CHIHAI MOTOR CHR-GM37-520 Brushed DC Gear Motor, 12V/24V, All-Metal Gears

Overview

CHIHAI CHR-GM37-520 is a 37 mm brushed DC gear motor built on a full metal gear train, sized for robot chassis, powered furniture and small automation where a plastic gearbox would wear out. The helical first stage is there for noise: it takes the load off the first mesh so a heavy drive train does not ring.

Nine nominal reduction ratios from 1:6.3 to 1:450 are offered on both 12 V and 24 V windings, with a double-flat shaft version of the 1:10 ratio for pulleys and couplings that need a positive grip.

Features

• All-metal gear train. Helical first stage, machined gears, brass posts: built to carry load rather than speed.
• Brushed permanent-magnet motor. Simple two-wire drive, reversible by swapping polarity, dimmable with PWM.
• Ø6 mm D-cut shaft. 21 mm long with a 12 mm flat, so pinions and couplings do not slip.
• Ø37 mm body. Six M3 tapped holes on a 31 mm circle for a standard GM37 bracket.
• Gearbox length follows ratio. 19 mm at 1:6.3 rising to 29 mm at 1:450, so check your clearance before picking the slowest ratio.
• Approx. 150 g. Provide a suitable mechanical mounting for the application.

Configuration Guide

12 V or 24 V

Same gearbox, different winding. At the same ratio the 24 V version is the quicker one (760 rpm against 660 rpm rated at 1:6.3) and draws less current; the 12 V version is the usual choice for battery packs and 12 V supplies. Choose the winding to match your supply rather than the speed.

Ratio

1:6.3 is the fast end and 1:450 the slow, high-torque end. Use the exact rated speed and torque for the selected ratio. The gearbox gets longer: 19 mm at the fast end, 29 mm at the slow end.

Double-flat shaft

The 1:10 double-flat variant uses the same ratio as the standard 1:10 but a shaft with two flats, which is what you want if a set screw has to bite without a keyway.

Stall limits at high ratios

The published chart stops giving stall torque at 1:270 and above and instead warns not to exceed 35 kgf·cm or stall the motor at those ratios. Avoid stall and overload; a continuous-duty cycle is not specified.

Specifications

Performance by Winding

Two charts, one per winding. Torque is published in kgf·cm with the mN·m equivalent. The 1:650 and 1:810 columns are shown because they appear in the source chart, but those two ratios are not sold in this listing.

DC 24V winding

Rated current ≤0.35 A · stall current 1.3 A

DC 12V winding

Rated current ≤0.45 A · stall current 2.4 A

Mechanical Dimensions

Body diameter Ø37 mm; overall length is the gearbox length plus the motor can, and the gearbox measures 19 mm at 1:6.3 up to 29 mm at 1:450. Output shaft Ø6 mm, 21 mm long with a 12 mm D-flat. Six M3 tapped holes sit on a 31 mm circle, and the front plate is 24.5 ± 0.1 mm across the flats. Motor alone weighs about 150 g.

The outline drawing in Visual Details carries every dimension needed to design a bracket or a chassis cut-out.

Package Contents

Applications

• Small robot chassis and balancing platforms
• Powered furniture and adjustable frames
• Camera cranes and slider drives
• Dispensers, cutters and light automation

FAQ

Is this gearbox self-locking?

No. It is a helical-and-spur gear train, not a worm drive, so the shaft can be back-driven. If you need a load to hold when power is removed, add a brake or use a worm-gear model.

Why do the charts list 1:650 and 1:810?

They come from the manufacturer's standard chart, but this listing does not sell those two ratios. Only the ratios in the option list are shipped.

What happens if I stall it at a slow ratio?

Above 1:150 the chart warns against stalling and caps load at 35 kgf·cm. A stalled motor draws locked-rotor current and will cook the winding, so size the load against rated torque instead.

Can I run it at 12 V and 24 V interchangeably?

No. Each variant is wound for one voltage. Running a 12 V winding at 24 V over-speeds and overheats it.

Visual Details