
Overview
The CHIHAI MOTOR CHR-GM 25-310T DC gear motor combines a compact 25 mm metal gearbox with a 7.4 V brushed motor. Choose a rear-shaft motor without feedback, an 11 PPR Hall encoder motor with or without rear cover, or a 360 CPR optical encoder motor. Select the package and reduction ratio independently from the actual available combinations.
Features
- Metal reduction gear train and copper armature winding.
- 4 mm D-shaped output shaft and forward/reverse operation.
- Feedback and rear-cover options for different integration needs.
- Motor-only, bracket and four distinct 65 mm wheel-kit choices.
Specifications
| Brand / model | CHIHAI MOTOR / CHR-GM 25-310T; ABHL Hall variants and optical variant as selected |
| Motor voltage | 7.4 V DC; permanent-magnet brushed motor, metal reduction gears and copper winding |
| Gearbox / motor diameter | 25 mm gearbox; 24.4 mm motor body reference |
| Output shaft | 4 mm D shaft, 3.5 mm across-flat reference, 12 mm projection, 8 mm flat length; 7 mm front boss and 2.5 mm shoulder reference |
| Front mounting | Two M 3.0 x 2 tapped holes on 17 mm spacing |
| Rear-shaft version | 18.1 mm motor section; 7.5 mm rear reference, 1.5 mm feature, 2 mm rear shaft, 18.5 mm feature and 3.2 mm section; rear 18.2 mm REF |
| Hall version | 24.6 mm REF motor/rear encoder section; diameter 13.5 mm magnet reference |
| Covered Hall version | 28.5 mm motor/rear cover section; PH 2.0-6PIN connection |
| Hall feedback | AB quadrature magnetic Hall, 11 PPR at motor shaft; 22 magnetic poles / 11 pole pairs |
| Hall electrical | Separate 3.3 V or 5 V DC logic supply; 100kHz response reference; onboard pull-up/shaping resistors; AB square wave |
| Optical version | 360 CPR optical encoder version; electrical pinout/supply not established by the Hall-only diagrams |
| Net mass | Approximately 65 g reference motor; ratio and accessories vary |
7.4 V Performance and Gearbox Length
Engineering ratios and their speed/load points are listed below. Selector 15/20/34/45/75/100/217/478 labels are nominal shortcuts for 15.46/20.41/34.01/44.9/74.83/98.78/217.31/478.08. Ratios 164.63 and 362.18 are family references only and are not selectable.
| Engineering ratio : 1 | No-load rpm | Rated rpm | Rated kgf.cm | Stall kgf.cm | Hall output pulse reference | Gearbox L mm | Gear stages |
|---|---|---|---|---|---|---|---|
| 4.4 | 2100 | 1470 | 0.1 | ≥0.25 | 48.4 | 19 | 2 |
| 9.3 | 1000 | 700 | 0.2 | ≥0.5 | 102.3 | 19 | 3 |
| 15.46 | 600 | 420 | 0.3 | ≥0.8 | 170.06 | 19 | 4 |
| 20.41 | 450 | 325 | 0.4 | ≥1.0 | 224.51 | 19 | 4 |
| 34.01 | 275 | 190 | 0.7 | ≥1.5 | 374.11 | 21 | 5 |
| 44.9 | 205 | 145 | 0.9 | ≥2.0 | 493.9 | 21 | 5 |
| 74.83 | 125 | 110 | 1.5 | ≥3.5 | 823.13 | 23 | 6 |
| 98.78 | 95 | 80 | 2 | ≥5.0 | 1086.58 | 23 | 6 |
| 164.63 | 56 | 40 | 3 | ≥7.5 | 1810.93 | 25 | 7 |
| 217.31 | 43 | 30 | 4 | Max 9 | 2390.41 | 25 | 7 |
| 362.18 | 25 | 18 | 7 | Max 9 | 3983.98 | 27 | 8 |
| 478.08 | 19 | 14 | 9 | Max 9 | 5258.88 | 27 | 8 |
No-load current:≤200 mA for 4.4/9.3: 1 and≤180 mA for the other ratios. Rated current≤0.65 A; stall current≤1.4 A. Maximum permitted gearbox torque 9kgf.cm; stall figures are not continuous operating ratings. The Hall output reference equals 11 base pulses multiplied by actual gear reduction; it applies to Hall versions, not the 360CPR optical version. Decoder edge-count conventions can differ. No-load and rated speeds must not be treated as the same operating point.
