Specifying a gearbox into a motor control cabinet is a paperwork problem before it is a mechanical problem: the gearbox certificate pack must prove enclosure class, lubrication, ATEX/IECEx zone, and thermal balance before the motor control center feeder is even sized.
The minimum evidence set covers the gearbox nameplate, the EU/UKCA Declaration of Conformity, the ATEX or IECEx certificate of conformity, the test bench report (no-load, loaded, overload, thermal-rise), and the lubrication and maintenance schedule. Each item must be cross-referenced to the MCC cabinet feeder circuit, the busbar short-circuit rating, and the motor's duty class.
Scope: What a Gearbox Certification Pack Must Cover
A gearbox delivered to an MCC integration shop is expected to ship with a multi-section dossier: mechanical drawings, gear geometry data, material certificates for the housing and shaft, balancing grade per ISO 1940-1, and a signed routine test report. The Linktron Group function test bench, published 2026-07-26, runs a 20 kW drive motor at up to 14,000 RPM with a ±45° bidirectional tilt envelope, illustrating the operating envelope that supplier test data has to bracket for new units [S1].
For the cabinet side, the gearbox certificate pack must also state the mounting position (foot, flange, shaft-mounted), the oil fill volume, the breather/vent position, and any paint or corrosion-protection specification. Skipping any of these items is the most common reason an MCC integrator has to stop the FAT clock and request a deviation note from the gearbox vendor.
The scope must explicitly include the input coupling or belt-drive interface, the output shaft seal, and the terminal-box position if the gearbox is supplied with an integrated backstop or speed sensor. Each interface point should be listed with its own tolerance and standard reference so the MCC wiring diagram and the gearbox outline drawing agree line by line.
Selection Criteria: Matching Gearbox Evidence to the MCC Feeder
Select the gearbox certificate set against four decision criteria: ambient and zone classification, mechanical load envelope, thermal balance, and electrical integration. The gearbox ATEX or IECEx certificate must name the exact zone (1, 2, 21, 22) and the temperature class (T1-T6), and that marking has to be compatible with the distribution cabinet environment where the MCC lineup is installed.
Mechanical envelope checking means reading the catalogue pages for radial load on the output shaft, axial load, and the permissible overhung load at the coupling point. The supplier routine test report should show no-load current, full-load current, full-load torque, and a thermal-rise curve at the rated duty. Where the duty is S3, S4, or S6, the report must identify the cyclic duration factor (e.g. 25%, 40%, 60%) so the MCC overload relay can be set to match.
Electrical integration criteria: the gearbox nameplate voltage, frequency, and current must align with the MCC feeder circuit's rated current and short-circuit withstand (Icw). The certificate pack should also list the terminal box IP class (typically IP55 or IP65 for industrial cabinets), the cable gland thread type (metric M20-M50), and the earthing terminal cross-section. A separate ATEX/IECEx certificate is required if the terminal box itself is in a classified zone.
Who This Checklist Is For, and Where It Stops
This checklist is built for OEM skid builders, EPC procurement engineers, and MCC panel builders who receive gearboxes as bought-out items and have to clear them through their own incoming inspection and FAT. It is not a substitute for the gearbox manufacturer's own type-testing, and it does not cover gear-mesh design calculations or bearing-life analysis, which remain the vendor's responsibility.
It is not aimed at end users who only operate the cabinet, nor at bearing-only or coupling-only procurement. For those scopes, a different checklist focused on lubrication intervals or coupling alignment is the correct tool, and a separate file should be raised.
The checklist is also not a safety case for the gearbox in isolation. The ATEX or IECEx certificate proves the gearbox is safe in its declared zone; the MCC integration engineer still has to verify the complete assembly, including cabling, glands, and the control-cable routing, against the relevant standards for the installation site. For a deeper look at how the control cable side of the integration is handled, see the [control cable](/encyclopedia/control-cabinet.html) reference entry.
Comparison: What Each Certificate Type Actually Proves
Four document types appear in almost every gearbox delivery, and a busy MCC shop can confuse them. The EU/UKCA Declaration of Conformity states the directives the gearbox complies with (typically the Machinery Directive 2006/42/EC and the Low Voltage Directive 2014/35/EU, plus ATEX 2014/34/EU if zone-marked). It is a self-declaration by the manufacturer and does not include test data. [S1]
The ATEX or IECEx Certificate of Conformity is a third-party-issued document and is the only paper that authorises the gearbox for use in a classified zone. It is the only document that should be used to clear the gearbox through an MCC FAT in a hazardous area. The routine test report, by contrast, is unit-specific and must be tied to the gearbox serial number, while the type test report applies to a family of units and is the basis for the EU/UKCA declaration.
