A 160-180 hp class motor grader with 15-16 t operating mass, a 3965×610 mm moldboard, and a turning radius near 7.8 m is the working envelope for tunnel-port grading and muck-handling duty [S2][S5].
The typical configuration is a Cummins 6BTA5.9 (or Shangchai D6114ZGB) diesel at 125-132 kW, a ZF-derived 6-forward/3-reverse power-shift transmission, caliper-disc service brakes on all four rear wheels, and a CE-marked cab with A/C for tunnel dust and heat [S2][S5].
Why a road grader, not a dozer, in a tunnel heading
Tunnel muck piles are loose, mixed with rebar offcuts and shotcrete rebound, and the invert must be graded flat enough for conveyor or rail muck cars to track cleanly — a fine-precision finish that a motor grader delivers through its 360° circle-turn moldboard, which a dozer blade cannot replicate [S2][S3]. SDLG F-series units with this type of moldboard geometry are now in service across more than 100 countries, including markets where confined-site grading is routine [S1]. The Cat 140/140 AWD platform and its long-standing 14 ft moldboard class dominate the European and North American underground-port fleets, with Finning IE listing graders explicitly for road construction, site prep, and material moving jobsites [S3][S6].
Power, weight, and dimensional envelope for low-ceiling headings
The PY180C reference unit weighs 16,000 kg with a 5,150 kg front axle load and 10,850 kg rear axle load, rides a 6,362 mm wheelbase, and measures 8,585×2,790×3,340 mm overall — a footprint that fits a 4.5 m wide tunnel invert with clearance to spare for the 7,800 mm turning radius [S2]. Operating pressure on the hydraulic system sits at 18 MPa, which is the working pressure for moldboard lift, circle rotation, and articulation, and 6 forward × 3 reverse gears take the machine to 38.2 km/h forward / 24.5 km/h reverse for portal-to-heading road transit [S2]. For tighter headings the SDLG F-series and the WME GR165/GR180/GR195/GR215/GR300 family bracket the same 125-300 hp envelope from 170 hp at 15 t up to higher-power units, allowing selection down-shift to a smaller frame when overhead clearance drops below 4 m [S1][S5].
All-wheel drive and braking for wet, blasted invert
AWD is the discriminator on tunnel invert work: the Cat 140 AWD variant lists all-wheel drive as a factory option specifically to keep the front wheels pulling on wet, freshly shotcreted or mud-contaminated surfaces where a 6×4 machine would sit down and lose grade control [S6]. Service braking uses caliper discs on the four rear wheels with a mechanical internal-expanding parking brake, and the tandem case uses a roller-chain drive with an integrated free-wheel anti-slip differential — important on greasy invert where blasting water and drill flush collect in the wheel tracks [S2]. The Cab with Air Conditioner and CE marking are baseline for underground diesel work, since Tier-equivalent particulate load inside a heading makes operator survivability the limiting factor on shift length [S2].
Attachment and drivetrain options for muck-shuttle support
Optional front bulldozing plate and rear ripper extend the grader into shotcrete muck cleanup and light face scaling — the PY180C spec lists both as factory options, which lets one machine replace a small dozer on a tight heading [S2]. The hydraulic system uses HUSCO five-way control valves with an imported equalizing valve on blade lift, and an electro-hydraulic pin puller on the drawbar is standard, which speeds up front-axle / attachment swaps during a maintenance cycle [S2]. A 1,500 PCS/month class supply capability on this 180 hp segment — versus 1,000 PCS/month for similar Asian-built 180 hp units on the export channel — signals that fleet operators can specify multiple identical graders for a multi-heading tunnel without bespoke sourcing risk [S2].
Selection criteria: who this spec fits, and who it does not
This 160-180 hp / 15-16 t / 3965 mm moldboard class is the right call for metro, rail, and road tunnel invert grading with cross-sections of 4.5 m or more, for muck-pile leveling between drill-and-blast cycles, and for portal road maintenance on haul-truck loops. It is the wrong machine for full-face hard-rock scaling (use a dedicated hydraulic motor-driven roadheader or breaker), for shotcrete robot mounting, or for headings under 3.5 m where the 3.34 m overall height plus A/C unit will not clear the crown. For higher-volume open-pit or highway work the same drivetrain philosophy scales up — see Motor Grader Selection for Road Construction: Power, Weight, and Drivetrain Match for the road-class envelope, and for demolition-style grading on uneven substrate the Motor Grader Selection Map for Demolition Projects lines out frame and tandem case options. [S2]
Comparison: 180 hp tunnel grader vs heavier road-class unit vs compact demolition unit
On the four criteria that drive a tunneling buy, the 180 hp CE-marked PY180C-class, a 220+ hp Cat 140/140 AWD-class, and a compact demolition-spec grader separate cleanly: (1) operating mass — 16,000 kg vs ~19-21 kg vs ~13-14 t, (2) moldboard — 3,965×610 mm vs 4,267×610 mm vs 3,658×610 mm, (3) turning radius — 7,800 mm vs ~8,300 mm vs ~6,800 mm, and (4) AWD availability — optional vs standard on the 140 AWD vs not typically offered [S2][S5][S6]. For tunnel-port work the 180 hp / 16 t class wins on power-to-mass and parts commonality with road fleets; for long portal haul roads the heavier Cat class wins on moldboard reach and AWD standard; for inside-the-heading finish grading the compact class is the only one that physically fits.
Operating cost, lead time, and sourcing signals to watch
Supply capability for the 180 hp class is running at 1,000-1,500 PCS/month through Shanghai-export channels, with TT or LC terms and CE marking as the export baseline [S2]. SDLG's F-series penetration in a single regional market reached roughly 40% in Oman, evidence that the 125-220 hp bracket is competitive with the legacy Cat 140-class on price-per-horsepower even outside China [S1]. Track two signals before purchase: OEM confirmation of AWD availability on the 16 t frame (not all 180 hp export units list it as a factory option), and on-site verification of aftercooler-equipped Tier-final or equivalent engine packaging for underground particulate compliance.
Component reference pages worth checking: ac motor.