Hall Encoder Connection
| Pin | Wire | Function |
|---|---|---|
| 1 | Red | M 1 / motor positive |
| 2 | Black | Hall GND |
| 3 | Green | C 2 / Hall B output |
| 4 | Yellow | C 1 / Hall A output |
| 5 | Blue | Hall VCC 3.3 V or 5 V |
| 6 | White | M 2 / motor negative |
This six-pin table applies only to the 11PPR Hall versions. Supply the motor with 7.4 V through red/white and the Hall logic with 3.3 V or 5 V through blue/black. Green and yellow are signal outputs. Keep motor voltage away from encoder logic, verify connector orientation and use compatible signal-input levels. Reverse motor polarity only after stopping to change direction. A matching PH 2.0-6PIN lead is included with the Hall versions.
The 360CPR optical model has a different feedback assembly. Do not apply the Hall pinout, logic-voltage or 11PPR specification to it; verify its actual marked connector and electrical requirements before connecting a decoder. A motor driver, feedback controller, power supply and MCU are separate.
Mechanical Fit and Accessories
| 65 mm wheels | Diameter 65 mm, width 27 mm; blue/red road tread, yellow basic or blue high-grip according to selected kit |
| Hex coupling | 18 mm length, 12 mm across flats, 13.75 mm across corners; 4 mm shaft bore and M 4 transverse threaded hole |
| Bracket front | 26.5 mm width, 33 mm height, 8 mm center opening; two 3.2 mm holes 17 mm apart |
| Bracket foot | 26.5x 33 mm, 3 mm thickness; 10 mm opening, four 3.4 mm holes on 16x 14 mm spacing |
Gearbox length depends on ratio; allow rear-shaft, encoder or cover clearance according to the selected version. Check the mounting holes and screw engagement before assembly, and keep screws clear of internal gears. The rear cover protects the Hall assembly from contact; it does not establish an IP or waterproof rating.
What's Included
- Motor Only: one selected-version, selected-ratio motor; matching encoder lead where pictured.
- Motor + Bracket: one selected motor and one mounting bracket.
- Each 65 mm wheel kit: one selected motor, one bracket, one hex coupling, one selected wheel and pictured mounting hardware/hex key.
Blue/red road-tread, yellow basic and blue high-grip wheel types follow the selected package. Photo angles identify configuration alternatives, not a multi-motor bundle. A 60 mm diameter x 32 mm wide Mecanum wheel appears only as a family accessory reference; it is not included in these selectable packages. A complete chassis or vehicle is not included.
Applications
Compact robots, balancing-vehicle development, small smart-home drives, motorized locks and mechanisms requiring the selected torque, speed, shaft and feedback interface. Printer, cleaning-robot, appliance and industrial-equipment examples illustrate possible motor applications; complete machines, firmware and controllers are not supplied.
Installation and Operation
Match the 7.4 V motor rating, confirm wiring and mechanical clearance, avoid overload and stall, and allow the motor to cool during commissioning. Speed and available torque vary with load; gear noise varies with speed and operating conditions. Do not treat stall torque as an allowable sustained load.
FAQ
Do all versions include an encoder?
No. The rear-shaft version has no encoder. Hall and optical feedback are separate selectable versions.
Can the Hall wiring table be used for the optical version?
No. It is specific to 11PPR Hall versions. Check the optical model's actual electrical interface before wiring.
Does every package include a wheel?
Only the four named 65 mm wheel kits include a wheel; choose its tread and color through the package option.
Visual Details






