Wrecker bed modification

[Welder Sam]

Have you ever tried to set a tank towbar on your bed by hand? Have you ever tried to put a tank towbar on your bed with the boom? Better yet, have you tried to lift that spare off of the bed? If you had, you would KNOW WHAT IM REFERRING TO. The hook does not reach even the edge of the bed. Man Z, youre really hung up on "your way is the only way". To think YOU accused someone previously of being negative. You dont have to agree but you should show some respect.

 

[doghead]

I've considered installing a winch on the deck, close to the center pivot, so I could pull a load onto the deck.

 

[zebedee]

Have you ever tried to set a tank towbar on your bed by hand? Have you ever tried to put a tank towbar on your bed with the boom? Better yet, have you tried to lift that spare off of the bed? If you had, you would KNOW WHAT IM REFERRING TO. The hook does not reach even the edge of the bed. Man Z, youre really hung up on "your way is the only way". To think YOU accused someone previously of being negative. You dont have to agree but you should show some respect.

Sam - I appologise for implying any of what you refer and was not trying to be negative.

Yes, I realise how heavy those bars are and yes, there isn't anywhere else for them to go.
Yes, I have struggled with the spare, I just throw it off but lifting it back on is a different situation, and I wish there was a better way.

I absolutely do not have all the answers, but I do have a pertty good background with which I base my opinions.

Perhaps I jumped the gun on what you were thinking without further info. To me, obtaining larger cyl's would be extremely expencive.

Again - I am sorry for sounding 'know it all'. I am very passionate about this subject, which obviously gets in the way of reality from other peoples perspectives.

I hope you accept my sentiments.

Regards.

PM and edit also.

 

[73m819]

Try loading stuff on a 819, I use a come-a-long

Think a spare tire is bad, try mounting it on a Austern Western crane

The crane can CAN ROTATE 360 deg. continuous, just by removing the stop on all the wreckers up to and including the m936.

 

[m16ty]

Has anyone thought of upgrading the lift rams? All of these wreckers could stand a bit more verticle ability. 2 stage cylinders would allow for a longer stroke in the same collapsed length. Thus possibly allowing items to be lifted from or placed on the bed.

I agree with this. A had a wrecker bed but sold it for this reason. With the short boom and 45 deg max angle, you can't get very close to you or lift very high. Most civilian cranes with go to around the 80 deg range. I guess because the primary use was a wrecker, they military figured 45 deg was enough.

I'm not sure just slapping some on telescopic cylinders will solve it though. You'll lose some lifting power in the second stage and I'm not sure if you'll have binding problems with the extra angle. It's definitely doable but with anything you modify that does overhead lifting, you better make darn sure you know what your doing and what the modification will affect.

 

[zebedee]

Has anyone thought of upgrading the lift rams? ............ Thus possibly allowing items to be lifted from or placed on the bed.

In light of my apparent "negative" responce earlier, I would like to look at the problem in a positive way and in conclusion offer a real cheap fix.

Along the ram idea, how about moving the lower ram point up a few inches, 'Cheating Peter to pay Paul' and having the fully collapsed height of the boom, no lower than transport height. Only a few inches gained - poor idea.
Or, longer rams with the top point mounted way out along the boom, collapsed height the same, but way more elevation - much better.

BUT, for a measly few dollars, a simple lug welded to the boom down by the crane cable drum, to attatch the hook cable end in a two part configuration, would, at full elevation bring the hook almost all the way in to the base of the crane. Add to that Ron's swivel stop removal and you could load the heavy stuff inc tow bar and spare, easily.

If I have time this weekend, I'll give it a go and do some pics.

Admitadly this is not for tons of lifting, really only for the few hundred pounds of the towbar and spare tyre and would require control of the cable to avoid damageing the flood lights etc.

 

[73m819]

WILL no work, there WILL be no control of the block, as soon as a load os applied to the block it Will want to pull into the back of the truck, try to raise the block you will be forced to pull the load away from the truck, as you raise the boom, things will get worse, once above the deck, as the boom is raised the block will RUN to the low side, not a place to be in that event.

