GM25-310T Covered Hall Encoder Gear Motor

Overview

The CHIHAI MOTOR CHR-GM25-310T ABHL DC gear motor combines a 25 mm metal gearbox, a 7.4 V brushed motor and an 11 PPR Hall encoder protected by a rear cover. Choose the motor with lead, add a mounting bracket, or select the bracket and 65 mm yellow wheel kit. The reduction ratio and no-load speed form a separate selection.

Features

Metal reduction gears and copper armature winding.
4 mm D-shaped output shaft for mechanical coupling.
AB quadrature Hall feedback for rotation measurement with a compatible controller.
Rear cover protects the encoder assembly from accidental contact; no waterproof or IP rating is claimed.
Forward and reverse motor operation by reversing motor polarity after stopping.

Specifications

Brand / model	CHIHAI MOTOR / CHR-GM25-310T ABHL
Motor supply	7.4 V DC; permanent-magnet brushed motor
Gear train	Metal reduction gears, copper motor winding
Gearbox / motor diameter	25 mm gearbox; 24.4 mm motor body drawing reference
Output shaft	4 mm D shaft; 3.5 mm across-flat reference; 12 mm projection; 8 mm D-flat length
Front mounting	Two M3.0 x 2 tapped holes, 17 mm spacing; 7 mm boss and 2.5 mm shoulder reference
Rear covered section	28.5 mm motor / rear-cover section; total body length also depends on gearbox L
Motor mass	Approximately 70 g; varies with gear reduction; accessories and shipping packaging additional
Encoder	AB dual-channel incremental magnetic Hall encoder with rear protective cover
Encoder supply	3.3 V DC or 5 V DC, separate from motor supply
Feedback	11 PPR base at motor shaft; output pulse reference = 11 x actual reduction ratio
Magnetic ring	22 poles / 11 pole pairs
Encoder response	100 kHz reference; A/B square-wave signals with onboard pull-up / shaping resistors
Connector	PH2.0-6PIN with matching lead
Motor current	No-load <=200 mA at 4.4/9.3:1, <=180 mA at other table ratios; rated <=0.65 A; stall <=1.4 A
Gearbox torque ceiling	9 kgf.cm; stall torque is not a continuous operating rating

Reduction, Speed and Load

The selectors use nominal rounded ratios. Their engineering ratios are 4.4, 9.3, 15.46, 20.41, 34.01, 44.9, 74.83, 98.78, 164.63 and 217.31:1 for the respective 4, 9, 15, 20, 34, 45, 75, 100, 165 and 217 selections. Use the 7.4 V figures below to distinguish no-load speed from the rated load point. The 362.18 and 478.08:1 rows are family references, not additional purchasable options.

Engineering ratio :1	No-load rpm	Rated rpm	Rated kgf.cm	Stall kgf.cm / limit	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	9 maximum gearbox limit	2390.41	25	7
362.18	25	18	7	9 maximum gearbox limit	3983.98	27	8
478.08	19	14	9	9 maximum gearbox limit	5258.88	27	8

Hall output pulse references use the actual gear ratio and 11 base pulses per motor revolution. Pulse counting depends on the decoder edge-count convention; do not assume these values already include quadrature multiplication. Maximum permitted gearbox torque is 9 kgf.cm. Stall values are not continuous ratings; avoid overload and stalled operation.

Encoder Wiring and Power

Wire color	Signal	Function
White	M2 -	Motor negative
Blue	VCC	Encoder supply 3.3 V or 5 V
Green	C2 / B	Encoder phase B signal
Yellow	C1 / A	Encoder phase A signal
Black	GND	Encoder ground
Red	M1 +	Motor positive

Connect the 7.4 V motor supply through red/white and the separate 3.3 V or 5 V encoder supply through blue/black. Green and yellow are signal outputs. Keep motor voltage away from logic pins. Verify connector orientation and compatible input levels before connection; wire colors identify functions rather than an inferred connector pin order. A motor driver and feedback controller are required separately for controlled motion.

Mechanical Fit

Allow clearance for the selected gearbox length and the rear encoder cover. Shaft projection is 12 mm and the D-flat length is 8 mm. Check shaft fit, the 17 mm mounting spacing and screw engagement before assembly; screws must not enter the gear train. The original engineering drawing is retained below so dimensions and geometry can be checked before machining.

Applications

Compact robots, balancing-vehicle prototypes, motorized smart-home mechanisms, appliance drives and lock mechanisms where the selected speed, torque, mounting and encoder interface meet the design requirements. Balancing operation requires a suitable chassis, driver, sensors and control software supplied separately.

What's Included

Covered Hall Encoder Motor: one selected-ratio motor with rear cover and matching six-wire lead.
Motor + Mounting Bracket: the covered encoder motor and lead, one bracket and pictured mounting screws.
Motor + Bracket + 65mm Yellow Wheel Kit: the covered encoder motor and lead, one bracket, one yellow 65 mm basic wheel, coupling and pictured screws / hex key.

Each selection supplies one motor. A wheel is included only in the yellow wheel kit. No power supply, motor driver, MCU, feedback controller or complete vehicle is included.

Installation and Operation

Use the rated 7.4 V motor supply and verify wiring before power-up. Avoid sustained stall, overload and rapid reversal. Reducing drive voltage can reduce available torque as well as speed; speed and gear noise vary with load and ratio. Keep rotating shafts and mounting hardware clear of the encoder cover and wiring.

FAQ

Is the encoder voltage also 7.4 V?

No. The motor uses 7.4 V, while the Hall encoder requires a separate 3.3 V or 5 V supply.

Does every option include a wheel?

No. Only the 65 mm yellow wheel kit includes a wheel, bracket and coupling.

Does 11 PPR describe the output shaft?

It is the base motor-shaft pulse reference. Multiply by the actual gear ratio for the output-shaft reference, then account for your decoder's counting convention.