The forward gear in our marine box was slipping off , we removed and opened it we where very confused on how it worked ( we expected something like sync rings like in a car manual gearbox ) and everything looked fine until I found your video ( the bronze clutch looks exaclty as your worned one ) . Thanks for your video It helped us a lot
Please clarify CPP's Wonder if you mean the system commonly used on a Diesel powered Pinnace. That had a scoop system with a pair of Helm Wheel that caused the scoops direct the crafts propeller thrust. No ruder and no reversing gear at all. My friend had one powered by a BMC Commadore with the ahead gearbox. Bloody thing sank more times than a Submarine but it would with a hole in the side the size of a car. Anyway ot was a laugh. ,
Thanks for putting this video together, a very clear and thorough explanation. I found this video while trying to find out what oil to use in this gearbox - I've just changed the oil in one for a friend. His Beta manual says engine oil, but the gearbox manual attached to it says ATF. Also found an older copy of the PRM120 manual that said engine oil, and then on the PRM website it says ATF, so I was at a bit of a loss with so much conflicting information. Thankfully your comment in this video when describing the friction material on the cone put that confusion to rest!
PRM being the manufacturer I take their information as fact. The mechanically operated drive selection units like the 120/125 use ATF. Also as it's states in the manual this oil is essential for cooling. The hydraulic boxes are different and usually have an oil cooler. I'd be interested to see the beta manual you have. Perhaps you can email me a picture of the oil grade for the gearbox you have. darrencrouch@dhcrouchmarineltd.co.uk It would also be worth informing Beta Marine. Thanks for watching the video. I'm glad the contents been useful.
@@dhcrouchmarineltd3049 Hi Darren, I have a prm 80 I just removed from my boat to check the drive plate, but I noticed a little play in the gearbox shaft, can you email me t.j.obrien69@gmail.com and I will send you a video for you to look at and can you advise me on what to do CHEERS T.J.
Hey. The screw thread like machining is called a helical spline or spiral spline, its the same principal as the bendix on starter motors that don't have a solenoid on the top. All the best.
Thanks for that explanation - I always wondered how the cone clutch system works. Had a new one fitted a few years back and and it sometimes doesn't engage in forward. However, if I slip it into reverse and then gently try again in forward it grips nicely.
I always try to bring the motor to idle before changing gear, but occasionally - very occasionally - a foot will trod on the gear change and demand reverse gear at full revs. Happily, not the other way. The gearbox is the Volvo MS2 on an MD17C and the box has a similar principle, albeit cast iron and heavier. Also, this clutch design is good for stopping the prop when sailing. Some say you musn't do it, but, 30 years on, we still do it. When we start sailing, we put the gearbox in reverse and the prop stops.
That was a very enjoyable video and for anyone (like me) who wants to know how these gearboxes work its a joy. I really like the talk through style of this video and appreciate the effort taken to do it while obviously getting the job done for someone. Isn’t it great how that scroll gear helps the clutch stay engaged. I am guessing the selector is on an eccentric to move that little rod that sits in the centre of the clutch?
Brilliant tutorial on how these work..just in the process of rebuilding a TMC 40 from a Beta 10. Is it possible to measure the thickness of the friction material on a used clutch cone thingy?
I would get a new clutch and compare the average over an area. I dont think its states it in the book. That being said I am sure something like 1.6mm springs to mind. The friction material is supposed to suspend oil while the clutch is working. But to gauge wear factor best guess is all I have to say atm. Typically you can tell if one is ok or not. Clutch plates are a bit easier to asses as they either warp or grind to death. I had a clutch I changed recently from a PRM 120 that showed dead spots in a band around the clutch. The friction coating was falling off. Hope that helps.
@@dhcrouchmarineltd3049 Thanks for the help , very much appreciated. Do I have to go to Beta for a new clutch , bearings and seals or is there a TMC supplier in the UK? Thanks
Brilliant video that, very we'll made. Iv always been fascinated by single lever control, the Morse mt3 box is my favourite. I would suppose with velvet drive and other hydraulic systems the fast movement from full ahead back into astern would be less of an issue due to the forward, neutral, reverse being fluid operated rather than direct mechanical. I could be wrong 😀😀
Brilliant video!! I have this gearbox and mine has stuck in forward gear. The cables are free but the lever on the side is stuck in forward. What would u suspect has failed??