Also the angle (pitch) of the cable coming off the block will be VERY flat, which means that a enormous load will be put on the cable (can get well over the swl very easy)anything over a 30 deg. pitch, is VERY BAD, The cable gets VERY, VERY over loaded VERY QUICK

also, as a side note, the rig down, rig up, rig down, rig up is a lot of time consuming work for a few lifts

 

[Welder Sam]

Well crud.. skip to the next one please

 

[Welder Sam]

I agree with this. A had a wrecker bed but sold it for this reason. With the short boom and 45 deg max angle, you can't get very close to you or lift very high. Most civilian cranes with go to around the 80 deg range. I guess because the primary use was a wrecker, they military figured 45 deg was enough.

I'm not sure just slapping some on telescopic cylinders will solve it though. You'll lose some lifting power in the second stage and I'm not sure if you'll have binding problems with the extra angle. It's definitely doable but with anything you modify that does overhead lifting, you better make darn sure you know what your doing and what the modification will affect.

Just off the top of my head, when considering a cylinder swap, psi and gpm available would be the first concern. Then consider how much larger bore could be reasonably sustained and how much more fluid a pair of these would require. I would reach out to several professionals to help with this. The binding issue would probably be a trial and error deal. I never suggested this would be cheap or simple by any means. Cost vs benefit would be up to the individual owner for sure. Its just a thought i figured id throw out there. Im far from an expert on hydraulics and the various formulas used to figure this stuff out. I see the max boom angle as a big downfall.

 

[73m819]

Don't see why not, more of the rear of the boom needing some place to go, a rebuild of the boom lift mounts will be needed to reflect the different load because of the different load angle,(as the boom angle get higher, the loading on the boom hoist mounts get higher not because of weight but because the angle between the boom and the lift cylinder get smaller).

 

[Stretch44875]

Didn't get too much into it, but the A/W crane on the M108, would hit the tank/toolboxes if it was raised any higher. The hoist drum almost touches the toolboxes when the boom is raised all the way. I can get stuff on deck though, with the boom up and retracted. Only on the rear deck.

 

[zebedee]

Lifting from bed

Despite the doubt of the suggested method, I tried out my idea.

I did not fab up a special bracket, just used the shipper brace retaining bracket and a spare large ring I had lying around.

After lifting the boom, lowering hook to the ground and dropping the boom, there was plenty of spare cable to make the change, as you'd have to for rigging changes - 1:1 to 2:1 or 3:1. (Perhaps the BII should have a small step stool so that this can be done easily!)

Time taken was surprisingly shorter than it took me to later rig from 2:1 to 3:1 since that requires two additional bolts and spacers to be removed from the mast head to get second cable loop over the second pulley wheel.

The whole time the hook stayed pretty well centered at the bottom of the 'V' in the cable, there was some resistance in the hook pulley so combined angles weren't always perfectly symetrical. This also meant that the hook did not 'run' in or out when the boom was raised or lowered. The heavier load actually smoothed out the movement of the hook.

- angles were ~ 60 deg over bed, but went up to almost 90 when I ran the boom all the way out and lowered to horizontal. This is way further than would be needed for lowering a tire or heavy kit to next to the side of the truck. But I wanted to explore the extent and limitations of this method.

Interference with boom accessories and structures was avoided using the offset of the retaining bracket.

I did switch the ring to a loop of 1/4" rod and loaded the hook with all four snatch blocks when the boom was out and horizontal - 90 deg included angle and the 1/4 rod did not break - so I think it is safe to say that nothing got overloaded.

I am going to make some kind of quick attatch ring/loop/hook thing for the cable end to hook to rather than doing up the bolt again.

First pic is the standard setup used to move the spare, all I did was lift the wheel from the floor. It was not really over the bed enough for easy positioning, though removing the slew stops would help.

Definately helped for lifting the heavy stuff on/off the bed - towbar, etc., and I'll use this mehod in future for returning stuff to the bed. Unloading - I'll probably stick to pitching over the side on to a rubber mat!

So, "Don't try this at home children and ask a grownup for help with the sharp things".


NB. That small gauge hook that fits on the crane hook, came with the truck - super usefull.

 

[Csm Davis]

Not too sure where on the bed you are thinking of putting stuff and what stuff? ....................... The manual does state that the spare wheel should be lifted down with the crane, so having accepted that, and assuming that the spare has to be hand moved to within the 270 deg (?) reach of the crane.........


