{"id":1948,"date":"2026-10-08T06:50:39","date_gmt":"2026-10-08T06:50:39","guid":{"rendered":"https:\/\/metalite.net\/?p=1948"},"modified":"2026-10-08T07:01:08","modified_gmt":"2026-10-08T07:01:08","slug":"rv-series-worm-gearbox-nmrv","status":"publish","type":"post","link":"https:\/\/metalite.net\/kk\/application\/rv-series-worm-gearbox-nmrv\/","title":{"rendered":"RV Series Worm Gearbox (NMRV): Frame Sizes, Ratios & IEC Motor Interface | Metalite"},"content":{"rendered":"
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The RV Series worm gearbox \u2014 widely referenced in the global market under the NMRV designation \u2014 is the most adopted general-purpose compact worm reducer format in the world. Its defining feature is a square-block flange housing with standardised motor mounting faces on all four sides, allowing a servo, induction, or brake motor to be bolted directly onto the gearbox body without separate brackets, adapters, or base plates. The result is a compact, self-contained motor-gearbox assembly that OEM machine builders can integrate in minimal installation space and commission quickly.<\/p>\n

This page covers the full RV Series specification: frame sizes, torque and power ratings, gear ratios, housing construction by frame size, IEC\/NEMA motor interface options, output configurations, and how to read the RV model code. For a direct comparison with the WP Series cast iron gearbox, see our RV vs WP Worm Gearbox comparison guide<\/a>.<\/p>\n

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RV Series and NMRV: Are They the Same Gearbox?<\/h2>\n
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\"RV<\/p>\n

RV Series (NMRV) worm gearbox \u2014 square-block flange housing, direct IEC\/NEMA motor mounting on any face<\/p>\n<\/div>\n

Yes \u2014 the RV Series and NMRV gearbox refer to the same product category. The difference is purely nomenclature: NMRV<\/strong> (Non-standard Modular Reduction Variator) is the designation that became common across Chinese and European manufacturers in the 1990s and now dominates global OEM supply chains. RV<\/strong> is the designation used internally by EPG Canada and a number of manufacturers to describe the same square-block, flange-housing worm gearbox format. The two are dimensionally interchangeable across the major frame sizes (025 through 150).<\/p>\n

What distinguishes both RV and NMRV from earlier worm gearbox formats (such as the WP Series or traditional foot-mounted units) is the housing geometry: a compact cube or rectangular block with a precise IEC\/NEMA motor flange machined onto one face, and optionally onto all four faces for omnidirectional motor mounting. This “motor-ready” interface eliminates the adaptor bracket and shaft coupling that traditional foot-mounted designs require.<\/p>\n

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Ordering note:<\/strong> When replacing an existing NMRV or NRV gearbox from any manufacturer, the EPG Canada RV Series is dimensionally compatible for the same frame size and ratio \u2014 confirm the output shaft diameter and keyway dimensions before ordering to ensure a drop-in fit.<\/p>\n<\/div>\n

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RV Series Frame Sizes, Torque and Power Ratings<\/h2>\n