Great video, I can now 'see' what's happening inside my Technodrive gearbox. I had an enging rev 'surge' when manouvering at very low speed - it felt as if the input jumped off the forward ourput. Assuming the clutch surfaces aren't worn out am I right in thinking that the clutch can be adjusted by putting an allen key on the selecter barrel/shaft to move the fork?
No, the selection fork needs the float shimmed. It wont help the clutch bite more. The centrifugal forces of the shaft spin will keep the clutch in drive engaged.
@@dhcrouchmarineltd3049 Sorry to be pressing you on this but an online manual has this: Clutch control unit adjustment: with the operating lever ref. 18 in neutral position, turn by hand the output flange ref. 26 and, at the same time, screw the adjusting screw ref. 28 with an alien wrench (4 mm) until the output flange rotation gets hard on a small arc only. Unscrew of 3/4 of turn the adjusting screw and fix it by locking the nut ref. 57.
Yes thats the float depth of the fork. To much in and it binds on the clutch gear. Shimming just keeps it from fowling and jamming on the clutch. So in a sense it is clutch adjustment but not in how the clutch "bites" rather the selection of the clutch cone. Hope that makes sense
Hi Darren, what is the material on the matching surface of the cones on the scroll gear, and can the material be replaced. Excellent detail, well explained. Great vid thanks very much.
The cones are coated, the gears are just hardened gears. I know PRM lap gears to suit a cone clutch. Not sure exactly what coating is used. I could probably find out. Tbh I suspect it's better to use a set of new gears and cone, at least PRM state you should when replacing a clutch. Hope that helps
Very very useful video. It gave me the inspiration to have a go at repairing my old PRM120 D2 which has been sitting in my shed for 8 years! Mine has a broken output shaft which I need to replace. I'm guessing that I will have to contact someone like ASAP to get a replacement? I can't find one listed anywhere. I do have the chance of a complete D3. I know that the gearing will be different, but I'm wondering if the output shaft will be the same?
Hi, we have this gearbox and we hear a noticeable clunk when selecting forward gear from neutral. The oil level is fine and the ATF oil has been replaced during the time we have had it. At first I suspected a drive plate issue but if it only happens selecting fwd I am now doubting my initial thoughts. Any suggestions? Thanks in anticipation.
Loud clunking, depends how loud. If the drive plate is trashed and someone over advanced the idle then the box will thump into gear. The idle needs to be low for a smooth engagement. That being said if the cone has any burrs itll bind a bit.
Hi Darren, what is the material on the matching surface (Grey in your video) on the scroll gear? The stuff that has been "sanded" away on the used scroll gear. Is the material magnetic? Wonderful video, i am glad I found it..
Do you mean the Cone clutch ? Ill find out the composition, but its a friction material. I believe its designed to absorb some oil which aids in the driving of the gear hub. I'll check back with some mote info once I work out the details.
To my knowledge they are the same. The cones can be used in most of the boxes with such a clutch. However the shafts might be longer. Great fun these boxes. So simple in a complex manufacturing kind of way.
Great vid thanks very much. I have one of these attached to a Canaline 38. There are dire warnings about not overfilling the gearbox with oil, why is this? Also I was thinking of upgrading to a 150, would I be wasting my money?
Hi Bob, the oil for the mechanical variants of PRM tend to use ATF fluid. This is very thin oil and very detergent. Its essential for cleaning but also critically cooling. If they dont allow for movement of oil they overheat. As heat will cause most mediums to expand you risk causing oil to bust past the lips seals. As I've said these are fabulous boxes. However the PRM150 D2 D2 hydraulically actuated units are fabulous too. They are very forgiving with respects to engaging drive. Inside these boxes are whats called wet multiplate clutch packs, you get for each drive. So one clutch for ahead and one clutch for astern. They are very much worth the value. Well my my humble opinion. I'll do a video on the 150 or 260 when I have a box to strip down.
Hi! Great video and very informative. Thanks for sharing it! I would appreciate if you can give a hand to solve my dilemma. I’m struggling on the gearbox topic for quite some time... The thing is that I am about to replace my old Yanmar YSE12 with Beta 14 TMC60A 7 degrees downwards. What I heard from the local mechanics is that this angled gearbox is not reliable.... I don’t if this is true. Might I ask you for your opinion.
