Knuckleboom: Back to Work: Re-Assembly

November 23, 2013

I got the parts I needed and now it was time to get everything back together.  I started by putting pipe thread sealant on each fitting and screwing it into its mating fitting.  Pipe thread sealant is so much better than Teflon tape!

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Here’s what the entire assembly looks like with all of the fittings together, and staged for how it goes into the truck:

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Now for a task I had been dreading: getting the PTO shaft apart where it should be a loose sliding assembly, but was not!

PTO shaft

It was locked solid!  I finally got the torch out, and after lots of heating cycles and hammering, I was able to get that shaft out of the coupling.  Not sure why it was so locked solid, but probably due to lack of regular grease, and years of dirt accumulation.  After some filing and belt sanding, I finally got it to slide in the coupling properly, and liberally greased it up.  The u-joints have some slop in them, probably due to slip coupling not allowing any movement, so sooner than later I’ll need to remove this shaft and rebuild the u-joints on both ends.

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Mounting Bracket: another one needed

With the secondary and tertiary tanks tied together, there was only 1 mount that was for the secondary tank, so another mount was going to be needed.  Here’s the completed picture so you can see where I’m going with this:

tank mounting brackets

After a bit of scrounging, I came up with some leftover C-channel iron chunks, and after a bit of measuring, I cut them down to size, cutout some flat plate, drilled some holes with the mill, and then tacked it all together.  Then I test fitted it into place, conveniently I was able to reuse some existing holes on the frame.  I also got some 1×2 tube steel to tie the 2 tanks together and to the mounts, and to also lift them a bit higher for better drain-back to the primary tank.  It fitted up nicely, so then I welded the main bracket together.  After that, I debated about continuing with assembly or to paint.  I decided I better take the time to paint, as otherwise it probably wasn’t going to get done!!!

In looking at the C-channel bracket, it was a bit scaly, so into the sand blasting cabinet that I had gotten at Harbor Freight.  Boy did that work slick!  I connected to my big air compressor setup, 7.5hp, 80gal tank tandem with another 80 gal tank and ½” hose, and it was able to pump up to full and shut off while I was sandblasting continuously!!!!  After about 10mins, I was had it all nicely prep’d.

The shop wasn’t particularly warm, only about 35F, so I needed a way to get things warmed up for paint.  I took the spray cans inside, and put them in a bucket of hot water, while those were warming up, I got the torch out, and heated the metal brackets bringing them up to warm/almost too hot to touch temperature.  Then I got the pre-heated spray cans, and doused them with spray paint.  It worked quite nicely, as after a few hours of curing, I was back to work installing them.

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It wasn’t all time lost, as it gave me time to think about how I was going to lift the primary tank with pump back up into position.  It’s heavy, I was going to be lifting by myself and getting all of the bolts lined up isn’t easy. Complicating the fact, I had to also line up and connect the PTO shaft, so if it shifted in position too much that shaft would come disconnected. One of my favorite sayings is “work smarter, not harder!” so I decided to figure out a lifting method with the pallet jack.

I wheeled the tank assembly over and underneath with a Harbor Freight dolly, got it lined up, then slide it onto a board across the ends of the pallet jack.  Then I was able to lift the pallet jack all the way up, then add blocks on each end of the 2×6, lower the pallet jack, then add more blocks under the 2×6 to the pallet jack and raise it again.  After 2 cycles of that, I was in perfect position to pop in the bolts, and tighten it down.  A bit of back and forth, but it was safe and easy!

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Now that that was done, and the paint seemed to be cured enough, I could continue work on the brackets and additional tanks.  First I needed to attach the 1×2 tubes to the tanks.  I like to drill and tap stuff, particularly when you have the right tap.  I use some special taps that push the chips forward, and allow you to tap with a drill!  Regular taps that require a tapping handle and lots of forward and back motion really suck to use and are slow.  Here’s a picture of this style of tap:


These are typically 2 or 3 flutes rather than the 4-flute that are typical of a bottoming tap.  The only limitation on these taps is that they’re mainly for thinner materials, and require a through hole or lots of room at the bottom of a closed hole for the chips.

A bit of tapping oil, and a good drill with forward and reverse, and tapping a hole takes about 5 secs!

I’ve gotten my taps through or Fastenal.

Here’s my setup partway through doing all of the tapped holes.  I did all 8 of them in probably 10 mins.


Now it was time to bolt the tanks onto the truck, now refer to the initial picture of this section!

Then I connected up the hose from the knuckleboom valve body to the tank, and then it was time to get the drain-back hose connected.  I had purchased 10’ of hose, but only needed slightly over 2’ of it.  Better to be safe than sorry when it comes to having enough!

I test fitted it up in there, then marked it for length and cut it off in the abrasive cut-off saw.  That’s the best way I’ve found for cutting this type of hose since it’s heavy rubber with steel wire embedded in it.

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Now for the final connections, I needed to reconnect the bed hoist hoses onto the valve body on the primary tank.  I added an additional swivel connector to make it easier to connect.

During this task, and many others on this job, I’ve been using the Stanley Squidbrite light.  I’ve had it for many years, and it continues to work reliably.  I really like having the magnet back on it, in this case I snapped it to the underside steel of the knuckleboom so it would shine down on the valve body while I worked on connecting the hoses.

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Whew, let’s see, did I connect everything??? Yup, looks good.  Now to add hydraulic fluid….it’s now 10pm, and I’m tired, but I’ve got to see if this is going to work!  After pouring in multiple pails, I had ~12 gals of fluid in the system, and all tanks were about ¾ full.  Now to fire up the truck and try this!

At first it didn’t seem to have much difference, but then after a bit of cycling of the cylinders (and getting out some air) it was working great!!!!!

The speed was what I would expect it to be and finally I could raise and lower the main boom in short order.  The only issue came when I started cycling the cylinders all the way closed, a gush of air entrained fluid came rushing into the tanks with enough force to blow the vent cap off the secondary tank!!!  That was a bit of a surprise, and made a bit of a mess, but once I cycled all of the cylinders to their fully closed positions slowly and got all the air out, things were working quite nicely!!!

It was now 10:30pm, and I was done for the day!  The knuckleboom was working like it should, which was a huge relief!

Good thing I pushed hard, as the next day was filled up by some cleanup, some other tasks, and packing to head back to China.

Unfortunately, I didn’t have a chance to take any videos, but we’ll be back in late December, and my wife will be with to run the video cameras.

Now, there’s still some items remaining on this project, which will need to be completed before I can put too much use to this:

  1. finish the 4th mount of the crane to the frame
  2. finish mounting the 2nd and 3rd tanks to the frame mounts, 2 bolts are done, 2 more needed
  3. slide the flat bed forward slightly, and make the final welds on the hinge and hoist
  4. clean the oil off of everything and add some paint to bare steel (this will have to wait until summer)
  5. start painting the knuckleboom so it doesn’t look so crappy with the peeling yellow paint over the peeling black paint
  6. Add some labels on the control levers, and get the opposite side levers mounted and attached
  7. Attachments!!!!! I have lots of ideas for attachment add-ons, and I’ve already been doing research and calculations on most of these:
    1. extended boom
    2. man basket
    3. claw for tree branches/logs