Question about CMP winch?

[Grant Bowker]

There is no provision for a shear pin as such on the setup used in the 101" wheelbase. The front of the flexible coupling is keyed to the output shaft of the transfer case and the rear of the coupling has 4 bolts similar to a universal joint (probably the same bolt pattern on the input of all versions of the winch but this hasn't been checked in the parts manuals). From memory, I think the cross section of the bolts exceeds the key but the areas are close enough that it would depend on the materials of the two parts which failed first. Neither one counts as a user freindly, field replacement item like a real shear pin should be.

[hrpearce]

Hi Phil,
I don't know the rated pull of the winch but when I got my blitz it was set up for log snigging. It's got a heavy 4" box section welded across the back of the chassis to back it up to a tree to ancre it. My Father in law said that if you used scotches and a log snaged the U bolts holding the axle on snaped.
The winch on mine was mounted above the chassis and geared down 2 to 1and even having double the engine power going to the winch the engine stalled before you reached the capasity of bolts or keys.

[Bob Carriere]

Hi Phil

Can't put my finger on it but I have references to 14000 pounds for the winch.

Now if the set up on my truck is correct the gear selection affects the speed an power of the winch..... in other words 4 speed forward when retrieving and one reverse when powering the rope off the drum.

I suspect that with the engine in high 4th gear at idle.... you would stall the 82 HP engine before shearing anything.

My expereince with winches is limited tot he Dodge M37 which conveniently blew a shear pin everytime the sucker was buried in deep mud..... installing a new pin meant digging a hole.... that filled with water/mud....... an laying on your back to replace the pin. Being ingenious and stupid we replaced our soft pins made of cheap 4 inch nails with concrete nails..... voila!!!!

When skidding heavy large dead elms the weigth of the tree trunk would pull the Dodge forward even with all four wheels locked.... so I would let it roll until I could rest the front bumper on a suitable stump..... push the gas..... and the screw drive held by 4 bolts on the face of the winch where the drive shaft would go in...... actually sheared and pulled itself out of the winch bending the small drive haft...... a visit to the junk yard for the parts set me back $350 for part of the truck I had purchased for $700...... was more carefull after that.

I am sure that nay heavy winching would have included tying the front of the truck's D rings onto something of substance. You are correct in making sure the end chain, hook, ect. is on par to the full potential of the winch.

When working with the Dodge we very seldomed used any engine speed above idle and still managed to pull other civilian 4x4 Blazers, etc. without any hesitation.

I would suggest getting/using a surplus deuce winch chains set for the CMP as they are probably readily available in the states.

How much cable could you safely wind up on the winch drum...?

Bob

[Keith Orpin]

Guys,
I've just been though my reference books and various manuals, and the plot thickens !
If you reference the early manuals, (and to be honest there is very little mentioned) they suggest 125ft of 5/8" cable should be used. However, if you refer to the MBC2 manual, it states that 125ft of 11/16" cable should be used, giving a figure of 14500 lbs as the winch capacity, little wonder Phil that your C60 was being dragged backwards !
Like Bob, I thought I had seen reference to 14000 lbs somewhere else, but so far this is the only evidence I have found.
As for a shear pin, I can find no mention of one, in any of the parts books or manuals, nor do I remember finding one when I rebuilt my Chevy.
Keep looking guys
Regards
Keith

[Phil Waterman]

Hi Keith and Everybody

You are correct in that the manual calls for 11/16th cable but as that is not readily available, I went with 5/8ths whats a 1/16th among friends.

Where did you find the figure of 14,500 lbs this is what I have not been able to find.

My reasons for asking these questions is that I know how much energy can be stored in a steel cable. Does anybody have a strength figure for 1941 11/16th cable as compared to modern cable?

Not with the winch but in the past I have seen what happens when you start loading steel cables near to breaking. I've shared the picture below the result of trying to pull a 4,000lb truck out of a snow bank with a 11,000 lb CMP the with a tow cable rated at 6000 lbs math just doesn't work, but the cable didn't break.

I'm really trying to figure out how to load limit the winch and attachments to something less than breaking strength.

The Ice Storm of 2009 has left me with a lot of broken and dieing trees that I want to snake out with out cutting truck sized holes around the house. Also I don't want to end up wearing a chunk of cable, or chain.

From the load in the truck you can see what I'm up to.

[Bob Carriere]

I know you like playing with the big truck like a big boy...... but it would be safer and simpler to buy a 8000 pound modern electric winch ...... cable is much lighter to use.....use a snatch block to double the pulling power or do angle pulling...... beauty is it will stall if over loaded... long before a good cable will break.

will look again for reference to winch capacity.

Boob

[Lynn Eades]

Surely you must be able to purchase something you can inlude in your rig, an element, with a known failure rate, or measues the load. Something in your rope behind the hook, that gives you a load measurement, regardless of how many layers of rope are on the drum.