The A-frame kit (hoist) for M35-let's talk about it

[Jakob]

How do you get a forklift home though? They aren't the lightest things on the planet.

 

[clinto]

Update:

I have been putting this off for a while, for a # of reasons and finally decided to get serious about it.

I did not want to use a towbar, because I wanted to make my a-frame modular, so you could adjust the height as necessary and make it a little taller.......

So I figured the best thing to do would be to mimic a medium towbar in terms of diameters and wall thickness. I say this because I am not a mechanical engineer and overdoing it would allow me a degree of safety margin.

So I go out and measure my medium towbar and it is about 2.9" OD and roughly 1/4" wall thickness.

I was discussing this with a friend of mine, asking him what steel pipe would cost (because I am not a fabricator and don't know prices) and he sent me the link for this website:

http://www.metalsdepot.com/

I see they have 2 kinds of steel pipe:

"Steel Structural Pipe"
WORKABILITY - Excellent for Welding, Drilling, Machining, Threading, Sawing, & Forming by means of machine or special fixture
APPLICATIONS - Fences, Frames, Structures, Truck Racks, Ornamental Work, Railings, Transferring of low pressure liquids, Etc.


"Steel Round Tube"
WORKABILITY - Drawn Over Mandrel is a cold drawn electric resistance welded tube with all flash removed. Compared to structural pipe, DOM Round Tubing is produced to more exact OD and ID tolerances and better finishes without a seam. Ideally suited for a wide range of structural and bushing applications. Widely used in stressful applications requiring higher quality, uniformity, strength, and soundness.
APPLICATIONS - Farm implements, construction equipment, racecar frames, motorcycle frames, automotive parts, off-road accessories, etc

To me, it seems steel round tube is the way to fly. But an 8' section of 3" OD, 1/4" wall thickness, 2.5" ID pipe is $271!!!!!!

Now, if you go to the Structural Steel Pipe, then a 2 7/8" OD, SCH 40 (2.875 OD X .203 wall) 8' long section is only $121.


That is still $500 of steel (4 pieces, inner & outer), plus the 1/2" wire rope to go back to the pintle, plus cable clamps and the various pins, clips, etc. you will need to finish it. I figure at the cheapest, that's $750.



Alright, let's have it guys. There are some pretty smart fellas here, let's hear thoughts & opinions. Am I using (pricing) the wrong stuff? Is there a better deal on steel to be had out there?

 

[gimpyrobb]

Clinto, the tow bars are made of tubing and rated at about 40,000 lbs. I think you could get away with using pipe for lesser loads.

 

[Jakob]

Clinto, the tow bars are made of tubing and rated at about 40,000 lbs. I think you could get away with using pipe for lesser loads.

Stretching loads are different than bending loads. Those my not be technical terms, but I'd be a little concerned using pipe for an A-frame. I'm no engineer either, so maybe I'm over reacting?

 

[gimpyrobb]

I don't see bending coming into play here. I wish I could remeber more of my tensions and stresses course, I think only compression applies to the pipe since it would be on a pivot point. The wire rope going to the pintle would have the tension on it.

 

[notso]

Any idea on how long you guys want to make the frame? The calculations are not that hard to find the size pipe needed

 

[m16ty]

I check around at the local scrap yard or a fap shop. I'd think finding a piece of used pipe wouldn't be that hard. Could pobally get it for a little over scrap price. If you go the new route and buy it from one of the on-line stores shipping is going to kill you on top of the high price of new steel. I've got a big selection of used pipe and tube of all sizes and length that I'd sell cheap but shipping is still going to kill you.

The towbar is rated a 40,000# but your a-frame is going to be longer so the ratings will change. That being said, I still think it would be strong enough because the load will be pushing stright down on it tward the bumper. A small piece of pipe will hold alot of load in this application. You din't want to build it so heavy you have to get another truck with a a-frame to put your a-frame on .

 

[Floridianson]

Just don't lower a whale down a well.
CAUTION
Do not use front winch to pay out line loads greater than 3,000 lb
(1,362 kg) for any distance greater than 10 ft (3. 1 m). Damage to
equipment may result. TM-9-2320-209-34-2-3

 

[Recovry4x4]

FWIW, I've used my towbar as an a frame before.

 

[Jakob]

Just don't lower a whale down a well.
CAUTION
Do not use front winch to pay out line loads greater than 3,000 lb
(1,362 kg) for any distance greater than 10 ft (3. 1 m). Damage to
equipment may result. TM-9-2320-209-34-2-3

I don't have my TM handy (it's in the truck), can you expand on what that means?

 

[m16ty]

Just don't lower a whale down a well.
CAUTION
Do not use front winch to pay out line loads greater than 3,000 lb
(1,362 kg) for any distance greater than 10 ft (3. 1 m). Damage to
equipment may result. TM-9-2320-209-34-2-3

I don't have my TM handy (it's in the truck), can you expand on what that means?

