The Forestry Forum is sponsored in part by:

iDRY Vacuum Kilns


Forestry Forum
Sponsored by:


TimberKing Sawmills



Toll Free 1-800-582-0470

LogRite Tools



Norwood Industries Inc.




Your source for Portable Sawmills, Edgers, Resaws, Sharpeners, Setters, Bandsaw Blades and Sawmill Parts

EZ Boardwalk Sawmills. More Saw For Less Money!

STIHLDealers.com sponsored by Northeast STIHL


Woodland Sawmills

Peterson Swingmills

 KASCO SharpTech WoodMaxx Blades

Turbosawmill

Sawmill Exchange

Michigan Firewood, your BRUTE FORCE Authorized Dealer

Baker Products

ECHO-Bearcat

iDRY Wood Lumber Vacuum Drying for everyon

Nyle Kiln Dry Systems

Chainsawr, The Worlds Largest Inventory of Chainsaw Parts

Smith Sawmill Service



Author Topic: Pully Diameter?  (Read 738 times)

0 Members and 1 Guest are viewing this topic.

Offline John Mc

  • Senior Member x2
  • *****
  • Posts: 5725
  • Age: 59
  • Location: Monkton, Vermont
  • Gender: Male
    • Share Post
Pully Diameter?
« on: September 01, 2021, 07:17:46 AM »
Is there a rule of thumb for minimum diameter for pulleys or sheaves to use with a given sized cable? Maybe something like ___ X the cable diameter?  Does it vary with the type of cable?

I have a 10mm (3/8+") cable I salvaged from my logging winch when it got a bad kink right in the middle of the length. It's swaged, if that makes a difference. Unfortunately, I don't know the details on the strand count. What is the minimum safe diameter pulley to  use with this without causing excessive "pigtailing".
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

Offline LeeB

  • Senior Member x2
  • *****
  • Posts: 8416
  • Age: 62
  • Location: Yellville Arkansas
  • Gender: Male
  • proud to be a TEXAN in Arkansas
    • Share Post
Re: Pully Diameter?
« Reply #1 on: September 01, 2021, 09:10:53 AM »
Minimum diameter is 18:1. European standard is 24:1.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

Offline John Mc

  • Senior Member x2
  • *****
  • Posts: 5725
  • Age: 59
  • Location: Monkton, Vermont
  • Gender: Male
    • Share Post
Re: Pully Diameter?
« Reply #2 on: September 01, 2021, 09:38:33 AM »
Minimum diameter is 18:1. European standard is 24:1.
Thanks, Lee.  That's larger than I thought. That would mean my 10 mm (0.394") cable should use a 7" diameter pulley (or almost 9.5" by European standards). I don't know that I've ever even seen a 7" self-releasing snatch block, let alone one 9+ inches. I own two of them, one is about 3.5" to the bottom of the groove, the other is 4.5".
Is that standard perhaps intended for overhead lifting?
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

Offline mike_belben

  • Senior Member x2
  • *****
  • Posts: 11804
  • Location: Middle TN
  • Pulp Friction
    • Share Post
Re: Pully Diameter?
« Reply #3 on: September 01, 2021, 09:42:04 AM »
the bigger the pulley radius, the more individual strands stay in tension. with a tiny radius, say 2x like a knot around a clevis pin, youll get a bunch of strands not just unslacked, but backed up in compression and jumbled while the fewer strands in tension are overloaded for lack of helpers.  

the bigger the radius, the more strands in tension, the higher the capacity.  a small radius is effectively using a smaller cable. thats why the ratings are radius dependant.  same with end terminations.  put a big thimble if you need the full rating at the termination. 
Isaiah 63:10

Offline LeeB

  • Senior Member x2
  • *****
  • Posts: 8416
  • Age: 62
  • Location: Yellville Arkansas
  • Gender: Male
  • proud to be a TEXAN in Arkansas
    • Share Post
Re: Pully Diameter?
« Reply #4 on: September 01, 2021, 02:56:31 PM »
That measurement is center of the cable to center of the cable, not bottom of the groove. Having said that, a 6" sheave would probable be just fine. 
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

Offline LeeB

  • Senior Member x2
  • *****
  • Posts: 8416
  • Age: 62
  • Location: Yellville Arkansas
  • Gender: Male
  • proud to be a TEXAN in Arkansas
    • Share Post
Re: Pully Diameter?
« Reply #5 on: September 01, 2021, 03:05:54 PM »
What load rating do you need? For a 5t rating, Mckissick snatch block is 4 dia for 3/8" - 1/2" wire rope. That's only 12:1 for 3/8", less than that for 1/2". So not really sure about the 18:1 figure. 