Getting back to the original thread by CsmDavis, redoing the lockers would allow the stowed BII equipment to be accessed by hand from the ground, with the exception of tow bar of course
I'm not trying to pee on your bonfire, just giving my opinion .... Love this thread, keep up the thoughts.

I haven't tried to get the spare or blocks out of the toolbox yet but I can reach the back deck I used my crane to pull my rear winch out after I busted it

 

[rizzo]

I used my crane to pull my rear winch out after I busted it

that sounds like an interesting story

 

[Csm Davis]

that sounds like an interesting story

Yeah need to write that one up it has video and all

 

[nf6x]

I like the idea of re-rigging the hoist cable to a spot lower on the boom to position the hook over the spare and toolbox area. How about replacing the bolt that secures the clevis end of the cable with a pin for easier removal? The pin would need to be strong enough, naturally, much like a tow bar pin.

My older medium tow bar that I bought many years ago fold up with the two legs parallel to each other, but the one that just arrived with my M936A1 is made a bit differently, so it doesn't fold flat. When I tried rotating my crane all the way around, the base of the crane encountered the tow bar and made some unfriendly noises, so I'll need to stow it in the bed differently. Dang, those things are heavy. I usually disassemble my old one to handle the halves separately, but the new one's hitch pin is bent and wedged in place at that pivot. I'll need to fix that for sure.

I think I saw a thread recently where somebody added a sort of catwalk along the left side of the wrecker bed to make it easier to get around the gondola. I've lost track of the thread, though. That looks like a good idea to me.

My M936A1 and M923 could both use some additional steps at the cab and rear end. My knees know Arthur Ritis, too. Maybe something like this one?

Flexible Step, 12" (5231112) | Welcome to Buyers Products Company​

I would LOVE to have hydraulic outriggers on my wrecker. I just avoid doing lifts that need them, since getting them in and out is hard on my weak engineer's couch potato back. I don't see a low-gumption way to modify the existing outriggers, though. I should take another look at them and see if any other ideas come to mind. Even something to assist with lifting and lowering them instead of fully hydraulic controls would be an improvement. Maybe there's some sort of trick kind of like how the outriggers on one of the MK48 RBUs use a cable attached to the lifting rams to help swing them up and down from the stowed position?

I've been thinking a lot about how to add good remote control to the crane without shelling out more than I paid for the truck. I haven't found the right solution yet, but I haven't run out of ideas yet, either. I think that adding remote control to the front and/or rear winches is much more do-able.

 

[indy4x4fab]

My M936A1 and M923 could both use some additional steps at the cab and rear end. My knees know Arthur Ritis, too. Maybe something like this one?

Flexible Step, 12" (5231112) | Welcome to Buyers Products Company​

I like the step I have seen on several semi trailers that uses 1'' cable instead of rubber for the sides.

 

[nf6x]

I have seen those wire rope suspended steps on telephone and power service trucks around here. I think that style was shown on the web page I linked to, also. I wonder how flexible they are? The cables are awfully thick.

 

[indy4x4fab]

They seen to have a fair amount of flex to them when the 250lb driver use them to step up in to the back of the trailers with lift gates. The 30'' step would make for a nice add on to each side of the cab step on the m939a1 and m939a2 for people how have shorter legs like my wife. Flexible Step, 30" (5231130) | Welcome to Buyers Products Company

9'' drop, 15'' wide, and a 4.75'' deep step, uses 1.5'' cable.
Cable Step, 9" T x 15" W, 4-3/4" Diamond Deck-Span Tread (5230915) | Welcome to Buyers Products Company

15'' drop, 15'' wide, and a 4.75'' deep step, uses 1.5'' cable.
Cable Step, 15" T x 15" W, 4-3/4" Diamond Deck-Span Tread (5231515) | Welcome to Buyers Products Company

main cable step page
Product Categories | Welcome to Buyers Products Company

 

[73m819]

Be careful using chain/cable supported steps or you WILL learn why they have the NICKNAME "shin knocker" , there are a few others names like @#$%^%$^&&^ step, ect.