Play in gearbox

[swift1894]

In dry dock at the moment and noticed about 5 degrees of circular "play" in the propeller when in neutral.

Is that acceptable/normal in a Gardner 2UC?

Edited May 7, 2015 by swift1894

[John Williamson 1955]

If it's in neutral, normally, the prop should be free to turn continuously, as there's no connection between it and the engine.

 

I'm not familiar with that box, does it have a propshaft brake?

Edited May 7, 2015 by John Williamson 1955

[swift1894]

If it's in neutral, normally, the prop should be free to turn continuously, as there's no connection between it and the engine.

 

What gearbox is fitted? Some of them have a propshaft brake, which could give the symptom you describe.

I can turn it freely but there's just 5 degrees of free loose movement before I can feel any resistance.

 

It's a Gardner 2UC box.

[John Williamson 1955]

Ah. You may have some play in the outlet shaft splines, or the box may just need adjusting. I'd have to be there and feel it ,myself to tell for sure. :-(

[Timleech]

Ah. You may have some play in the outlet shaft splines, or the box may just need adjusting. I'd have to be there and feel it ,myself to tell for sure. :-(

 

I don't think you can have ever seen a 2UC box

 

As with a similar question about a Blackstone box a little while ago, it's very hard to give any constructive judgment at a distance.

5 degrees could be at the top end of what's acceptable, but are there any symptoms which give rise for concern?

 

Tim

[John Williamson 1955]

For a fiver, the OP can download or buy a reprint of the manual.

[swift1894]

For a fiver, the OP can download or buy a reprint of the manual.

No need cos I've got an original manual

Hmm. Section 23 Checking Backlash of Bevel Gears.......maybe the answer's in there somewhere. I'll have a read.

I don't think you can have ever seen a 2UC box

 

As with a similar question about a Blackstone box a little while ago, it's very hard to give any constructive judgment at a distance.

5 degrees could be at the top end of what's acceptable, but are there any symptoms which give rise for concern?

 

Tim

5 degrees could be at the top end of what's acceptable, but are there any symptoms which give rise for concern?

 

Tim

No everything is fine. Just wondered if there should be any free movement in the prop shaft. Edited May 7, 2015 by swift1894

[John Williamson 1955]

Fore and aft, no, even if there is a plummer block. Laterally, no. There will be a tolerance for rotational slackness, and that will be in the manual.

[RLWP]

Just wondered if there should be any free movement in the prop shaft.

 

Yes, it's inevitable. The various gears always run with some clearance, the diameter of the propeller and the ratio of the reduction box magnifies this

 

Richard

[swift1894]

Fore and aft, no, even if there is a plummer block. Laterally, no. There will be a tolerance for rotational slackness, and that will be in the manual.

The play is only rotational. The section on this in the manual is far too complicated for me to even think about trying to measure, not having the instrumentation required.

[swift1894]

Yes, it's inevitable. The various gears always run with some clearance, the diameter of the propeller and the ratio of the reduction box magnifies this

 

Richard

Thanks, that's reassuring to know. I wasn't particularly worried but I just like to check things like this to increase my knowledge so I can "nip things in the bud" in case things are going wrong.