Hi thanks for the feedback, my experience has lead me to choose a PRM as a first choice. They have a resilient nature in the way they are designed. I've seen TMC fail with light use but would suggest this was down to being badly installed with misalignment issues. The clutch fails. I think It would advantageous to ask Betamarine if buying new for alternative options if you have concerns.
@@dhcrouchmarineltd3049 Hi thanks for the advice appreciate it! Sure I’ll check with Beta for options. What I can see from the Beta homepage they offer PRM 60 and 90. The standard configuration has TMC 40 I have no idea what’s the difference is between those indexes 40,60 and 90...Btw I’ve got quite interesting offer from Yanmar for 2YM15 with KM2P-1 gearbox for the price as Beta. Now is getting even harder to choose UK or Japanese gearbox :)
Very useful video. I currently have my PRM120D2 in pieces following a cockerpoo-induced engine overspeed (> 4000rpm for about 15 seconds) which trashed the drive plate and flexible coupling on my narrowboat. Having replaced both of those items, I have got rid of the excessive vibration that resulted but there is still a distinct rumble in forward at low rpm that seems to get worse after 15 - 20 mins of use. I haven't got as far as removing the clutch yet but do you have any idea on what kind of damage I can look out for that would result from such an incident?
How powerful is your engine? How many cylinders and what's its HP and 4k rpm The manual for the gearbox will have a max torque curve for input. Provided you didn't over load the box you may be ok
@@dhcrouchmarineltd3049 Thanks for the reply. It is a Beta 38 so 4 cylinder. They quote a max 35HP at 2800 rpm but that is as far as the power curve they give is shown. I don't know the true rpm as the rev counter only shows up to 4000 and the needle was up against the end stop with the throttle lever pushed to maximum. It all happened very quickly so I was concerned with the change in rpm from around the 1200 rpm we were cruising in such a short space of time.
Very informative. I have two very similar boxes though mine are made in Italy. One thing I don’t get though is the manual says CCW only input? Is there any reason it couldn’t be CW input do you know? I’m actually intending to use one to drive a railway locomotive and a CW input would save me having to go through a 90 degree box as I could mount the engine and gear box in a line as opposed to directly driven off the engine
Hi Chris, I've looked through the PRM manual but I must have missed this reference. Or perhaps it's in your manual. Can you send me a copy via email with the section highlighted. I'd love to read. darrencrouch@dhcrouchmarineltd.co.uk Initially I suspect the bearings are what make the rules on how the boxes are driven. Taper bearings won't like pulleys for example.
If you have the opposite rotation on the input shaft, then the scroll gear will tend to pull the clutch out of engagement, rather than holding it in (in both forward and reverse gears).
Amazing video! I have this gear box and I might be a bit guilty of the “crash reverse”. Now I get a clunk/slap when I engage gear. It’s worse in reverse. Enough to make the engine move on its mounts. Do I need to replace the clutch? Can I use one of those scope things down the oil hole to inspect it?
D H CROUCH MARINE LTD strangely enough, I just lowered the engine idle on my mates boat today and fixed his issue (think you were chatting to him on FB, DanD). I’ll check mine in the morning. Think it ticks over at 450. Engine mounts bolts are all good and snug. Rubbers look ok, no obvious wear, do they harden over time? Strangely enough I’ve got to change them in my old Volvo wagon too!
@@phillcanning check the propeller for bent blades that can cause engines surging about. I assume there is no thrust bearing? Like an aquadrive? Because that would make that last invalid. Have you changed the oil in the gearbox recently if so was it discoloured?
D H CROUCH MARINE LTD props are straight. Oil is clean and pink (ATF) I topped up recently. Although it was an after market dip stick with only one line. It doesn’t “look” overfilled when I look down the oil hole. But maybe I have 🤔. It’s a big old slap. I’ll send you a vid tomorrow if that ok? On FB.
Hi Darren Do you know of a good company that supplies parts for these boxes. I have a PRM120D1 I think on a beta 28. Here in Australia is ridiculous trying to find agents so any help would be appreciated. Regards Darren
Great video. How pricey would it be to change the reduction ratio on one of these? I've been offered a good deal on one but i have very little data for the torque and powe curves of the electric car motor i will be driving it with.
