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U1450L DOKA
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Discussion Starter · #21 ·
OK, Chas -
Some more thoughts on this FTB cab tilting process .

A. How much heavier is the DOKA cab than a standard cab ? According to the UHN builder's guide, the DOKA cab adds an additional 270 Kg to the cab weight ( 595.2 Lbs). This is probably pretty close to what you and I have, as the cab structure has remained pretty consistent.
The UHN regular cab has been stretched a few inches over the SBU cab of your era, but the additional DOKA weight should be pretty close, I think. The later UHN's have a revised Rear Seat structure, but I don't think that is would have affected the weight appreciably. I'd just round it up to 600 Lbs.

B. If I had to tilt my cab up enough to get the engine out, I'd lighten the cab as much as possible. I'd take the rear seat cushions out completely (Very Easy to do) and empty out the storage compartment under the seat - take out the jack and anything else stashed under there, leaving the Webasto Aux heater. Once you get the rear seat out, that rear space really looks rather large ... and you may start pondering... I did anyway.
I have the seat-and-a-half on the passenger side, so I'd pull that out. I believe that you have the single passenger seat -
I might pull that at well, maybe both seats, since lighter is better.

C. The front Pivot pins - these things are being asked to support the extra weight of the DOKA cab, at an angle that the DOKA cab is not designed to reach, which is why I'd lighten the load as much as possible, within reason. The photos of the DOKA at an elevated level from Schüssler show the pins working, so if they are in good shape they would appear to be up to the task.
I'd grease them up so the pivoting process would be smooth and the clamps would not hang up or grind into the paint too much.
Assuming the engine has to come out, then I'd probably leave the cab up until the engine was returned to its spot, as I think that minimizing the up and down cycles would tend to reduce the chance of damage.

D. The Pins - I looked at them thinking that I might find a way to brace them to the floor. I was thinking that backing them up to the floor or the bumper would help eliminate the potential bending moment that would be induced by the cab during the pivot and at rest in the FTB position.
The problem is that there really isn't enough room to grab the pin on either side of the pivot clamps (hinges) - whatever was put in place might interfere with the smooth movement of the cab as it rotates, which could lead to some big problems.
Once the cab is all the way up, then I'd look to fit a leg from the Clamp / Pin combination to the floor to counteract some of the load on the pin. This would take the load straight to the floor, so you would not have to worry about the weight of the cab bending the pins if it had to sit for an extended period of time, while your engine block was out being chromed or something.
Because the hinge clamps are attached to the the bumper support, by fitting jack stands directly under the bottom of the clamps, you would take the load to the floor, rather than having the full weight of the cab pushing the pins down onto the front springs. The jack stands would take the suspension out of the mix, and 'push back' against the pins.

Another thing that might work is to use the extra eye on the pin assembly meant for the cab shock. You might be able to make a leg that bolts to this eye and extends to the floor. Again, I'll have to look at this in the flesh, but it might be a handy way to attach a leg. This could not be used until the cab was fully rotated, because the shock mount is slightly off axis in relation to the cab pins.

Jack stands are probably the simplest solution, and a few minutes looking at my truck should verify this. Easy and the quicker solution.

E. Elevating the cab - I think I'd prefer to hoist it from above using the two cab rings, rather than pushing it up from below. The factory hydraulic jack only goes so far, and will have to be disconnected for the cab to reach the full height, so disconnecting it at the upper mount on the cab and ignoring it might be the way to go.
I think that an ideal way to hoist the cab would be with a chain hoist mounted on a traveling dolly on a beam crane, in a shop with a ton of head room. The dolly would allow for the crane to be directly over the rings for the whole process, rather than being offline as the cab rotates.
In lieu of the dolly on a beam crane, rolling the UNIMOG on the shop floor, under a hoist in a fixed position should achieve the same effect. Looking at the body of the DOKA, you would not want to be in a position where you are pulling over the top rear corner of the cab - it is much better to lift directly up on the rings and roll the UNIMOG to the rear to keep the rings under the hoist throughout the lift.
Once the cab is in the FTB position, then maintaining a little tension on the rings will also take some load off of the pivot pins. Just a little, as you don't want to damage the rings.

