Pajero 4WD Club of Victoria Public Forum Pajero 4WD Club of Victoria Public Forum

Go Back   Pajero 4WD Club of Victoria Public Forum > General Information > Techniques

Techniques Winching - Recoveries - Chainsaw Safety - Proper aproach to 4wding etc

Reply
 
Thread Tools Display Modes
  #11  
Old 05-06-17
Ent Ent is offline
Valued Member
 
Join Date: Apr 2014
Location: Tasmania
Posts: 1,591
Default

One thing I am curious about is the rope strength required. 10mm rope is rated at 17,600lb breaking strain. Standard winch is 9,500lb so doubling the pull using a single block gives 19,000lb potential pull on the vehicle. Is that not above the breaking strain?

Friend on the SES was looking at some winch tables for recovering a vehicle and was rather amazed at the amount of pull required. I bogged DooSo to his bash plates in a bog hole and had to drag him up steep slope. We used a 1.6 tonne lift 3.2 tonne pull Tirfor and we "stalled". Using Maxitraxs and all difflocks we managed to drag him out but using a 9,500lb winch with block would by the sounds of it run the risk of breaking the rope.
__________________
2014 PC Challenger, manual, factory tow-bar, factory front diff protector, TJM inter-cooler plate, Bushskinz manual transmission protection plate, ProRack S16 roof racks, front elocker, Drummond Motor Sport front struts, custom 16mm King rear springs with Bilstein Dampeners, Buzz Rack Runner 3 bike platform, Eclipse Nav head unit, GME TX3800BW UHF, 16x8 CSA Raptor rims, 265/75R16 Maxxis MT-762, orToyo AT/2 265/70R16 Triton rims, BFGoodrich 235/85/R16 Triton rims, or Factory tyres and rims.
Reply With Quote
  #12  
Old 05-06-17
P4J3R0 P4J3R0 is offline
Valued Member
 
Join Date: Jun 2013
Location: Brisbane
Posts: 826
Default

Wouldn't the force on both cars be the same? The force exerted through the winch is actually 3 times less than if it were a straight line pull.

To reduce the load on the front of the winching car the winch would need to be restrained by something (tree) to reduce the load to the vehicle.
__________________
NS Pajero, with stuff.
Reply With Quote
  #13  
Old 05-06-17
twisted32 twisted32 is offline
Senior Member
 
Join Date: Jan 2015
Location: Adelaide
Posts: 256
Default

Quote:
Originally Posted by Ent View Post
One thing I am curious about is the rope strength required. 10mm rope is rated at 17,600lb breaking strain. Standard winch is 9,500lb so doubling the pull using a single block gives 19,000lb potential pull on the vehicle. Is that not above the breaking strain?

Friend on the SES was looking at some winch tables for recovering a vehicle and was rather amazed at the amount of pull required. I bogged DooSo to his bash plates in a bog hole and had to drag him up steep slope. We used a 1.6 tonne lift 3.2 tonne pull Tirfor and we "stalled". Using Maxitraxs and all difflocks we managed to drag him out but using a 9,500lb winch with block would by the sounds of it run the risk of breaking the rope.
The tension in the cable does not increase above the X Newtons of force applied by the winch. The multiplication occurs due to the multiple application of force X on the top vehicle by 3 cable attachment points.
__________________
MY14 GLX Pajero DID auto with Lift, 265/70 R17 MT51s, Full Bushskinz plates , Scotts Rods 3" TBE, Johnny Tig FMIC, TME ECU remap, Provent, OL Bullbar, Ironman 9500lbs winch, dual batteries, torque converter lockup, nomad valve body, aeroflow AF72-6000 transmission cooler with 9" fan and radiator cooler bypass, 3.15 reduction gears, traction contol mod (on/off), Uniden 8080S, flappy paddles, Rhino flat rack mounted on ARB rails, 42" Stedi ST3K light bar and custom drawers
Reply With Quote
  #14  
Old 05-06-17
Ent Ent is offline
Valued Member
 
Join Date: Apr 2014
Location: Tasmania
Posts: 1,591
Default

Just trying to my head around this. With a single block you move the vehicle half the distance for the length of rope. So torque is doubled, correct? That means if the winch stalls at 9500lbs then it is pulling 19,000lb of force with a single block.

Ok my head hurts. What you are saying is a strain gauge will still show 9,500lbs of force on the rope, and part of my brain agrees as the winch can not pull more the 9,500lb regardless the number of pulleys. But at the same time you are putting 19,000lbs of force to shift the vehicle.