@@dhcrouchmarineltd3049 it is a 48v 13kW electric car motor giving peak power at 2400 rpm. Per vicprop that is enough power to throw my 17 1/2 x 12 ish triple blade prop at 1000 rpm and give me 5 knots. So a 2.4:1 ratio would be ideal but there are some 2:1 boxes going cheap. Gearbox also helps with mounting and thrust loads.
Hi Darren, its Jim Swarbrick from Mission Beach Qld , love your video , my PRM80D2 , is the smaller version mechanical gearbox , i pushed the tolerance to 17 degrees at the install, and started the motor while the yacht, was on full heel , so maybe the oil couldn't get to where it should ,the metal on metal squeaking lasted a few minutes, took the box out to my local marine machinery agent, he has sent for oversized clutch cones apparrently there are four sizes including the original, the first oversized cone arrived and was installed, he was not satisfied as there was a gap between the clutch cone face and the receptical / cup of 1 thou, so we sent for the next size up , reinstalled , it still not happy , do you think that the gap is a critical factor , he is now talking about replacing the receptical / cup /cog are we on the right track, your advise / comment would be appreciated Many Thanks Jim
Hi how are you? Interesting issue, need to ask a few questions before I can offer help. Was this box new ? What oil has been used? Did your engineer say what had worn? I've looked at the manual but I can't see a specific tolerance for clearance on the clutch face to drive gear. But this appears to be subject to the shimming stage of the main support bearings. Possibly they were to tight? Not enough shimming maybe ?
D H CROUCH MARINE LTD Thanks for your reply, yes new engine gearbox 33hp Kubota, sea trails , the gearbox had done 12 hrs max, original oil, off the shop floor (had sat for 7 yrs , not a popular size) the engineer says the clutch cone had worn, he has not mentioned shimming, PRM , declined any warranty, we now consider over filling the gearbox 10% due to the angle of installation,many thanks for your comment- ? Jim
D H CROUCH MARINE LTD Hi Darren , the engine the engine was aligned to the best of our ability A cardan shaft was installed 2 x universal joints to accomodate ant vertical or horizontal annomilys, that being said the was an inordinate amount of vibration , which has been improved on with heat exchange supports in place and a further engine mount tightening , I didn’t consider that as a potential problem for the gearbox
@@dhcrouchmarineltd3049 I'm a machinist. It's common for plastics like water bottle lids. Anything that needs lots of longitudinal movement without much rotation. I'm rebuilding my transmission now but I have the plate style zf/hurth ... But the cone style is far superior in my opinion.
The forward gear in our marine box was slipping off , we removed and opened it we where very confused on how it worked ( we expected something like sync rings like in a car manual gearbox ) and everything looked fine until I found your video ( the bronze clutch looks exaclty as your worned one ) .
Thanks for your video It helped us a lot
Glad it helped. Very repairable boxes good luck
Great video! I learned a lot about my twindisc tmc260 which is practically the same I think.
A measured clear instruction. Now as an amateur yachtsman I understand.
Our gearbox is only a reduction as we have CPP’s but I need to know how a reversing gearbox works for my exam. This has helped, thank you!👌🏻
Please clarify CPP's
Wonder if you mean the system commonly used on a Diesel powered Pinnace. That had a scoop system with a pair of Helm Wheel that caused the scoops direct the crafts propeller thrust. No ruder and no reversing gear at all.
My friend had one powered by a BMC Commadore with the ahead gearbox.
Bloody thing sank more times than a Submarine but it would with a hole in the side the size of a car. Anyway ot was a laugh.
,
@@dhcrouchmarineltd3049 Sorry I meant Controllable Pitch Propellers. Not heard of a scoop system before, I’ll have to look it up.
Thanks for putting this video together, a very clear and thorough explanation. I found this video while trying to find out what oil to use in this gearbox - I've just changed the oil in one for a friend. His Beta manual says engine oil, but the gearbox manual attached to it says ATF. Also found an older copy of the PRM120 manual that said engine oil, and then on the PRM website it says ATF, so I was at a bit of a loss with so much conflicting information. Thankfully your comment in this video when describing the friction material on the cone put that confusion to rest!
PRM being the manufacturer I take their information as fact. The mechanically operated drive selection units like the 120/125 use ATF. Also as it's states in the manual this oil is essential for cooling.
The hydraulic boxes are different and usually have an oil cooler.
