Newage-PRM gearbox noise XP
Roger Millin
On my new boat with Gardner engine and PRM 500 hydraulic box the
gearbox makes a rather unpleasant crash/crunch noise as the the box
goes into forward or reverse. I have been told that this is not
unknown with PRM boxes, but PRM deny that it is due to their box. They
blame anything and everything but, including low engine revs, prop
shaft, prop shaft coupling, large prop etc etc.
They were, I am informed, developing a modified valve block to cure
the problem some time ago but have now given up on the project. Quite
why they would develop a modified valve block to cure a problem that,
according to them, doesn't exist, I don't really know! There was in
existence at one time an Italian proprietary valve block that cured
the problem also, I believe.
Does anyone else have a crunching gear change on a 500 box (or any
other PRM for that matter)and has anyone a solution to the problem?
Roger.
Michael J Wooding
news:99d09ed4.01090...@posting.google.com...
We have but a mere 260 Roger, but no crunching
Mike
Krystyna & Michael Wooding - tug DRACO
Michael: NABO Webmaster http://www.nabo.org.uk
Michael: CIBC Webmaster http://www.cutweb.org.uk
The CUTPICS site: http://www.cutpics.org.uk
Krystyna: Draco Crafts - http://www.dracocrafts.co.uk
Tony Brooks
I am only familiar with the guts of the samller PRM boxes, but
assuming yours is just larger and stronger - ie twin countershaft and
oil operated multi-plate clutches - I can see no reason for the box to
crunch. In fact I would have said it was not possible.
I would be looking for a mechanical explanation like the drive plate
(if it has one), worn bearings, partiall detatched clutch housings
etc.
Tony Brooks
On 5 Sep 2001 05:02:52 -0700, roger....@tinyworld.co.uk (Roger
timleech
Millin) wrote:
Crunching gearchange seeps a bit improbable with the standard PRM
design (I don't know the 500).
What's quite common is rattling on tickover, particularly on marinised
vehicle engines where the flywheel isn't heavy enough to damp out the
torsional fluctuations.
The cure for that can be to fit a heavier flywheel, or some additional
weight (I've done that successfuly to a couple of 4LK's) ; to increase
the tickover speed (not usually what you want to do) ; or to use a
'softer' drive plate. R&D do some 'asymmetrical', for want of a better
word, drive plates which are supposed to help with this. A rubber or
Metalastik coupling in the prop shaft might also help.
'Proper' marine Gardners had massive flywheels compared with the
vehicle versions, partly to aid hand starting but also to help avoid
gearbox rattle.
Cheers
Tim
Tim Leech
Dutton Dry-Dock
timl...@dutondok.u-net.com
Traditional & Modern canal craft repairs
Roger Millin
> Crunching gearchange seeps a bit improbable with the standard PRM
> design (I don't know the 500).
> What's quite common is rattling on tickover, particularly on marinised
> vehicle engines where the flywheel isn't heavy enough to damp out the
> torsional fluctuations.
> The cure for that can be to fit a heavier flywheel, or some additional
> weight (I've done that successfuly to a couple of 4LK's) ; to increase
> the tickover speed (not usually what you want to do) ; or to use a
> 'softer' drive plate. R&D do some 'asymmetrical', for want of a better
> word, drive plates which are supposed to help with this. A rubber or
> Metalastik coupling in the prop shaft might also help.
> 'Proper' marine Gardners had massive flywheels compared with the
> vehicle versions, partly to aid hand starting but also to help avoid
> gearbox rattle.
Following up on both Tim and Tony's postings. The salient facts are:-
1. It's all brand new, and the noise has been there from new.
Therefore there is nothing *worn*.
2. There is no bell-housing, the box is mounted on a separate plate to
allow access to the flywheel for generator belt drive, so no *clutch
housing* rattle.
3. There is the most flexible drive plate in the system that R&D do.
4. There is a metalastik coupling immediately after the output flange.
5. It has had a modified valve block fitted that was designed to stop
the poblem.
6. There is no rattling at low speed whatsoever. My only complaint is
the crunch when engaging gear.
However, knowing how the trolling valve works on this box, I came up
with an idea, which by total coincidence was also suggested by the guy
at Lancing Marine (totally without my prompting) so I am going to have
a go. Will tell you whether it works when I've had a chance to try it.
Roger.
Neil Arlidge
news:99d09ed4.01090...@posting.google.com...
> 6. There is no rattling at low speed whatsoever. My only complaint is
> the crunch when engaging gear.
......just a thought after Tony's usual excellent advice......
Are you 100% sure that the gearbox is def not even a teeny weeny bit loose
on the housing?
One of the *Un* fleet suffered a similar fault and you could barely feel the
movement between the gearbox and housing.
--
Neil Arlidge, nb Earnest - Commode D'Or © TNC on Tour.
Follow the travels of Neil and the TNC in hire-boats, Beatty and Earnest at
http://www.tuesdaynightclub.co.uk
See nb Earnest being built at http://www.nbearnest.co.uk
See the newsgroups photo call at
http://www.tuesdaynightclub.co.uk/Photocall.html
Tony Brooks
Millin) wrote:
snip
>2. There is no bell-housing, the box is mounted on a separate plate to
>allow access to the flywheel for generator belt drive, so no *clutch
>housing* rattle.
I was actually refering to the clutch housings on the counter shafts
in the gearbox, not the engine bell housing or what have you. TMP
boxes were renown for problems in this area (but not PRMs)
>However, knowing how the trolling valve works on this box, I came up
>with an idea, which by total coincidence was also suggested by the guy
>at Lancing Marine (totally without my prompting) so I am going to have
>a go. Will tell you whether it works when I've had a chance to try it.
