Winch mount

Rotazuk · Post by **Rotazuk** » Tue Jul 12, 2005 10:38 pm

Ok so the winch turned up today , cool . Started to think about mounting it . How many of you have wiches mounted with the bolts in tesion ( bolts for and aft ) as oposed to sheer ( bolts up and down ) ?

Sheer should be stronger but my instructions ( yes I read them ) imply either way . In tension is easier from me , in sheer is possible with a bit of work .

Cheers
Chris

mumad · Post by **mumad** » Wed Jul 13, 2005 5:43 pm

I would say which ever way is easiest, as long as you can get as many bolts as possible in. I would recommend 3 12mm hi-tensile bolts minimum per side for the chassis mounts, and the winch itself, as many as possible, better to be too strong than too weak and break!!

tristanp · Post by **tristanp** » Wed Jul 13, 2005 6:32 pm

im just wondering if the direction of mount (and the direction of pull) has more to do with stressing the casing on the winch than anything else.
sheer load on bolts is much higher than the pulling load
in a pull load the threads are doing all the work, in a sheer situation the threads just hold it in place while the shaft diamater takes the load

padero · Post by **padero** » Wed Jul 13, 2005 6:37 pm

hi, i just mounted a winch to my pajero. me and mike just made a plate up with 3 hole either side through the chassis and mounted the winch on top. with stright up and down bolts nice and easy + very strong.
the plate is about 10mm thick from the underside of a jet boat of all places lol

if want some pic's im willing to email you some jsut let me know your addy

ad

Rotazuk · Post by **Rotazuk** » Wed Jul 13, 2005 6:43 pm

Hi
Mounting the plate its on to the chassis is not a worry , all bolts in sheer there .
Winch inst say a 6mm plate to bolt the winch to but I don't think the supplied bolts are long enought to mount it to a 6mm plate :-)

. Not an issue .
But its the four bolts that mount the winch to the plate that I am wondering about . They come with squre nuts that sit in the winch bearing castings . Other winches are mounted the same way So wondering what the consensus is .

Cheers
Chris

padero · Post by **padero** » Wed Jul 13, 2005 8:45 pm

what winch have you got ?? i got a ep9i superwinch and the bolts that came with it fitted throu 10mm plate..

hey they must be strong enuff or else they wouldnt use them

Rotazuk · Post by **Rotazuk** » Wed Jul 13, 2005 10:01 pm

I got one of the winches of Steve . Will do the trick for the odd time I take the rangie out .
Agree the bolts will do , no question in sheer just doubting in tension .

Guess there is only one way to find out .

Cheers
Chris

Post by **mike** » Wed Jul 13, 2005 10:02 pm

Generally it shouldnt be the bolts shear that stop it moving its the pressure applied from the bolts on the mating surfaces causing friction. If that is to loose then the clearence is taken up in the holes with an audible clicking sound on recovery. Of course this won't be the case when pulling on the threads. Just a bit of useless info for you :wink:

Mike

Rotazuk · Post by **Rotazuk** » Wed Jul 13, 2005 10:11 pm

This would then imply it can only be in sheer :-(

Will have to ask the engineers at work what the strength of a 8.8 bolt in tension is .

Chris

Post by **mike** » Wed Jul 13, 2005 10:29 pm

Don't take my word for it though

, Just years of clamping things down on large machines and noting what you can get away with and what happens when you don't :shock:

Mike

Rotazuk · Post by **Rotazuk** » Wed Jul 13, 2005 10:43 pm

See this is what surfing the net does for you .
Grage 8.8 bolt and nut has a tensile strenght of 120,000 psi .
Bolts are 3/8" so dia is .375 . Now area = Pi *r sq . so .1875*.1875 = .03515625 now * Pi = 0.110461

So 120,000 * .110461 = 13255 pounds . If I have 4 bolts and the winch can only pull 12000lbs I have a safty factor of over 4 :-)

I get the feeling my maths are wrong but will look at it in the daylight tomorrow and see what I get then

Chris

mumad · Post by **mumad** » Thu Jul 14, 2005 6:59 pm

You are no the right track, just think how much pain goes on your tow hooks and there is only 2 bolts, if you follow the instructions and your mount is strong enough, then i can't see anything wrong with the bolts it tension, especially 4 12mm grade 8.8's.

hiriklux · Post by **hiriklux** » Thu Jul 14, 2005 8:12 pm

just another thought :idea:

for a nut and bolt to work properly you must have 6 threads past the nut so my engineer mate tells me :shock:

make any sense????

SupraLux · Post by **SupraLux** » Thu Jul 14, 2005 9:57 pm

I was told by an engineer who did a study on thread strength at university that only the first three turns of the thread in a nut actually do any work...

Who do you believe? I tend to go up a size and use the strongest bolt I can... if it says M10 8.8 I use an M12 Capscrew (think they work out to about grade 11 or thereabouts).

I love overengineering

Steve

mumad · Post by **mumad** » Fri Jul 15, 2005 4:32 pm

I have been told that you should have at least 3 threads past the nut, and also that it is not a good idea to use bolts that have a tensile strength greater than 10 or 10.5 as any harder than this the bolts are brittle and have no give, so if they get a hard jerk they may break, which is why i use 8.8's. Cap screws are usually about grade 14 i think, but that's just what Ive been told by the head desiginer at the engineering company i work for. Thats my 2 cents anyway.

hiriklux · Post by **hiriklux** » Fri Jul 15, 2005 7:56 pm

aaah the joys of nuts and bolts :lol:

it was so easy with the meccano set if it didn't fit bend it lol!!!!!!!!!!!!!!!!!!!!

mumad · Post by **mumad** » Fri Jul 15, 2005 8:04 pm

aaaah the joys of having a 130 ton brake press and a 50 ton single ram press, if it don't fit, bend it, if it still don't fit then get the plasma :twisted: