
Overview
The CHIHAI MOTOR CHR-GM25-BK370 combines a black-can permanent-magnet brushed motor with a metal reduction gearbox. Select the 6V or 12V winding, nominal reduction ratio and motor, bracket, lead-pair or wheel-kit package. This DC gear motor is suited to compatible small robots, model racing cars, trucks and drive mechanisms.
Features
- All-metal reduction gears and replaceable extended carbon brushes.
- 4 mm D-shaped output shaft with a 12 mm projection reference.
- Reversible brushed DC construction.
- Motor-only and accessory packages retain distinct contents.
Specifications
| Specification | Value / scope |
|---|---|
| Model | CHIHAI MOTOR CHR-GM25-BK370 black-can permanent-magnet brushed DC gearmotor |
| Selectable windings | 6V DC or 12V DC; match the selected winding |
| Selected nominal ratios | 4.4:1,10:1,15:1,20:1,34:1,45:1,57:1,75:1,100:1 |
| Gear construction | All-metal reduction gears |
| Brush construction | Extended, replaceable carbon brushes |
| Body diameter | 25 mm gearbox reference;24.4 mm rear motor reference |
| Output shaft | 4 mm D-shaft;3.5 mm flat reference;12 mm projection;8 mm flat-length reference |
| Front mounting | Two M3 tapped holes on 17 mm drawing reference |
| Other drawing references | 7 mm front register;2.5 mm front step;29.3 mm motor can;7.5 mm rear-cap reference;8 mm rear register |
| Gearbox length L | 19–29 mm series reference;see ratio table |
| Motor weight | Approximately85–87 g,ratio-dependent |
| Series body-length reference | 48.5–59 mm;check the complete drawing for shaft and rear-cap allowances |
| Supply capacity reference | Compatible DC supply rated at least 10A;voltage must match selected motor |
| Gearbox load ceiling | Maximum permissible 8.0 kgf·cm(approximately 0.8 N·m),not a minimum or continuous rated torque |
Performance by Voltage
These are voltage-specific reference tables. The6V table uses a 10000 rpm motor input and an 8W maximum-power reference; the 12V table uses 20000 rpm and 26W. Maximum power is a separate operating reference, not continuous rated output at every ratio. No-load and rated speeds describe different loads.
The selected 15:1 version has no corresponding performance or gearbox-length entry in these tables. Do not substitute data from another ratio. The125:1,217:1 and 478:1 columns are series references and are not selectable configurations here. A dash in the torque column means no individual rated torque is provided; the 8.0 kgf·cm gearbox limit must not be treated as that rated torque.
6V reference
No-load current ≤320 mA.
| Nominal ratio | No-load rpm | Rated torque(kgf·cm) | Rated torque(N·m) | Rated rpm | Rated current(A) | Stall current(A) | Gearbox L(mm) |
|---|---|---|---|---|---|---|---|
| 4.4:1 | 2250 | 0.3 | 0.03 | 1750 | ≤1.4 | ≤8.0 | 19 |
| 10:1 | 1000 | 0.60 | 0.06 | 790 | ≤1.4 | ≤8.0 | 19 |
| 20:1 | 490 | 1.2 | 0.12 | 390 | ≤1.4 | ≤8.0 | 19 |
| 34:1 | 280 | 2.0 | 0.20 | 230 | ≤1.4 | ≤8.0 | 21.5 |
| 45:1 | 220 | 2.7 | 0.27 | 175 | ≤1.4 | ≤8.0 | 24 |
| 57:1 | 175 | 3.5 | 0.34 | 135 | ≤1.4 | ≤8.0 | 24 |
| 75:1 | 130 | 4.5 | 0.44 | 100 | ≤1.4 | ≤8.0 | 26.5 |
| 100:1 | 100 | 6.0 | 0.59 | 80 | ≤1.4 | ≤8.0 | 26.5 |
| 125:1 | 80 | — | — | 60 | ≤1.4 | ≤8.0 | 29 |
| 217:1 | 45 | — | — | 37 | ≤1.4 | ≤8.0 | 29 |
| 478:1 | 20 | — | — | 18 | ≤1.4 | ≤8.0 | 29 |
12V reference
No-load current ≤600 mA.
| Nominal ratio | No-load rpm | Rated torque(kgf·cm) | Rated torque(N·m) | Rated rpm | Rated current(A) | Stall current(A) | Gearbox L(mm) |
|---|---|---|---|---|---|---|---|
| 4.4:1 | 4500 | 0.5 | 0.05 | 3500 | ≤2.7 | ≤16.0 | 19 |
| 10:1 | 2000 | 1.1 | 0.10 | 1580 | ≤2.7 | ≤16.0 | 19 |
| 20:1 | 980 | 2.3 | 0.21 | 780 | ≤2.7 | ≤16.0 | 19 |
| 34:1 | 580 | 3.50 | 0.34 | 460 | ≤2.7 | ≤16.0 | 21.5 |
| 45:1 | 440 | 4.50 | 0.44 | 350 | ≤2.7 | ≤16.0 | 24 |
| 57:1 | 350 | 6.00 | 0.59 | 275 | ≤2.7 | ≤16.0 | 24 |
| 75:1 | 260 | 7.00 | 0.69 | 210 | ≤2.7 | ≤16.0 | 26.5 |
| 100:1 | 200 | — | — | 160 | ≤2.7 | ≤16.0 | 26.5 |
| 125:1 | 160 | — | — | 130 | ≤2.7 | ≤16.0 | 29 |
| 217:1 | 90 | — | — | 75 | ≤2.7 | ≤16.0 | 29 |
| 478:1 | 40 | — | — | 37 | ≤2.7 | ≤16.0 | 29 |
The gearbox maximum permissible load is 8.0 kgf·cm(approximately 0.8 N·m). The merged limit applies in place of individual high-ratio torque figures in the illustrated tables; exceeding it can damage gears. Never operate stalled or overloaded. Stall-current figures describe a limiting condition, not a recommended operating point.
Mounting and Wiring
Check the 4 mm shaft,3.5 mm flat,12 mm projection,8 mm flat length and two M3 mounting holes against the mechanism. Use the complete drawing to account for gearbox length, motor can, rear cap and shaft clearance. The drawing lists L =19 mm for 4.4:1,10:1 and 20:1;21.5 mm for 34:1;24 mm for 45:1 and 57:1;26.5 mm for 75:1 and 100:1;29 mm for 125:1,217:1 and 478:1 series references. No dimension is inferred for 15:1.
Connect a DC supply matching the selected 6V or 12V winding. The motor-series supply recommendation is at least 10A capacity; select suitable switching, wiring and current protection for the actual starting and running conditions. Reverse motor-terminal polarity to reverse rotation. Test with temporary leads before permanent installation and keep the output free of obstruction.
Applications
Compatible small robot drives, model racing cars, trucks and compact mechanical drive assemblies. Select the reduction ratio by required speed and allowable load. Running speed changes with load; reducing supply voltage can also reduce available torque.
What's Included
| Selected package | Contents |
|---|---|
| Motor Only | 1 motor |
| Motor + Mounting Bracket | 1 motor and 1 mounting bracket |
| Motor + Spade-Terminal Lead Pair | 1 motor and 1 red/black spade-terminal lead pair,20 cm20AWG reference |
| Motor + Bracket + Hex Coupler + 65 mm Wheel | 1 motor,1 mounting bracket,1 hex coupler with shown fastening hardware and 1 65 mm wheel; wheel style may vary |
The wheel-kit photo shows three alternative wheel styles, not three included wheels. One65 mm wheel is supplied and its style may vary. A motor-only selection does not include the bracket, coupler, wheel, leads, power supply or speed controller.
FAQ
Is8.0 kgf·cm the rated output of every ratio?
No. It is a gearbox maximum permissible load. Use the individual rated-torque entries where provided and avoid overload.
Can the 6V and 12V tables be interchanged?
No. Match the table to the selected voltage winding; their speed, power and current references differ.
Where are the 15:1 performance figures?
The15:1 option is selectable, but no corresponding performance or gearbox-length data is provided. Other ratios must not be substituted.
Does the wheel kit include three wheels?
No. The photo shows alternative styles. The package includes one 65 mm wheel with the motor, bracket and hex coupler.
Can this motor reverse?
Yes. Reverse the DC motor-terminal polarity using a suitable switching arrangement and avoid reversing a stalled or overloaded mechanism.
Visual Details