F. Once the cab is up, I'd add two legs under the rear corners. I'd probably use 4x4's cut to length, with both legs attached to a single 2x6 or 2x8 flat against the floor (if possible), and then cross brace the legs to each other, and then finally ratchet strap them to the frame to keep them in place.
Based on the angle indicated in the Schüssler photos, it may be that the (angled) legs have to wind up on top of the frame rails, butted up to the rear box. It is one of those things that you have to figure out once the cab gets up there.
As a safety, I'd run ratchet straps from the two lifting eyes to fixtures on my rear box, so the cab could not over-rotate if something failed in the hoist.
You could use screw jacks (shoring props) or steel, but with a Skilsaw and some lumber I could bang it right out.
I'd chock the wheels every which way.

G. A team. The more the merrier, but I think two is the bare minimum. I got mine tilted by myself, but it would have been better with a second pair of eyes on station (and, I was not going all the way up). One guy on the hoist, one at each front corner would be good, and they could roll it as it was being elevated. That would be reasonable - three people. More if you have them.
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1991 1250L Doka Unimog, 2002 ML320
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Really great thoughts Truktor!! Thank you. I hadn't thought to try and support the pivots from underneath. I'm still trying to figure "the from above" portion. When I built my shop I should have put more structure up there. The Amish who built it were way to quick and I barely had time one night in the dark to put wires in the walls.

I need to process a deer this weekend and then I'm pulling it in to start.....I might pull it in sooner because, as you know, it is supposed to get chilly again early next week. Greenhouse is staying above 32 degrees, so that is nice. Too bad it isn't set up for a mog....
Chas
 

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Discussion Starter · #24 ·
Just goofing off here.
The orange lines represent the difference between the high (3760mm) and the low (2810mm)marks on the diagram. The difference is 950mm. Adding 950mm to the high mark equals 4710mm, which is 15' 5.43", and which comes close to the top point of the FTB cab position.
Does this represent the actual top height of the FTB DOKA ? Probably not exactly, and you'd be better off with your FatMAX tape (hopefully, and not a puny, floppy tape) which would give you a more accurate number. Just an exercise while lounging around watching football. The Green lines represent my estimated outline of the DOKA cab. Just lines on 'paper', nothing real.
So Far, so good, now if Notre Dame can just beat USC later today. Yes, I went to graduate school at USC, but my dad played football for UCLA, so becoming a USC fan was never a possibility, so....come on Irish!


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Discussion Starter · #26 ·
After some thought, I'm changing my opinion and going with what Scott said - Tilt it, get the engine out, and set it back down. Once it is back down, 'Nothing' bad is likely to happen. Keep it down until it is time to reinstall the engine, etc., then up and down again.Once the engine is installed, then owering it to the 'normal' high position for a DOKA will allow you plenty of room to button things up and inspect and fiddle with anything else on the chassis, without having the cab at the extreme angle.

When it is all up in the air to the FTB position...gremlins could intervene.

Looking to b101uk's tilting procedure posted above, he drops the steering box, so he does not have to worry about aligning the spines while doing the (Regular Cab, in his case) tilting operation by himself. With two people or more, I'd keep the steering box in place, but it is another wrinkle to have in the back pocket, if you need it.

Slow and steady, with a team of people, while going up and down is what I would try to do.
 

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1991 1250L Doka Unimog, 2002 ML320
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Deer is in nice little white packages...the way the Hand Brake likes them!!
My 21 year old Optimas finally gave up the ghost....RIP. It might have had something to do with leaving the ignition on the last time someone wanted to hear it (in June)....Grrrrr. So, it took some serious love and time to get the ol' girl started and in the shop. At least it still had snow on it to drip on the floor! Oh that's right, I didn't quite get the woodstove in this summer. Nice that I like it cool.

Monday I'll get the lower "stuff" off and pan. We'll see how bad it looks. I started thinking that I should look at the oil filter that was in the old housing and the new one I just put in.

