FUK-18: An 18-Ton Underground Truck Built for Tight Tunnels

Why an underground truck has to be low and bendy

Underground roads aren't like surface roads. Drifts run about three metres wide and not much taller, with ventilation ducts, cables and people to make room for. A regular dump truck either hits the roof or can't make the corner. So underground haulers are designed low, narrow and maneuverable from the start. The FUK-18 uses an articulated frame: the two body sections pivot in the middle, so the truck folds when steering. The inner turning radius is 4.39 m, and the wheels track almost the same line, which keeps tyre scrub down. In a tight stope, a few fewer reversing moves add up over a shift.

What 18 tonnes looks like

Rated payload is 18 t in a 7.5 m³ body made of manganese steel, with an optional baffle. The truck is 8.3 m long, 2.1 m wide and 2.31 m high, and weighs 15.5 t empty. It has four forward and four reverse gears and tops out at 31.1 km/h. Loaded gradeability is 14%, and maximum tractive effort is 160 kN. The body raises to a discharge height of 4.2 m and completes a lift in about nine seconds, which sets the pace at the ore pass. For a machine that climbs ramps all day, the grade and traction numbers say more than top speed.

Powertrain tuned for ramps

The engine is a Cummins QSB6.7 making 163 kW and 949 Nm at 1500 rpm, with emissions at EPA Tier 3 / EU Stage IIIA / China III. That detail matters more underground than on the surface: ventilation is one of the biggest operating costs in a mine, and a cleaner exhaust means less ventilation to build and run.

The driveline is a DANA torque converter and a powershift transmission. Powershift means the drive isn't cut while changing gear, so on a ramp the truck doesn't lose momentum or roll back between shifts. Axles are KESSLER D81 rigid planetary units with a limited-slip differential. Planetary wheel ends multiply torque at the wheel and take load off the half-shafts; if one wheel loses grip on wet ground, torque goes to the other and the truck keeps moving.

Brakes and safety: the parts you don't cut corners on

Dust is hard on conventional drum brakes. The FUK-18 uses fully enclosed wet multi-disc brakes, with the friction discs running in oil. They stay sealed against dust and keep consistent braking on long downhill runs. The parking brake is spring-applied: hydraulic pressure holds it open, and if pressure is lost the springs clamp the brakes on. For a truck that parks on ramps, that fail-safe design is the difference between safe and very expensive.

The cab is built with 6 mm reinforced steel, the roof meets ROPS/FOPS, and air conditioning is optional. A manual fire extinguisher is standard; central fire suppression and centralised lubrication are optional. The hydraulic system runs at 16 MPa, with pumps and valves from Parker, Rexroth and WABCO, and the truck is 24 V with two batteries.

Where it works

Trucks like this usually work metal mines, gold, copper and zinc among them, plus non-metal mines with drifts around three metres; tunneling projects use them too. The FUK-18 belongs to a family that spans 6 to 42 tonnes, so mines pick the size that fits their output and drift dimensions. An underground truck earns its keep by hauling more, climbing, and staying out of the workshop. Nothing fancy about that.