Busted gear box?

[Tony Brooks]

For future reference.The PRM 120 is a mechanical gearbox and it uses ATF oil. Yours is a hydraulically actuated PRM  and uses engine oil. Please forget the 120 from now on, it is likely to get you the wrong advice.

Edited April 1, 2020 by Tony Brooks

[MtB]

3 minutes ago, Tony Brooks said:

For future refernce.The PRM 120 is a mechanical gearbox and it uses ATF oil. Yours is a hydraulically actuated PRM  and uses engaging oil. Please forget the 120 from now on, it is likely to get you the wrong advice.

 

Thanks for posting that Tony, I thought the same but wasn't sure enough I was right to actually say so!

 

its a PRM150 I suspect... 

 

 

[David Mack]

2 hours ago, Bern0 said:

 

 

is it safe to use the engine now (for charging) even though it's starting straight in gear?

 

OK you're beyond this point now, but be aware that running the engine in gear while moored is not permitted by CRT as the wash created damages the canal bank. But now you can operate the control lever on the gearbox directly you can select neutral to run the engine for charging, until you can replace the cable.

[Alan de Enfield]

24 minutes ago, Tony Brooks said:

For future refernce.The PRM 120 is a mechanical gearbox and it uses ATF oil. Yours is a hydraulically actuated PRM  and uses engaging oil. Please forget the 120 from now on, it is likely to get you the wrong advice.

 

We know what you mean but for the sake of the OP could you correct 'engaging oil'

[magnetman]

Normal engine oil like a 10w30 for a prm 150 (previously called a PRM delta). I've got two Delta boxes on one of my boats. Nice gearboxes. My other boats have PRM 260 and 160 (same actual gearbox but the numbers were changed when they renamed the Delta as the 150 to avoid the 160 getting confused with the 150). 

 

150/Delta is aluminium the 260/160 is a cast iron job. 

 

Obvious question here: 

 

Why did the Morse cable break? 

 

Is there a design fault or an operator fault? 

 

When moving through from forwards to neutral and reverse always do it slowly. I personally tend to put control into neutral when approaching a lock and just give a little blip in reverse to ensure gear linkage(s) are working correctly before performing close quarters manoovering. 

 

This is because I have seen damage caused by broken cable resulting in gearbox being in ahead gear. Person at helm thinks increasing engine speed is going to stop boat as they assume it is in reverse. 

 

It isn't. So boat going forwards even faster. Situation deteriorates rapidly at this stage.

 

 

 

 

 

 

 

 

Edited April 1, 2020 by magnetman

[Richard T]

Cables do break at the most incovenient time. We had our throttle cable break about 18months ago. It went at the joint between the solid rod and the flexible cable at the single lever end of it. I guess it was caused by metal fatigue. We used a bit of string for about half an hour until we could get to a good morring point. It then took me about half an hour to change it - I carry a spare.

[Tony Brooks]

12 minutes ago, Alan de Enfield said:

 

We know what you mean but for the sake of the OP could you correct 'engaging oil'

done, thanks

[Tony Brooks]

6 minutes ago, magnetman said:

Normal engine oil like a 10w30 for a prm 150 (previously called a PRM delta). I've got two Delta boxes on one of my boats. Nice gearboxes. My other boats have PRM 260 and 160 (same actual gearbox but the numbers were changed when they renamed the Delta as the 150 to avoid the 160 getting confused with the 150). 

 

150/Delta is aluminium the 260/160 is a cast iron job. 

 

Obvious question here: 

 

Why did the Morse cable break? 

 

Is there a design fault or an operator fault? 

 

When moving through from forwards to neutral and reverse always do it slowly. I personally tend to put control into neutral when approaching a lock and just give a little blip in reverse to ensure gear linkage(s) are working correctly before performing close quarters manoovering. 

 

 

 

On the throttle cable the swaged joint between the end fitting and the inner cable wire at the control end gets swung through an ark whenever you go between gears. Often the stiffness of the whole cable or excess bundling clamping prevents the outer moving so eventually the inner cable fatigues and snaps.