Thanks for all the assistance folks.
Chas
 

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1988 U1300L RW1 Working gears Dual Tanks AC Rigged for Camping Plus: 91 F250 HD 4x4
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Okay, I am largely on board with TRUKTOR's lift menu, but not completely. Some thoughts I have on this whole escapade:

First is a call out for anyone who can supply cab weight of a regular SBU cab, and even more, I would really love it if someone can find the center of gravity of said cab, in XYZ planes. More on that later. [much later, as it turns out]

The front pivot pins are the weak link in a cab lift, in all likelihood, and especially if there is rust present, and super-especially if the rust is present in a DOKA cab to be lifted. Both conditions, I'd do a straight lift-off, or rebuild the box beams that the pivot pins attach to (if I had other reasons to attack the front sheet metal). Jumping ahead, I would not fuss at all with supporting the pin or the Clamp to the floor. Look at the photos, the Clamp has never been shown to fail (it is in pure compression, and stout metal), but the pin gets torqued upward regularly, if the underlying frame is rusted.

The key to understanding is to look at the photos with the fender skin removed. The "box beam" that the pin is welded to at the end, and carries the load up to the firewall (and distributes it over a more substantial and more substantially braced area), has a very small dimension L-R at the pin point. With the cantilever of the pin, out to where it rests on the Clamp, there is a significant force multiplier/ torque on the attachment of the pin to the sheet metal. This wants to compress/ crush the outer sheet metal, and put the inner side of the "box beam" in tension. The real trouble starts when one observes that the "box beam" is NOT a box section, but rather an open "C" section. An open C performs fairly poorly as far as resisting torque about the long axis, which is the case here. This is made worse, or maybe not ameliorated by, welding or joining the outer skin of the fender to the C section, which could complete the box and greatly improve torsional strength. The fender metal is joined to the metal that supports the pin, but only at the very bottom. My take is, this is the explanation for the dimpling that is seen up around the turn indicator lights, as the compression loading from an intact bottom connection is transmitted up through the unbraced panel/ skin, where it shows up as a buckling failure of the panel, at the weakest point, which will be around the turn light cutout.

If I had to do any serious rust repairs in this area, I would probably do something extreme to strengthen this pin attachment. I would likely try and work with the existing C section, but most likely bend up another C section of much heavier gauge metal (14g, even 12g) and nest it into the existing, with full welds to join the "seams". This would create a very sturdy, torsion-resisting, true box section. I would probably try and seal the new assembly, maybe one small drain at the bottom end, and then use cavity wax (and plug the injection hole). I would also likely use a heavy (like even 1/8" would be better than OEM) piece of flat bar as the vertical face of the reinforced box section, so that the torque placed on the pin would not be able to crumple the thin stuff. Trying to integrate the outer fender skin into this is a possibility, but seems to be fraught with too many complications, hence the ideas presented above. My take on this is that the damage is done on the initial lift, once the cab is near FTB, the loading is more or less along the long axis of the "box beam", and the bottom flange of the C section is better aligned to take the compression loading, and direct it up to the firewall.

All this begs the question, why did Ma Benz do such a crappy job on all this? Well, as costly as a Mog is, I presume there is some element of bean-counting going on. The extra work to insure integrity is clearly not needed, on a fairly new and un-rusted vehicle. The failures are most likely to occur on vehicles long out of warranty, and therefore with no financial burden on M-B. If an individual owner has to do a repair rebuild, the equation changes dramatically, as now even a small probability of future failure is very costly. And, the extra weight (and $) of more and heavier metal is inconsequential to the one-off guy, the true cost is in doing anything at all to repair it. I find that this sort of cost-benefit scenario plays out in a lot of produced items (like houses, my usual genre). Basically, I am saying one should be wary of paying too much respect to the original engineering.

If I were faced with lifting a DOKA cab that seems to be basically intact, but not absolutely guaranteed, I would fabricate a brace strut, and do a temp install before the lift. Stealing imagery from a prior post, it could look something like this:

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Well, that ran a bit long, other comment will have to wait for a next post.

Just my two foot-pounds worth.

Lee
 

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Discussion Starter · #32 ·
Good, I'm glad that further discussion has been generated.

A couple of notes :

-I don't think I described the beams a 'box beams'. They look like they might be from peering at them from inside the engine compartment, but once you look at them with the fender skin removed, it is apparent that they are not true Box Beams.