The frame size number corresponds to the worm centre distance in millimetres. Frame sizes 025 through 090 use die-cast aluminum alloy housings; from frame 110 upward, cast iron is used as the larger torques require greater wall section strength. This is the same cross-over point used across all major NMRV manufacturers.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Frame Size<\/th>\nCentre Distance (mm)<\/th>\nMax Output Torque (Nm)<\/th>\nInput Power Range (kW)<\/th>\nOutput Shaft Dia. (mm)<\/th>\nHousing<\/th>\n<\/tr>\n<\/thead>\n
025<\/td>\n25<\/td>\n4<\/td>\n0.06 \u2013 0.09<\/td>\n11<\/td>\nAluminum<\/td>\n<\/tr>\n
030<\/td>\n30<\/td>\n8<\/td>\n0.06 \u2013 0.12<\/td>\n14<\/td>\nAluminum<\/td>\n<\/tr>\n
040<\/td>\n40<\/td>\n25<\/td>\n0.09 \u2013 0.37<\/td>\n18<\/td>\nAluminum<\/td>\n<\/tr>\n
050<\/td>\n50<\/td>\n50<\/td>\n0.18 \u2013 0.75<\/td>\n25<\/td>\nAluminum<\/td>\n<\/tr>\n
063<\/td>\n63<\/td>\n100<\/td>\n0.37 \u2013 1.5<\/td>\n28<\/td>\nAluminum<\/td>\n<\/tr>\n
075<\/td>\n75<\/td>\n200<\/td>\n0.55 \u2013 2.2<\/td>\n35<\/td>\nAluminum<\/td>\n<\/tr>\n
090<\/td>\n90<\/td>\n350<\/td>\n0.75 \u2013 4.0<\/td>\n40<\/td>\nAluminum<\/td>\n<\/tr>\n
110<\/td>\n110<\/td>\n600<\/td>\n1.5 \u2013 7.5<\/td>\n50<\/td>\nCast iron<\/td>\n<\/tr>\n
130<\/td>\n130<\/td>\n980<\/td>\n2.2 \u2013 11<\/td>\n60<\/td>\nCast iron<\/td>\n<\/tr>\n
150<\/td>\n150<\/td>\n1,760<\/td>\n4.0 \u2013 15<\/td>\n70<\/td>\nCast iron<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

* Max output torque values at lowest efficiency point. Multiply calculated application torque by your service factor before selecting frame size. Contact our team for full thermal power ratings on continuous-duty applications.<\/p>\n

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Standard Gear Ratios and Output Speed Reference<\/h2>\n

All RV Series frame sizes cover the same standard ratio range in a single stage. Dual-stage (two RV units coupled in series) extends this significantly for very low output speed requirements.<\/p>\n

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Single Stage: 5:1 to 100:1<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Ratio<\/th>\nOutput RPM (1,450 in)<\/th>\nOutput RPM (1,400 in)<\/th>\n<\/tr>\n<\/thead>\n
5:1<\/td>\n290<\/td>\n280<\/td>\n<\/tr>\n
7.5:1<\/td>\n193<\/td>\n187<\/td>\n<\/tr>\n
10:1<\/td>\n145<\/td>\n140<\/td>\n<\/tr>\n
15:1<\/td>\n97<\/td>\n93<\/td>\n<\/tr>\n
20:1<\/td>\n72<\/td>\n70<\/td>\n<\/tr>\n
25:1<\/td>\n58<\/td>\n56<\/td>\n<\/tr>\n
30:1<\/td>\n48<\/td>\n47<\/td>\n<\/tr>\n
40:1<\/td>\n36<\/td>\n35<\/td>\n<\/tr>\n
50:1<\/td>\n29<\/td>\n28<\/td>\n<\/tr>\n
60:1<\/td>\n24<\/td>\n23<\/td>\n<\/tr>\n
80:1<\/td>\n18<\/td>\n17.5<\/td>\n<\/tr>\n
100:1<\/td>\n14.5<\/td>\n14<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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Dual Stage: Up to 3,600:1<\/p>\n

Two RV units in series multiply ratios. Common combinations:<\/p>\n\n\n\n\n\n\n\n\n\n
Combined Ratio<\/th>\nExample Combination<\/th>\n<\/tr>\n<\/thead>\n
400:1<\/td>\n20:1 \u00d7 20:1<\/td>\n<\/tr>\n
900:1<\/td>\n30:1 \u00d7 30:1<\/td>\n<\/tr>\n
1,600:1<\/td>\n40:1 \u00d7 40:1<\/td>\n<\/tr>\n
2,500:1<\/td>\n50:1 \u00d7 50:1<\/td>\n<\/tr>\n
3,600:1<\/td>\n60:1 \u00d7 60:1<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
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Note:<\/strong> Dual-stage efficiency is the product of both stages \u2014 verify thermal rating carefully. Provide both required ratio and duty cycle when enquiring for dual-stage units.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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Housing Construction: Material, Finish, and Worm Wheel Options<\/h2>\n
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\"RV<\/p>\n

Aluminum Alloy Housing (Sizes 025\u2013090)<\/p>\n