rotational play in propeller

[jenevers]

Last time I dry docked I checked the prop and noticed there was 1 degree of play. I wondered if this is OK or if there's some adjustment in the Gardner gearboxes that could reduce it down to nothing.

[dmr]

You need to work out where this play is occurring, if its between the prop itself and the shaft then it needs urgent attention, if its in a drive coupling that could be serious, but you suggest its in the gearbox. If its the gearbox then its called gear backlash and is normal....this is why gearboxes sometimes rattle at low tickover speeds. A bit of backlash is required else when things get hot and expand the gears might lock solid. 1 degree sounds pretty good to me.

 

A few gear systems get zero backlash by using two gears with a spring forcing them apart (in a rotational sense), one example of such a sophisticated system was the camshaft drive gear on the Citroen 2CV engine

 

................Dave

[Kingdom Isambard Brunel]

Ahh, there was an engine! Wish more could have been engineered like those beauties.

[Stilllearning]

The 2CV engine was a total joy to work on with some lovely sensible bits of design, if we had a garage we would have one now.

On the op’s question, one degree of play on a prop shaft or in the rotation of the prop is not enough to worry about.

[dor]

I had a similar degree of play in my Python Drive.  It concerned me at first, but it has been fine for the last ten years.

[Kingdom Isambard Brunel]

15 minutes ago, dor said:

I had a similar degree of play in my Python Drive.  It concerned me at first, but it has been fine for the last ten years.

Same with my Aquadrive so I Locktited the splined  center shaft in, sorted. Its  a recommended fix.

[jenevers]

2 hours ago, dmr said:

You need to work out where this play is occurring, if its between the prop itself and the shaft then it needs urgent attention, if its in a drive coupling that could be serious, but you suggest its in the gearbox. If its the gearbox then its called gear backlash and is normal....this is why gearboxes sometimes rattle at low tickover speeds. A bit of backlash is required else when things get hot and expand the gears might lock solid. 1 degree sounds pretty good to me.

 

A few gear systems get zero backlash by using two gears with a spring forcing them apart (in a rotational sense), one example of such a sophisticated system was the camshaft drive gear on the Citroen 2CV engine

 

................Dave

It's in the gearbox so no worries then?