 

 

[magnetman]

I must have been lucky then. There I was thinking it was related to careful handling of the control lever. 

 

I wondered about the op wording. It seems to imply an operator fault  :

 

"

I was going from forward to reverse repeatedly, without resting in idle in between."

 

 

Edited April 1, 2020 by magnetman

[ditchcrawler]

21 minutes ago, magnetman said:

 

 

This is because I have seen damage caused by broken cable resulting in gearbox being in ahead gear. Person at helm thinks increasing engine speed is going to stop boat as they assume it is in reverse. 

 

It isn't. So boat going forwards even faster. Situation deteriorates rapidly at this stage.

 

 

 

 

 

 

 

 

Saw that on the Wey with a day boat he hit the bank quite hard. He rang the hire company and they said they sometimes stick in forward, make sure its in reverse before opening the throttle. If I hadn't been there I wouldn't have believed it

[magnetman]

That's why I routinely disengage forward and engage reverse for a short time before performing any manoovers which involve slowing down like mooring or approaching locks. 

 

Cuts out any nasty surprises. 

 

It's not that arduous to do. The point is that if you put it in neutral then reverse you will hear it going into reverse, from neutral. Assuming the boat is a canal boat not a large cruiser. 

 

It's impossible for this gear engagement noise to be forward because you have shifted from forward to neutral and into reverse. If it doesn't do anything after neutral or you still have water going out the back then it's stuck in forward. 

 

I've also seen a L&L shortboat in a Thames lock lose astern propulsion and yes the person at the helm did think it was in reverse so he applied extra throttle to slow it down.. I was glad to be behind that boat that day. It hit the top cill so no lock damage or damage to other boats. In that situation it was not a cable but still any connection between gearbox and control lever wants testing -before- you get to the point where it could cause a problem. 

 

I like listening to the engine and gear noises it's also a good way to detect prop fouling problems. 

 

Maybe it's a bit odd but I always like to helm a boat as if loss of propulsion is imminent. Specially when slowing down. Always plan for a situation where you get a rope on the prop at the wrong moment and allow yourself to glide into the side slowly. 

 

It's not a car. 

Edited April 1, 2020 by magnetman

[Keeping Up]

Once I left a lock which had just emptied, then engaged reverse gear to stop in the lock tail and wait for my wife who was shutting the gate behind me. The cable snapped so it stayed in reverse gear when I engaged neutral after the boat had stopped so the boat reversed back into the gate, knocking my wife over, and then continued all the way back into the lock until it hit the cill (gently because I'd stopped the engine by then). My wife's comments were quite uncomplimentary!

[Tony Brooks]

1 hour ago, ditchcrawler said:

Saw that on the Wey with a day boat he hit the bank quite hard. He rang the hire company and they said they sometimes stick in forward, make sure its in reverse before opening the throttle. If I hadn't been there I wouldn't have believed it

Especially when the box is a Lister LH150 that is low on oil. Seen a few ram lock gates because of that.

[Balliol]

4 hours ago, Bern0 said:

 

The rather sharp bend in the cable just above the cable clamp will not help. Try and lose the bend.

Edited April 1, 2020 by Balliol
Mistype

[alan_fincher]

4 hours ago, magnetman said:

Normal engine oil like a 10w30 for a prm 150 (previously called a PRM delta). I've got two Delta boxes on one of my boats. Nice gearboxes. My other boats have PRM 260 and 160 (same actual gearbox but the numbers were changed when they renamed the Delta as the 150 to avoid the 160 getting confused with the 150). 

 

150/Delta is aluminium the 260/160 is a cast iron job.

Whilst they are similar, I don't believe that a PRM 150 is just a renaming of the Delta.

I would be fairly confident that there are differences between them, but I'm happy to be corrected if I'm wrong.

[magnetman]

I'd be happy to be corrected on it. 

 

I suppose a quick Google image search would help 

 

Edited April 1, 2020 by magnetman

[Keeping Up]

18 minutes ago, alan_fincher said:

Whilst they are similar, I don't believe that a PRM 150 is just a renaming of the Delta.