Just what it says. 3,000# max on the a-frame, no further out than 10' in front of the truck or things will start to break like the bumper, frame, etc. The a-frame will place a great load on the front of the truck with 3,000# hanging 10' in front of the truck.

 

[gimpyrobb]

Yeah, talk about axle overload!

 

[Jakob]

Just don't lower a whale down a well.
CAUTION
Do not use front winch to pay out line loads greater than 3,000 lb
(1,362 kg) for any distance greater than 10 ft (3. 1 m). Damage to
equipment may result. TM-9-2320-209-34-2-3

I don't have my TM handy (it's in the truck), can you expand on what that means?

Just what it says. 3,000# max on the a-frame, no further out than 10' in front of the truck or things will start to break like the bumper, frame, etc. The a-frame will place a great load on the front of the truck with 3,000# hanging 10' in front of the truck.

For some reason that just wasn't registering right in my head. It's clear now though. I wouldn't have any need to lift anything that far out, or high, anyway. I might make a 4 foot bar or so, on top of the bumper, that'd be more than I'd ever need.

 

[Lorax]

Speaking as a mechanical engineer, the wire rope going back to the pintle will be in tension, the towbar/pipe/whatever the uprights are made from will ONLY be in compression, assuming the pipe is attached as a pivot at the lifting shackles on the bumper. If the uprights are slipped thru the lifting shackles, and "wedged" against the shackle brackets, then bending may come into play. Just make sure the pipe is attached to the lifting shackle or lifting shackle brackets in a way that allows the pipe to pivot, then there won't be any torque on the pipe, only compression.

As an example, if you attach the pipe to the shackles, tilt them to whatever angle you want them to be at, let them go and they stay pointed towards the sky (without the wire rope attached), then they will have torque (bending) stress on them...not good. Attach the pipe so that if you point it towards the sky, then release the pipe(s) they fall back onto the ground, pivoting on the lifting shackles.

Clinto, in your picture above, the cross member at the top of your rig DOES have combined stresses (tension, compression, shear, Von Mises, etc). Also, it looks like the wire rope is slack, which means the uprights are supporting themselves inside the lifting shackles. If you lift that crate without tightening the wire rope you're running the risk of buckling the uprights inside the shackles. Tighten the wire rope until it has pulled back on the uprights some.

 

[gringeltaube]

...... or things will start to break like the bumper, frame, etc. ....

I don't think that the frame or bumper would be the weak link here but I've found a tendency for the stamped frame extensions to bend downwards, as well as cracks to the lower rear portion of the (stamped) winch brackets. See pics.
3000 lbs @ 10' is definitely a lot of leverage!

G.

 

[Floridianson]

You can look at the sticky the Emmado22 posted on winch use and they don't show a A frame. I took it as just not to pay out load more than ten feet. My guess the automatic brake is going to be getting hot. My fear would be that we tighten the brake down tight enough to hold load then we start driving around and load starts to bounce this is going to change load , brake slips and we just hope no one is hurt. The lack of ability to change the brake ( if u can call it that ) on demand is the only weak point I really see. I know when in service many thing were done with the winch and A frame but when the bad happens with them seems like as long as no one was hurt then just order up some new parts and keep on getting up. I don't know if I trust the winch brake to do heavy work where people,fingers and toes were a concern.

Put a load (1) on end of cable (2)
Raise load (1) with winch, then stop winch. Refer to
TM 9-2320-209-10. Winch must hold load.
If winch does not hold weight (1), tighten adjusting screw (5)
1/2 turn.
Do steps 2 through 6 again until winch holds load (1).
If automatic brake overheats, loosen brake adjusting screw (5)
1/2 turn.

 

[vinny-socom1]

good old post!!!!


Vinny

 

[jesusgatos]

Good thread. It's got me thinking that I ought to build an A-frame by extending a towbar so that I'll have both with me, in case I need either. Would a 'medium' towbar be the best one to use?

 

[jesusgatos]

Finally found a nice towbar. Found this old thread while I was searching for info about chain hoists. I'm trying to figure out how to swap an LDS into Mah Deuce and I'm wishing there was some way I could use an A-frame to do it, but that sounds a bit like operating on yourself.

 

[RangerDave]

I just noticed a thread about "A" frames... I was wondering what the hunk of "A" shaped steel in the back yard was..... Hmmmm... Must investigate! I think I have a picture here, but if not I'll try and get one tomorrow before it gets snowed over again!!! What is really cool about ours is that it is built really heavy and has a roller fairlead assembly like a small logging skidder. Looked military, but who knows. We salvaged it from the old guy that had trained the guy who is training me about welding, fabrication and heavy mechanics...