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Hurth transmission freewheeling

terrythatcher

Terry Thatcher
I have been advised by Pacific Northwest ZF Hurth distributor not to freewheel the transmission on my Perkins 4-108.. Always engage in reverse when sailing. I have an older Hurth HBW 10. I had previously been given opposite advice--and the new advice means I cannot use my shaft alternator. Anyone out there have any other information of Hurth transmission freewheeling?
 
Hi,
I have the same Tranny and the manual that I have states " rotation of the propellor without load while the boat is sailing, being towed or at anchor will have no detrimental effects on the gearbox. Never leave gear in the forward position when under sail.Locking the prop shaft can be done by leaving gear in reverse position."
I hope this helps. I also hope that it is OK to post this on your site. I don't own a Morgan, but I often find that the information here is useful for my older Perry designed CheoyLee so I lurk here from time to time.
Cheers,
David
 
Letting the shaft rotate has got to wear out the bearings, even under no load. This said, now you would have to determine if the bearings would wear out faster than the clutches or other parts in the tranny that wear out with normal use.
Based on the statement on the manual I would assume that something else will wear out before the bearings do.
Adding to this would be your shaft alignment and other vibrations that are transmitted from the shaft to the transmission that would increase bearing wear. This was probably not taken into account when the manual was written.
I guess that this is a judgement call. Do you need the extra speed, or power generating? How good is your shaft alignment? How old is your cutlass bearing( this will wear too)?

My two cents!

Jose Santin
S.V. Siboney
 
Howdy...it's a bit late for this, but maybe the next guy to read this thread will benefit.
The shaft freewheeling question is one that I put to the Hurth factory boys a couple of years ago, and here is their answer. It does no harm, whatsoever, to the transmission to leave it in neutral while sailin, letting the prop free-wheel. They said that there is a little bit of wear, but it is so negligible that it's a non-issue. On the other hand, if the tranny is not placed in neutral, it very much matters which gear the tranny is left in while sailing. The only way you can stop prop rotation with the transmission is to shift it into reverse. You should NEVER leave the tranny in forward while sailing because water flow over the prop will cause the shaft to exert rotational forces on the forward clutch. This clutch will continuously slip, with it ultimately becoming worn/permanently glazed and therefore prone to slippage under load. The reason for this is that the two clutches (one for forward and one for reverse) each have a spring loaded (or centrifugal) mechanical clamping system that locks the clutch against slipping in the direction that holds the load. The clamps, however, will definitely slip in the other direction and that is what causes all the mischief with wear and tear on the disc.
Hope this helps.
Jim
 
Jim, what Hurth factory guys? I tried Florida and they were no help. You go to Germany? Italy. Do you still have a number or contact point so I could pursue this a bit more? Thanks.
 
A few things, first my manual says neutral is ok provided the ATF fluid is kept at the upper mark on the dipstick. I am new to this transmission and am hoping for some advice. I have just bought a Beneteau oceanis 400 with a perkins prima 50 pushing the HBW 10. Upon noticing some "chatter" in forward just above idle but not at higher rpms, I checked fluid level and found the level below stick(not reading) so I added 6 oz to bring up to correct level. Also noticed fluid badly burned brown and smelly. Have changed fluid but chatter remains. Clutch seems fine as boat takes up speed promptly. Any advice on rebuild needed? Sounds sweet in reverse still.
Brad
 
Hi Hurth fans. I have an old Hurth 15 fitted to a Mercededs 616 engine. I have had it rebuilt twice, but hear it is really too old to get spares for. I want to update it and believe the 150 is a direct replacement. Does anyone have the Italian dealer / factory details? I am in Ostia, near Rome wintering and guess they should be somewhere around here.

Thanks, Graham. 101456.1713@compuserve.com
 
When i purchased my Morgan 384 2 years ago she needed a new trans day one ! So the 4108 had a hurth10 in it . I went with a 15 so to have no trouble down the line with at least the trans.
 
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