Ussülekande reduktori kataloogikoodid dekodeeritud: NMRV/WP/SK/SCWS

A practical decoder for the four major catalogue families — Italian NMRV, Chinese WP, German Nord SK, Japanese Mitsubishi SCWS — with frame size translation, suffix codes, and the decoding mistakes that cause specification errors.

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A worm gear reducer catalogue code looks compact on the nameplate — usually 8 to 14 characters separating family, frame size, ratio, mounting class and accessories. The same physical specification carries radically different codes between Italian NMRV, Chinese WP, German Nord SK and Japanese Mitsubishi SCWS catalogues. Procurement engineers managing mixed-vintage and mixed-brand installed bases need to translate fluently in both directions: from a legacy nameplate to a modern equivalent, and from an engineering specification to the family code each supplier expects. The article below provides the decoder rules for the four major families, a cross-family frame size translation matrix, a suffix code chart, and five mistakes that account for most translation errors.

CODE ANATOMY — TYPICAL NMRV SPECIFICATION

NMRV0754/10071B5F

FAMILY

NMRV

Aluminum body, Italian RV pattern

FRAME SIZE

075

Centre distance 75 mm

RATIO

4/100

i = 100 (4-start worm)

MOTOR MOUNT

71B5

IEC 71B5 motor flange

OUTPUT

Flange-mount output

Why Catalogue Codes Matter for Worm Gear Reducer Specification

A worm gear reducer catalogue code is the procurement engineer’s primary handle on a specific physical configuration. Get the code right and the supplier ships the matching unit; get it wrong by a single character and the delivered hardware mismatches mounting hole patterns, output shaft diameter, motor flange size or accessory provisions. The cost of a mismatched code is not just the unit value — it includes shipping back, restocking fees, project schedule slip, and the labour to identify and order the correct replacement.

Each worm gear reducer catalogue family encodes the same set of engineering attributes — frame size, ratio, motor mount, output type, accessory pack — but in different positional and notation conventions. NMRV separates segments with slashes and uses centre-distance frame numbers (the “075” means 75 mm centre distance). WP separates with no delimiters and uses sized model numbers (the “70” in WPA70 means a 70-frame, with no direct millimetre meaning). SK uses two-digit codes (SK 12, SK 22) where the number progresses through the catalogue rather than encoding any single physical dimension. SCWS uses the metric centre distance directly (SCWS 175 means 175 mm centre distance).

Translating worm gear reducer codes across families means understanding what each segment encodes in each system, then mapping the engineering attribute (not the literal character) to the equivalent character in the target catalogue. The four decoder cards below cover each family in detail.

NMRV / RV — The European Aluminum Family Decoder

The NMRV (Motovario) and RV (generic Italian-pattern) family covers aluminum die-cast worm gear reducer specifications across the small-to-medium frame range. Korean OEMs frequently specify NMRV codes for packaging machinery, food-processing conveyors and light industrial drives. The full worm gear reducer code uses 5 segments separated by slashes, dashes or spaces.

PATTERN: NMRV {SIZE} {STARTS}/{RATIO} – {MOTOR} – {OUTPUT}

▸ SIZE: centre distance in mm — 030, 040, 050, 063, 075, 090, 110, 130, 150
▸ STARTS/RATIO: e.g. “1/100” (single-start, i=100), “4/15” (four-start, i=15)
▸ MOTOR: IEC frame + flange — 71B5, 80B14, 90B5
▸ OUTPUT: F (flange), FA (flange + axial), VS (hollow shaft), HS (hollow + special)

Example decoded: “NMRV 090 1/40 – 90B14 – VS” → centre distance 90 mm, single-start worm, ratio 40, IEC 90 motor with B14 flange, hollow output shaft.

WP — The Chinese Cast Iron Family Decoder

The WP family covers cast iron worm gear reducer specifications across the medium-to-large frame range across the medium-to-large frame range, dominant across Chinese manufacturing and frequently encountered in Korean industrial maintenance contexts where Chinese-spec replacement units are used. The WP code carries a 2-letter family suffix that distinguishes mounting/output orientation.

PATTERN: WP{ORIENTATION}{OUTPUT}-{SIZE}-{RATIO}

▸ ORIENTATION: A (input on top), S (input on side), O (input opposite output), D (input on top, base mount)
▸ OUTPUT: blank (solid output), KS (with keyway, hollow output), DS (double output)
▸ SIZE: 50, 60, 70, 80, 100, 120, 135, 147, 175, 200, 250, 300
▸ RATIO: direct ratio number — 10, 15, 20, 30, 40, 50, 60, 80, 100

Example decoded: “WPDA-100-30” → WP family with input on top + base mount + solid output, frame size 100, ratio 30. “WPSO-147-20-KS” → WP with input on side + opposite output, frame 147, ratio 20, hollow output with keyway.

