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brian and clare · 25-09-2007, 18:16

As far as projects we havent gotten near our mythical giant trading schooner quite yet. There is a steel boat on trademe in cristchurch that is sooo tempting, but no engine, mast sails, interior, well, no everything really, so we would have to figure out the bits needed. The engine I was aking about is a perkins 4-154 with 62 HP from the 70s that has toasted the transmission. Are the transmissions put on the engine with studs, or bolts? And as a follow up, do those nut breakers (insert joke here) that you clamp onto the nut and wind down on actually work? They look so promising on the shelf of the tool store, but I havent heard many folks talk about them.

**Alan Wheeler** · 25-09-2007, 21:27

The box will be bolted on. And yep, the nut breakers do work. I doubt it will be as hard to remove as you fear. Hey email me a link so I can take a look at her.

S/V Antares · 26-09-2007, 07:34

I have replaced dozens of Hurth/ZF mechanical boxes. All fail due to heat. Heat is usually caused by undersizing (Trans/engine), over proping or alignment. Rotation is another issue. The mechanical boxes (ZF10, 12 etc )will run in reverse with a left hand prop but it will be noisy and burn up quickly. .

Motorsailing can be hard on the alighnment Tie a tight string Port to starboard in the cabin about waist high see how it sags when beating to wind. On some boats the alignment can really be affected.

When you say " Have to rev engine to get it into gear" This indicates the throw on the shift lever is not long enough or not adjusted. Try disconecting the shift cable and shifting manually. These are "Dog" clutches and must have enouhg travel to engauge the "Dogs" or it will do exactly what you mention.

I had to change the fulcrum point (Drill a new hole closer to the shaft for the ball end) in order to get enough throw on my boat. Cost me a gearbox because I was too lazy to fix the real alignment and cable issue.

Depending on the bellhousing iand access it can be easy. Check the damperplate while in there.

Will Heyer

brian and clare · 30-09-2007, 16:19

I dont have a picture unfortunately. But imagine a huge blue chunk of steel covered in rust and you pretty much have it. I imagine the box is a hurth from looking at other pictures in Nigel Claders book, and pics online of the hurth transmissions. No plate or anything on motor that is readable. Should a hurth shift lever (when disconnected from linkage) engage when pushed foreword then stop like it cant go any further (like when you shift into gear on a car), or is there a "sweet spot" where the gears engage, and if you push the lever too far foreword it will fall out of engagement? I guess the question is can you push the lever too far foreword?

Thanks,
B

**Alan Wheeler** · 01-10-2007, 01:46

Nope. As far as I know, they go into gear and the lever stops. Their should be a small ball detent internally that locks the lever into the three positions. But I am guessing here. I have not had one apart. A parts breakdown will show you what is inside.

Wannafish · 01-10-2007, 05:20

"...(like when you shift into gear on a car), ..."

It was much funnier the way it was originally worded

Steve Pope · 01-10-2007, 14:29

On my Hurth/ZF the lever can carry past the selection position without appearing to upset the selection.

cooper · 02-10-2007, 00:49

M Mechanical clutch actuation. NR Non-Reversing. NR 2Non-Reversing, two shafts (input above output).NR2B Non-Reversing, two shafts (input below output). DS Dual Speed (NOT power-shifting). TS2-Speed (power-shifting) NO LETTER Vertically offset (input above output).A Down-Angle. IV Integral Vee-drive (flanged on to engine).V Remote Vee-drive . D Diagona. lH Horizontal. C Coaxial. B Input below output-----------------------------The box is a mechanical box. ---------------------------------------------------There is a distinct click when you engage the clutch. The minimum stroke for the bottom hole is 30 mm with a further "range " of 13 mm, The minimum stroke for the top hole is 35 mm with a further "range" of 15 mm. When it is in the range area the lever is quite floppy. These measurements are in a straight line horizontaly from the centre (neautral) position.

**GordMay** · 02-10-2007, 02:17

ZF Marine Transmission Support Documents:
http://zf-marine.com/ZFR/Support/index.cfm?PID=3&TZ=-4&SC=1024:768:32

And, the previously posted Model Index (Key to Designations ...):
http://zf-marine.com/ZFR/Transmissions/index.cfm?PID=AE

"ZF Marine Hurth SpA" has been re-named "ZF Marine Arco SpA"

**Alan Wheeler** · 02-10-2007, 11:27

Quote:

It was much funnier the way it was originally worded

Brians been in NZ too long. He talks like a Kiwi now.

S/V Antares · 03-10-2007, 06:08

Brian & Claire The Hurth/ZF are aluminum housings. The Perkins 4-154 normally came with a Borg Warner "Velvet Drive" which is a hydraulic "Planetary Gear" unit with a cast iron housing tha rusts badly if not coated regularly. The input and output shaft is on the same line/plane. No drop/offset. They are usually fitted with an oil cooler

Pictures at: Velvet Drive Marine Parts Books

S/V Antares · 03-10-2007, 06:22

Steve, Cooper has the specs. The mechanical units will engage the gears and travel a bit past in fwd. or reverse. If the gears do not engage when the lever is moved past the detent point and/or you need to rev the motor it is a sign of internal problems adjustments etc. Not good. Most shops do not even rebuild as the parts cost are high enough to justify a new box. Twinn Disc makes a direct replacment for some Hurth ZF and is much cheaper and I think migh be better.

brian and clare · 03-10-2007, 12:43

Thanks for that. It would make sense to not mount an aluminium transmission to a steel engine. I am definitey not sure what the box is, but it is not a rounded unit, definitely square-ish. No oil cooler mountedto it that I could see either, though maybe the oil coller was not mounted directly on the transmsission but on the engine instead? Definitely square though.