- The whole beam structure is curious to me, and not a good design. Dating from the early to mid 70's, and continuing on to the present, the design has not changed much, noting the extra material added at some point, as illustrated in the Mission Impossible truck thread.
The beam projects downward at an angle from the firewall, and besides carrying the sheet metal skin of the fender, it is tasked with carrying and locating the pivot pin.
Vertically from the pin structure, there is a lightweight metal 'angle iron' type of deal, which helps secure the edges of the grill opening, but, like the beam, it ends up dangling in space, stabilized (if you can call it that) only by the presence of the skin of the fender.

Mercedes-Benz started to engineer in some energy-absorbing structures into their cars as early as 1959. It wasn't until
the introduction of automobile safety ratings in the late 70's that 'crumple zones' really started to take off. These are now standard in passenger cars and light trucks, but they are not generally part of over-the-road freight trucks (where airbags are still a relative rarity).

OK, back to the UNIMOG beams - I think is is safe to say that given the timeframe of the design of the Square Cabs, as well as their elevated chassis and cab position, that crumple zones were not part of the design criteria that affected the design of the beam structure up front.

One of the side effects of the beam structure and it's flimsy, almost non-existent support of the front upper fender corners is the occurrence of fender dimpling, which can occur during the cab tilting process. A problem for sure, and something that I have experienced on the Green DOKA when a shop tilted the cab. Somehow, I avoided it when raising the cab on the current DOKA. This has been covered elsewhere.

- Starting with a clean sheet of paper :

A. I would beef up the structure of the current beam, and attach it to the firewall more substantially - maybe split into a 'Y', with a high and a low point on the firewall, so it has better support.
B. I'd likewise beef up the vertical element at the lower end of the beam, and take it all the way up to the top of the fender.
C. Next, rather than leaving the vertical element dangling in space with its sheet metal fender skin, a third beam would
connect to the vertical strut and run from the top fender corner horizontally back to the firewall.
D. These three beams, which essentially form a triangle would be a single structure, which bolted to the firewall via threaded inserts. This 3-beam triangle could be a stamped structure that was sandwiched and welded together, or it could be two or three pieces that bolted together. The single uni-structure probably makes more sense.
E. The Fender skin would no longer weld onto the single beam and the cowl as it currently does, but would bolt onto the new triangular beam structure.
F. The Pivot Pins - These would be bolt-on, replaceable components that would be fitted to a new structural body beam that ran across the bottom of the grill opening. This new beam would be engineered and placed so the cab would pivot on its axis, and it would not be affected by winches, PTO shafts and so on. This new beam would bolt to the new triangle beam structures on each side, and the pins would be completely exposed, and not buried within the fender, hidden away in the rust soup kitchen.
In addition to the two pivot pins, a center guide collar/pivot (with Zerk Fittings) would give the cab an additional, stable connection to the frame during the lift. This could become two collars, aligned with the frame rails, if that worked out better, which...it probably would.
This beam would serve as a proper front cab mount, and would have to be built so as to not hinder frame flex or cab articulation, and yet still provide a solid pivot for tilting the cab. It could be that the built-in flexibility is neutralized for cab lifting by simply installing 4 nice bolts provided for the purpose. When the cab was back down, take the 4 bolts out and go back to driving mode, with the articulation intact.
With the pins (having been increased in diameter) part of a bolt-on structure, the could be removed from the ends of the new pivot beam and repaired, replaced, or chromed...as needed.
The Pins would be retained, because they allow the extreme outside corners to articulate freely, and yet be anchored for the cab tilt. The new crosswise body beam would anchor to the new Triangular Super Beams, but would also be floating with the body at the corners.
G. Packaging challenge - Basically the air intakes on the front body panels, for the heater intake and the engine intake, pierce the sheetmetal, and would tend to be in the way of my mythical new Triangular Super Beams. A minor issue here in Dreamland, but lengthen the nose, move the intakes to fit into the open center voids of the Triangular Super Beams, or move the intakes to the rear of the cab (engine), or top of the cowl (Heater), or something.
This is Dreamland - I'd assign that to the Packaging Team, while I checked in with the Body Skin Team to see how they were coming along. They'd be busy assessing the available stock of Titanium sheets from decommissioned MIG factories for the cab, as well as getting bid prices from Pennsylvania regarding the stainless steel fenders and so on.

