Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 25-04-2009, 19:03   #1
Registered User

Join Date: Aug 2006
Location: Leucadia, California
Boat: Stevens 47 Komaru
Posts: 428
Percentage of Pulley in Contact with Belt

I have a Lehman 4D220 engine that I have completely rebuilt, is now ready to crane back into the boat.

My question is in regards to the percentage of the v-belt that will be in contact with the drive pulley. This is the application.

I have constructed a bracket that bolts onto the engine, it is very solid. This bracket has a flat bed with a place to bolt a York refrigeration compressor and an additional (2nd) alternator. Both the compressor and the alternator have 1/2 double v-belts. Does anyone know what the minimum percentage of the engine drive belts that contacts the engine pulley would be needed to prevent belt slippage or failure.
__________________

__________________
Stevens 47 is offline   Reply With Quote
Old 25-04-2009, 20:48   #2
Moderator Emeritus
 
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: San Francisco Bay
Boat: research vessel
Posts: 10,152
Check with the engine manufacturer on this. Sometimes the engineered tolerance is so close that just increasing the alternator output is enough to cause slippage or premature wear.
__________________

__________________
David

Life begins where land ends.
David M is offline   Reply With Quote
Old 25-04-2009, 21:37   #3
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
I couldn't find anything definitive on this but it seems to me that the top of a correctly sized belt should sit at about the level of the pulley flange. It should not be more than about 1/8" proud of the pulley flange. Now that is just from memory, so I would check with the distributor. Calder recommends Gates Green Stripe belts.

Here is part of what it says in Calder's book, paraphrased a bit:

The pulley grooves must be sized so the belt does not bottom out in the pulley. The driving force of the belt must be delivered by the sides of the belt, not the base of the belt. Also the standard industry pulley has a 38 deg. taper to the sides of the groove, whereas many alternators come with 34 or 36 deg. pulleys, which will accelerate belt wear. Replace the pulley with a 38 deg. pulley.
__________________
DeepFrz is offline   Reply With Quote
Old 25-04-2009, 21:49   #4
Registered User

Join Date: Feb 2009
Posts: 1,848
Steve I would guess on the large drive it would be close to 40% Something to consider The water pump bearing is the weak link on these motors Does you drive system include the water pump? I would guess not. American diesel could give you your answer
__________________
motion30 is offline   Reply With Quote
Old 25-04-2009, 22:17   #5
Senior Cruiser
 
delmarrey's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Now in Blaine, WA
Boat: Modified Choate 40
Posts: 10,702
Images: 122
Quote:
Originally Posted by Stevens 47 View Post
Does anyone know what the minimum percentage of the engine drive belts that contacts the engine pulley would be needed to prevent belt slippage or failure.
That's one of those questions that can not be completely answered. It's relative to the circumstance.

As for the wrap of the sheave, it should be around 120 + for most power units. If there is a strong pull like on compressors or hi amp alt's. then 160 + would be better. If that's not enough then a double belt is needed.

But like on some serpentine belts there is a back-side idler/tensioner which gives a belt more wrap as much as 240.

You'll just have to try it to see for sure. If there is any slippage you'll see a black powder forming around the slipping sheave.



Then there is the positive traction belts.
.................................................. _/)
__________________
Faithful are the Wounds of a Friend, but the Kisses of the Enemy are Deceitful! ........
A nation of sheep breeds a government of wolves!

Unprepared boaters, end up as floatsum!.......
delmarrey is offline   Reply With Quote
Old 26-04-2009, 03:08   #6
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,583
Images: 240
See the “Pulley And Belt Calculator”: Pulley And Belt Information Calculator

And Belts, Tensioners, & Pulleys 101:

http://www.gates.com/common/download...n/428-7174.pdf
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 26-04-2009, 12:04   #7
Registered User

Join Date: Aug 2006
Location: Leucadia, California
Boat: Stevens 47 Komaru
Posts: 428
Thanks to all for your input

Quote:
Something to consider The water pump bearing is the weak link on these motors Does you drive system include the water pump? I would guess not. American diesel could give you your answer
Yes the water pump is on a separate pulley v-belt system with a smaller alternator. I agree the water pump bearing is the weak link in the system.

Quote:
But like on some serpentine belts there is a back-side idler/tensioner which gives a belt more wrap as much as 240.
The installation of a idler has been a thought, seems that they cause the v-belts to wear faster. What are your opinions on this.

The engine pulley (it bolts onto the original Lehman pulley) in question has 3 grooves. I used Gord's link for the calculator (thanks for that Gord just what the doc ordered). My first thought was to have the second alt and the compressor on the same circuit with a unused 3rd groove. The alt creates the belt adjustment. It looks like the best that I can do is 130 degrees the calculator calls for 165, I would have to install a idler.

The other options would be to run the alt and the compressor on there own separate circuits. The alt with two 1/2" belts and the compressor on the single. The problem would maybe be that the compressor may require 2 belts. The other option is to turn up a 4 groove pulley, placing both loads in opposition. What do you think
__________________

__________________
Stevens 47 is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Serpentine belt conversion for Universal Diesel SaltSeaSailor Engines and Propulsion Systems 2 22-04-2009 10:01
Looking for belt driven autopilot Bombay 31 General Sailing Forum 0 05-09-2008 06:12
March 11th - Belt and Sospenders, plus the kindness of strangers skipgundlach General Sailing Forum 1 19-06-2008 20:51
Galley Belt Charlie Provisioning: Food & Drink 12 01-03-2008 22:33
How to contact administrator? Mark W. Preston Forum Tech Support & Site Help 1 13-08-2005 09:14



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 01:08.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.