I'd be interested to see the beta manual you have. Perhaps you can email me a picture of the oil grade for the gearbox you have.
darrencrouch@dhcrouchmarineltd.co.uk
It would also be worth informing Beta Marine.
Thanks for watching the video. I'm glad the contents been useful.
Same with the TMC60 my transmission says Sae 30 on the label a Frend off my has the same engine and trans his label says ATF oil , a lithle confust
Great video, thanks 👍 looking forward to the hydraulic gearbox video
Coming soon!
Thanks, Darren - very instructive. As others are I am waiting with bated breath for a 150 or 260 Video.
As soon as I've got a 150 or 260 I'll do a video.
@@dhcrouchmarineltd3049 Hi Darren, I have a prm 80 I just removed from my boat to check the drive plate, but I noticed a little play in the gearbox shaft, can you email me t.j.obrien69@gmail.com and I will send you a video for you to look at and can you advise me on what to do CHEERS T.J.
darrencrouch@dhcrouchmarineltd.co.uk
Kind regards
Excellent detail , well explained . Thanks
Brilliant and informative. I agree an elegant design clutch mechanism.
Thanks for watching!
Hey. The screw thread like machining is called a helical spline or spiral spline, its the same principal as the bendix on starter motors that don't have a solenoid on the top.
All the best.
PRM said it's called a Scroll gear. But thanks for that. Either way it's a nice bit of machining.
Ahh yes an older style inertia forced starter motor. Very simple but did kit.
Commonly found on Perkins some ford cross flow etc
Thanks for that explanation - I always wondered how the cone clutch system works. Had a new one fitted a few years back and and it sometimes doesn't engage in forward. However, if I slip it into reverse and then gently try again in forward it grips nicely.
No worries. Glad you got something helpful from the video.
I always try to bring the motor to idle before changing gear, but occasionally - very occasionally - a foot will trod on the gear change and demand reverse gear at full revs. Happily, not the other way. The gearbox is the Volvo MS2 on an MD17C and the box has a similar principle, albeit cast iron and heavier. Also, this clutch design is good for stopping the prop when sailing. Some say you musn't do it, but, 30 years on, we still do it. When we start sailing, we put the gearbox in reverse and the prop stops.
I can actually see that being fine. Once locked its in place. Handy.
Good day that gear box is compatible 80hp engine? Thanks
@@Joseph-xv1sq 80 hp is too much for that gearbox.
@@dhcrouchmarineltd3049 max power is 67 hp and max input speed 5000 rpm.
That was a very enjoyable video and for anyone (like me) who wants to know how these gearboxes work its a joy. I really like the talk through style of this video and appreciate the effort taken to do it while obviously getting the job done for someone. Isn’t it great how that scroll gear helps the clutch stay engaged. I am guessing the selector is on an eccentric to move that little rod that sits in the centre of the clutch?
Yes it is. A bronze piece and the sector rod floats inside this. Very elegant stuff.
Brilliant tutorial on how these work..just in the process of rebuilding a TMC 40 from a Beta 10.
Is it possible to measure the thickness of the friction material on a used clutch cone thingy?
I would get a new clutch and compare the average over an area.
I dont think its states it in the book. That being said I am sure something like 1.6mm springs to mind.
The friction material is supposed to suspend oil while the clutch is working.
But to gauge wear factor best guess is all I have to say atm. Typically you can tell if one is ok or not.
Clutch plates are a bit easier to asses as they either warp or grind to death.
I had a clutch I changed recently from a PRM 120 that showed dead spots in a band around the clutch. The friction coating was falling off.
Hope that helps.
@@dhcrouchmarineltd3049 Thanks for the help , very much appreciated. Do I have to go to Beta for a new clutch , bearings and seals or is there a TMC supplier in the UK? Thanks
This is just brilliant! Thank you so much!
Brilliant video that, very we'll made. Iv always been fascinated by single lever control, the Morse mt3 box is my favourite. I would suppose with velvet drive and other hydraulic systems the fast movement from full ahead back into astern would be less of an issue due to the forward, neutral, reverse being fluid operated rather than direct mechanical. I could be wrong 😀😀
Brilliant video!! I have this gearbox and mine has stuck in forward gear. The cables are free but the lever on the side is stuck in forward. What would u suspect has failed??
Only way to find out is strip it down. How old is it
called a bendix gear used on many old starter motors as well
I think the engineered gear shown around the three minute mark is a ‘helical scroll gear’
You’ll probably find a similar thing on your flypress.
