Prop shaft brake - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 
  #1  
Old 07-04-2008
Junior Member
 
Join Date: Jul 2008
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
pullark is on a distinguished road
Prop shaft brake

Hi,
I have a PRM hydraulic gearbox in my boat. I have a three blade conventional prop. The prop/gearbox rotates as I sail along. It's been suggested to me this is not a good idea as it will cause wear to gearbox bearings. Should I instal a prop shaft brake to prevent wear on transmission? Will drag increase or decrease as a result? Any simple design ideas for a braking system appreciated.
Thanks
Kevin
Reply With Quote Share with Facebook
  #2  
Old 07-05-2008
canadianseamonkey's Avatar
Caribbean Surveyor
 
Join Date: Sep 2006
Location: Now in Sosua, DR
Posts: 511
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
canadianseamonkey is on a distinguished road
Hi Kevin and welcome to Sailnet, I have the same tranny. It depends on how long you sail, I don't always lock mine , it won't heat up right away, but as a precaution a break is best. I looked at those breaks they sell and settled on a pipe wrench. It works just fine as long as you don't forget it when you start your engine. Many people I spoke with use this fix. Give it a try. Good luck.
Reply With Quote Share with Facebook
  #3  
Old 07-05-2008
Senior Member
 
Join Date: Sep 2007
Posts: 451
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 7
RXBOT is on a distinguished road
Shaft brake

I have very limited experience with hydraulic gearboxes but lots of experience with hydraulics and lots with mechanical gear reducers.I seriously doubt that while saiing the RPM of the prop would be fast enough to be of any concern. However if you engaged the drive with pipe wrench in place you may have a new thru hull opening plus severe trauma to other components.
Reply With Quote Share with Facebook
  #4  
Old 07-05-2008
Junior Member
 
Join Date: Jul 2008
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
pullark is on a distinguished road
Guys, thanks for your thoughts. I agree the consequence of forgetting to remove the wrench on engine startup could be quite scary.
Cheers
Kevin
Reply With Quote Share with Facebook
  #5  
Old 07-05-2008
Senior Member
 
Join Date: Jun 2007
Posts: 2,710
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
SEMIJim will become famous soon enough SEMIJim will become famous soon enough
Our mower has hydraulic drives (two: one for each drive wheel). Neutral is simply no drive power. To actually get the two wheels to free-wheel, I have to flip a manual release on each drive. Then they don't drive anymore, either.

It's been years and years since I've owned a car with an automatic transmission, but I thought that, in anything but neutral, the drive train was not free to move.

How are these PRM hydraulic gearboxes different?

Jim
Reply With Quote Share with Facebook
  #6  
Old 07-05-2008
timebandit's Avatar
Senior Member
 
Join Date: Sep 2002
Posts: 928
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 12
timebandit is on a distinguished road
A simple brake can be made from 2 pieces of 2x4 with a a V cut into each and clamped to gether with carrage bolts with springs and wing nuts.

Just tighten the brake enuff to stop the shaft.

If you start the motor it will allow the shaft to spin but if you run for to long the wood will start to over heat and let you know you forgot it.

Rick
Reply With Quote Share with Facebook
  #7  
Old 07-06-2008
Ilenart's Avatar
Senior Member
 
Join Date: Jul 2007
Location: West Australia
Posts: 507
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 8
Ilenart is on a distinguished road
Some hydraulic drives are ok to freewheel

Pullark,

some hydraulic drives are ok to freewheel. My boat has a Velvet Drive hydraulic marine transmissions from Borg Warner and it's been freewheeling all the time & the boat is almost 30 years old. You might want to do some research into your particular gearbox.

I previously found the following on another website.
A number of major gearbox manufacturers have dispelled an earlier unfounded fear of gearbox damage due to improper lubrication while freewheeling. However some gear box manufacturers do not advise leaving the prop to free wheel as this can cause mechanical problems within the box (overheating due to lack of lubrication).

Ie - From “Velvet-Drive”:
It has been determined by tests and practical experience that all Velvet Drive marine transmissions call be free-wheeled without risking damage in sailing or trolling applications. Caution should be taken to be sure that proper oil level is maintained prior to freewheeling as well as normal running. Freewheeling one propeller of a twin engine boat at trolling speeds will not cause damage to the transmission connected to the freewheeling propeller.
Extended periods of free-wheeling at high speeds may cause the transmission to overheat; therefore, it is recommended that transmission sump temperature be monitored and free-wheeling discontinued whenever 230 degrees F or 111 degrees C is reached.


Sailing with tansmission in N or R - Cruisers & Sailing Forums
Ilenart
Reply With Quote Share with Facebook
  #8  
Old 10-27-2008
Junior Member
 
Join Date: Oct 2008
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
wesselouki is on a distinguished road
Prop shaft brake

I have the same issue and am considering a folding prop. Does anyone know if a feathering prop will fold while sailing without locking the prop shaft? This would eliminate the potential for the pipe wrench effect and solve the gearbox issue.
Mike
Reply With Quote Share with Facebook
  #9  
Old 10-27-2008
AllThumbs's Avatar
midlife crisis member
 
Join Date: Jul 2008
Posts: 960
Thanks: 0
Thanked 5 Times in 5 Posts
Rep Power: 7
AllThumbs is on a distinguished road
I dunno about the gearbox wear but the drag will be least with the prop locked
__________________
The people who find fault in what you build typically don't build anything at all.
Reply With Quote Share with Facebook
  #10  
Old 10-27-2008
Senior Member
 
Join Date: Jul 2008
Posts: 239
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 7
LittleWingCA is on a distinguished road
Is there harm in just leaving it in gear when the engine is stopped? I don't know what engine manufacturer you have, but for my Yanmar, the manufacturer recommends putting the transmission in reverse after shutting down the engine to keep the prop from free spinning. They recommend reverse over forward.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

LittleWingCA
1980 Pacific Seacraft Orion 27
Sailing Grounds: Southern California
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Prop shaft runout tolerance voyagersail Gear & Maintenance 0 06-07-2007 04:25 PM
prop shaft assy pmcandrew Gear & Maintenance 1 01-23-2005 04:41 PM
Choosing the Right Propeller Sue & Larry Gear and Maintenance Articles 0 02-04-2003 07:00 PM
Drive Train Vibration Tom Wood Gear and Maintenance Articles 0 10-10-2002 08:00 PM
prop shaft thomasstone Gear & Maintenance 3 03-27-2002 03:03 PM


All times are GMT -4. The time now is 04:08 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012