Hirth Gearbox failure

[johnneale]

I have a friend currently in Horta (Azores) who has following problems with his hydraulic gearbox fitted to Perkins 4108.
No drive in Forward gear, - Reverse does engage, but seems to slip a lot.
Hydraulic fluid level is OK,
Gear lever doesnt 'clunk in' in forward, though at max travel...

Any ideas as to the fault and is there anything he can do in situ pro-tem to get drive, or is it an engine/gearbox out trick in which case he said he will sail it home without the engine.

Thanks again for this excellent forum


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[HenryB]

I once lost all drive through my Hurth gearbox and this eventually was traced to the failure of the flexible driving plate which links the gearbox to the crankshaft. Its a bit like a car clutch plate but without the clutch! As you state that the reverse "slips", it may not be a gearbox fault at all. My Hurth is mechanical not hydraulic although it uses hydraulic fluid and, in common with most Hurth boxes has basically two separate drive paths, one for forward and another for reverse. It isn't usual for both to fail - a friend once travelled 30 miles along the Italian coast in reverse when forward failed.
On my unit it was a quick and easy job to separate the gearbox from the engine to confirm that the drive plate had failed.

Regards,

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[Anchorite]

Re: HURTH Gearbox failure

It will be a mechanical box on a 4.108, probably a HBW100. The gear lever on
the RHS of the box is fixed onto the box with a screw (13mm hex). Check that
this screw is tight - it holds the coupling onto the (round) shaft that goes into
the box. This shaft has no flats so the coupling if not tight can spin.
Digging deeper: need to drain the oil in the box and then remove the small
flange that holds the afore-mentioned shaft. Inside is a (about) 60° sector
with a small pin (about 4mm long, 2mm diameter) that engages for'd or astern.
Could be broke (find it...) replace with something else. Not difficult, no springs
will jump out etc: 4 bolts, 13 mm hex.
Don't run far in reverse: it's a bushing, forward is on bearings. Saw one die (RH
prop on LH box, running in "reverse"): it lasted less than 12 hours.


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[dickh]

Re: HURTH Gearbox failure

I had problems with my Hurth HBW50 last year - I got a workshop manual direct from Hurth in UK - can't remember the name but I have the card at home and they were very helpful and didn't charge for the manual! I'll get it tonight and post the info tomorow.
My gearbox would engage OK in forward gear at idle speed, but the clutch would slip when revved and then engage with a clunk. Reverse was OK. I stripped the clutch but could find no obvious wear, but replaced the clutch packs as a matter of course. It now works fine. Hurth spares are expensive but you can get pattern parts from [urlwww.asapsupplies.com/url] who do a mail order service.
Another part that fails is the sintered thrust washer, again easy to replace.
All taper bearings are obtainable from local bearing suppliers, as well as oil seals.

Anchorite, when I stripped my box there were no bushings - all on proper taper bearings at both ends of the shaft - where is this bushing?

<hr width=100% size=1>dickh
I'd rather be sailing... /forums/images/icons/smile.gif

 

[Anchorite]

Re: HURTH Gearbox failure

Dick: don't know. This incident concerned a HBW 10 (ancestor of HBW100)
mounted on a 4.108. The box died at Charleville Mezieres, having started
new at Namur. The bushing "explanation" was given by a competent
engineer. It may have been old technology. I have a HBW10 in a time capsule
(plastic bag) somewhere awaiting rebuilding, Urgent Item no. 127. I'll let
you know (when the time comes...)

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[dickh]

John,
The contact at ZF Marine for Hurth Gearboxes is Adi Licence - Tel No 0115 986 9211; Dirct Line 0115 935 5426; eMail:- adi.licence@zf-group.co.uk
Hope this helps.

<hr width=100% size=1>dickh
I'd rather be sailing... /forums/images/icons/smile.gif

 

[johnneale]

Great news chaps - I hope my matey in the azores is picking this up - If not will save this lot for him if/when he gets back.
Tks John

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