So, Simple...

Next, my crackpot theory of pushing back on the current pivot pins when the DOKA Cab is raised to the FTB position.
OK, I could be wrong here, but here is what I'm thinking -
First of all, I am counting on the pins being structurally sound, rust-free, and in perfect shape. Anything else has to be dealt with on a truck-by-truck basis.

So, The DOKA cab is packing an extra 600 Lbs of weight, for a round number. Secondly, to get the engine out, we are talking about taking it higher than it is 'supposed' to go - to the FTB position. There may be a MB technical directive out there specifying that the DOKA cab shall only be taken to the 'Normal' (Low) tilt position or hoisted off completely, and that the FTB position represents a form of insanity, and is straight out.

It is possible.

So, ignoring that possible reality, lets say I'm taking my DOKA cab to FTB position, and standing its whole boxy self on its nose, resting entirely on two pins. I will ignore the possible up-loading on the two rear hoisting rings for the moment.

I see the cab pushing down on the two pins, the pins pushing into the hinge clamps, the clamps pushing into the bumper support structure, and then that (and the frame, etc) pushing into the front coil springs. Everything from the Pins on is being pushed Down, and once the springs are compressed and stablized, then the clamps and all of their buddies are a static backstop. They are pushing back in the sense that they can't go any further, but as far as the force exerted on the pins from the DOKA cab, it has not been reduced, it has reached its maximum. The pins are still taking all the weight.

I think.

Changing up my solution a bit, if I position a bottle jack on each side, just below the pins / pivot clamps and crank them up a bit, then I am actively pushing back against the weight of the cab. The jack pushes the clamp Up, the clamp is cradling the Pin, so there is no slop there, so the clamp pushes against the pin. Before using the jacks, all of the weight of the cab is trying to bend the pins down and snap them off of the cab. Once I jack 100-200 lbs of force into the pins from below, then I am trying to bend the pins up, in the opposite direction. This would, in crackpot land, effectively reduce, to some minor degree, the force pushing down on the pins.
The jacks would ideally be angled to be pushing in a line through the pins, parallel with the bottom of the cab and on to the rear lifting rings. That might be a little tricky, but doable. It might take something on the floor and something on the bottom of the clamp.
I think I might do it, as well as loading the hoist against the lifting rings, just to reduce the effective weight a little bit.
I would not expect to get too much out of it, and I would not want to get in a force war over the pins by trying to lift the front wheels off of the ground or anything, but a little might help 'a little'.

In Dreamland, the shop overhead is pretty amazing, and there is another beam crane above the beam crane that has ahold of the the rings on the cab. This second crane will allow me to take a large nylon lifting sling and loop it through the rear doors of the DOKA or, well, I'd use a padded spreader bar, and by positioning the upper chain hoist at the perfect angle, I'd start hauling up on the cab, taking some amount of weight off of the pins that way.

Then, I'd go on vacation, and have the Dreamland crew install Downward Dog's new, fully bulletproof production version of his engine in the thing, and tell them to give me a call when it was ready to have the key turned. The plans for the Dry Ice Hopper for the twin intercoolers in the front compartment of the Head Wound Box could come along later...

The weight of the standard cab - I have looked, but have not found it as yet.

Drilling and tapping the end of the pin was part of one of my plans earlier... but I left it on the shelf for now.
 

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1988 U1300L RW1 Working gears Dual Tanks AC Rigged for Camping Plus: 91 F250 HD 4x4
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Okay, in for a penny, in for a pound............or 1600 of them, if that is what a DOKA cab actually weighs.

IF I had a DOKA, and up to me to lift it, I would go for the embedded suggestion first last and foremost:

Jack stands are probably the simplest solution, and a few minutes looking at my truck should verify this. Easy and the quicker solution.

E. Elevating the cab - I think I'd prefer to hoist it from above using the two cab rings, rather than pushing it up from below. The factory hydraulic jack only goes so far, and will have to be disconnected for the cab to reach the full height, so disconnecting it at the upper mount on the cab and ignoring it might be the way to go.
I think that an ideal way to hoist the cab would be with a chain hoist mounted on a traveling dolly on a beam crane, in a shop with a ton of head room. The dolly would allow for the crane to be directly over the rings for the whole process, rather than being offline as the cab rotates..........