McKissick® 419 Light Champion Snatch Blocks - Crosby Group
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

Offline John Mc

  • Senior Member x2
  • *****
  • Posts: 5725
  • Age: 59
  • Location: Monkton, Vermont
  • Gender: Male
    • Share Post
Re: Pully Diameter?
« Reply #6 on: September 01, 2021, 07:28:00 PM »
What load rating do you need? For a 5t rating, Mckissick snatch block is 4 dia for 3/8" - 1/2" wire rope. That's only 12:1 for 3/8", less than that for 1/2". So not really sure about the 18:1 figure.

McKissick® 419 Light Champion Snatch Blocks - Crosby Group
My winch is only rated at 7700#.
I've been reading up on cable and pulley specs. Apparently, the two big factors are the ration of pulley to cable diameters and the type of construction of the cable (cables with more & finer strands can handle smaller diameter pulleys for the same diameter cable).
I'm not so worried about breaking the cable - either through outright pulling or through fatigue. The stuff I'm pulling does not require doubling the line, so we're not talking 180˚ bends. I'm more wondering about putting a permanent set in the cable by pulling it over a smaller pulley under load.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

Offline mike_belben

  • Senior Member x2
  • *****
  • Posts: 11804
  • Location: Middle TN
  • Pulp Friction
    • Share Post
Re: Pully Diameter?
« Reply #7 on: September 01, 2021, 07:31:30 PM »
i am a destructive testing type of person.  shooting from the hip here, anything over 3" wont kink.  if you jam it into the corner of a cheap chinese fairlead, yeah, thatll leave a mark.   
Isaiah 63:10

Offline LeeB

  • Senior Member x2
  • *****
  • Posts: 8416
  • Age: 62
  • Location: Yellville Arkansas
  • Gender: Male
  • proud to be a TEXAN in Arkansas
    • Share Post
Re: Pully Diameter?
« Reply #8 on: September 01, 2021, 08:37:25 PM »
If you are running the same section of cable over the sheave all the time it will fatigue and fail even with a larger than required sheave. Same way a band blade will eventually break from running around the wheels.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

Offline John Mc

  • Senior Member x2
  • *****
  • Posts: 5725
  • Age: 59
  • Location: Monkton, Vermont
  • Gender: Male
    • Share Post
Re: Pully Diameter?
« Reply #9 on: September 01, 2021, 10:22:31 PM »
If you are running the same section of cable over the sheave all the time it will fatigue and fail even with a larger than required sheave. Same way a band blade will eventually break from running around the wheels.
This piece I salvaged from my old cable is just not seeing enough use for fatigue to be a major concern. It was removed from the winch due to the bad kink 110' in to a 230 ft length. The rest of the cable was still in very good shape - which it why I saved a length of it.
My winch use is far from a full-time thing, and this spare cable gets used even less.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow


Share via delicious Share via digg Share via facebook Share via linkedin Share via pinterest Share via reddit Share via stumble Share via tumblr Share via twitter

moved
MOVED: timber framing peg diameter vs peg hole diameter

Started by chet on Forestry and Logging

0 Replies
432 Views
Last post February 08, 2018, 09:17:07 AM
by chet
xx
timber framing peg diameter vs peg hole diameter

Started by metroplexchl on Timber Framing/Log construction

16 Replies
4507 Views
Last post February 09, 2018, 11:38:41 AM
by Heartwood
xx
Belt pully to pto?

Started by 1wkinsley on Sawmills and Milling

13 Replies
2880 Views
Last post September 15, 2015, 11:33:09 PM
by svart ole
xx
12 V Auto starters used for other applications- modified to accept pully

Started by woodbowl on Sawmills and Milling

36 Replies
9272 Views
Last post March 25, 2006, 09:44:31 PM
by sandman2234
 


Powered by EzPortal