Ural-2M herringbone gearbox: worn teeth regained metal, motor current dropped

OJSC Dnepropetrovsk Tube Rolling Plant, TVTs-2 shop · measurements — chief mechanic services and the plant electrical laboratory

Ukraine · report dated 12.12.2002 · service between measurements — 526 h of normal operation

PRODUCTXADO revitalizantin the report — XADO “restorative” lubricant

TREATED UNITStage 2 gear drivegear and pinion, m = 20 mm, Novikov gearing · stage 1 (m = 11.2 mm) left untreated

DOCUMENT TYPEReport of OJSC Dnepropetrovsk
Tube Rolling Plantapproved by the chief mechanic · six signatures of the commission

Key results

↑0.4-0.6mm

tooth thickness of stage 2 gear and pinion, on average over 526 h of operation

↓12.5%

drive motor current under load, 440 → 385 A

UNIT	CONDITION AT THE START OF TESTING	WHAT WAS MEASURED
Ural-2M gearbox, stage 2 — treated	Tooth wear over 30 % of thickness; scoring, chipping and pitting up to 4 mm deep	Tooth thickness of gear and pinion (m = 20 mm) before treatment and after service
Ural-2M gearbox, stage 1 — not treated	Standard lubricant, same gearbox, same operating hours	Tooth thickness of gear and pinion (m = 11.2 mm) — control group
Gearbox drive motor	Standard mill operation, tube drawing in 2 strands	Current draw at no load and under load

Tooth thickness of the treated stage 2 — before treatment and after 526 hours of operation

PART · RIM · SECTOR	BEFORE, mm	AFTER, mm	GAIN, mm
Gear, left rim · S1	31.6-31.9	31.9-32.1	0-0.4
Gear, left rim · S2	31.4-31.6	31.8-32.3	0.3-0.9
Gear, left rim · S3	31.6-31.85	31.9-32.1	0.05-0.4
Gear, right rim · S1	31.35-31.8	31.8-31.9	0-0.45
Gear, right rim · S2	31.1-31.3	31.6-31.8	0.45-0.6
Gear, right rim · S3	31.05-31.25	31.6-31.9	0.55-0.7
Pinion, left rim · S1	22.8-22.9	23.2-23.4	0.4-0.5
Pinion, right rim · S1	23.15-23.4	23.7-24.0	0.45-0.8

ShZN-40 gear tooth caliper; the same marked teeth were measured before treatment and after 526 h. The table gives the mean tooth section at height h = 25 mm.

Control: stage 1 of the same gearbox, untreated

PART · RIM	BEFORE, mm	AFTER, mm	CHANGE ON THREE TEETH, mm
Stage 1 gear, right rim	19.0-19.1	18.6-18.7	−0.4 · −0.4 · −0.35
Stage 1 gear, left rim	18.7-18.8	18.75-18.9	+0.05 · +0.1 · +0.05
Stage 1 pinion	17.0-17.1	16.95-17.05	+0.05 · −0.05 · −0.15

Stage 1 (m = 11.2 mm) stayed on the standard lubricant and was not treated: same gearbox, same duty, same 526 h.

Drive motor current draw

OPERATING MODE	BEFORE TREATMENT	AFTER 526 H	CHANGE
Under load — tube drawing in 2 strands	440 A	385 A	−12.5 %
No load	30 A	22 A	−26.6 %

Measurements by the plant electrical laboratory: protocol No. 272 — before treatment, protocol No. 44 — after 526 h of operation.

Working surface of stage 2 teeth: inspection before and after

BEFORE TREATMENT	AFTER 526 HOURS OF OPERATION
Transverse scoring, chipping and pitting up to 4 mm deep over the entire working surface of the gear and pinion teeth; tooth thickness wear over 30 %	Damage depth decreased, ridges smoothed out, minor damage on the contact patches disappeared; the working surface levelled out and became smoother

Inspection by specialists of the plant technical services and representatives of XADO LLC during a scheduled gearbox shutdown.

Findings of the plant commission

The plant commission recorded in the report: before treatment the wear of the stage 2 teeth was found to be catastrophic — “tooth thickness decreased by more than 30 %”, and over the entire working surface of the gear and pinion there were “transverse scoring, chipping and pitting up to 4 mm deep”. After 526 hours of normal operation, repeat measurements showed that “tooth thickness increased on average by 0.4-0.6 mm”, while the motor current draw fell “at no load by 26.6 % and under load by 12.5 %”. The report concludes: “after treatment with the XADO revitalizant, not only was the catastrophic wear stopped, but a partial restoration of tooth thickness also occurred owing to the metal-ceramic layer that had formed”, which, in the commission’s estimate, extends the gearbox service life before overhaul “by at least 1.5×”. The gearbox was neither disassembled nor taken out of service.

The results relate to the two-stage Ural-2M herringbone gearbox of a rolling mill and to its normal operating duty; on other units and duties the figures may differ. Geometry and current measurements were made by the plant services; the treatment was carried out by XADO LLC and Agrotekhkomplekt LLC, whose representatives were part of the commission. The original signed report is published in full and available for download.

Current equivalent

Revitalizant gel for gearboxesGearboxes · transmissions · gear drives
Revitalizant gel for compressors and bearingsCompressors · bearings · spindles

How such units are treated: Reduction gearbox Gear drive Electric motor

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