How does a Marine gearbox work?, PRM DELTA 20

Here I try to share the wonder of modern finesse that is the PRM hydraulically actuated boxes. This is the small delta 20 but the principle is the same with many gearboxes that use hydraulic force.
Any advice or suggestions here are taken at your own risk, no liability for your own actions can be taken.
If in doubt seek professional advice either with us directly or independently.
Thank you.

[@DangarMarine]

Thanks for making this vid. I have a PRM in my boat, very interesting to see.

[@krishnakumar-py9vx]

Haloo master..

[@dhcrouchmarineltd3049]

Glad it helped

[@chriswatkeys9907]

Great video - before watching this I only had a loose understanding of the function of the clutch (I knew it either engaged or disengaged the drive), but this vid was really well explained and has given me a much better understanding. Cheers Darren!

[@darrengreen9957]

Thank you, fantastic explanations. I say that as plural because I've learnt so many things . I thought the highlight was finally learning how the clutch plates work, but then the Staffie stuck is head round the door :)

[@johnmoore3859]

Excellent video. Thanks for taking the time to make it. Clever engineering by those that initially designed these gearbox's. Loved the Motorcyle analogy. That made things very clear.

[@dhcrouchmarineltd3049]

I have played with so many marine gearboxes and these are so simple. Glad you enjoyed it.

[@halldorgislason6580]

Thank you for a great video, very helpful in understanding how gearbox works.

[@alfonsedaudet7678]

Love the dog 😺

[@deborahleitert4203]

Very well done with appreciation from Canada

[@skunkjobb]

Excellent explanation. I already knew how it works but it's much better than the simple animations I've seen before.

[@dhcrouchmarineltd3049]

Thank you. Im pleased you've enjoyed it.

[@dandoran5854]

Great video, I'm working on my Reintjes GBA120 and this has been very helpful to me.

[@rafaelpontes1655]

Very interest video. Very useful for the new marine engineers coming up to the vessels. I want to learn everything about marine main machinery, and you are helping a lot!

[@arildrognskog1758]

Great video! Big thanks from Norway !

[@interludo]

So much in this video again.Can feel the love you have for this. Careful or you ll end up as a teacher 😂 Impressive support - en français - on top of that!

[@jesman20]

Love this video, very explanative(new word). Love the in depth instructions and you explain things very well.

[@dhcrouchmarineltd3049]

Thank you, glad you enjoyed it.

[@ironhorse3497]

Thanks mate, this makes perfect sense. Thanks for sharing!

[@samculver9405]

Thanks for a great video!

[@pondfeature]

Thank you, Bloody great clip! I now understand lol....

[@alaashahin6844]

great work sir

[@dhcrouchmarineltd3049]

Thanks for that.

[@floris1988span]

Thanks a bunch for your explanation. Just took a PRM 302 from behind a clients Perkins 236M for repair, great to have a better understanding of the inner workings.

[@dhcrouchmarineltd3049]

Good luck

[@dhcrouchmarineltd3049]

Also are you aware there is a new Perkins engine pages Facebook. It might be helpful.

[@zeekwolfe6251]

Many years ago automobile manufacturers developed systems for operating windows up and down at the touch of a switch. Windshield wipers the same. The windows were powered by hydraulic fluid pumped into the doors and the windshield wipers by vacuum hoses from the engine. The clutch plates in the video remind me a little of the old cork clutches in Hudsons although not conical in shape. With modern electronics and materials gear boxes like this should have been long since obsolete. In some ways marine engineering has not progressed since the Model T. Oh, vacuum hoses to power windshield wipers were used as recently as 1969 in some makes.

[@dhcrouchmarineltd3049]

Interestingly a friend of mine said his VW camper van uses air pressure to drive the fluid from the screen wash while moving forward. Interesting concept. And to your second part, yes in the sector of Marine equipment I see, it is stuck in the past in many ways.

[@kresimirmilisa5560]

nice explained thanks.

