Slewing Drive — validation & limitations

What it calculates

• N identical drives on one ring, evenly spaced or at entered angles, with a load-share factor K_γ for the most-loaded drive
• External or internal ring, rated as a finite gear pair on the real involutes — not the rack limit
• Internal ring root: the exact shaper-cut root when the cutter is known, else the conservative rack limit
• Load duration distribution with moving, oscillation and standstill rows; ISO 6336-6 Miner damage and the safety factor by iteration, per member
• Ring load passes from the parking arc and the drives inside it — the parked teeth's real cycle count
• ISO 6336-5 material lines (through, induction, case-carburized; ML / MQ / ME) from hardness, flank-only induction hardening with a weakened root, or your own certificate values
• Extreme moment, N−1 (one drive out), emergency stop, calipers stopping the motors, motor-brake engagement and direct-on-line start as static cases
• Brake holding at the low pad friction plus the motor brakes, with γ_hold — and the drag of residual brake pressure while turning
• Motor RMS, turning and start torque, motor speed; gearbox equivalent and static output torque against the maker's ratings
• IEC 61400-1 yaw-gear target classes 1 and 2, general machinery minimums or your own
• Max spectrum scale and max extreme moment the current drive takes with all its checks met

Validation evidence — independent reference cases (2)

Each case runs the tool's engine on a worked example whose values come from a published source or a hand derivation from the cited equations, and an automated regression test asserts the engine against those values within the stated tolerance. "Conservative" means the engine is known to sit on the safe side of the reference and the test asserts that side. Sources are cited; their text is not reproduced.

• Wind yaw drive on an external ring: spectrum safety per member, static safety, brake holding, motor RMS

  Agrees

  Source: Hand derivation (research/audit/slewing-drive/goldens/c_drive_hand.py, case W1, independent Python) from the contact path of both members, ISO 6336-3 Method B root and ISO 6336-2 pitting (as implemented), ISO 6336-6 Miner with S by bisection, brake holding at the low pad friction

  Inputs: External ring m 18, z 170, b 140 mm, through-hardened 280 HV; 6 pinions z 13, x 0.5, b 150 mm, case-carburized 700 HV; K_gamma 1.4, i 1200, eta 0.92; six reversing rows 700 to 2400 kN·m; extreme 2600 kN·m; IEC class 2

  Quantity	Reference value	Tolerance
  Spectrum root S pinion / ring	1.4277 / 1.1692	1e-6 relative
  Spectrum flank S pinion / ring	1.1721 / 0.6164 (FAIL)	1e-6 relative
  Static ring root / flank S	1.1337 / 0.5078	1e-6 relative
  Holding capacity / motor RMS	4486.15 kN·m / 17.658 N·m	1e-6 relative

  tests/golden/REF-slewing-drive-yaw-external.golden.test.ts

• Internal ring: published internal-gear contact example and a crane slewing drive

  Agrees

  Source: ISO/TR 6336-30:2017 Example 6 (internal gear pair); hand derivation (research/audit/slewing-drive/goldens/c_drive_hand.py, case C1, independent Python; ring root in the rack limit)

  Inputs: Example 6: z 15 / -99, m 12, b 125 mm, x1 0.323, centre distance 500 mm, T1 1 kN·m. C1: internal ring m 14, z 160, b 110 mm; 2 pinions z 15, x 0.4; i 300; four rows 150 to 420 kN·m at 1 rpm; extreme 650 kN·m x 1.35

  Quantity	Reference value	Tolerance
  Example 6 contact ratio / Z_B / Z_D	1.57 / 1.01 / 1	0.005 absolute
  Example 6 nominal contact stress	286 N/mm2	0.5 N/mm2
  C1 spectrum root S pinion / ring	1.1830 / 0.9192 (FAIL)	1e-6 relative (ring 1e-5)
  C1 spectrum flank S pinion / ring	1.2993 / 0.7231	1e-6 relative

  tests/golden/REF-slewing-drive-internal-ring.golden.test.ts

Limitations

Not checked by this tool

• The slewing bearing itself: raceway static capacity, rating life, ring bolts — Check the bearing with /slewing (moment capacity, DG03 life) and the ring bolts with /bolts
• Gearbox internal stages, bearings and service factor — Only the output torque against the maker's rated and max static torque is compared; rate the planetary stages with /planetary or the maker's data
• Pinion shaft, gearbox output bearings and housing / bedplate under F_t and F_r — Check them with /shaft and /bearings using the per-drive forces shown; the bedplate stiffness also sets K_Hbeta
• Ring deformation and bearing tilt clearance in the mesh (the face-load factor) — K_Hbeta is the open-gearing estimate (ASSUMED) unless entered; take it from the maker or an FE deflection analysis
• Scuffing, micropitting and wear of the open mesh; grease lubrication — Not rated (ISO/TS 6336-20/21/22); open slewing gears are greased - follow the bearing maker's lubrication interval
• Tooth breakage from shock beyond the entered extremes (collision, bucket impact) — Only the entered extreme moment and the computed transients are checked; enter the worst event as the extreme moment
• Yaw / slew control dynamics and brake disc, caliper and pad strength — The caliper clamp force is taken as entered; size the disc, calipers and their bolts with the brake maker
• Motor thermal duty in start / stop cycles and the motor brake wear — RMS torque and the start torque are compared; check the S-duty class and brake work with the motor maker or /motors