A 15-tonne PY165C-2 class motor grader running a 3,965 mm moldboard delivers 125 kW (170 hp) at 2,200 rpm, the entry tier most municipal road maintenance fleets lock on first [S2].
The engineering question is not "how big a motor grader," it is which combination of operating mass, engine curve, and moldboard width survives the actual haul-road profile without paying for surplus steel. Used Cat 140G units on the resale market in 2026 sit in the 14-16 t class with 14-15 ft blades, the workhorse band for county-road maintenance [S4]. A motor grader's defining hardware is the long, flat blade called a moldboard, set between the front and rear axles to cut, mix, and spread surface material [S1].
Operating Mass Class and Axle Distribution
Operating mass on 2026 production units clusters in three bands: 15 t (GR165 / PY165C-2), 16-17 t (GR180 / PY180C-2, 18 t PY220C-2), and heavier 19 t+ class machines for mining haul roads [S2][S6]. Front axle load on a 15 t PY165C-2 is 4,150 kg versus 11,850 kg at the rear axle — a roughly 74/26 split that defines the machine's blade-down stability margin and steering authority under load [S2]. The 18 t PY220C-2 shifts the split to 5,820 kg front / 11,080 kg rear, moving the centre of gravity forward to support a longer 4,267 mm moldboard and wider tire fitment [S2]. A machine's tire pair per axle and the rear-tandem oscillating geometry are what let the moldboard float over a crowned road surface without chatter [S1]. Mass selection is not arbitrary: under 13 t, moldboard pull on a wet clay base course is insufficient; over 22 t, transport between job sites triggers road-permit thresholds in most US states.
Engine Power and Transmission Mapping
Engine output spans 125 kW (170 hp) on the GR165 up to 220 kW (300 hp) class on the GR215 / GR300, all rated at 2,200 rpm on Tier-2/3-equivalent SHANGCHAI D6114-series diesels in the 2026 China-domestic line-up [S6]. The 15 t PY165C-2 is governed to a 36.8 km/h maximum forward speed with 8 forward / 4 reverse powershift gearing typical of this class [S2]. Horsepower per tonne works out to roughly 8.3 kW/t on the PY165C-2 and 9.3 kW/t on the PY180C-2, the operating-mass-to-power ratio most road-maintenance contractors target as the minimum for sustained moldboard pull in granular material [S2]. Above 11 kW/t, fuel burn climbs faster than productivity; below 7 kW/t, the machine stalls in cohesive soils. Reference [S3] is a general electric-motor sizing procedure that has nothing to do with combustion-engine grader power curves, do not cross-apply its torque/inertia formulas to diesel graders [S3].
Moldboard Geometry: Length, Height, and Arc of Cut
Moldboard width on the 15 t GR165 is 3,965 mm with a standard 610 mm height; the GR180 / GR195 / GR215 step up to 4,267 mm width to cover a full lane in one pass [S6]. A 14 ft (4,267 mm) blade on a used Cat 140G remains the de-facto 2026 resale spec for county roadwork, paired with the 24 in (610 mm) moldboard height that defines base-course finishing geometry [S4]. Moldboard rotation is hydraulic on every modern unit in this class, typically ±360 degrees, with a hydraulic sideshift of ~2,160 mm left or right of the machine centerline, which is what lets the operator reach a ditch line without repositioning the tractor. Cutting depth is governed by wheel lean and blade pitch, not by the moldboard's own thickness; the operator trades speed against depth in low gear, and the transmission's lowest forward ratio dictates finish-quality productivity on a tight tolerance cut.
Application Tiers: Maintenance vs. New-Build vs. Mining
Three application tiers drive 2026 selection. First, road maintenance — ditching, snow removal, regravelling — fits a 14-16 t / 125-160 kW / 3,965 mm moldboard machine; the entry PY165C-2 or used Cat 140G both sit here [S2][S4]. Second, new road construction with a base course of 200-300 mm of granular material needs the 16-18 t / 160-195 kW / 4,267 mm class to maintain pass depth at speed; GR180 / GR195 / PY180C-2 map to this band [S6]. Third, mining haul-road grading — 30 m wide running surfaces, 4% grade, 24/7 cycle — jumps to 19 t+ and 220 kW+ (GR215 / GR300), where moldboard wear packages and frame articulation rates diverge from the road-build spec [S6]. Specifying a mining-tier grader for a county road wastes 40-50% of the acquisition cost on features the operator will never use. For a deeper decision flow on which spec gates to lock first, see Motor Grader Selection 2026: 7 Spec Gates Buyers Lock First.
Operating-Mass-to-Power Comparison: PY165C-2 vs. PY180C-2 vs. PY220C-2
Side-by-side against three decision criteria — mass, power, top forward speed — the 2026 PY-series line reads as: PY165C-2 at 15,000 kg / 8.3 kW/t / 36.8 km/h; PY180C-2 at 16,000 kg / ~9.4 kW/t / similar top speed; PY220C-2 at 16,900 kg / ~10.7 kW/t / same 36.8 km/h governed top end [S2]. The PY165C-2 is the cost-down entry for maintenance fleets with mixed soil; the PY180C-2 adds ~6% mass and ~13% power for marginally better cohesive-soil performance; the PY220C-2 trades a longer wheelbase and higher front-axle load for moldboard reach, not for raw speed. Front axle load climbs from 4,150 kg to 5,820 kg across the three models while rear axle load is nearly flat (10,850-11,080 kg), confirming that the engineering variable being scaled is front-end stability for sideshift work, not tractive effort at the rear tires [S2]. When food-and-beverage plant site grading is the duty case rather than haul-road work, the spec cut diverges — see Best Motor Grader for Food and Beverage: 2026 Spec Cut for that narrower profile.
Sourcing, Resale Value, and Chinese OEM Supply
Used Cat 140G units in 2026 listings on Construction Equipment Guide sit in the 14-16 t class and represent the most common resale tier in North American road-maintenance fleets [S4]. New-unit supply for the 15-18 t class is dominated by Chinese OEMs (XCMG, Shantui, Sany, Liugong) selling the GR165 / GR180 / GR195 / GR215 / GR300 model ladder with SHANGCHAI D6114-series engines at 125-220 kW [S6]. For a procurement-side read on the related hardline category that often ships in the same container, the Strapping Band Selection: 4 Spec Gates for Load, Material and Tooling walk-through covers the steel-band spec logic that complements any heavy-machinery export. Procurement on the 15 t class in mid-2026 runs in three price tiers: entry Chinese OEM new-unit, 5-7-year-old used Japanese/US nameplate at 40-55% of new, and refurbished 10-year-plus machines at 25-35% of new, with financing lead-time being the actual constraint for most municipal buyers rather than headline price.
Trackable signals for the next 90 days: GR215-class quotation validity from Chinese OEMs (typical 30-day window), and 2026 Q3 used-Cat 140G inventory turn rate on Construction Equipment Guide, both of which move before the next road-maintenance budget cycle locks fleet replacement plans [S4].
For component-level specifications, see motor grader, linear guide, and crossed roller guide.