[@Adam-en4zm]

Wow, thanks for filming this very fascinating video. What are the most common failure points in these kind of designs? I'd guess the clutch packs wear down if the shift lever is only halfway applied for long periods. Also the rubber gaskets look like they'd crack with old age. Thanks again!

[@dhcrouchmarineltd3049]

The rubber seals do get harder with age and some oils.

[@kamodernchannel5337]

Nice explaination sir..its very nice marine gearbox..how i wish to have that in my place and really want buy it..

[@Erik_Sharp]

I really enjoyed this. I am having a narrowboat built and have been curious as how the systems work. It is very interesting how it does not rely on engaging gears as in a motorcycle transmission. When I was younger I remember how changing gears in a two stroke outboard had that 'clunk' when engaging and was wondering if my transmission (Beta 43) was going to be the same. Seems that this would be much smoother transitioning such as when mooring or winding. I wonder how much power is lost through viscosity grab for the opposite direction. I suppose when cold this would be more apparent. Thanks for making these.

[@dhcrouchmarineltd3049]

Glad you enjoyed it. I love making them. As for the outboard, the clutch in them is called a dog clutch. I will get to making a video on soon.

[@Neptuneboy1959]

Really informative, the best explanations are hands-on, and you're totally conversant. I'm right now stripping my Perkins Prima M50, and PRM box as proactive measure, >30yo, unknown hrs, aa looking tired, hoses, pumps, timing belt/ idler... burning/ consuming oil. Running sweet though, except rattling buzz from gearbox at idle when in gear, though fine once revs up a tad. It'll be 1986 to 1990 vintage, looks like the Delta 20, but poss the 150? Do they share parts? Unfortunately the makers plate has gone AWOL.🤔 Really appreciating your generosity sharing your wisdom. Phil

[@dhcrouchmarineltd3049]

Hey Phil, glad the content has been helpful. The clutch plates and drive plates are all interchangeable across the hydraulic actuation range of boxes. But ultimately the delta and 150 are very different. The 150 input shaft is bigger. There are a lot of similarities but each box is its own thing. One thing to note is the delta box relies on the adaptation plate to finish the casing. If you take the box off the plate oil can fall out. The 150 uses blanking caps. Good luck

[@Neptuneboy1959]

@@dhcrouchmarineltd3049 very kind of you to get right back and reassuring that I should at least still be able to source these parts, as common to other models. I'll be forewarned about drive plate potentially dropping off as I pull box off engine ... though was half expecting it may be seized on splines. Looks like may first have to cut a couple nuts first, down low on adaptor casting, as only room for open- end spanner, well rusted from historic dripping raw water pump above. That's boats hey... can see the appeal of electric propulsion at such times😉 But soon all will be well for next 30 years. 👍 Thanks again🙏

[@smithysmithy1]

We called them "Get you home " bolts

[@dhcrouchmarineltd3049]

Makes sense to me.

[@chrish5096]

Really appreciate the video. I am curious however as to how this transmission compares in size to other marine transmissions. Is this one relatively small, or normal, (I imagine it is not large)? For example, what size boat would you see a transmission like the one shown found in, and how large of an engine would it typically be mated to? (I understand these things can vary greatly, depending on the particular setup, but just a rough idea) Again, really appreciate the video, gave me the basic mechanical knowledge on a marine transmission I’ve been seeking for some time.

[@dhcrouchmarineltd3049]

This particular one is a small unit commonly found on light duty craft. PRM have the 280 which is for wide beam craft. Each box will have a torque max curve. The biggest unit is the 1000 if I recall. This video features a now obsolete unit which has been replaced by the 150. In physical size terms it's about the same size as a football and weighs about the same as a 5ltr bottle of water. Roughly speaking

[@chrish5096]

D H CROUCH MARINE LTD good to know. Appreciate the reply, and the time that went into making this video. Having only really ever messed with outboards, this video taught me a lot.

