Before ordering a one way clutch bearing, buyers should provide: shaft bore and tolerance, housing size, required torque, operating overrunning speed, the application mode (overrunning, indexing or backstopping), lubrication, and rotation direction. With these seven details a supplier can quote the correct model and avoid costly returns. Missing any one forces guesswork and can lead to a clutch that slips, overheats or will not fit.
When a buyer sends only a bore size, the supplier must guess torque and speed. The result may be a clutch that fits but fails under load, or an oversized unit that costs more and runs slower. A complete request shortens lead time, avoids re-quotes and protects the buyer from returns and downtime.
SUMA DC series sprag clutches use a cage of precisely formed sprags between an inner and outer race. In one rotation direction the sprags tilt and lock, transmitting torque; in the opposite direction they freewheel. The cage is made from GCr15 bearing steel with surface hardness HRC 60–62 (minimum 0.6 mm depth) and core hardness HRC 35–45, and is supplied without races, so the machine's shaft and housing act as the raceways and must be hardened to match.
| Parameter | Why It Matters | Buyer Should Check |
|---|---|---|
| Torque Capacity (TKN) | Sets the load the clutch transmits before slipping; peak torque is about 2 × TKN. | Required drive torque, shock load and safety factor. |
| Overrunning Speed | Too high a freewheel speed causes sprag lift, heat and wear. | Inner-race (nimax) vs outer-race (namax) speed. |
| Bore Size & Shaft Fit | Wrong fit causes slip or seizure and uneven sprag loading. | Shaft tolerance and race hardness (HRC 60–62). |
| Width / Sprag Space | Determines axial space and the minimum race plain width. | Housing width and race plain width. |
| Application Mode | Overrunning, indexing and backstopping load the clutch differently. | Which duty the clutch performs. |
| Lubrication | Prevents wear and heat; the wrong lubricant affects lock-up. | Oil or grease recommended for the version. |
| Rotation Direction | A one way clutch locks in one direction only. | Machine rotation and mounting orientation. |
| Information | Why the Supplier Needs It | Example |
|---|---|---|
| Shaft bore & tolerance | Sets the correct fit. | 50 mm, h7 |
| Housing size | Defines the outer race. | OD 66.381 mm |
| Required torque | Sizes TKN with margin. | 400 Nm steady |
| Overrunning speed | Checks nimax and namax. | 2500 rpm |
| Application mode | Chooses the type. | Backstopping |
| Lubrication | Affects life and lock-up. | Oil bath |
| Rotation direction | Ensures correct lock-up. | Clockwise drive |
Overrunning drives in one direction and releases in the other, common in two-speed and dual drives, where the overrunning speed is the limiting factor. Indexing converts continuous rotation into precise intermittent motion, so torque and indexing accuracy dominate. Backstopping prevents reverse rotation on inclined conveyors and gearboxes, so holding torque and lock-up reliability are critical while freewheel speed is usually low. Confirm the duty before comparing models.
Q1: Is bore size enough to order?
A: No, provide torque, speed, duty, lubrication and direction too.
Q2: What if I do not know the overrunning speed?
A: Share the drive speed and which race overruns so the supplier can advise.
Q3: Why provide rotation direction?
A: A one way clutch locks in one direction only, so it must match the drive.
Q4: Does a complete RFQ speed things up?
A: Yes, it prevents re-quotes and wrong models.
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