I would be fairly confident that there are differences between them, but I'm happy to be corrected if I'm wrong.

Yes I agree with you, I think they were different. I think we had a Delta for a while, then replaced it with a 150 (they were both a LOT better than the Borg Warner that we had when the boat was new). I believe the Delta, for example, had a thinner input shaft which meant the drive splines wore out more quickly - at least they certainly did on ours.

[magnetman]

Looking them up it appears there was a Delta 20 and a delta 30. Not sure which ones mine are.

 

I must say I assumed the 150 was the same unit as it has the same aluminium body. It's certainly possible that the 150 has different internals. 

 

Happy to withdraw my earlier comment if it was incorrect. I was mainly talking about the actual item rather than the size of shafts. 

Edited April 1, 2020 by magnetman

[Keeping Up]

I just looked up my old receipts and sure enough it was a Delta that I first had as a warrantee replacement for the useless Borg-Warner. It always leaked badly, it wasn't until it was removed for replacement by the 150 (after its input splines failed) that the reason became apparent: one half of the casing was aluminium and one half was steel, so the difference in thermal expansion meant the gasket couldn't maintain the seal. I guess that proves that the casings of the Delta and the 150 were dimensional similar.

[Movin' on]

Join RCR and then you've got the job done and peace of mind for your first 12 months whilst you learn about your new boat app £150 well spent

[magnetman]

9 hours ago, Keeping Up said:

I just looked up my old receipts and sure enough it was a Delta that I first had as a warrantee replacement for the useless Borg-Warner. It always leaked badly, it wasn't until it was removed for replacement by the 150 (after its input splines failed) that the reason became apparent: one half of the casing was aluminium and one half was steel, so the difference in thermal expansion meant the gasket couldn't maintain the seal. I guess that proves that the casings of the Delta and the 150 were dimensional similar.

That's odd. The PRM Delta gearbox is made in two halves both of which are Aluminium. 

 

As confirmed in the manual. Who was it who told you that half of it was steel? 

 

PRM DELTA MANUAL SCREENSHOT

 

The PRM 150 does have a larger diameter input shaft but I believe other than that it is the same unit as the Delta. 

 

PRM 150 screenshot

 

 

Edited April 2, 2020 by magnetman

[Tracy D'arth]

PRM150 and the Deltas are very different animals.

Some of the Deltas on BMC 1.5Ds had the bearings for the intermediate shafts in the back of the bell housing rather than in the casing front half. The cases are all aluminium, never seen a steel one.

Quote

 

 

[Keeping Up]

As my Delta was supplied by Duffields as a warrantee replacement for the Borg Warner, rather than directly from PRM, I strongly suspect they cut their losses by putting together a makeshift box for me from an old and probably broken aluminium Delta mated with a spare steel back-end from one of the newly-released 150's. There's no doubt; when UCC removed it from the boat to replace it with a new 150, Jono called me over in amazement to show me the two halves on his workbench.

[magnetman]

That makes sense to an extent. 

 

Not sure where they would have got the steel part from as both the Delta and the 150 are described as two halves of cast aluminium. 

 

I know Jono at UCC knows his stuff so would not argue it's just odd and not original to the PRM gearbox. 

 

I suppose it's possible some cast iron casings were made for testing purposes. 

 

Or maybe there were some cast iron PRM 150 gearboxes. The 160 and 260 are cast iron as are the larger units. 

Edited April 2, 2020 by magnetman

[Onewheeler]

20 hours ago, Tony Brooks said:

 

On the throttle cable the swaged joint between the end fitting and the inner cable wire at the control end gets swung through an ark whenever you go between gears. Often the stiffness of the whole cable or excess bundling clamping prevents the outer moving so eventually the inner cable fatigues and snaps.

 

That's what happened to mine. We had a spectacular landing onto the VM pontoon in Bristol Floating Harbour which caused some amusement to the bloke in the boat behind where we were aiming, 30 minutes boating before heading out to sea (well, Portishead). There;s a Force 4 shop just over the way who sorted me out with a new cable. Ten minutes work to replace it.