SK — The Nord Modular Family Decoder

The Nord SK worm gear reducer family uses a different encoding philosophy from NMRV and WP — the SK number progresses through the catalogue (SK 1, SK 11, SK 12, SK 13, SK 21 etc.) rather than encoding a specific frame dimension. The first digit indicates configuration class (1 = single-stage worm, 2 = 2-stage worm-helical, 3+ = larger frames); the second digit indicates frame within the class.

PATTERN: SK {NUMBER} {RATIO}-{IEC MOTOR}-{ORIENTATION}

▸ NUMBER classification: SK 1/11/12/13 = single-stage worm, SK 02/22/32 = 2-stage helical-worm, SK 92/102 = larger 2-stage
▸ RATIO: direct number — 10, 20, 50, 100, 300 etc.
▸ IEC MOTOR: motor frame size — 80, 90, 100, 112, 132 etc.
▸ ORIENTATION suffix: M (foot mount), F (flange mount), VS (hollow shaft), VL (with motor lantern)

Example decoded: “SK 12-30-100B5” → SK 12 single-stage frame, ratio 30, IEC 100B5 motor mount. “SK 22-200-90B14-VS” → SK 22 (2-stage helical-worm), ratio 200, IEC 90B14 motor, hollow output shaft.

SCWS / SHVW — Mitsubishi Family Decoders

Mitsubishi worm gear reducer codes use the centre-distance number directly (similar to European NMRV) but distinguish family by orientation prefix. SCWS (Solid output Centre-distance Worm gear Single-stage) covers the standard cast iron range; SHVW (Solid output Hollow shaft Vertical Worm gear) covers the vertical-output specialty configuration. SCAUF and SEHV designate base-mounted and hollow-shaft variants respectively.

PATTERN: {FAMILY}-{SIZE}-{RATIO}-{MOTOR}

▸ FAMILY: SCWS (standard solid), SHVW (vertical output), SCAUF (base mount), SEHV (hollow shaft)
▸ SIZE: centre distance in mm — 110, 130, 175, 200, 250, 300
▸ RATIO: direct number — 10, 20, 30, 40, 50, 60
▸ MOTOR: JIS frame size — 90, 100, 112, 132, 160

Example decoded: “SCWS-175-30-132” → standard cast iron 175 mm centre distance, ratio 30, JIS 132 motor mount. “SHVW-200-50-100” → vertical output 200 mm centre, ratio 50, JIS 100 motor.

Frame Size Translation Across Families

The “frame size” segment encodes different things in each family — millimetres of centre distance for NMRV and SCWS, sized model number for WP, catalogue progression number for SK. The translation matrix below maps equivalent frame sizes across the four major families at common power classes. Browse our ussiülekande reduktori kataloog for sized frames in any of these family conventions.

Power Class (Approx.)	NMRV	WP	SK	SCWS
0.18-0.55 kW	030 / 040	50	SK 1	—
0.75-1.5 kW	050 / 063	60 / 70	SK 11 / 12	110
2.2-3.7 kW	075 / 090	80 / 100	SK 13 / 22	130
5.5-7.5 kW	110	120 / 135	SK 32 / 42	175
11-15 kW	130 / 150	147 / 175	SK 92 / 102	200
22-30 kW	—	200 / 250	SK 132 / 172	250
37+ kW	—	300+	SK 232+	300+

Worm gear reducer power-class mapping is approximate because each family applies different service-factor assumptions and bronze wheel materials at each frame size. For precise cross-family substitution, verify the rated torque specification against the actual application torque after applying the correct service factor (covered in our companion service factor guide). For sized planetary alternatives at higher power classes, see related notes on planetary gearbox sizing.

Reading Suffix Codes — Mounting, Output, Accessories

Worm gear reducer suffix codes after the main code segment specify the mounting orientation, output shaft type, and any accessory pack (motor lantern, torque arm, brake, encoder). Most worm gear reducer decoding errors happen at the suffix layer because the codes are short, family-specific, and occasionally reused with different meanings across vintages.

Suffix	Meaning	Common In
F	Flange-mount output, solid shaft	NMRV, SK
FA	Flange + axial output extension	NMRV
VS	Hollow shaft output	NMRV, SK
KS	Hollow shaft + keyway	WP
DS	Double output (both sides)	WP, SCWS
M	Foot mount, solid output	SK
VL	With motor lantern (no integrated motor)	SK
B5/B14	IEC motor flange standard (B5 = larger, B14 = smaller)	All families
+TA	Torque-arm accessory included	NMRV, SK
+BR	Brake accessory included	SK

Five Common Code-Translation Mistakes

Five mistakes account for the majority of worm gear reducer mismatch incidents we see when Korean and Asian buyers translate worm gear reducer catalogue codes between families. Each carries a recognisable signature that procurement teams can audit against incoming orders before commitment.

