U-joint, CV-joint, Thompson coupling

Discussion in 'Propulsion' started by brian eiland, Mar 16, 2007.

  1. brian eiland
    Joined: Jun 2002
    Posts: 4,777
    Likes: 150, Points: 73, Legacy Rep: 1903
    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

  2. Guillermo
    Joined: Mar 2005
    Posts: 3,644
    Likes: 183, Points: 63, Legacy Rep: 2247
    Location: Pontevedra, Spain

    Guillermo Ingeniero Naval

    Interesting. Thanks Brian.
     
  3. FAST FRED
    Joined: Oct 2002
    Posts: 4,519
    Likes: 109, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    TECH Fallout is getting faster and faster , but if you think boat stuff is expensive , wait till you purchase from the Helicopter folks parts bin!,

    Still waiting for boats to use a common power bus (ring) and electric for simple controls to operate hyd power packs , done on fighters for decades.

    Imagine a windlass or bow thruster with no service time limits , and the no blown fuses of hyd power!

    FF
     
  4. SeaJay
    Joined: Jun 2007
    Posts: 211
    Likes: 5, Points: 0, Legacy Rep: 112
    Location: Sacramento

    SeaJay Senior Member

    I want one!
     
  5. mjbtx
    Joined: Oct 2007
    Posts: 2
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Texas

    mjbtx New Member

    Cool stuff. Need some to replace my merc cv couplings.
     
  6. Landlubber
    Joined: Jun 2007
    Posts: 2,640
    Likes: 123, Points: 0, Legacy Rep: 1802
    Location: Brisbane

    Landlubber Senior Member

    Thanks Brian, it is unbelievable.
     
  7. Frosty

    Frosty Previous Member

    Well I tried to down load the movie but 1: hour 45minutes was just too much. It looks like a normal UJ in a frame???
     
  8. Landlubber
    Joined: Jun 2007
    Posts: 2,640
    Likes: 123, Points: 0, Legacy Rep: 1802
    Location: Brisbane

    Landlubber Senior Member

    That is the brilliant simplicity of this Frosty, it really is just a double version, but the second ring makes it all work. It truely is a CV joint.
    Most good inventions are simple.
    I am simple, but can only try to be good.
    Where did I go wrong, I can nod my head up and down move it left and right and even pivot it at the same time, but not in CV.....
    Maybe this conversation should be in the drivel thread eh
     
  9. brian eiland
    Joined: Jun 2002
    Posts: 4,777
    Likes: 150, Points: 73, Legacy Rep: 1903
    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

  10. DCockey
    Joined: Oct 2009
    Posts: 3,957
    Likes: 144, Points: 63, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    Why would the Thompson joint be better than any of the multitude of other CV joints currently available?

    Does the amartech RPS even need a CV joint? Based on the illustration in their website it appears to me that the shaft is only turning with the unit deployed and the angle change of the shaft in the swivel joint is small enough that a simple Carden joint would be sufficient.
     
  11. brian eiland
    Joined: Jun 2002
    Posts: 4,777
    Likes: 150, Points: 73, Legacy Rep: 1903
    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

    You might recall that in a propeller application the prop is transmitting a very appreciable thrust load up the shaft (axial load to the joint). Most CV's and Carden joints don't like high axial loading.
     
  12. DCockey
    Joined: Oct 2009
    Posts: 3,957
    Likes: 144, Points: 63, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    The Thompson joint is similar to a nested double Cardan joint. No reason it would be any happier with axial loading than a Cardan joint. Corvettes for many years used the half-shafts with Cardan joints on the ends as the upper lateral control links for the rear suspension and those joints saw axial loads. Also some CV joints are designed for axial loads.

    No reason a propeller shaft has to transmit thrust to a U-joint. A thrust bearing can be used between the propeller and the U-joint.

    Looking at the drawing of the Amartech RPS system on their website (click on the illustration and then click on the arrows for the third slide) it appears that it uses a thrust bearing at the end of the propeller shaft in the swivel joint housing.

    Several firms produce propeller shaft systems which use a seal and thrust bearing in the stern post, with an intermediated shaft which Cardan joints at either end between the thrust bearing and the engine/reverse gear. Advantages include allowing soft mounting of the engine for reduced vibration. I'd consider it proven technology for boats in the small and medium size range.
     
    Last edited: Feb 6, 2012
  13. Petros
    Joined: Oct 2007
    Posts: 2,937
    Likes: 137, Points: 63, Legacy Rep: 1593
    Location: Arlington, WA-USA

    Petros Senior Member

    that is a great invention, would make u-joints and cv joints obsolete. looks costly to manufacture however, too many detail parts, so not likely we will ever get to see them on mass produced cars.
     
  14. mydauphin
    Joined: Apr 2007
    Posts: 2,166
    Likes: 49, Points: 48, Legacy Rep: 575
    Location: Florida

    mydauphin Senior Member

    I am still looking for an inexpensive thrust bearing, the CV joints aren't the problem.
     

  15. brian eiland
    Joined: Jun 2002
    Posts: 4,777
    Likes: 150, Points: 73, Legacy Rep: 1903
    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

    I'm not saying that Cardan joints don't accept axial loads, but when you are directing pushing maybe 200-400 hp thru them to push your vessel, i don't believe they would hold up for long

    Here is that dwg. I'm not so sure you could place the trust bearing in the rotating member and have it do its job properly. I suspect the trust bearing is after the 'pivotable joint' where the shaft enters the hull??
    Amaratec retractable drive.jpg

    Understood. One must also consider extracting the prop shaft for servicing, particularly in the case of bending the shaft upon striking an object
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.