DC Planetary Gearmotors & Gearboxes

The product family has two starting paths

Application-specific platform

The 28 mm tailgate strut planetary gearmotor is KEY-CRON’s flagship focus. It starts from a defined package and application direction, then confirms ratio, motor direction, output coupling, wire and connector, mounting, controller interface, movement, current, noise, temperature, endurance, and system approval around the actual strut program.

Standard reference range

The 10–42 mm all-metal planetary series provides published diameter, voltage, power, ratio, speed, torque, and length references for preliminary screening. It is not one universal configuration: each diameter contains motor and ratio combinations with different working points and limits.

If neither path fits, the project can define a modified standard configuration or a more application-specific program. Feasibility, non-recurring work, tooling, MOQ, samples, validation, and timing are then scoped explicitly.

Select the complete motion system

1. Start at the mechanism

Define what moves, how motion reaches the load, and where the worst operating point occurs. A direct shaft, belt, cable drum, lead screw, spindle, wheel, valve, or linkage converts gearmotor output differently. Include continuous, starting, peak, holding, shock, obstruction, and back-drive cases.

2. Establish speed and ratio

An initial ratio is the expected loaded motor speed divided by required output speed. The nearest available ratio must then be evaluated on the actual motor curve. Higher reduction generally lowers output speed and can increase available output torque, but may add stages, length, loss, backlash, noise, cost, and cycle time.

The ratio calculation guide explains the initial equations and screening steps.

3. Check torque with efficiency and gearbox limits

Ideal multiplication overstates output. Estimate with motor torque, total ratio, and configuration-specific efficiency, then check rated and time-limited gearbox torque, input speed, radial and axial load, bearing support, shock, stall, and holding conditions. Stall torque is not a continuous operating point.

4. Check current and thermal duty

Confirm voltage at the motor, controller current limit, starting and peak current, run/rest cycle, reversals, ambient temperature, enclosure, airflow or conduction path, and winding or gearbox temperature. A short successful movement does not prove repeated-cycle thermal suitability.

5. Define interfaces

The controlled interface may include:

• output shaft, D-flat, thread, spline, gear, coupling, or customer geometry;
• output bearing support, radial and axial load, retaining features, and lubrication boundary;
• mounting face, hole pattern, orientation, housing, seal, and adjacent parts;
• motor direction, leads, terminals, connector, pinout, wire length, routing, and strain relief;
• Hall sensor, encoder, switch, current sensing, or another feedback interface where applicable.

Interface customization is not only a drawing change. It may affect tooling, component sourcing, assembly, inspection, balance, sealing, noise, capacity, and MOQ.

Validation must use defined conditions

Performance

Measure speed, torque or force, current, efficiency where required, movement time, holding, start, obstruction, and back-drive under agreed voltage, load, temperature, mechanism position, and controller behavior.

Acoustics and feel

Define airborne or structure-borne noise, distance, mounting, background, load, speed, travel position, temperature, equipment, processing, and pass/fail value. Also consider vibration, backlash, torque ripple, and perceived smoothness.

Thermal and endurance

Define cycle profile, run/rest time, direction changes, load distribution, voltage, temperature, orientation, lubrication condition, inspection interval, allowable drift, and failure criteria. Accelerated tests require a stated relationship to the intended use.

Environmental and interfaces

Depending on the product, confirm temperature and humidity exposure, vibration, shock, dust/water boundary, corrosion, chemicals, wire retention, connector, mounting, output interface, packaging, and transport.

Production release evidence

The release package is project-specific and may include:

• product datasheet and released dimensional/interface drawing;
• approved motor, ratio, shaft, connector, wire, mounting, and direction;
• incoming, in-process, functional, torque, current, noise, or final-inspection records;
• material, component, RoHS/REACH, or other agreed declarations;
• approved sample, boundary sample, test report, serial or lot traceability, and packing list;
• PPAP, FMEA, control plan, capability, or customer-specific records when contracted.

These documents are not automatic. Name required evidence before quotation and sample release.

Manufacturing relationship and certification boundary

KEY-CRON is the product and project coordination contact. Manufacturing may be performed by the long-term Zhuhai partner or another approved source matched to the model and scope. Before representing a certification or capability, verify the legal entity, production site, process, model, certificate scope, validity, and any subcontracting relevant to the project.

Factory management-system certification does not certify a gearmotor for an application. The customer retains final product and application approval unless a different responsibility is explicitly contracted.

When the gearmotor is only one component

KEY-CRON can coordinate molded gears and housings, mold tooling, metal brackets, wire harnesses, electronics, functional testing, assembly, packing, and delivery around the primary motion component. The advantage for a small Western team is a direct English engineering path across those interfaces—not an assumption that every adjacent task is included without scope.