CHIHAI GM25-370 25mm DC Gear Motor

Overview

The CHIHAI MOTOR CHR-GM 25-370 DC gear motor combines a compact 370 brushed motor with a 25 mm metal spur gearbox. Choose a 6 V, 12 V or 24 V winding, a reduction ratio, and the motor-only or accessory package for your small robotic drive or mechanism.

Features

All-metal reduction gears and a permanent-magnet DC motor.
Copper-wire armature winding and a D-shaped output shaft for secure coupling.
Reversible rotation by DC polarity reversal after stopping.
Optional bracket, couplers, 65 mm wheel kits, PWM controller or solderless connection board.

Specifications

Brand / model	CHIHAI MOTOR / CHR-GM 25-370 (25GA 370 class)
Motor	Permanent-magnet brushed DC gear motor; 370 motor and metal spur reduction gears
Voltage	Separate 6 V, 12 V and 24 V windings; use selected nominal voltage
Diameter	25 mm gearbox; 24.4 mm motor reference
Shaft	4 mm diameter D shaft; 12.0±0.5 mm projection; 8 mm flat length; 3.5 mm across-flat reference
Mount	TwoM 3 tapped mounting holes, 17 mm spacing; confirm actual screw depth before assembly
Lengths	Motor section 30.8 mm; gearbox lengthL±0.3 mm varies 19/21/23/25/27 mm by reduction
Front/rear features	Front shoulder 2.5 mm reference; rear boss 6.4 mm diameter
Motor mass	Approximately 100 g; varies by reduction and configuration
Direction	Reverse DC polarity after stopping to reverse rotation
PWM controller	Optional board; 4.5–35 V DC input reference; match motor voltage; never connect AC mains
Protection	Avoid overload and stall; do not switch direction while rotating; gearbox load torque must not exceed 9.0kgf.cm

Speed and Torque by Reduction

These operating points cover the 6 V, 12 V and 24 V winding references at their respective nominal voltages. No-load and rated speeds describe different load conditions. The selectable ratio labels 45, 75 and 100 correspond to the 44.9, 74.8 and 98.8 family rows. Ratios 15 and 362 are family references only and are not selectable here.

Nominal ratio : 1	No-load rpm	Rated rpm	Rated torque kgf.cm	Stall torque kgf.cm / limit	Gearbox L mm
4.4	1360	1000	0.15	0.60	19
9.3	640	480	0.35	1.10	19
15	400	300	0.55	2.00	19
20	300	225	0.75	2.70	21
34	175	130	1.30	4.50	21
44.9	130	100	1.80	6.00	21
74.8	80	60	3.00	9.00	23
98.8	60	45	4.00	9.0 load ceiling	23
165	35	27	6.00	9.0 load ceiling	25
217	27	20	8.00	9.0 load ceiling	25
362	16.5	14	8.00	9.0 load ceiling	27
478	12.5	11	8.00	9.0 load ceiling	27

The 9.0kgf.cm gearbox-load ceiling is not a continuous torque rating or an unrestricted stall rating. Avoid stall and stop the motor before reversing. Performance depends on supply, load and duty cycle.

Voltage-Specific Electrical Reference

Winding	Maximum power reference	No-load current	Rated current	Stall current
24 V	3 W	≤40 mA	≤0.16 A for 4.4–217; ≤0.24 A at 362; ≤0.22 A at 478	≤0.8 A
12 V	2 W	≤80 mA	≤0.25 A	≤0.8 A
6 V	1.6 W	≤100 mA	≤0.5 A	≤2.6 A

Maximum power is a separate reference from the rated speed/torque operating point. Do not substitute one voltage winding for another. Use a regulated DC supply with appropriate current capacity and protection.

Mechanical Fit and Gearbox Length

Exact reduction : 1	Gear stages	Gearbox L mm
4.4	2	19
9.3	3	19
15.46	4	19
20.41	4	19 drawing / 21 performance
34.01	5	21
44.9	5	21
74.83	6	23
98.78	6	23
164.63	7	25
217.31	7	25
362.18	8	27
478.08	8	27

Dimensions are in mm. Shaft projection is 12.0±0.5 and gearbox length tolerance is±0.3. The motor section is 30.8 long. The front mounting face has twoM 3 tapped holes 17 apart. Check screw penetration, shaft alignment, coupler fit and all clearances before installation. The optional bracket is 26.5 wide with 33 mm upright/base references and 3 mm thickness. Its front has two 3.2 mm holes 17 mm apart and an 8 mm center opening; the base has fourM 4 threaded holes on 16×14 mm spacing and a 10 mm center opening. Motor-to-bracket screws are included with the bracket; four base screws are not.

For the 20: 1 option, the mechanical drawing and performance table give 19mm and 21mm gearbox-length references respectively. Confirm the exact unit before machining a mounting envelope. The drawing also marks a 7mm front boss and an ISO M 3.0×2 tapped-hole callout at two places; confirm the actual thread engagement before installing screws.

Connection and Speed Control

The bare motor has two power terminals. Reverse supply polarity to reverse rotation only after the shaft stops. The illustrated rear terminal marked RED+ identifies the positive reference; verify the actual terminal orientation before wiring. The optional solderless board provides a matching plug-and-lead connection and interference-suppression components, avoiding direct hand soldering at the motor terminals.

The optional PWM board has a knob with speed adjustment/on-off function and an on/off indicator. Its DC input reference is 4.5–35 V; the selected motor must receive its suitable voltage. Connect the DC supply to the board power terminals and the motor to its motor-output terminals. Never connect 220 V AC or reverse the controller supply polarity. If rotation is wrong, stop and isolate power before swapping the motor-output leads. The pictured controller has no separate forward/reverse switch.

Applications

Small line-following and balancing vehicle models, smart-car drive mechanisms, robot projects, electric curtains, camera pan mechanisms and other compact motorized equipment where the selected reduction and shaft fit are suitable.

What's Included

Selected package	Contents
Motor Only	One selected motor.
Motor + Bracket	One motor and one mounting bracket; motor-to-bracket screws included, base mounting screws not included.
Motor + Flange Coupler	One motor and one flange coupler.
Motor + Hex Coupler	One motor and one hex coupler.
Motor + 65 mm Drift Wheel Kit	One motor, one bracket, one hex coupler, one 65 mm blue drift-style wheel, and pictured screws/grub screws/hex key.
Motor + 65 mm Road Wheel Kit	One motor, one bracket, one hex coupler, one 65 mm blue road-style wheel, and pictured screws/grub screws/hex key.
Motor + PWM Controller	One motor and one open PWM speed-control board.
Motor + Solderless Board and Lead	One motor with solderless connection board and matching two-wire lead.

Each package supplies one motor and only the named accessories. Wheel kits contain one wheel, not a pair. A battery, power supply, complete car/chassis, robot and additional loose gearbox are not included. A gearbox-only picture is a family accessory reference and is not a selectable retail package here.