HF0812 One Way Clutch Bearing — 8 × 12 × 12 mm, Drawn Cup Roller Clutch

HF0812 is a drawn cup roller clutch: 8 mm shaft, 12 mm outside diameter, 12 mm width, rated torque 3.15 N·m, mass 3.5 g. It transmits torque in one direction and freewheels in the other with no lever, no solenoid and no control circuit — the ramps formed in the pressed cup do the work. The cup presses into a plain housing bore and the shaft itself is the inner raceway, so the clutch costs less than a separate bearing plus a backstop. PA66 cage, stainless steel springs, GCr15 rollers, from 100 pieces.

Shaft 8 mmD 12 mmC 12 mmM_d3.15 N·m3.5 gPA66 cage

HF0812 Specifications

How a Drawn Cup Clutch Locks and Frees

The cup is pressed from steel strip and the inside is formed into a series of shallow ramps. Each roller sits in a ramp, pushed by a small spring:

• Driving direction. The shaft drags each roller up its ramp, the roller wedges between shaft and cup and the clutch locks. Torque passes through the rollers in compression — that is how a 12 mm clutch holds 3.15 N·m.
• Free direction. The shaft pushes the rollers down the ramp, the springs hold them clear of the wedging angle and the shaft spins free.
• No adjustment, no wear-in. Engagement happens within a few degrees of rotation, every cycle.

Reading Torque and Speed

A clutch run continuously at its speed limit with a light torque load will still run hot if lubrication is poor — a grease with a low base-oil viscosity, or oil mist, is the usual fix.

HF Series Size Chart

Nominal values for the standard HF series; torque is the transmissible torque of the clutch, not a bearing load rating. If your design uses a size outside this table, send the drawing and we quote against the actual envelope.

HF0812 Compared With Its Family

Typical Applications

Installation Notes

• Press fit only. Press the cup into an N7 housing bore with a flat-faced arbor on the cup face — never press through the cage or the springs. Bore chamfer 0.3 × 20°.
• Plastic housing? Use the R (knurled) version; the knurl bites into the bore and takes the reaction torque.
• The shaft is the raceway. 58–62 HRC, ground to Ra ≤ 0.2 µm, h5/h6. A soft or turned shaft will indent and the clutch will slip under load.
• Locking direction is fixed by the part. Tell us which way the shaft turns when driving, or send a sketch — reversing the direction is the most common return reason on this product.
• No radial load. Support the shaft with a separate bearing; HF0812 only centres it. Use HFL0822 if space does not allow a second bearing.
• Lubrication. A light grease fill covers most duties; oil is better at high overrunning speed.
• Alignment. Shaft and bore must be concentric within the clearance of the bearing that supports the shaft — a clutch is not a self-aligning element.

Quality Control on Every Batch

• 100% check on F_w, D and C
• Torque test at rated torque on a sample from every lot
• Spring force and free-running drag torque checked
• Roller gauge sorting to 1 µm
• Rotation direction verified against the marking
• Material certificate 3.1 and inspection report with the shipment

Packing, MOQ and Delivery

10 pcs per VCI bag, 1 000 per carton, cartons on a pallet or in a plywood case. MOQ is 100 pcs. Stock ships in 3–7 days; production orders 20–30 days. Air, sea LCL and FCL available.

Frequently Asked Questions

What are the dimensions of HF0812?

8 mm shaft diameter, 12 mm outside diameter, 12 mm width and 3.5 g mass.

What torque can HF0812 transmit?

3.15 N·m rated. Apply a service factor of 1.5–2 for shock or reversing loads, which puts practical continuous duty at about 1.6–2.1 N·m.

How fast can HF0812 overrun?

Two limits are published, 12 000 and 17 000 r/min. The applicable one depends on whether the shaft or the outer ring overruns and on the lubrication — send us the duty point and we confirm it with the offer.

Which way does HF0812 lock?

It locks in one fixed direction and freewheels in the other. The direction is set by the ramp geometry and cannot be changed by flipping the part, so specify the driving rotation at order.

Does HF0812 carry radial load?

No. It centres the shaft, but a separate bearing must take the radial load. HFL0822 has an integrated radial bearing if space is tight.

What is the difference between HF, KF and R?

HF has stainless steel springs, KF has plastic springs for light duty, and R adds a knurled outer ring for plastic housings. None of the suffixes changes the size.

Does HF0812 need an inner ring?

No. The shaft is the inner raceway and must be hardened to 58–62 HRC and ground to Ra ≤ 0.2 µm.