>Roger.
Please do - this is the way we all learn
Tony Brooks
Michael Clarke
"Neil Arlidge" <neila...@tuesdaynightclub.co.uk> wrote in message
news:5y0m7.14447$592.1...@news2-win.server.ntlworld.com...
> "Roger (clunk, clunk, stop) Millin" <roger....@tinyworld.co.uk>
wrote in message
> news:99d09ed4.01090...@posting.google.com...
>
> > 6. There is no rattling at low speed whatsoever. My only complaint
is
> > the crunch when engaging gear.
>
> ......just a thought after Tony's usual excellent advice......
>
> Are you 100% sure that the gearbox is def not even a teeny weeny bit
loose
> on the housing?
> One of the *Un* fleet suffered a similar fault and you could barely
feel the
> movement between the gearbox and housing.
Ah no, the gearbox is OK, it's the owner that has a loose screw ;-) In
fact, I even think he is pulling his hair out at the moment (what
little he has left) with some of the "other" problems he's
experiencing :-(
--
Regards - Michael Clarke
Email: michael...@skynet.be
Web Pages: http://users.skynet.be/sky34301/index.html
Roger Millin
> Are you 100% sure that the gearbox is def not even a teeny weeny bit loose
> on the housing?
> One of the *Un* fleet suffered a similar fault and you could barely feel the
> movement between the gearbox and housing.
If that were the case then I would have thought that I would have seen
some signs of fretting where the box is mounted to its support plate.
This is not the case and the paint is uncracked.
Roger.
Vic and June
between the engine and the road wheels when changing gear. Can you adjust the
cluch clearance. This I did on an old vannet box on a two pot petter, if the
crunch is from forward to reverse wait in nutral before selecting reverse.
Clogdancer on a fat boat. Abandoned the north to explore the other half before
it sinks.
Roger Millin
> I was actually refering to the clutch housings on the counter shafts
> in the gearbox, not the engine bell housing or what have you. TMP
> boxes were renown for problems in this area (but not PRMs)
>
> >However, knowing how the trolling valve works on this box, I came up
> >with an idea, which by total coincidence was also suggested by the guy
> >at Lancing Marine (totally without my prompting) so I am going to have
> >a go. Will tell you whether it works when I've had a chance to try it.
> >Roger.
>
> Please do - this is the way we all learn
needs a little refinement, I think, to have the problem largely (if
not completely) cracked. Watch this space, but sshhhh, don't tell PRM
;-)
Roger.
Roger Millin
> On some waggons a cluch brake was incorporated to adjust the diference in speed
> between the engine and the road wheels when changing gear. Can you adjust the
> cluch clearance. This I did on an old vannet box on a two pot petter, if the
> crunch is from forward to reverse wait in nutral before selecting reverse.
No the clutches are not adjustable. They are hydraulically operated
multi-plate clutches that cause the drive to be transmitted from
whichever gear has been selected by the spool valve operation.
No matter how long you wait in neutral the crunch occurs on selecting
gear. Basically I am asking the gears to accelerate an 11 foot prop
shaft coupled to a 22 inch prop from rest to nearly 300 rpm in zero
seconds (approx 400 rpm tickover, 1.5:1 ratio box due to fine pitch 22
x 16 prop, reduces prop walk in reverse), so that's why the gears
protest a little. See my other post though because my modification is
looking very promising indeed, just needs a bit of further refinement.
Roger.
Tony Brooks
Me thinks we might be getting back to On 8 Sep 2001 15:30:24 -0700,
roger....@tinyworld.co.uk (Roger Millin) wrote:
Me thinks we might be getting back to some type of restriction to the
oil flow, so the clutches engage more slowley. Being wet clutches
there should not be too much of a wear problem due to slip.
Tony Brooks
Roger Millin
> Me thinks we might be getting back to some type of restriction to the
> oil flow, so the clutches engage more slowley. Being wet clutches
> there should not be too much of a wear problem due to slip.
I'm not going to tell you until I've proved it out to my satisfaction
(or finally admitted that my idea is no good). Just to throw another
spanner in the works I think I should add that my idea will not work
without another person's idea/mod being implemented first. There, that
should have muddied the waters a little I think ;-)
Roger.
nb Teaser
Graham Till
Millin) wrote:
>Hi All,
>On my new boat with Gardner engine and PRM 500 hydraulic box the
>gearbox makes a rather unpleasant crash/crunch noise as the the box
>goes into forward or reverse..
I caught this thread late due to being away. My boat with a Gardner
4LK and a big PRM also crashes into forward, especially if I'm too
sharp with the Morse. I have tried all sorts of things over three
years with only partial success - the most effective being experiments
with differing the length of the control cable. So if there's a
secret fix, I'd be very glad to know it.
Graham Till
Roger Millin
> I caught this thread late due to being away. My boat with a Gardner
> 4LK and a big PRM also crashes into forward, especially if I'm too
> sharp with the Morse. I have tried all sorts of things over three
> years with only partial success - the most effective being experiments
> with differing the length of the control cable. So if there's a
> secret fix, I'd be very glad to know it.
me further encouragement, some changes are now effectively silent. As
soon as I have done some more experimentation (so that I'm not putting
my foot in my mouth) I will let anyone who is interested know how I
have made the improvement and more importantly the dimensions
involved. Establishing the correct dimensions for the mod is the time
consuming (and very important) part.
Roger.
