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Winching manual.


 
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Joined: 30 Dec 2007
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Location: Cornwall

PostPosted: Wed Jan 23, 2008 14:26    Post subject: Winching manual. Reply with quote

Hope this doesnt kill the server!  Shocked

The Winching Manual


A winch is basically a drum onto which a rope is wound with a device to stop the rope unwinding until required to do so. A basic hand winch employs the handle as motive power and a ratchet to stop the rope unwinding.

Modern winches come in varying types, but in the 4x4 world you will most likely come across the two main ones. Electric and hydraulic (PTO). Electric are powered through the battery on the vehicle, a PTO or Power Take Off, use power from the vehicles’ engine through a separate gearbox, If driven whilst the PTO is engaged untold damage will occur! . Most are powered through planetary drives or through worm drives, and have a clutch or dog clutch in place of the ratchet.

Associated with the winch and rope is the roller fairlead. A fairlead is a device that the rope passes through to enable it to lay on the drum correctly. A fairlead MUST NOT be used for pulling at an angle!

The strength of a winch is decided by the manufacturer as it depends on the diameter of the drum, and the size of the motor. Most winches have a thermal or current overload device which will stop the winch should its load be too high. This prevents the mounts of the winch being torn out whilst winching. It is therefore VERY important to have your rope and winch matched correctly. A higher strain rope on a weaker winch will inhibit the cut out from working. It must also be noted that by changing the diameter of the rope, will lessen the safe working load of the winch. This is due to the number of lays that the winch is designed for will be less. When renewing rope change like for like, and ensure you have the correct handed rope!!

Ropes come in various sizes, and either left or right handed. Even some suppliers are not always aware of that surprisingly! Quick way to find out, is lay your hand palm up. If the rope lays in the direction of your thumb on the left hand, its left handed, the opposite hand for right! Doesn’t sound very important, but ever seen a winch cable that ‘spirals’ and coils as its unwound? This is very difficult to use and is cause by a right hand cable on a left handed drum or vice versa.  Wire ropes are heavier but more robust than synthetics, but must be regularly checked for stretching, kinks, broken core strands and fatigue. Synthetic ropes are not recommended for main use as they are severely affected by acids, alkalines others by solvents, and none can withstand heat!

A rope should always be laid neatly on the drum. This will prevent damage to the wire and keep the drums’ capacity as stated. A loosely wound drum, or birds nest, will not only become jammed, but also very dangerous causing jerks and unnecessary strain on the rope. A winch is at its maximum pull when 4 lays (rotations) are on the drum. This is also the minimum that should stay on the drum. Never use the full length of the rope!!


Always mount a winch on a chassis mounted winch plate. A winch is only as strong as its mount! Bumpers are often just not man enough to take the vehicles weight and more!          THAT’S’ THE BORING BIT OVER!!  (PHEW!!)
ALWAYS try to winch in a straight line! Winches pull straight to themselves. If this is not possible, use a snatch block or ground anchor. These will enable you to winch at angles. NEVER wrap a winch cable around the casualty vehicle, use a suitable strap and attach the hook to that. Winch rope must never be bent as this will damage to rope and core causing kinking and fatigue.

                 Resistance to winching

Winching a vehicle requires power from the winch, and in order to make an educated guess at what power will be required, we take three main factors into account.

1. The surface it is resting on (rolling resistance)

2. The condition of the vehicle (damage resistance)

3. How much slope has to be overcome (gradient resistance)

Rolling resistance

Divide the weight of the casualty by the following values;

Smooth Road          25
Grass        7 – 4
Gravel        7 – 5
Beach Shingle        3
Sand        6 – 2
Mud        3 – 2
Soft Clay       2

Multiply  the weight of the casualty by the following values;

Bogged to axles weight
Bogged to top of wheels 2
Bogged to top of bonnet 3


To give an example; Lets just say that a 1500kg truck has lost its front wheels on a level hard surface. To assess what winch power is needed, you need to calculate its DAMAGE RESISTANCE.

