Parsons D reverse gear

[MtB]

Not quite sure where this question should be. I think we need a gearbox board!

 

Anyway, my question. I have a Parsons D series mechanical gearbox. Will it work in either direction, or is the direction of rotation of the engine it is connected to important?

 

If they are directional, how can I determine which direction of rotation mine is designed for?

 

Many thanks,

MtB

[davidg]

The D type (and big brother the F type) doesn't care which way the input shaft rotates.

 

In head gear the bevel gears are locked up & the cage & output shaft rotate in the same direction as the input shaft; in stern gear the bevel gear cage is held & the bevel gears do their stuff to reverse the rotation.

[Timleech]

Not quite sure where this question should be. I think we need a gearbox board!

 

Anyway, my question. I have a Parsons D series mechanical gearbox. Will it work in either direction, or is the direction of rotation of the engine it is connected to important?

 

If they are directional, how can I determine which direction of rotation mine is designed for?

 

Many thanks,

MtB

So far as I can remember, the only 'directional' aspect is the reducing gears, which are (I'm fairly sure, certainly true on the bigger Parsons boxes) helical and they will create or transfer a certain amount of thrust. I don't think this should be a worry, though. Prop thrust is fully taken care of by the output bearings, and the bearings on the main shaft ought to be specified to carry the incidental thrust from the reducing gears.

Some boxes are actually designed to use the reducing gears to transfer thrust to the main shaft and assist with clutch engagement, but those are boxes with a sliding main shaft which does not include the Parsons box.

 

Tim

[MtB]

The D type (and big brother the F type) doesn't care which way the input shaft rotates.

 

In head gear the bevel gears are locked up & the cage & output shaft rotate in the same direction as the input shaft; in stern gear the bevel gear cage is held & the bevel gears do their stuff to reverse the rotation.

 

 

Thank you. That's what I thought, but Simon Wain is of a differing opinion, and I had asked him to fit mine to an anti-clockwise rotation engine.

 

 

So far as I can remember, the only 'directional' aspect is the reducing gears, which are (I'm fairly sure, certainly true on the bigger Parsons boxes) helical and they will create or transfer a certain amount of thrust. I don't think this should be a worry, though. Prop thrust is fully taken care of by the output bearings, and the bearings on the main shaft ought to be specified to carry the incidental thrust from the reducing gears.

Some boxes are actually designed to use the reducing gears to transfer thrust to the main shaft and assist with clutch engagement, but those are boxes with a sliding main shaft which does not include the Parsons box.

 

Tim

 

Thanks Tim. This is a 1:1 box so no reduction gears. So the board seems to agree it will work correctly with the input shaft driven driven in either direction.

 

One further question, does anyone have a manual for this gearbox please? Or suggest where I can get one?

 

Many thanks,

 

MtB

[Timleech]

 

 

Thank you. That's what I thought, but Simon Wain is of a differing opinion, and I had asked him to fit mine to an anti-clockwise rotation engine.

 

 

 

Thanks Tim. This is a 1:1 box so no reduction gears. So the board seems to agree it will work correctly with the input shaft driven driven in either direction.

 

One further question, does anyone have a manual for this gearbox please? Or suggest where I can get one?

 

Many thanks,

 

MtB

 

There's been somebody offering Parsons manuals on fleabay recently, may be worth checking. They really don't tell you much, though. Come back if you're really stuck.

 

One point has occurred to me, just check that the oil catcher/distributor under the cover plate is symmetrical. This collects oil thrown up by the oil thrower at the front of the box, and helps it to run back down to the points where it's needed. Obviously in your case it'll need to do the job with either rotation.

 

Tim

[MtB]

Ok thanks Tim. I'll check ebay then, but in the meantime I've just been googling and found a manual for £12, here:

 

http://www.parsonsmathwaymarine.co.uk/manuals.htm

 

Next task is to find out if I have Mk1 or a Mk3.

 

I'll take the top off and have a look inside for the oil catcher. Trouble, the gearbox is 100 miles away from me at the moment...

 

 

MtB

[James Owen]

Ok thanks Tim. I'll check ebay then, but in the meantime I've just been googling and found a manual for £12, here:

 

http://www.parsonsmathwaymarine.co.uk/manuals.htm

 

Next task is to find out if I have Mk1 or a Mk3.

 

I'll take the top off and have a look inside for the oil catcher. Trouble, the gearbox is 100 miles away from me at the moment...

 

 

MtB

The oil catcher is symmetric IIRC but I'll check later this week Mike, save you a journey

[davidg]

 

 

Thank you. That's what I thought, but Simon Wain is of a differing opinion, and I had asked him to fit mine to an anti-clockwise rotation engine.

 

I'll have a word with Simon in the morning!

[James Owen]

I'll have a word with Simon in the morning!

I spoke to Simon a while ago and confirmed that, after initial concerns, in fact the Type DA wasn't directional and this wouldn't be a problem.

 

This information obviously didn't reach Mike before this thread was started.

[MtB]

I spoke to Simon a while ago and confirmed that, after initial concerns, in fact the Type DA wasn't directional and this wouldn't be a problem.

 

This information obviously didn't reach Mike before this thread was started.

 

Well that's interesting. I called in and chatted with Simon on Saturday afternoon (day before yesterday) and he still seemed to think it was very likely a problem, and left it to me to do the research and find out for sure!

 

MtB

[James Owen]

Yup, sounds like Simon

 

In all seriousness, we decided the gearbox wouldn't pose a problem as it will work perfectly in either direction.

 

Only alteration might involve propeller hand if the rotation was different from the engine that was being removed, otherwise, all good!!

If you're still unsure however, Parsons Mathway are the people to speak to. I can't recall the chaps name off hand but he believed there wouldn't be a problem, and that spares are still 'available' !!

[RLWP]

Parsons Mathway are the people to speak to. I can't recall the chaps name off hand but he believed there wouldn't be a problem, and that spares are still 'available' !!

 

More so than they used to be too. Parsons Mathway changed hands a couple of years ago and the new owner is keen to make spares available again

 

http://www.parsonsmathwaymarine.co.uk/parsons_gearboxes.htm

 

Richard

Edited October 28, 2014 by RLWP

[MtB]

Yup, sounds like Simon

 

In all seriousness, we decided the gearbox wouldn't pose a problem as it will work perfectly in either direction.

 

Only alteration might involve propeller hand if the rotation was different from the engine that was being removed, otherwise, all good!!

If you're still unsure however, Parsons Mathway are the people to speak to. I can't recall the chaps name off hand but he believed there wouldn't be a problem, and that spares are still 'available' !!

 

Thanks for that James. Parsons Mathway are the peeps I found selling the manual I mentioned earlier in the thread. The least I can do is buy the manual from them given what Richard has just said too!

 

MtB

[MtB]

Only alteration might involve propeller hand if the rotation was different from the engine that was being removed, otherwise, all good!!

 

 

Forgot to mention in my last post, the blade on REGINALD has "P19215" stamped on the boss, which I interpret as 19" x 21.5". Certainly looks about 19" in diameter. And it's a LH blade. The Gleniffer is anti-clockwise as is the Skandia.

 

Another number stamped on the blade boss is "10281", the meaning of which I have no idea.

 

MtB