SIGGEAR · miniature gearboxes and geared motors

SIGGEAR
Fit the gearbox to the actuator’s envelope and duty.

SIGGEAR’s 22 mm and 28 mm metal planetary gearboxes are component choices for compact motor/actuator integration. Stage count changes their length, permitted load and efficiency. Start with the space, motion cycle and motor interface, then compare one complete configuration.

Compare PG22 and PG28 Read stage-specific ratings →

Small diameters, distinct shaft limits

Compare the mechanical envelope first.

Both official pages list metal housings/gears and ball-bearing outputs. The supplier gives a continuous-running input-speed ceiling of 8,000 rpm and gearbox temperature range of −40 to 120°C. Confirm those conditions for the ordered motor, lubricant, duty and assembly; they do not automatically describe a complete geared motor.

SG-PG22 · original manufacturer illustration.

SG-PG22 · 22 mm

Radial load listed: ≤1.6 kgf · approximately 15.7 N
Axial load listed: ≤0.5 kgf · approximately 4.9 N
No-load backlash: ≤1.5° · 90 arcmin
Radial / axial play: ≤0.04 / ≤0.2 mm

Existing PG22 product information →

SG-PG28 · original manufacturer illustration.

SG-PG28 · 28 mm

Radial load listed: ≤6.0 kgf · approximately 58.8 N
Axial load listed: ≤3.0 kgf · approximately 29.4 N
No-load backlash: ≤1.2° · 72 arcmin
Radial / axial play: ≤0.04 / ≤0.3 mm

Existing PG28 product information →

The pages do not define the radial load’s lever arm or a complete combined-force/life calculation. Send the actual load position and direction for confirmation. The no-load backlash values above are in degrees, not the ≤1–3 arcmin precision class used by some larger servo reducers.

A longer stage stack changes the load and efficiency.

The table uses one example ratio from each official stage row. More discrete ratios are listed on the source pages, and custom ratios require a separate design. L is the supplier’s stage-dependent length, not a complete motor/shaft assembly length.

Model / stages	L	Example listed ratio	Rated permitted load	Instantaneous permitted load	Table efficiency
PG22 · 1	22.6 mm	4	8 kgf·cm ≈0.78 Nm	16 kgf·cm ≈1.57 Nm	90%
PG22 · 2	27.9 mm	16	10 kgf·cm ≈0.98 Nm	20 kgf·cm ≈1.96 Nm	80%
PG22 · 3	33.2 mm	64	15 kgf·cm ≈1.47 Nm	30 kgf·cm ≈2.94 Nm	73%
PG22 · 4	38.5 mm	256	25 kgf·cm ≈2.45 Nm	50 kgf·cm ≈4.90 Nm	66%
PG28 · 1	25.6 mm	4.4	20 kgf·cm ≈1.96 Nm	40 kgf·cm ≈3.92 Nm	90%
PG28 · 2	31.9 mm	19.4	25 kgf·cm ≈2.45 Nm	50 kgf·cm ≈4.90 Nm	80%
PG28 · 3	38.2 mm	85.2	35 kgf·cm ≈3.43 Nm	70 kgf·cm ≈6.86 Nm	73%
PG28 · 4	44.5 mm	326.2	50 kgf·cm ≈4.90 Nm	100 kgf·cm ≈9.81 Nm	66%

Preserve the row’s efficiency.

The pages’ summary says 90% per stage, while the detailed rows give 90%, 80%, 73% and 66% for one to four stages. Use the detailed stage row when estimating the selected assembly; do not pair a four-stage load/ratio with one-stage efficiency.

Keep transient and running load separate.

The instantaneous permitted load is not a continuous torque rating. Give peak duration, repeat rate, starts/stops, motor stall behaviour and controller current limit. Ask for the permitted transient cycle and expected life at the actual running load.

Use coherent units.

Nm equivalents here are rounded calculations using 1 kgf·cm = 0.0980665 Nm. Original kgf·cm values remain visible for source comparison. A “50” in this table does not mean 50 Nm.

PG28 official cutaway · stage stack and output components.

Actuator integration

The gearbox is one part of the axis.

Specify the motor voltage, loaded speed, duty, available diameter/length and motor-side mounting. Agree pinion/input connection, flange/pilot, fastening, shaft geometry and complete assembly drawing. The supplier accepts special specifications; a custom interface needs a drawing revision and sample acceptance plan.

For a small positioning actuator, give the required repeatability under load, reversal pattern and sensor location. A catalogue no-load backlash maximum alone does not establish final closed-loop positioning accuracy.

For a wheel or overhung mechanism, show bearing support and radial/axial forces. If shaft loading exceeds the selected miniature gearbox’s confirmed bearing capacity, consider an external support or a different drive architecture. SIGGEAR’s hub and integrated-joint products are distinct families with their own ratings.

For a medical or wearable design, define the complete machine’s safety and regulatory requirements, temperature/noise constraints and fault behaviour. A listed application sector is not certification of the PG22/PG28 component for a finished device.

Turn the development scope into measurable sample acceptance.

The official development page lists gear manufacturing, assembly and inspection equipment, including backlash, dynamometer, life and temperature-test facilities. Use those capabilities to discuss the test required for the ordered design, with loads, speed, cycle and failure criteria agreed in advance.

Official development/facility image · machining equipment photograph.

Sample evidence to request

Agree loaded speed/current, continuous and peak torque tests, efficiency at the chosen operating point, backlash measurement, shaft play, noise measurement conditions and a representative life cycle. Confirm material, lubricant, motor winding and drawing revision so production matches the approved sample.

Independent industry context

The national standards platform names the Chinese legal company as a drafting participant in plan 20254685-T-604, “Test method for plastic gear reducers,” shown at consultation stage when reviewed. This is standards-development context for the company, not certification of these metal PG models or proof that a particular order has passed a test.

Prepare an actuator integration brief.

Give the motion cycle and packaging constraints so a standard or custom gearbox can be selected coherently.

Prepare sourcing request

Actuator function, quantity, prototype and production expectations.
Motor voltage, input speed and required loaded output speed.
Continuous/peak torque with units, duration and repetition.
Diameter, complete available length and mounting/interface drawing.
External shaft forces, support and permitted play/backlash.
Ambient conditions, duty, noise and target life/test cycle.
Sample criteria, drawing revision and production traceability.