That's my new MOC. It's a Airport Crash Tender, a specialized fire engine designed for use in aircraft rescue and firefighting at aerodromes. The scale is about 1:14.

It was inspired by the Magirus Super Dragon X8, but I haven't created an exact copy of it (especially in the front).

It's 8 wheels drive, moved by 4XL Motors connected to the wheels via a driveline, it has a differential per axle. 

The 1st and the 2nd are steering axles via 2 PF Servo motors (one for each axle), with 
different turning radius.

The suspensions system consists in 4 live axles, with an anti-roll bar for each of them to avoid the lie down on one side (like the Unimog). I added another "arm" on the 3th and 4th axles for reduce side movements.

For reproduce the right wheelbases, I built this Moc with a unusual configuration. The 1st and the 4th axles are rotated. Practically the ball joints through which passes the drive shaft, for the 2nd and the 3rd axles, are directed to the center of the vehicle, on the contrary the ball joints of the 1st and the 4th are directed to the outside of it. In addition this configuration gives a positive caster angle to the 1st axle.

The Hydro-pneumatic system consists in a L pump without the spring that sends pressurized air to 2 "lungs" (one per side). Downstream of them there is a pneumatic valve (moved by a PF M Motor) that sends the air alternatively to the 2 water tanks (also these one per side for balancing). One tank is for the main water cannon an the other is for the bumper water cannon.

The MOC has an elevated extinguishing arm moved by 2 L motors. The nozzle can move up and down and can rotate via 2 PF M Motor. Even the bumper cannon could move up and down via 1 PF M Motor.

The lightening system consist in 2 PF Led in the front and 1 in the back for the headlights. The emergency lights consist in 10 PF Led connected to 2 PF switch (5+5). Those are actioned by a PF M Motor that give the flashing effects.

I used 5 non Lego parts. The 4 tanks (for air and for water) and an SBrick.

Other non technical features are:

- Openable sliding doors (manually) that allow access to detailed interiors of the cab. It has 4 seats, the areas around the driver's seat and the firefighting system controller's seat are detailed...using a bit of fantasy, especially for the firefighting area. 

- The 2 hatches between the 2nd and the 3th axle can be open and give visibility about the water level.

- Also the complete side walls, placed above the hatches just mentioned, may be opened to access and refill the water tanks.

- Above the 3rd axle there are 2 hatches on the sides and 1 on the roof for access to the battery packs.

- 5 openable grids are placed on the engine compartment in the back. 2 are on the sides, 2 in the back and one on the roof. Those grids give access to the detailed engines compartment. There are placed 2 6-inline engines (like in the Superdragon X8). Using a differential they run with the pneumatic pump and/or with the drive motors. More or less like done by Sheepo on his Peterbilt (I think). In addition there are exhausts pipes with silencers and turbochargers, air filters with some pipes and radiators on the top. Even here I used a bit of fantasy, it was hard to find specific informations.

- Hook ladder on the roof, extendable manually.

Technical description:

Length: 126 studs (100,8 cm)
Width: 27 studs (21,6 cm) (without mirrors)
Height: 37 studs (29,6 cm) (without antennas)
Weight: 7,8Kg dry, 8,3Kg with filled water tanks

PF Elements

4 XL Motors for driving.

2 Servo Motors for steering.

3 L Motors, 2 for elevate the extinguishing arm and 1 for the pump.

5 M Motors, 2 for rotate and for move up and down the nozzle on the elevated extinguishing arm, 1 for move up and down the nozzle on the bumper, 1 for the pneumatic valve and 1 for the emergency lights.

3 Switch, 1 for invert one Servo motor (in the steering system) and 2 for the emergency lights.

13 Led, 2 in the front 1 in the back 4 in the front emergency lights, 4 in the rear emergency lights and 2 on the front bumper.

2 Li-Po battery for drive and steering.

1 Battery pack for all the other functions.

5 IR receivers, 2 for drive and steering, 3 for move the water cannon and for control the pneumatic valve.

1 SBrick (not really a PF elements but...) for headlights, emergency lights and pump.

Several (I don't remember the number) extension cables. Something like 4 by 20cm and 4 by 50cm.

I hope you enjoy!