Small Worm Gear Motors for DIY Projects: What the HH-370 Can (and Can't) Drive

The HH-370 worm gear motor is small in every sense that matters for a DIY build: a 46 × 32 mm gearbox, 150 g of weight, and a motor that draws under one watt. That smallness is its whole appeal — it hides inside display bases, models, and curtain mechanisms where a bigger motor would not fit. But small also sets hard limits. This guide shows what the HH-370 is genuinely good for, where it stops being enough, and how to pick the right gear ratio for your build.

Small in Three Ways

Small gearbox. At 46 × 32 mm, the HH-370 fits where most gear motors do not: inside a display plinth, behind a curtain pelmet, or in the base of a small mechanism. If your build has a space constraint, measure first — this is often the motor that fits when others do not.

Small weight. 150 g means the motor itself barely loads the structure carrying it. That matters for hanging mechanisms and lightweight models, where every gram counts against balance.

Small power draw. At 0.94 W (12V) or 0.95 W (24V), the HH-370 sips power. A small wall adapter or a modest battery runs it comfortably, and it stays well within the range of ordinary switches and controllers. Power is rarely the constraint with this motor — torque and shaft load are.

The Ratio Table: Speed and Torque Together

The HH-370 is sold by voltage (12V/24V) and gear ratio, and ratio decides what the motor can do. Rated figures under load (12V and 24V versions share the same values):

Read the table the same way every time: pick the speed you need first, then check the torque in that row. Torque caps at 10.0 kgf·cm — from 950:1 upward, higher ratios only buy slower speed, not more torque. And always use the rated speed under load: the 40:1 ratio's 163 RPM no-load figure is 130 RPM once the motor is actually working.

What the HH-370 Is Good For

Small display turntables. A light display that turns at a few RPM is the classic HH-370 job: pick a high ratio (950:1 or above) for slow, steady rotation with the full 10 kgf·cm available.

Curtains and small mechanisms. Light curtain drives and small moving mechanisms suit the mid-range ratios, where speed is moderate and torque demand is low. The worm drive's self-locking holds the curtain in place when power is off — it does not drift back.

Slow, precise motion. Down to 1.0 RPM at 5300:1, the HH-370 covers the very slow end that larger motors cannot reach. A mechanism that indexes once a minute, or a display that creeps almost imperceptibly, lives here.

Tight-space builds. When the mechanism must fit inside something small — a model, a display base, a compact enclosure — the 46 × 32 mm gearbox is often the deciding factor on its own.

Where It Stops Being Enough

Heavy loads. Anything approaching or above 10 kgf·cm of torque demand is beyond this motor. Do not size by hope: if your load is near the limit, step up to the HH-31ZY (25.0 kgf·cm) instead of running the 370 at its maximum.

Overhung or side-loaded shafts. The Ø6 mm D-shaft is rated for only 1 kgf radial load and 0.7 kgf axial load, with 10 kgf maximum press-in force. A heavy plate mounted off-center, or a mechanism that pushes along the shaft, can exceed these figures even when torque is fine. Support the load on its own bearing if it is heavy, and let the motor shaft transmit rotation, not carry weight.

Fast motion with real torque. The low ratios spin fast (130 RPM) but deliver only 0.6 kgf·cm. Speed and torque trade against each other in this table — you cannot have both at once from this motor.

Installation Notes Worth Knowing

Use the D-shaft flat. The Ø6 mm output shaft has a flat (D-shape). Use a hub or coupling that engages the flat rather than relying on a set screw on the round side alone — the flat is what prevents slipping under load.

Respect the press-in limit. Do not press a hub onto the shaft with more than 10 kgf of force. Support the gearbox, not the shaft, when fitting parts.

Use the self-locking. The worm drive holds position with power off, within rated load. Design around that: you do not need a brake or a latch to keep a display or curtain where you left it.

Mind the direction. Output rotation direction varies across ratio segments in the datasheet. If your build depends on a specific direction, confirm it for the exact ratio you order.

Backlash is small but real. Rated at 2° or less, backlash shows up as a small dead zone when reversing. For back-and-forth mechanisms, design the motion to tolerate it.

FAQ

Can the HH-370 lift things?
It rotates; it is not a linear actuator. For pushing and pulling in a straight line, you want a linear actuator, not a gear motor. The HH-370 turns shafts, wheels, and turntables.

Is 12V or 24V better?
Per the datasheet, rated speeds and torques are the same for both versions. Choose the voltage your system already uses.

Can I run it from a battery?
Yes — at under one watt, battery power is practical for portable builds. Size the battery for the runtime you need; the motor's voltage and current draw are the only electrical constraints.

What if I need more torque than 10 kgf·cm?
Step up to the HH-31ZY, which is rated to 25.0 kgf·cm with a larger 58 × 40 mm gearbox and Ø8 mm shaft. See our HH-370 vs HH-31ZY comparison and the 31ZY ratio guide.

The Short Version

The HH-370 is the right motor when the job is small, light, slow, or tight on space — and the wrong motor the moment torque approaches 10 kgf·cm or the shaft has to carry real side load. Check the ratio table, check the shaft limits, and it will do exactly what it promises.