[MOC] [MOD] All-pneumatic 42008 Service Truck

[arik]

Hi,

I'd like to present my mod of the 42008 Service Truck. We've seen the excellent all-PF mod by Arachnid, but I took a completely different route: all-pneumatic functions! :-)

To summarize, the modifications were:

- pneumatic outriggers (instead of mini-LAs)

- pneumatic boom raising/lowering (instead of large LA)

- dual air pump, located at the side

- switch for engaging compressor or hook winch (run by the M motor), located at the other side

- air tank

- lights at the top

All four pneumatic switches are located at the top of the vehicle, plus winch release lever in the original place, making it easy to operate functions. I think this improves playability considerably. Hook can be wound with the 6th lever on the left side of the vehicle. The same lever is used to engage the compressor, which doesn't need to be running at all times because of the air tank.

In the original model the boom raises way too high, but it is non-issue as the LA can be extended only little as needed. Pneumatic cylinder is much more difficult in this respect, so I decided to use only part of the range of movement, so the boom is either lowered or raised to a reasonable height. Of course this is easy to modify if needed.

I relocated the pump to make room for the air tank, but mostly because I like to watch it operating. :-) Also there's now shorter route from motor to it. As there are now four large and two small pneumatic cylinders, I felt a single pump wouldn't be sufficient, so I came up with design for dual pump setup. Having them run side-by side in opposite phases would have taken too much space, so I set them up counter-rotating in the same plane. Even though the pumps are supported only from one side, it doesn't appear to be a problem.

I wanted to have the compressor and winch under the same switch (there's really no reason to operate both at the same time). I connected the changeover catch and PF switch with the same axle, so the motor is only engaged when either gears are engaged. This also ensures the winch is wound only in one direction (given that battery box switch is in correct position). I don't know if this is 'legal' or not (if the angles for co catch and pf switch are the same), but appears to work nicely.

Video here: https://flic.kr/p/oPKXvM (ignore crappy audio)

I'll be making an LDD model of this later on (possibly improving the design here and there), so stay tuned if interested. Thanks for reading, comments are appreciated!

[Rishab N]

Great work! You managed to squeeze all the tubing in and kept the original looks which is good

[Appie]

Very cool! Still looks like the original, nice. Love that pump setup. I love looking at that stuff too

[Paul B Technic]

Very well done :)

[jantjeuh]

Great job!

[Jeroen Ottens]

Cool, I really like the catch/switch combo.

What is the advantage of the double pump in combination with an airtank? Do you get a higher pressure in the system? Or do you just get a faster pressure build up in the tank?

[TinkerBrick]

I really like your modification. I never understood why TLG mixed pneumatic elements with LAs in this model anyway. the visible compressor is a nice feature. But is having two pumps and an air tank not to much.

[arik]

Thanks all.

Cool, I really like the catch/switch combo.

What is the advantage of the double pump in combination with an airtank? Do you get a higher pressure in the system? Or do you just get a faster pressure build up in the tank?

The catch/switch combo works nicely as long as you remember to turn the switch all the way and not stop already when the motor starts spinning. It looks like it might not get all the way into the transmission ring, but at least here it works nicely (not very high torque).

I wanted to have an air tank so that the functions can be used without constantly running the motor (especially as my 2 year old son likes to play with the truck). Then again filling the tank takes long time with only one pump, so another is a must. Also using the large cylinders quickly depletes the air pressure. So yeah, the reason is to get the tank filled quicker. I don't think dual pump would affect max pressure.

I've been contemplating adding an air tank override switch to the system. The simplest way would be to have the tank in a separate T-branch behind a switch (i.e. connected only with one tube). It would also allow pressure release. But I don't know whether an air tank works well with only one tube and running compressor (the other end blocked, obviously).

I really like your modification. I never understood why TLG mixed pneumatic elements with LAs in this model anyway. the visible compressor is a nice feature. But is having two pumps and an air tank not to much.

Thanks. The tank isn't needed if running the compressor at all times, but it's nice to have. :-) I hate it when the pressure builds up too much and strains the motor (and the pump I guess).

The only advantage using LA in this model is control of the height of the boom (which of course gets ridicuously high). Maybe it could be simulated using pneumatic cylinders in sequence...

Having completed the build I noticed one problem. I geared down the winch quite a bit (maybe half the speed from original model), so now it is maybe too difficult to unwind. I'll probably need to redesign it with fewer gears and/or less gearing down.

[N-4K0]

Good job, squeezing so much into the truck.

[arik]

Hi again.

I finally completed this also in LDD, and made some improvements along the way. The functions and overall design remained the same, though.

Here's the LXF file. I designed it so that you only need to build the main module and recycle/build from official instructions the cab, boom, outriggers, and side panels. (Although you need to flip one 3x5 beam in each of the side panels.) I used the 42008 LXF file I found in the EB LDD forum for those.

And some pictures:

Main module:

Closer look at the transmission:

Unfortunately I couldn't reproduce the tubing or wiring in LDD, but it shouldn't be too difficult to figure out. Also, all pneumatic cylinders and pumps are replaced with yellow beams. :-)

[afol1969]

Hi again.

I finally completed this also in LDD, and made some improvements along the way. The functions and overall design remained the same, though.

Here's the LXF file. I designed it so that you only need to build the main module and recycle/build from official instructions the cab, boom, outriggers, and side panels. (Although you need to flip one 3x5 beam in each of the side panels.) I used the 42008 LXF file I found in the EB LDD forum for those.

Unfortunately I couldn't reproduce the tubing or wiring in LDD, but it shouldn't be too difficult to figure out. Also, all pneumatic cylinders and pumps are replaced with yellow beams. :-)

Very cool job, well done!

I think it isn't too difficult to reproduce the model with LDRAW. A tracing of the wires with a picture program or more photos will be helpful

We had so many MOC's with PF, so it's fine too see something with full pneumatic functions.

Greetings

Alex