My brain is stuck in loop. One side says you have doubled the pulling torque but the other is saying you can not increase the tension on the rope. So what am I missing?

Oh hang on I get it now. With a single pulley you actually have "two ropes" pulling 9500lb so one side of the pulley has two forces of 9,500lb and the pulley single attachment point has 19,000 lbs. Finally got there. The more attachment points the more the torque applied. So when tying pullies to a vehicle use different points to spread the load.
__________________
2014 PC Challenger, manual, factory tow-bar, factory front diff protector, TJM inter-cooler plate, Bushskinz manual transmission protection plate, ProRack S16 roof racks, front elocker, Drummond Motor Sport front struts, custom 16mm King rear springs with Bilstein Dampeners, Buzz Rack Runner 3 bike platform, Eclipse Nav head unit, GME TX3800BW UHF, 16x8 CSA Raptor rims, 265/75R16 Maxxis MT-762, orToyo AT/2 265/70R16 Triton rims, BFGoodrich 235/85/R16 Triton rims, or Factory tyres and rims.

Last edited by Ent; 05-06-17 at 10:00 PM.
Reply With Quote
  #15  
Old 05-06-17
old Jack's Avatar
old Jack old Jack is online now
Valued Member
 
Join Date: Jun 2011
Location: Adelaide
Posts: 6,708
Default

The force required to unbogging the car does not change regardless of a single, double or triple line pull. By using a multi line pull the load on the winch and on the cable/rope will be halved by a double line pull and reduced by 2/3's on a triple line pull. Also you get a similar reduction in amp draw but you are winching for a longer period as the recovery speed is also reduced by the same factors.
Using a different attachment point for each attachment is a a good practice or using a bridle as a central connection point.

OJ.
__________________
2011 PB Base White Auto, Smartbar, Cooper STMaxx LT235/85R-16,TPMS, HR TB, 3 x Bushskinz, front +40mm Dobinson , rear +50mm EHDVR Lovells, Dobinson MT struts and shockers, Peddars 5899 cone springs, Windcheater rack, GME UHF, Custom alloy drawer system inc. 30lt Engel & 2 x 30 AH LiFePo batteries + elec controls, Tailgate hi-lift/long struts, Nightbreaker +130LB & Phillips +100 HB, Lightforce 20" single row driving beam LED lightbar, Scanguage II.
MM4x4 Auto Mate, Serial No 1 .
Reply With Quote
  #16  
Old 05-06-17
twisted32 twisted32 is offline
Senior Member
 
Join Date: Jan 2015
Location: Adelaide
Posts: 256
Default

Quote:
Originally Posted by Ent View Post
Just trying to my head around this. With a single block you move the vehicle half the distance for the length of rope. So torque is doubled, correct? That means if the winch stalls at 9500lbs then it is pulling 19,000lb of force with a single block.

Ok my head hurts. What you are saying is a strain gauge will still show 9,500lbs of force on the rope, and part of my brain agrees as the winch can not pull more the 9,500lb regardless the number of pulleys. But at the same time you are putting 19,000lbs of force to shift the vehicle.

My brain is stuck in loop. One side says you have doubled the pulling torque but the other is saying you can not increase the tension on the rope. So what am I missing?

Oh hang on I get it now. With a single pulley you actually have "two ropes" pulling 9500lb so one side of the pulley has two forces of 9,500lb and the pulley single attachment point has 19,000 lbs. Finally got there. The more attachment points the more the torque applied. So when tying pullies to a vehicle use different points to spread the load.
Correct. If you put a force gauge in any leg/section of cable it would show X Newtons, if you put the same gauge between the pulley and its mount ie the car, it would show 2X Newtons
__________________
MY14 GLX Pajero DID auto with Lift, 265/70 R17 MT51s, Full Bushskinz plates , Scotts Rods 3" TBE, Johnny Tig FMIC, TME ECU remap, Provent, OL Bullbar, Ironman 9500lbs winch, dual batteries, torque converter lockup, nomad valve body, aeroflow AF72-6000 transmission cooler with 9" fan and radiator cooler bypass, 3.15 reduction gears, traction contol mod (on/off), Uniden 8080S, flappy paddles, Rhino flat rack mounted on ARB rails, 42" Stedi ST3K light bar and custom drawers
Reply With Quote
  #17  
Old 06-06-17
RoyHarvey RoyHarvey is offline
Senior Member
 
Join Date: Mar 2008
Location: Adelaide
Posts: 307
Default

Quote:
Originally Posted by twisted32 View Post
Correct. If you put a force gauge in any leg/section of cable it would show X Newtons, if you put the same gauge between the pulley and its mount ie the car, it would show 2X Newtons
Hmmmm...... Going to have to keep a lookout for a cable like that, must be a use for a cable that can be variably stressed along it's length.
__________________
2016 NX Pajero GLX
Prev....2002 NM petrol passed on to SIL
Reply With Quote
  #18  
Old 06-06-17
Kumabear Kumabear is offline
Valued Member
 
Join Date: Sep 2013
Location: Sydney, Macarther Region
Posts: 696
Default

I am not entirely sure I agree with the power draw comment.

