M923 Knuckleboom Speculation

[nf6x]

Inspired by the various knuckleboom deuces and similar trucks that SS members have created, I have idly dreamt for many years about replacing my tired M543A2 wrecker with a knuckleboom crane mounted on a 900-series truck. That just sounds like a wonderful combination to me. My wrecker has been a wonderful yard crane, but it seems to me that a knuckleboom crane would add a whole new level of versatility and FUN!

A really nice-looking M923 came up in a GL auction that ended last Thursday, and I got the winning bid. It's a 1984 truck that appears to have been overhauled in 2009, with only 27 more miles on the odometer since the overhaul. It appears to have the ABS MWO, too. I'm really excited about picking it up! And now that I'm adding an M923 to my collection, it's time for me to begin seriously considering a knuckleboom conversion!

My budget won't allow me to just drive down to Joe's Knucklebooms and Coffee (a wonderful shop that exists only in my mind) and buy a brand new knuckleboom, so I expect that I'll be scouring eBay, Craigslist and the SS classifieds for a long time before I find the right crane at the right location and cost. I don't have hands-on experience with using, buying or installing knucklebooms, so I'd like to pick folks' brains to learn more about them and to get some inspiration about how to do the conversion on my new truck.

First of all, let me explain my minimum requirements. I'm setting the bar for minimum capability based on the standard that whatever I end up with needs to be able to load and unload the commo shelter on my HMMWV, much as I can with my wrecker. So, it'll need to lift over a ton (call it two tons for margin) at 10 feet from the side of the truck, with the hook at least 18 feet over the ground at maximum lift. Then, it'll need to move the load about 10 feet parallel to the truck. My wrecker handles that maneuver pretty handily. If I can do the same thing with a knuckleboom while operating the controls from ground level, that'll be an improvement, since one of the most common headaches I work around when using my wrecker is the need to be up on the wrecker to operate the controls, often resorting to using a rope to rotate the load while it's in the air.

So with that in mind, I'd like to learn more about what sorts of knucklebooms I need to look for. What range of load capacities and sizes are likely to be a good match for a behind-cab installation on an M923? Are there any specific brands, styles or models to prefer or avoid? Are there any specific features that I should look for? How much might I need to be prepared to spend if I expect to spend 6-12 months looking for the right deal?

Once I find a suitable knuckleboom, I'll need to plan my installation. Does anybody have any advice about how to handle the bed modification/replacement? It seems to me that my options include sliding the existing bed back about 2 feet, cutting and re-welding the existing bed to make it a couple feet shorter (I don't know if that lies within my capabilities), or swapping out the bed... possibly with the bed off my M35A2C. I've also speculated about putting a crane in the bed, with cutouts in the floor for the outriggers. I don't know if that's actually practical, though. I can foresee advantages and disadvantages with each of those approaches, so I'd welcome some opinions on the matter.

To further muddy the waters, I have an S280-equivalent commo shelter that fits a 12' deuce bed. I'm contemplating the possibility of dropping it into the bed of the converted truck, but that may not be a good idea if the shelter would interfere with the crane's movement too much. I'm also not sure whether I'd end up with a knuckleboom that's suitable for loading and unloading that large shelter, presumably with a lot of headroom for the necessary lifting sling.

I'm attaching GL pics of my new M923, and pics of my M35A2C that might become a bed donor. The M923 looks like it has the troop seats but no cargo bows. I have a set of bows for my M35A2C, but no troop seats. I'm throwing in a picture of my wrecker a-wrecking just because I love y'all so much. Sadly, I never took any pictures of my S250 shelter suspended by my wrecker.

So, what do y'all think about my nutty ideas? Can anybody offer some edutainment on this?

 

[Stonepicker1]

I plan on doing the same thing to my M923 when I find the time.

 

[Stonepicker1]

More info on my crane.

 

[nf6x]

That crane looks beautiful! If I understand the load curves properly, it would do everything I need and much more, in any of the boom sizes shown in the pamphlet. I'm looking forward to reading about your installation! Do you mind sharing how much it cost you? It looks like NOS government surplus.

 

[Lawrence of Arabia]

I have an M816 wrecker and an M923 Cargo. I love both of the trucks, but putting a Pal Finger on my M923 would eliminate the need for 2 trucks. The wrecker is just so impractical. It is worth it's weight in gold for what I need it to do, but a knuckle boom would serve me better. I repair them for a living, but have yet to stumble across one that a customer wants to aprt with.

 

[nf6x]

The wrecker is just so impractical. It is worth it's weight in gold for what I need it to do, but a knuckle boom would serve me better.

That's exactly what I think about my M543A2. It looks awesome, it's fun to play with, and it has served me well for many lifts. It's also a pain to keep climbing down from the truck to handle the load and back up to operate the controls. And for this non-athletic guy who sits in front of a computer all day, handling those manual outriggers is such a pain that I just avoid doing any lifts that require them. I love my wrecker, but I think I'd love a knuckleboom a lot more!

 

[nf6x]

P.S.: Also, there's very little on my wrecker that doesn't need fixing... I think that installing a knuckleboom on a well-running truck will be less work, even if I need to fire up my welding torch!

 

[m16ty]

Anybody have anything to add to this thread? I'm thinking about putting a knuckleboom crane behind the cab of my M932. I'd use it for general lifting duties but would also like some sort of grapple on it.

I've had several people in the past wanting me to pick up scrap iron and such but it's small pieces that just isn't economical to load with a forklift or by hand. I figure I could use the knuckleboom and grapple to load this stuff onto a trailer I'm pulling. I could also use it in the building demo I sometimes do.

I've also thought about some sort of clam bucket. That way I could load gravel,sand,and such.

 

[quickfarms]

This is a great idea but you may have to register it as a commercial vehicle.

 

[Derrickl112]

Subscribed.

 

[m16ty]

This is a great idea but you may have to register it as a commercial vehicle.

It already is.

 

[Derrickl112]

My grove crane has a remote with a 30' cable.

 

[nridr124]

i am currently building the same concept knuckleboom behind cab of a m923 that was overhauled oct 2010 however they didnt put the motor together corectly and keep getting antifreeze in the oil so im swaping it for a used nhc250 or would like to put a 400in it but dont see that hapening anytime soon will post pics

 

[nridr124]

my knuckle boom reaches 40ft so im taking 2 m105 trailers and making a dual axle trailer frame to pull behind it with another 14ft dropside on it

 

[spicergear]

I just mounted an 8000 series Palfinger on my 931A2. The pic below where the crane is unfolded a bit is not its final orientation, I spun it 180* on the chassis for the final mounting. The other pic is setting and the other is test fitting a 12' deuce dropside behind it. It basically ends up being a short wheelbase 923. I'm pretty sure I'm NOT extending the frame either. I have other plans for the truck so using the crane to pop the bed off. I'm also intending on putting a spool on this crane to use it like a 'normal' crane instead of having to bring the hook everywhere.

Mounting on the 931 was interesting in some spots as the frame has a lot of stuff on it PLUS the big transfer case sticks above the frame over 3". I used 3x3 square tube as a base then 1.25" thick plate welded to that to get the crane high enough and have a mount substantial enough to my liking. I've taken it around my powerlines and climbed up a shale bank my neighbor says he wouldn't take his four wheeler and the crane hasn't budget. Along with the long bolts sandwiching the frame and under mount plates and all together, I also utilized the mount for the tire rack and also the heavy stack mount too. It's not going anywhere. It's rated around 8,800lbs and I *think* around 3,000lbs extended. I forget the low number...been a while since I looked at the plate.

Oh, and deuce crane is for sale!