Yes, it's much the same on the my press.
I spoke to PRM who said they call it a scroll gear. But it's cool stuff.
Very interesting! Can you do the same for the PRM 150 ??
There is a video on my Channel already for the 150
@@dhcrouchmarineltd3049 oops sorry, will have a look!!
Great video, I can now 'see' what's happening inside my Technodrive gearbox. I had an enging rev 'surge' when manouvering at very low speed - it felt as if the input jumped off the forward ourput. Assuming the clutch surfaces aren't worn out am I right in thinking that the clutch can be adjusted by putting an allen key on the selecter barrel/shaft to move the fork?
No, the selection fork needs the float shimmed. It wont help the clutch bite more.
The centrifugal forces of the shaft spin will keep the clutch in drive engaged.
@@dhcrouchmarineltd3049 Sorry to be pressing you on this but an online manual has this:
Clutch control unit adjustment: with the operating lever ref. 18 in neutral position, turn by hand the output flange ref. 26
and, at the same time, screw the adjusting screw ref. 28 with an alien wrench (4 mm) until the output flange rotation gets
hard on a small arc only. Unscrew of 3/4 of turn the adjusting screw and fix it by locking the nut ref. 57.
Yes thats the float depth of the fork. To much in and it binds on the clutch gear. Shimming just keeps it from fowling and jamming on the clutch.
So in a sense it is clutch adjustment but not in how the clutch "bites" rather the selection of the clutch cone.
Hope that makes sense
@@dhcrouchmarineltd3049 👍
Hi Darren, what is the material on the matching surface of the cones on the scroll gear, and can the material be replaced. Excellent detail, well explained. Great vid thanks very much.
The cones are coated, the gears are just hardened gears. I know PRM lap gears to suit a cone clutch.
Not sure exactly what coating is used. I could probably find out. Tbh I suspect it's better to use a set of new gears and cone, at least PRM state you should when replacing a clutch.
Hope that helps
Very very useful video. It gave me the inspiration to have a go at repairing my old PRM120 D2 which has been sitting in my shed for 8 years! Mine has a broken output shaft which I need to replace. I'm guessing that I will have to contact someone like ASAP to get a replacement? I can't find one listed anywhere. I do have the chance of a complete D3. I know that the gearing will be different, but I'm wondering if the output shaft will be the same?
How has the output shaft broken? They are quite heavy duty.
If you email me the details I can help. I have an order to place with PRM
@@dhcrouchmarineltd3049 Emailed thanks,
Hi, we have this gearbox and we hear a noticeable clunk when selecting forward gear from neutral. The oil level is fine and the ATF oil has been replaced during the time we have had it. At first I suspected a drive plate issue but if it only happens selecting fwd I am now doubting my initial thoughts. Any suggestions? Thanks in anticipation.
Loud clunking, depends how loud. If the drive plate is trashed and someone over advanced the idle then the box will thump into gear.
The idle needs to be low for a smooth engagement. That being said if the cone has any burrs itll bind a bit.
Very Informative, Thank you very much :)
Glad it was helpful!
Hi Darren, what is the material on the matching surface (Grey in your video) on the scroll gear? The stuff that has been "sanded" away on the used scroll gear. Is the material magnetic? Wonderful video, i am glad I found it..
Do you mean the Cone clutch ?
Ill find out the composition, but its a friction material. I believe its designed to absorb some oil which aids in the driving of the gear hub.
I'll check back with some mote info once I work out the details.
Great concise vid, do you know if the helix differ in various HP gearboxes shallower for low HP or Steeper for high power units?
To my knowledge they are the same. The cones can be used in most of the boxes with such a clutch. However the shafts might be longer.
Great fun these boxes. So simple in a complex manufacturing kind of way.
Thank you, mate.
Great vid thanks very much. I have one of these attached to a Canaline 38. There are dire warnings about not overfilling the gearbox with oil, why is this? Also I was thinking of upgrading to a 150, would I be wasting my money?
Hi Bob, the oil for the mechanical variants of PRM tend to use ATF fluid. This is very thin oil and very detergent. Its essential for cleaning but also critically cooling. If they dont allow for movement of oil they overheat. As heat will cause most mediums to expand you risk causing oil to bust past the lips seals.
As I've said these are fabulous boxes.