A plain comparison: routine test = serial-numbered, sample of one; type test = family-level, sample of a design series; Declaration of Conformity = self-attestation; ATEX/IECEx certificate = notified-body or certification-body attestation. An MCC procurement engineer who can read the difference between these four will reject far fewer files in the FAT room.
Real Use Cases: Three Integration Paths
Use case 1, indoor pump room, non-classified: a helical-bevel gearbox coupled to a centrifugal pump, fed from a fixed MCC lineup at 400 V / 50 Hz. The certificate pack needs the EU Declaration of Conformity, the routine test report, the lubrication schedule, and a terminal-box IP rating that matches the room's IP requirement. No ATEX document is needed unless the room is classified. [S1]
Use case 2, Zone 1 / Zone 21 paint line: a helical-worm gearbox with integrated backstop, fed from a withdrawable-unit MCC. The pack must include the ATEX certificate with named zone and temperature class, the IECEx certificate if the project is outside the EU, the cable-gland certificate, and a separate earthing-bonding test record. The MCC feeder circuit must use a certified control cable with the matching temperature class.
Use case 3, outdoor wastewater plant, IP55 minimum: a parallel-shaft gearbox under a canopy, fed from a motor control center with a soft-starter section. The pack needs the IP55 declaration on the terminal box, the paint specification (typical C3 or C4 per ISO 12944), the breather-plug position, and a thermal-rise curve that accounts for summer ambient. The checklist for inductive sensors used in a similar workcell is a useful parallel reference; see Inductive sensor certification checklist for a robotic workcell.
Limitations, Failure Modes, and Common Audit Findings
Common audit findings on gearbox certificates in MCC integration: the ATEX certificate is for a different serial-number range than the unit delivered; the IP rating on the terminal box does not match the IP rating on the gearbox body; the lubrication oil type is listed as "mineral" with no viscosity grade; the routine test report is missing the overload test result or the thermal-rise curve; and the type test is more than five years old without revalidation evidence. [S1]
Failure modes the checklist is designed to catch: thermal overload of the gearbox in an S3 or higher duty, ignored by an MCC overload relay set to the motor's full-load current rather than the gearbox's service factor; ingress of water through a top-mounted breather on a vertical gearbox; bearing failure from misalignment of the input coupling, which a routine vibration test report would have caught at the FAT.
Limitations of the certificate pack itself: it is a paperwork chain, not a measurement on the delivered unit. The integrator should still perform an incoming visual inspection, a nameplate data check against the purchase order, a coupling alignment check, and a no-load run before energising the motor from the MCC feeder.
Sourcing, Standards, and How to Verify a Certificate
Primary standards to expect on a European gearbox certificate pack: ISO 6336 for gear strength calculation, ISO 1940-1 for balance grade, ISO 12944 for paint, ISO 4014 for fastener grades, EN 60079-0 and EN 60079-1 for ATEX terminal boxes, and IEC 60034-1 for the motor rating. For ATEX zone marking, the gearbox certificate must reference ATEX 2014/34/EU and list the notified body number; for IECEx, the certificate body and the ExTR (test report) number must be visible. [S1]
Verify a certificate by cross-referencing the notified body or certification body number against the European Commission's NANDO database for ATEX, or the IECEx OD database for IECEx. A certificate that does not appear in the database, or that has been amended without an amendment number, is a red flag. The gearbox serial number on the certificate must match the nameplate on the unit, and the certificate's issue date must be after the date of the standards listed on it.
Where the gearbox is bought out of China, the China Compulsory Certification (CCC) mark may also appear and should be checked against the CCC database. For a buyer's-eye view of OEM versus ODM sourcing risk on adjacent rotating-equipment lines, see OEM vs ODM for LNG Equipment: Which Model Fits the Buyer's Spec Gate, which uses the same evidence-chain logic. Final sign-off at the FAT should be a stamp on the certificate pack, not on the gearbox itself, and a copy of the stamped file should travel with the MCC lineup to site.