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Marine gear comparison - Velvet Drive vs ZF Hurth
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Jeff Thompson
Nov 5, 1998, 3:00:00 AM11/5/98
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I need to consider a replacement marine gear on a new Perkins 4-236 4
cyl 80 hp diesel. I have a Borg Warner Velvet Drive 71-C now. I can
install a new unit or a Hurth gear, Hurth model not known yet. I hear
that the Hurth gears don't need a shaft brake as they automatically lock
the shaft when in reverse with the engine stopped - true ? If so, that's
a big plus. Any repair or failure comparisons & comments welcome. The
71-C is a reverse rotation gear - I would need a reverse rotation Hurth
or a new prop. The Hurth gear is shorter - means a new longer shaft. The
71-C case is cast iron (?) the Hurth is cast Alum. Not much price
difference apparently. Anything else ?
cyl 80 hp diesel. I have a Borg Warner Velvet Drive 71-C now. I can
install a new unit or a Hurth gear, Hurth model not known yet. I hear
that the Hurth gears don't need a shaft brake as they automatically lock
the shaft when in reverse with the engine stopped - true ? If so, that's
a big plus. Any repair or failure comparisons & comments welcome. The
71-C is a reverse rotation gear - I would need a reverse rotation Hurth
or a new prop. The Hurth gear is shorter - means a new longer shaft. The
71-C case is cast iron (?) the Hurth is cast Alum. Not much price
difference apparently. Anything else ?
eteneyck
Nov 5, 1998, 3:00:00 AM11/5/98
to Jeff Thompson
I have had two boats with Velvet Drives and I like the ease with which
they shift. Being hydraulic, they automatically adjust for plate wear.
Also being hydraulic, they will rotate unless locked. You probably
don't want to spend the extra money for a brake. I have limited
experience with a Hurth but on one of the boats that I skippered I did
have a Hurth that failed and the parts couldn't be replaced so a new
unit had to be installed. If you have a sailboat, a mechanical
shifting gear which can be stopped by leaving it in reverse may be your
best bet. Skipper Ed
they shift. Being hydraulic, they automatically adjust for plate wear.
Also being hydraulic, they will rotate unless locked. You probably
don't want to spend the extra money for a brake. I have limited
experience with a Hurth but on one of the boats that I skippered I did
have a Hurth that failed and the parts couldn't be replaced so a new
unit had to be installed. If you have a sailboat, a mechanical
shifting gear which can be stopped by leaving it in reverse may be your
best bet. Skipper Ed
--
Visit my Marine Web Site:
http://ed.teneyck.com
Bryon Kass
Nov 6, 1998, 3:00:00 AM11/6/98
to Jeff Thompson
The Warner reductions are about 7-10" longer than a Hurth. The
newer larger Hurths are now hydraulic and may not lock as the
older mechanicals can. I have a takeoff gear that looks like it
was never used a model 400 mechanical. The newer 450s are now hyd.
WIth hyd gears the shifting is smoother and you can cool the gear
easier with a pump. This gear or the 250 would go onto your engine.
The 250 needs the Hurth to Warner adapter where the 400 is already
Warner ready. Most of the Hurths can run 100% both directions for
LH or RH props. To confirm this contact a Hurth trans dealer in your
area for the particular model you want.
Bryon Kass
webmaster and
Custom Design
150 Mechanic St.
Foxboro, MA 02035
508-543-9068 or fax 508-543-5127, Foot yard 508-384-2415
in THE ENGINE ROOM http://home.ici.net/~cusdn
newer larger Hurths are now hydraulic and may not lock as the
older mechanicals can. I have a takeoff gear that looks like it
was never used a model 400 mechanical. The newer 450s are now hyd.
WIth hyd gears the shifting is smoother and you can cool the gear
easier with a pump. This gear or the 250 would go onto your engine.
The 250 needs the Hurth to Warner adapter where the 400 is already
Warner ready. Most of the Hurths can run 100% both directions for
LH or RH props. To confirm this contact a Hurth trans dealer in your
area for the particular model you want.
Bryon Kass
webmaster and
Custom Design
150 Mechanic St.
Foxboro, MA 02035
508-543-9068 or fax 508-543-5127, Foot yard 508-384-2415
in THE ENGINE ROOM http://home.ici.net/~cusdn
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