However the PRM150 D2 D2 hydraulically actuated units are fabulous too. They are very forgiving with respects to engaging drive.
Inside these boxes are whats called wet multiplate clutch packs, you get for each drive. So one clutch for ahead and one clutch for astern.
They are very much worth the value.
Well my my humble opinion.
I'll do a video on the 150 or 260 when I have a box to strip down.
@@dhcrouchmarineltd3049 Thanks for the great info.
Hi! Great video and very informative. Thanks for sharing it!
I would appreciate if you can give a hand to solve my dilemma. I’m struggling on the gearbox topic for quite some time... The thing is that I am about to replace my old Yanmar YSE12 with Beta 14 TMC60A 7 degrees downwards. What I heard from the local mechanics is that this angled gearbox is not reliable.... I don’t if this is true.
Might I ask you for your opinion.
Hi thanks for the feedback, my experience has lead me to choose a PRM as a first choice. They have a resilient nature in the way they are designed.
I've seen TMC fail with light use but would suggest this was down to being badly installed with misalignment issues. The clutch fails.
I think It would advantageous to ask Betamarine if buying new for alternative options if you have concerns.
@@dhcrouchmarineltd3049 Hi thanks for the advice appreciate it! Sure I’ll check with Beta for options. What I can see from the Beta homepage they offer PRM 60 and 90. The standard configuration has TMC 40 I have no idea what’s the difference is between those indexes 40,60 and 90...Btw I’ve got quite interesting offer from Yanmar for 2YM15 with KM2P-1 gearbox for the price as Beta. Now is getting even harder to choose UK or Japanese gearbox :)
I am of course Biased. British Made PRM are fabulous.
Japanese engineering is of course good.
Very useful video. I currently have my PRM120D2 in pieces following a cockerpoo-induced engine overspeed (> 4000rpm for about 15 seconds) which trashed the drive plate and flexible coupling on my narrowboat. Having replaced both of those items, I have got rid of the excessive vibration that resulted but there is still a distinct rumble in forward at low rpm that seems to get worse after 15 - 20 mins of use.
I haven't got as far as removing the clutch yet but do you have any idea on what kind of damage I can look out for that would result from such an incident?
How powerful is your engine? How many cylinders and what's its HP and 4k rpm
The manual for the gearbox will have a max torque curve for input. Provided you didn't over load the box you may be ok
@@dhcrouchmarineltd3049 Thanks for the reply. It is a Beta 38 so 4 cylinder. They quote a max 35HP at 2800 rpm but that is as far as the power curve they give is shown.
I don't know the true rpm as the rev counter only shows up to 4000 and the needle was up against the end stop with the throttle lever pushed to maximum. It all happened very quickly so I was concerned with the change in rpm from around the 1200 rpm we were cruising in such a short space of time.
Very informative. I have two very similar boxes though mine are made in Italy. One thing I don’t get though is the manual says CCW only input? Is there any reason it couldn’t be CW input do you know? I’m actually intending to use one to drive a railway locomotive and a CW input would save me having to go through a 90 degree box as I could mount the engine and gear box in a line as opposed to directly driven off the engine
Hi Chris, I've looked through the PRM manual but I must have missed this reference. Or perhaps it's in your manual. Can you send me a copy via email with the section highlighted. I'd love to read.
darrencrouch@dhcrouchmarineltd.co.uk
Initially I suspect the bearings are what make the rules on how the boxes are driven. Taper bearings won't like pulleys for example.
If you have the opposite rotation on the input shaft, then the scroll gear will tend to pull the clutch out of engagement, rather than holding it in (in both forward and reverse gears).
Amazing video!
I have this gear box and I might be a bit guilty of the “crash reverse”.
Now I get a clunk/slap when I engage gear. It’s worse in reverse. Enough to make the engine move on its mounts.
Do I need to replace the clutch? Can I use one of those scope things down the oil hole to inspect it?
Is the engine idle set correctly. To high and you'll get the clutch doing that. Also are the mounts ok?
D H CROUCH MARINE LTD strangely enough, I just lowered the engine idle on my mates boat today and fixed his issue (think you were chatting to him on FB, DanD).
I’ll check mine in the morning. Think it ticks over at 450.
Engine mounts bolts are all good and snug. Rubbers look ok, no obvious wear, do they harden over time?