Damage Resistance = weight of casualty                               (1500kg)
Multiplied by number of damaged wheels (2)     (3000kg)
Divided by total number of wheels (4) (750kg)

So the power the winch would require to drag that vehicle would be 750kg. The weight of the vehicle divided by two!

Just one more quick one to demonstrate Gradient resistance which must of us come across off road!

                                                Gradient Resistance

Pulling a vehicle up a slope will require extra effort. The rule here is that for every degree of the slope add one sixtieth of the weight of the vehicle. In other words, weight of the vehicle divided by sixty multiply by the slope in degrees!

Sounds complicated but you don’t have to be totally accurate, and you will get used to judging angles. To help a little, a 1;10 hill, is only about 6 degrees. 45 degrees is about the steepest you would try to get up and that 1;1. 1;2 is 30, and 1;3 is about 20. If steeper than 45 degrees, call it total weight of the vehicle.

For example, a 4x4 weighing 1500kg with a broken front axle, stuck in mud at a slope of 30 degrees would need the pull of;

Rolling resistance ; 1500 divided by 2 = 750kg

Damage resistance;  1500 x 2 divided 4 =750kg

Gradient resistance;  1500 x 30 divided 60 =750kg

Total Pull from winch =2250KG

This just emphasises that say you hand a small two ton winch for a one and half ton vehicle, the situation here would leave you in trouble! You may think that you can get it out but you wouldn’t have the power!


There are ways that you can overcome this with the use of snatch blocks, ground anchors or a dead man. (thats’ a vehicle used as an anchor point – not a corpse!)

There are two types of snatch, a block type typically with a large hook on one end. Or the other quite common is the palm snatch. This is pretty flat and has a large hole one end. This open by simply twisting, the block type has a screw handle.

Both have their uses, a palm is fine for smaller vehicles, but has an inherent design fault in the fact that they suffer from fatigue due to mixed metals! The casing is steel, the roller is aluminium. The winch rope is also usually steel. This means that the snatch is often corroded by its steel shell, and damaged by the rope. Look for pitting of the roller, and movement. This will cause failure.

The block type is heavier but more reliable and suffers no real fatigue problems. It pays to have both in your kit as they are both very useful.

You can use as many ‘lay ups’ or ‘double ups’ as you like, or have to equipment for. I will stick to single rope lay ups as this will more commonly be used, as is less confusing (like you’re not already!) When laying up you take your rope, an attach it to a ground anchor being that your vehicle, a tree or a dead man (second vehicle parked next to you) KEEP THE ROPE AS PARALLEL AS POSSIBLE. Anything over or near 45 degrees you will lose the pull!
Setting your winch to freespool, pull out and put through the snatch block. Go to the casualty vehicle and attach via a suitable rated strap or tow point. The rope should leave your winch, go to the casualty and return to the anchor point.

Check that you have AT LEAST four lays of cable on your drum! You now have the capacity to pull DOUBLE the amount of weight.

Some quick rules of the road! Lol!

1. Never straddled the winch rope whilst winching. They are under tension and you will get hurt!

2. Always wear gloves! Wire winches can have stray wires that will cut, synthetics can burn!

3. Use a winch blanket, a jacket, or similar to protect from recoil if the rope should snap – if it does it will go sideways and whip back!

4. Never stand next to a winch cable in use or under tension.

5. Never bent the cable without snatch blocks

6. Never use any damaged cable or equipment – check regularly!

7. ALWAYS lay a cable on the drum correctly. Level and tight.

8. Never use the fairlead at an angle.

9. Always leave 4 lays (turns) of rope on your drum.

10. Always assess the power required before winching.

11. Never stop whilst winching up a slope. Keep it smooth gentle and moving!


Hooks, shackles etc are cast and must be checked for straightness, make sure the pin screws all the way in, and it is not fatigued. Rest the shackle on the tip of your finger with pin in the other hand. Gently tap with the pin. It should have a long high pitched ring. If not it is flawed! Throw away!

Chains must be checked for stretching (elongated) Strain (hour glass shape to rings) and generally fatigue and cracking. Renew if any are apparent!