Once the cab is in the FTB position, then maintaining a little tension on the rings will also take some load off of the pivot pins. Just a little, as you don't want to damage the rings.
I have lifted my single cab, in my shop, using a 1000# cable puller. Not too hard, setting back down on the steering gear splines was the biggest aggravation. A brief run-through, to illustrate what I see as issues (or non-issues). I did not take photos of the lift apparatus, so will have to describe, mostly.

Here is my truck, sitting peacefully at home:

Tire Automotive parking light Wheel Vehicle Motor vehicle


You might surmise that I pulled from the double Lvl beam below the rafters. Not so. I pulled from the marked slot in this photo, which can actually be observed in the previous, if one knows where to look:

Wood Road surface Architecture Asphalt Grey


Just fed a 1" strap through, and hooked up the cable puller. I used this because the beam was offline sideways, and I needed more headroom (only have 14 feet below the rafters). For those freaking out about pulling the roof down, here is why that did not happen:

Design loads here are 30 to 40 psi live load (snow, which wasn't present for the lift). 15 foot span, 2 foot loaded width says 900# total live load (15' x 2' x 30 lbs), which can be met with a nominal deflection limit of L/ 180. Structures are largely designed with deflection limits controlling things like joists and rafters, and the results rarely come near absolute breaking strength/ failure mode. Guessing my cab was about 1000#, but I am only taking half, by lifting from the back-of-cab ring, gave me complete faith in the setup. And faith was justified, the photos are taken years after the lift, still can't see sky. You might ask, what is the beam and chain fall for? Well, to lift really heavy stuff off my truck, then drive out, and set the load down on rollers. For example:

Hood Building Wood Beam Motor vehicle


This is the other truck bay. The 2800 pound mill came in on my truck in the photo, and was lifted and set down, rolled into position.

Basically, using the roof framing as a hoist point is not necessarily that scary or dangerous, with a few caveats. Solid sawn rafters can take a small hole at the 2/3's up in depth location, no big problem. Wood I joists CAN NOT be loaded on the bottom flange, they can be pulled apart. There are ways to pack the web and reinforce them, and support a load just fine, we did this on a job only two weeks ago. Get help with this if you want to do it, and don't know building structural engineering. Trusses are another can of worms, you CAN NOT load the bottom horizontal members, but it is possible to hang a beam from the vertical web members. Again, one needs to know the engineering, but very doable. Biggest issue, at least for the OP, is if there is enough headroom to get that DOKA to FTB.

Now, on to the good stuff. If I had to lift a DOKA, and had the headroom, I would hang a WF beam (kind of along the lines of what I showed for my wood beams) and get a trolley to fit. This whole operation is a lot better and safer if the lift rig is always vertical, meaning able to move down axis to stay in line above the rings, on the trolley. I understand the concept of rolling the truck, but to me that is too fraught with possibilities to go badly. In fact, I would most likely set the truck FRAME on jack stands or cribbing, so that it did not go up or down on the springs, as the weight shifted, and this is looking ahead to the engine lift, as much or more than for the cab lift. I myself like to eliminate uncertainty in the interests of personal safety. Even the single cab puts some heavy loadings on things. In fact, I set my strap so that I pulled forward over the top edge of the cab, with the cable actually laying over a 3/4 plywood corner board (about 2 ft long) used as a cab edge protector. I did not need FTB, and stopped with the cab well up and the cable pulling slightly to the rear, but all went well. I did make a custom steel (1 1/2" x 3/16 wall TS) safety strut to fit in the OEM lift hydraulic jack points, before I would poke my head under. I think that the DOKA cab would be a nightmare if the lift point stayed fixed relative to the frame, as the horizontal displacements get much larger, with sharper angles and therefore high loadings.

