Steering sheave matters: they move in all directions. Clever engineering or FUBAR?

[antaris]

And we have an array of 6 of those, under the aft cabin - routing the oversized cable to steering column. All works fine.

Today, as part of annual (let's say "continuous") maintenance, I came to the realisation that the sheaves ROTATE IN ALL DIRECTIONS. First, and foremost, they rotate 360 around the main axis as they should (let's call it the X axis) - but they also rotate on the Y and Z. when rotated, they touch the U brace. Is that part of some very clever 70's engineering or are the sheaves totally gone? I loosened the cable and there is no "play" around each axle - the bore hole seems to be right.

They are Goiot brand, in a 1978 Gin fizz.

As you can presume, I could not remove the axle bolt to inspect, as they are seized in place. Solution probably involves removing cable and full assemblies, heat, inspection and replacement sheaves (?)...

 

[coopec]

The only reservation I would have is the sheave diameter. Are they too small?

Safety update - Small craft wire cable steering controls January 2011 - Maritime NZ

Open wire sheaves

 

[PetiteFleur]

As long as the sheaves rotate with no play, and no broken wires in the cable, make sure all axles are lubricated, they should be fine. I've just replaced my steering cables and one cable had several broken strands due to misalignment of the outer cable which is impossible to rectify, been like it from new(now 41yrs old) Just have to keep inspecting it.

 

[coopec]

I think it is great that they self align as I had to do mine very carefully manually with string.

 

[antaris]

As long as the sheaves rotate with no play, and no broken wires in the cable, make sure all axles are lubricated, they should be fine. I've just replaced my steering cables and one cable had several broken strands due to misalignment of the outer cable which is impossible to rectify, been like it from new(now 41yrs old) Just have to keep inspecting it.

Yeap, no play and the wire has been replaced by previous owners!

 

[antaris]

I think it is great that they self align as I had to do mine very carefully manually with string.

Have never come across self-aligning sheaves, therefore my post! If this is the case... super happy about it.

 

[rogerthebodger]

This is a wire steering sheave from one of my local suppliers showing the articulation.

Steering pulley block | Boat tent caravan awning parts

 

[coopec]

I'm using heavy 7/19 Stainless cable which required a minimum of 7 inch diameter sheaves. I needed X8 of them and to buy them off the shelf was going to cost $300+/each so I converted V belt pulleys.

 

[Norman_E]

The only reservation I would have is the sheave diameter. Are they too small?

Safety update - Small craft wire cable steering controls January 2011 - Maritime NZ

Open wire sheaves

I have the same reservation and think a previous owner has probably replaced the original wire with a larger size. I suggest measuring the wire and the sheaves. If the wire is 7x19 stainless the ratios in that article are the minimum, i.e 6mm wire needs a minimum 150mm sheave diameter. I have never measured the sheaves on my boat and suspect that they are only just about big enough. Years ago I built a crane to lift my small steam locomotive and initially used 4mm wire, which failed because the sheaves I made were too small.

 

[antaris]

Thank you all. My original issue was the play in the axles - and now I have a new one (the wire gauges!).


Jokes aside, I learned a lot and will look into the wire gauge next winter, after substantial research is complete! Thank you all!