This should keep you and others safe! I have tried to make it brief as possible, whilst covering everything a total novice, to someone with experience can understand so if some things are not clear I apologise! I have not included pics to keep space down on the site. If you have questions just ask!
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PostPosted: Wed Jan 23, 2008 14:26    Post subject: Google Ads keep this community free to join!


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PostPosted: Wed Jan 23, 2008 14:46    Post subject: Reply with quote

BRILLIANT Very HappyVery HappyVery Happy Really well written... Never knew about now winching off the fairlead's...

Can we have as sticky please?
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666
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PostPosted: Fri Feb 01, 2008 10:31    Post subject: Re: Winching manual. Reply with quote

While your guide is very well written and simple to understand, i feel i must point out one thing

auto wrote:

11.Never stop whilst winching up a slope. Keep it smooth gentle and moving!


While this quote is true for hydraulic winches and winches with PTO systems it is not generally true for an electric winch! An electric winch is not designed for continuous use under extreme loads, as this could kill a battery that has not got much life left in it and could also result in a burnt out motor! It would only be able to cope uphill if the load was a rolling load on a fairly hard surface, not if you were dragging it up a hill through 2 ft of mud/clay

Any electric winch should never be used continuously while under extreme load!! (Check the warnings on your winch)

The Warn winch gude Here

Cheers

Mark
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Now running an Isuzu 2.8TD

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auto
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Location: Cornwall

PostPosted: Sun Feb 03, 2008 0:49    Post subject: Reply with quote

Agree to disagree on that one! Purely due to physics!

You use 60 percent MORE POWER to pull from standstill up a slope. You use momentum to keep you going. Winches do not have brakes, only a clutch and it is far better to allow the winch you get hot than to strain its motor and burn it out starting again. Thats not the only problem, as doing this causes fatigue in the rope. It puts vast strain on it. You really need to keep it steady. keep it safe!!  It has a thermal cut out, if it cuts out, it does! Until then keep winching for your maximum 10 mins, then allow the 20 mins cool down. This applies more to electric winches than any other as they have less power and overheat faster!!

The vehicle will weigh far more half up a slope than it will when its moving! In truth, you shouldn't need more time than that!

If you were working in two feet of clay up a hill, then you would have to snatch a few lays, in which case it wouldn't overheat. Bear these things in mind when buying a winch.....if these are the situations you are likely to encounter, buy a heavier duty version. At the end of the day, its up to the person winching to work out the odds. The manufactuers guides are usually 'on the safe side' - it makes their winches more reliable! If a winch is under-used it lasts longer, which means it sells more! If you are not sure of a winches ability - dont buy it!
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666
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PostPosted: Sun Feb 17, 2008 13:31    Post subject: Reply with quote

Yep

Guess we will have to Agree to disagree Laughing  Laughing  Laughing  Wink

auto wrote:
Winches do not have brakes, only a clutch and it is far better to allow the winch you get hot than to strain its motor and burn it out starting again.


Most electric winches have brakes built in to the drum that work when the motor stops the weight that is being pulled applies preassure against the motor spindle in the opposite direction of the direction the motor was pulling, this causes the brakes to be applied via a cam on the end of the spindle close to the motor, it is worth stripping down a winch that has been dunked in the sticky stuff and clean all the dirt out of the brakes as this can cause them to bind and make the free spool operation very difficult  

this link will take you to a Warn site and shows exploded diagrams of a few winches all with brakes in the drum. these are very similar to the brakes fitted to both of the winches fitted to my truck.

Also below is part of the user manual for my winch, and if you read the second line it does clearly state "WARNING - Intermitent use only." This i believe is the norm for winches with the electric motors on the end of the drum but does not necceserily apply to winches with worm drive such as the Warn 8274




Cheers

Mark
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Now running an Isuzu 2.8TD

Mac Challenge 2009 Team 01
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PostPosted: Wed Sep 10, 2008 9:10    Post subject: Reply with quote

For anyone who does use a winch it might be worth having a look at this thread showing what happens to a winch motor when the brakes fail.  It goes to prove that learning to strip down and clean all the moving parts and the brake blocks can save on some expensive repairs/replacements and possibly injury or death Wink

Cheers

Mark
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Now running an Isuzu 2.8TD

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