▣MISTAKE 01

Treating frame numbers as directly equivalent

“NMRV 075” ≠ “WP 75” — the 075 means 75 mm centre distance, while WP 75 is a sized model number unrelated to centre distance. Use the translation matrix.

▣MISTAKE 02

Confusing IEC and JIS motor frame codes

European IEC 80B5 has different bolt circle than Japanese JIS 80 — even though the number matches. Always verify the standard (IEC vs JIS vs NEMA) before specifying.

▣MISTAKE 03

Missing the worm-start prefix in NMRV ratio

“NMRV 075 100” is ambiguous — it might mean 4/100 (4-start, ratio 100) or 1/100 (single-start, same ratio). The two have different efficiency and self-locking. Specify the start prefix.

▣MISTAKE 04

Reading WP orientation suffix wrong

“WPS” (input on side) vs “WPA” (input on top) ship in different physical orientations. Mounting hole patterns differ by 90°. Verify orientation from the application drawing.

▣MISTAKE 05

Forgetting SK number ≠ frame dimension

SK 12 is not 12 mm or any direct dimension. Cross-reference SK to NMRV via the translation matrix; never substitute a “75 mm centre distance” worm gear reducer for SK 12 by direct number match.

Catalogue Code Decoder FAQ

Q: Are NMRV and RV codes interchangeable, or do they refer to different worm gear reducer specifications?

A: For most Korean and Asian worm gear reducer engineering work, the two codes refer to the same family. NMRV is Motovario’s branded naming; RV is the broader industry name for the Italian aluminum centre-distance pattern. Frame sizes, ratios and mounting standards are identical between the two. Sourcing from suppliers using different naming (e.g. RV from a Chinese factory vs NMRV from Italy) generally delivers compatible hardware on like-for-like specifications.

Q: How do I read a code I cannot identify against any of the four families covered above?

A: Other worm gear reducer catalogue families exist — Bonfiglioli VF, SEW S, Sumitomo Cyclo HE, STM RD, etc. Each follows similar segment logic (family + size + ratio + suffix). Cross-reference the unknown code segment-by-segment against the manufacturer’s catalogue or contact the supplier directly. The frame size segment is usually the easiest to identify because it correlates with measurable physical dimensions on the existing unit. Once frame size is matched, ratio and motor suffix follow.

Q: My nameplate shows partial code only — how do I reconstruct the full specification?

A: Identify the worm gear reducer family first (often visible), then measure centre distance from input shaft to output shaft to determine frame size. Output shaft diameter and motor flange dimensions narrow down the rest. For complete reconstruction, measure: centre distance, output shaft Ø and length, motor flange Ø and bolt circle, total housing length, foot mounting hole pattern. Send measurements to the supplier with photos for catalogue cross-reference. A correctly reconstructed worm gear reducer specification matches the original on physical dimensions even if the original code is fully lost.

Q: Why do some catalogues use single-start vs multi-start worm encoding in the ratio segment?

A: NMRV and SCWS encode the worm-start count in the ratio segment (“4/100” = 4-start worm, ratio 100) because the start count affects efficiency, self-locking and tooth profile — engineering attributes that change the unit’s behaviour even at the same ratio. WP and SK encode ratio only; the start count is implicit from the ratio range. For worm gear reducer applications where self-locking matters (low-ratio lifting drives), explicitly specify single-start in the procurement specification regardless of which family code applies.

Q: Can I substitute a smaller numerical frame across families if the power class matches?

A: Numerical match across worm gear reducer families is not a reliable substitution rule. NMRV 075 and WP 75 differ in service factor assumption and bronze wheel material, so the rated power at the same numerical size can differ by 30%. Use the power-class translation matrix above as the primary mapping, then verify torque and centre distance directly against the original specification. For critical applications, request a side-by-side dimensional comparison drawing from the supplier before committing.

Q: How do I specify a worm gear reducer code that includes accessories like brakes or torque arms?

A: Most families append accessory codes after the main code with a “+” or “-” separator. NMRV uses “+TA” for torque arm, “+ENC” for encoder. SK uses “+BR” for brake, “+VL” for motor lantern. WP and SCWS typically order accessories as separate line items rather than embedding in the main code. Verify the supplier’s accessory naming convention from their current catalogue rather than assuming consistency across vintages — accessory codes change between catalogue editions more often than main codes do.

Need a Catalogue Code Cross-Reference?

Send the legacy worm gear reducer code, nameplate photo, or physical dimensions. Our Korean engineering team returns a verified cross-reference with matching frame, ratio, motor mount and accessory pack across NMRV, WP, SK, SCWS or any other catalogue family within 24-48 hours.

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