While yes the total amount of energy expended to recover the vehicle will most certainly not change due to conservation of energy, the rate at which that energy is expended will be reduced in line with the net gain of mechanical advantage.

This is important because the charging system is much better able to keep up with a halved current draw for twice as long.

I love snatch blocks, saved my ass once when I got stuck hard enough to stall out my winch, which I was surprised by as it is a good 12000lb winch. Started to flatten the battery then it stalled, I got out and rigged up a 2 line pull and it just walked it out.
__________________
2011 MY12 NW Pajero GL (White)

Factory Rear Diff lock | Modded Traction Control | Hankook RT03 MT LT265/70/17 | Uniden 7760nb UHF | Opposite Lock 3 Loop steel bar with fog lights |Runva EXW12000 | Bushskinz plates and sliders |Ultimate Suspension true 50mm Lift (above factory trim)

Wishlist:
Reply With Quote
  #19  
Old 06-06-17
nj swb's Avatar
nj swb nj swb is online now
Resident
 
Join Date: Jun 2007
Location: Adelaide
Posts: 5,650
Default

Quote:
Originally Posted by RoyHarvey View Post
Hmmmm...... Going to have to keep a lookout for a cable like that, must be a use for a cable that can be variably stressed along it's length.
Have another read. Nothing has been said about the cable being "variably stressed".
__________________
NT Platinum. DiD Auto with 265/70R17 Toyo MT, Lift, Lockers, Lockup Mate, 3.15 gears, LRA Aux tank, bullbar, winch, lights, lots of touring stuff. Flappy paddles. MMCS is gone!

Project: NJ SWB. 285/75R16 ST Maxx, 2" OME suspension, 2" body lift, ARB 110, 120l tank, bullbar, scratches, no major dents. Fully engineered in SA. NW DiD & auto in place - a long way to go....

Scorpro Explorer Box
Reply With Quote
  #20  
Old 06-06-17
nj swb's Avatar
nj swb nj swb is online now
Resident
 
Join Date: Jun 2007
Location: Adelaide
Posts: 5,650
Default

Quote:
Originally Posted by Kumabear View Post
I am not entirely sure I agree with the power draw comment.
Which "power draw comment"?

Whether single, double or triple pull, if the stuck car is dragged the same distance using the same force on the stuck car then the winch has (nominally) done the same "work". If the double or triple line pull takes longer, then same work over longer time equals lower power.

Total energy drawn from the battery is a different matter. Lower power for longer can be same total energy consumption. Less current can be less resistive losses, so greater efficiency. Then, as you pointed out, winching for longer gives the alternator a better chance to keep up, so the battery should be in a higher state of charge when it's all over.
__________________
NT Platinum. DiD Auto with 265/70R17 Toyo MT, Lift, Lockers, Lockup Mate, 3.15 gears, LRA Aux tank, bullbar, winch, lights, lots of touring stuff. Flappy paddles. MMCS is gone!

Project: NJ SWB. 285/75R16 ST Maxx, 2" OME suspension, 2" body lift, ARB 110, 120l tank, bullbar, scratches, no major dents. Fully engineered in SA. NW DiD & auto in place - a long way to go....

Scorpro Explorer Box
Reply With Quote
Reply

Thread Tools
Display Modes

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Advanced Settings in MMCS v2 christish Generation 4-3 Pajero 14 31-07-14 06:24 PM
HH OBD Advanced Bluetooth doongle csimic Generation 4-2 Pajero 9 22-05-14 03:09 AM
Batteries winching and help lovespaj Generation 2 Pajero 7 06-03-13 05:47 PM
Winching Batteries ( Which ones) lovespaj Bolted on bits, factory and aftermarket accessories 12 06-03-13 05:37 PM
winching techniques Eastie General Info 3 12-12-08 07:47 AM


All times are GMT +10. The time now is 10:43 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.