........ I'm still trying to figure "the from above" portion. When I built my shop I should have put more structure up there. The Amish who built it were way to quick and I barely had time one night in the dark to put wires in the walls.
So, this was a brief primer, but should serve to take some of the scare factor out of the prospective job. Chas, you are welcome to PM me for more detail, if you want to go this route. I have my new identity and matching passport in hand, I am not too worried about the outcome. /s

Next thoughts are about the lift rings. As described, I used my single ring, for my single cab. I have no rust, had no issues. On a DOKA I would for sure lift with a hoist, from the pair of rings. I would absolutely make a spreader bar for that lift, unlike what I see in a couple of the photos that TRUKTOR posted. Reason is, the pair of slings coming in at an angle apply a higher total force to the rings, and could start a sideways tear in the sheet metal, especially if there is some rust already. The less the headroom, the shorter the pair of slings, and the higher the side loads. The spreader bar will keep the forces on the rings straight vertical, the minimum. A lot of rust, I'd do the sheet metal repairs and augmentation first. Lifting from the front/ back like this keeps all forces to the minimum.

Fianl thought, make sure there are stops for the trolley. If the CG of the cab is significantly above the floor pan, then at FTB, there is a good possibility of the CG going forward of the pivot pins, and then wanting to pull the trolley forward, until all slop and slack in the hoist cable was used up. Could be a bit disconcerting, if it happens unexpectedly.

All FWIW,

Lee
 

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Discussion Starter · #35 ·
Dreamland Super Beam doodle, with some M.C. Escher work on the near beam. The Green lines are the additional pivots on top of the frame rails, which are semi-rigid pivots (Urethane bushings, maybe). Being mounted to the frame rails, which are tied together with welded tubes all down the run of the ladder frame, they would not be subjected to a lot of twisting and deflection, but even if they were, as long as the outboard ends were not anchored, like the existing pins and their clamps, then it shouldn't matter.
Maybe these would replace the outboad pins, or maybe they'd all work together. Myths are like that - mechanical harmony, supervised by Unicorns.
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Discussion Starter · #36 ·
I realize that it is a shadow detail, created by the lighting, but the rafters above the lifting beam looked like they had scarf joints at first glance, as unlikely as that would be.
 

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Discussion Starter · #37 ·
Amended notes -

- I offered up the rolling truck solution if a traveling overhead dolly was just not an option. It would work, and it would not preclude putting the frame up on stands before the engine was removed.
I'd lay 8" X 8" posts down as travel limits for the tires front and rear, and have wheel chocks positioned to kick into the frontside of the the tires so the truck went as far as I wanted it to go during each stage, and no further.
A controlled roll could be effected by using a come-along. Slow and steady, a few clicks at a time, just keeping pace with the hoisting operation.

-Next, since Scott has indicated that he has lifted the DOKA cabs on the pins... I don't think I'd bother with my bottle jack, counter-force attack on the pins. Scott's statement is ambiguous, as he does not actually say that he took the DOKA cabs to FTB position and yanked engines, but I'm assuming that is what he meant.
It's not that I think that pushing up on the pins wouldn't have some effect, I just don't think it is worth the hassle.

Mainly, because it does not seem to be necessary. If Scott has taken the DOKA cabs up high enough for engine removal, then why worry ? Also, the photos from Schüssler UNIMOG show that they have hauled a DOKA cab well up into the sky on the factory pins. Whether the Schüssler DOKA is high enough to remove the engine or not, the weight on the pins is clearly in the 'Full weight of the cab' neighborhood. No sense in fooling around with jacks for no reason. The factory pins look to be fine on their own, without any assaults by the Lunatic Fringe. I don't think an engine overhaul was part of Schüssler's civilianization of that DOKA, but I'll check just for the heck of it.


- While I may not have referred to the front fender / pin beams, as 'Box Beams', closer inspection has convinced me that they actually are Box Beams. They have all four sides of the box, as the photos show. They are constructed out of various pieces and not out of a chopped piece of a conventional steel rectangular tube, but they are a box structure.

This is all fun and educational, but I have to say I'm going to be somewhat fanatical about my engine maintenance so I can avoid all of this, hopefully.

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Discussion Starter · #38 ·
I didn't find any mention of pulling the engine out of the Ex-Danish Rocket carrying DOKA at Schüssler. They did install a Claas OD, which would require a cab tilt.

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