balanced trailer). I drove into a hole on a > dirt road > > >> followed by a bump and the primary line and the safety line of > the > > >> left side > > >> snapped. The rear hit the ground and dug into the dirt. The bike > is ok > > >> and so > > >> am I, but I am glad that this didn't happen on the road with > traffic > > >> behind > > >> me. So, a 300kg strong link between rocker arm and swing arm is > not > > >> enough for > > >> my setup. I think I need to go at least twice as high, but > preferably > > >> up to 1 > > >> ton for safety margin. If I were to use quality rod ends, that > would > > >> mean M12 > > >> for size. This size rod ends are quite big and heavy (I use them > for > > >> the pivot > > >> point) and wouldn't like them for the links. I need to find some > 500kg > > >> strings.... I might try some 5mm hunting rope. Polypropylene is > not as > > >> good as > > >> dyneema, but 5mm is quite a bit thicker than I have now. > > >> > > >> Anyway, before things broke down, I had a great 75km cycling > trip. > > >> First, the > > >> lines seemed to be damaged a bit by the nut when the rocker arm > > > >> turned. I > > >> fixed this provisionally with a loop under the attached line > around > > >> the bolt. > > >> See: http://cycle.free-creativity.com/images/string_rockerarm.jpg > This > > >> seemed > > >> to work fine. > > >> The other end was durable enough and I left it the way it was: > > >> http://cycle.free-creativity.com/images/string_swingarm.jpg > > >> That setup was nearly wear free for 150km. So I think that > pulleys or > > >> the like > > >> are not really needed. A simple bolt will do. > > >> Last Friday I went for a garden job with the trailer (2x20km > trip). > > >> Including > > >> my garden tools the trailer weighs about 50kg and the trike > seemed to > > >> benefit > > >> from the extra load on the hook/rear. Though, the ride felt a bit > more > > >> bumpy. > > >> Handling was excellent, but a bit slower than without trailer. > Going > > >> to the > > >> dump site with garden waste of a total of about 100kg, the trike > was > > >> still > > >> stable and ok to handle, but tight cornering needed more leaning > it > > >> seemed. > > >> Braking with this load with only having a front brake, still felt > > > >> safe. At > > >> least, a test by pulling hard on the brake didn't do weird things to > > >> steering/balance or anything. > > >> > > >> > > >> Side note; I just read some stuff about strings/ropes on the > internet. > > >> Mentioned are safety margins of 5 times the applied load. That > means > > >> at least > > >> 1,5 tons for me! And a knot reduces the strenght to 50%. O > dear... I'd > > >> better > > >> take the 7mm hunting rope. > > >> > > >> Good hunting, > > >> Patrick > > >> > > >> > > >> From: whpthomas@xxxxxxxxx > > >> To: python@xxxxxxxxxxxxx > > >> Subject: [python] Re: Pythonjetrike > > >> Date: Thu, 15 Sep 2011 12:57:01 +1000 > > >> > > >> Hi Patrick, > > >> I concur with your observations. A loss of traction from braking > or > > >> cornering > > >> too hard is a real hazard with tilting delta trikes. Having > crashed my > > >> Jetrike > > >> on one such occasion, once the front wheel went down, I had no > time to > > >> recover. I took the bike back later and took this photo. You can > see > > >> the skid. > > >> The wider area at the bottom is where my shin hit the ground and > the > > >> painful > > >> gravel rash began :( > > >> Best regards to everyone. > > >> -h > > >> Henry Thomas > > >> On 15/09/2011, at 3:46 AM, Patrick van Gompel wrote:I fixed the > wheel > > >> today > > >> and did some more testing. > > >> With the fixed rocker arm and strings to the swing arms it works > > > >> sweet. The > > >> simple setup of bolts and nuts as pivot points for the strings is > > > >> working > > >> fine, although I probably need to adjust it a bit for better > > > >> durability. > > >> I did a bunch of heavy brake runs. If the pavement is ok and I > brake > > >> hard, the > > >> bike stays stable, but it is hard to stay in the seat. If you go > a bit > > >> forward > > >> out of the seat the back of the bike will come loose. If I manage > to > > >> stay put, > > >> the front wheel did slip sometimes. But this is at maximum > braking and > > >> is > > >> quite a bit more than I can achieve on my mountainbike. The weak > point > > >> of a > > >> leaning delta trike is when the front wheel is really blocked by > the > > >> brake and > > >> it slips for a longer time. When going straight over a field of > grass > > >> while > > >> slipping, makes the trike rather hard to handle (leaning and > > > >> steering). When > > >> going over dirt/gravel and going into a corner while braking, the > > > >> front wheel > > >> breaks out, which makes the rider fall into the corner. When this > > > >> happens it > > >> seems unlikely to recover from it, although you can put your feet > down > > >> to > > >> prevent falling to the ground. But, compared to a mountainbike > when > > >> only > > >> applying the front brake, the performance is likely the same. So > for > > >> slippery > > >> surfaces I do need rear brakes on my trike. > > >> I tested how the trike reacted when leaning to the front. The > trike > > >> becomes > > >> unridable as soon as a shift in leaning to the right or left is > > > >> needed. This > > >> might be because you don't have the grip of the seat anymore to > > > >> control the > > >> leaning, but possibly the changed CoG has the most impact. > > >> I changed the steering pivot angle: going up in degrees makes the > > > >> trike more > > >> relaxing to ride and going down makes it more aggressive. I think > that > > >> the > > >> wheelflop had the most impact on this. 65-70 degrees seems like a > > > >> sweet spot > > >> to me. > > >> I tested the use of the handlebar for leaning. It is only usefull > for > > >> stopping > > >> and keeping the feet on the pedals. Steering the leaning when > cycling > > >> didn't > > >> feel right and was even dangerous when really trying to. > > >> > > >> All in all I tested quite a few settings, but it's really hard to > get > > >> an idea > > >> what does what. There are so many variables and while you adjust > one, > > >> a few > > >> others might change too. So if I would make another trike, it > would be > > >> hard to > > >> optimize the design without changing the feel of the ride. > > >> For example, I am still puzzled how the steering interacts with > the > > >> leaning. > > >> It is a bit hard to see how the trike leans when riding on it, > but > > >> with the > > >> handle bar for leaning I could feel which way and how much is was > > > >> going. > > >> Steering and leaning seems to go together like a natural thing. > Even > > >> when I > > >> tried to stay in the same position on my seat, the bike still > seemed > > >> to lean > > >> with every corner. I can think about reasons to justify this, but > > > >> honestly I > > >> have no clue. > > >> > > >> Anyway, I proved it is possible to crash the delta trike, but the > feel > > >> and > > >> stability is really what I wished for when I started to think > about a > > >> trike. > > >> Thanks again to Jürgen and Henry for sharing those great ideas! > > >> Now I need some durability tests and get a fully loaded trailer > > > >> hooked... > > >> > > >> Happy cycling, > > >> Patrick > > >> > > >> > > > > > > http://dirk.steuwer.de > > > ============================================================ > > > > > > This is the Python Mailinglist > > > > > > //www.freelists.org/list/python > > > > > > Listmaster: Jurgen Mages jmages@xxxxxx > > > > > > To unsubscribe send an empty mail to > > > python-request@xxxxxxxxxxxxx > > > with 'unsubscribe' in the subject field. > > > > > > ============================================================ > > > > > > > > ============================================================ > > > > This is the Python Mailinglist > > > > //www.freelists.org/list/python > > > > Listmaster: Jurgen Mages jmages@xxxxxx > > > > To unsubscribe send an empty mail to > > python-request@xxxxxxxxxxxxx > > with 'unsubscribe' in the subject field. > > > > ============================================================ > > > > > ------------------------------------------------------------------------ > > No virus found in this message. > Checked by AVG - www.avg.com <http://www.avg.com> > Version: 10.0.1410 / Virus Database: 1520/3907 - Release Date: 09/19/11 >
Attachment:
2011-09-20_08-06-35_465.jpg
Description: JPEG image