[@NarrowboatWill]

I've got a prm120 d box on my beta 38. It's recently started making a ringing sound like an old alarm clock going off. If I pull over it stops. It also doesn't make the noise constantly like a loose bolt catching the bell housing or something. It's intermittent getting more ringy. Really hard to describe. I made a video. Could I send it to you to see what you think? I thought it was some angle iron rattling in my engine compartment at first. That's the sort of sound. Thanks Will

[@dhcrouchmarineltd3049]

Of course. Try here facebook.com/D-H-Crouch-Marine-LTD-901371766716284/

[@dhcrouchmarineltd3049]

Not sure if you've seen my other videos. I've made one of the box you have.

[@johntarling1077]

How can I remove the output shaft bearing without splitting the gear box..

[@dhcrouchmarineltd3049]

You cant. The output flange is part of the shaft and held in place by the rear bearing. You have to split it. Check the exploded diagram in the manual.

[@workingboat]

Do you pre soak the plates before fitting, and what is the main reason for failure of the box

[@dhcrouchmarineltd3049]

The plates are coated once you fill the box. And this one was taken apart to inspect it but mostly because the seals had failed. I usually run the input shaft to test the operation on the bench. It's not a load test but it circulates the oil and works the clutches.

[@dotsie1978]

I have a Borg Warner M & I Trans 23-01-039-902 and I can’t find anywhere that can tell me what oil it uses. Every Borg Warner gearbox I see online is one called a velvet drive. My gearbox make a rattle and seems to lose power then reengages. Have you ever come across a similar gearbox?

[@dhcrouchmarineltd3049]

ATF fluid is the current standard.

[@anandgaraban5110]

Can u make a video with a advance marine gearbox

[@dhcrouchmarineltd3049]

I'd need a box to do so.

[@MrPascal340]

Bonjour, Est-ce que c’est le même système que le PRM 150 ? Merci de m’aider svp 😉

[@dhcrouchmarineltd3049]

Bonjour Monsieur, Oui, c'est le même que le PRM 150. Les boîtiers Delta 20/30 ont été remplacés par la gamme PRM150. Voir ce lien pour une démo de 150. kzbin.info/www/bejne/oZmrdXx4mbmhftE Notez également que le premier PRM150 était un boîtier en fonte avec une plaque supérieure. Veuillez noter que je connais très peu le français et que j'ai utilisé google translate.

[@MrPascal340]

@@dhcrouchmarineltd3049 bonjour, je vous remercie de la vitesse de renseignement, j ai besoin d aide , votre vidéo est très instructif, j ai un soucis au niveau de l échangeur perte d huile hydropique, pouvez vous m aider à comprendre ? Merci

[@dhcrouchmarineltd3049]

Je ne suis pas sûr de ce que tu veux dire. Si vous voulez dire à l'extérieur, en ce qui concerne le refroidisseur d'huile? Ou voulez-vous dire que vous avez perdu la pression d'huile interne?

[@MrPascal340]

@@dhcrouchmarineltd3049 une perte d’huile à l’inverseur sûrement un bourrage ?

[@dhcrouchmarineltd3049]

Ahhh ok donc, en supposant que vous avez un PRM150, les packs d'embrayage à l'avant ou à l'arrière ont deux anneaux de contrôle d'huile en métal, si l'un d'eux est cassé, vous pouvez perdre le débit d'huile vers le pack. Avez-vous effectué un test de pression d'huile? Ou si les joints souples à l'intérieur du pack échouent, cela peut entraîner une faiblesse du pack d'embrayage. Quant à un blocage possible, quelle variante du PRM150 avez-vous? est-ce le boîtier en fonte antérieur ou le boîtier en aluminium plus récent?

[@TOMVUTHEPIMP]

Why would a transmission have trouble going in forward gear, but no problem going in neutral and reverse? Something is not “biting” in forward

[@dhcrouchmarineltd3049]

What type of box do you have?

[@TEKKKNO]

Almost same as automatic cars trans they also gearing by oil pressure

[@dhcrouchmarineltd3049]

Makes for a super smooth system.