Strangely enough I’ve got to change them in my old Volvo wagon too!
@@phillcanning check the propeller for bent blades that can cause engines surging about. I assume there is no thrust bearing? Like an aquadrive? Because that would make that last invalid.
Have you changed the oil in the gearbox recently if so was it discoloured?
D H CROUCH MARINE LTD props are straight. Oil is clean and pink (ATF) I topped up recently. Although it was an after market dip stick with only one line. It doesn’t “look” overfilled when I look down the oil hole. But maybe I have 🤔.
It’s a big old slap. I’ll send you a vid tomorrow if that ok? On FB.
@@phillcanning yes please, if i can help i will
Hi Darren
Do you know of a good company that supplies parts for these boxes. I have a PRM120D1 I think on a beta 28. Here in Australia is ridiculous trying to find agents so any help would be appreciated.
Regards Darren
I can supply PRM parts no problems. Drop me an email darrencrouch@dhcrouchmarineltd.co.uk
I'll do my best to help.
Great video. How pricey would it be to change the reduction ratio on one of these? I've been offered a good deal on one but i have very little data for the torque and powe curves of the electric car motor i will be driving it with.
You can buy them in about three varying ratios as they are built to suit. Why are you using a gearbox with an electric drive ?
@@dhcrouchmarineltd3049 it is a 48v 13kW electric car motor giving peak power at 2400 rpm. Per vicprop that is enough power to throw my 17 1/2 x 12 ish triple blade prop at 1000 rpm and give me 5 knots. So a 2.4:1 ratio would be ideal but there are some 2:1 boxes going cheap. Gearbox also helps with mounting and thrust loads.
Hi Darren, its Jim Swarbrick from Mission Beach Qld , love your video , my PRM80D2 , is the smaller version mechanical gearbox , i pushed the tolerance to 17 degrees at the install, and started the motor while the yacht, was on full heel , so maybe the oil couldn't get to where it should ,the metal on metal squeaking lasted a few minutes, took the box out to my local marine machinery agent, he has sent for oversized clutch cones apparrently there are four sizes including the original, the first oversized cone arrived and was installed, he was not satisfied as there was a gap between the clutch cone face and the receptical / cup of 1 thou, so we sent for the next size up , reinstalled , it still not happy ,
do you think that the gap is a critical factor , he is now talking about replacing the receptical / cup /cog
are we on the right track, your advise / comment would be appreciated
Many Thanks
Jim
Hi how are you? Interesting issue, need to ask a few questions before I can offer help.
Was this box new ?
What oil has been used?
Did your engineer say what had worn?
I've looked at the manual but I can't see a specific tolerance for clearance on the clutch face to drive gear. But this appears to be subject to the shimming stage of the main support bearings. Possibly they were to tight? Not enough shimming maybe ?
D H CROUCH MARINE LTD
Thanks for your reply, yes new engine gearbox 33hp Kubota, sea trails , the gearbox had done 12 hrs max, original oil, off the shop floor (had sat for 7 yrs , not a popular size) the engineer says the clutch cone had worn, he has not mentioned shimming, PRM , declined any warranty, we now consider over filling the gearbox 10% due to the angle of installation,many thanks for your comment- ? Jim
Was the engine alignment spot on ?
D H CROUCH MARINE LTD
Hi Darren , the engine the engine was aligned to the best of our ability
A cardan shaft was installed 2 x universal joints to accomodate ant vertical or horizontal annomilys, that being said the was an inordinate amount of vibration , which has been improved on with heat exchange supports in place and a further engine mount tightening , I didn’t consider that as a potential problem for the gearbox
very similar to the Kanzaki gear box
Thanks for letting me know
Made in Coventry
I have now made a video on a hydraulic box.
ua-cam.com/video/b0aMb1h6mJs/v-deo.html
That's a multi start thread.
I have never heard that name before. Really appreciate that feed back.
@@dhcrouchmarineltd3049 I'm a machinist. It's common for plastics like water bottle lids. Anything that needs lots of longitudinal movement without much rotation.
I'm rebuilding my transmission now but I have the plate style zf/hurth ...
But the cone style is far superior in my opinion.
@@84Rabbitz The cone clutch is indeed a better and more simple mechanism.
friction is independent of pressure, useless fact for you.
Have you seen the two phone book together. Thats a cool experiment and the pages weigh almost zero.