HF series Drawn Cup Roller Clutches

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I. Core Working Principle: The Realization of Unidirectional Transmission

The core function of the unidirectional bearing is based on the wedge effect. Imagine a narrow wedge-shaped space, into which a roller is placed. When rotated in one direction, the roller will roll to a wider area and cannot be firmly fixed; while when rotated in the opposite direction, the roller will be pushed into the narrow part of the wedge-shaped space, thus being firmly held. 

This "wedge-shaped space" is composed of three surfaces: 

Inner ring (usually connecting the input shaft) 

Outer ring (usually connecting the output component) 

"Slopes" or "cams" (machined on the inner or outer ring) 

II. Main Types and Working Modes

Depending on the different components that achieve the "wedge effect", the most common types of one-way bearings are as follows: 

Roller single-directional bearing

This is the most classic and common type. 

Structure: Composed of the outer ring, inner ring, rollers and springs. The inner surface of the outer ring usually has a wedge-shaped slope (cycloid groove). 

Work process: 

Locking direction (driving): When the outer ring attempts to rotate relative to the inner ring in the locking direction, the rollers, under the action of friction and spring force, are pushed into the narrow end of the wedge-shaped space, thereby locking the outer ring and the inner ring together and achieving the transmission of torque. 

Free Direction (Beyond): When the outer ring attempts to rotate in the free direction, it will drive the rollers to roll towards the spacious end of the wedge-shaped space, thereby releasing the jammed state. The inner and outer rings can then rotate freely relative to each other (beyond). 

2. Wedge-type one-way bearing

Its principle is similar to that of the roller type, but instead of using rollers, it employs special wedge-shaped blocks. 

Structure: Utilizing a component similar to a "peg", its outline has been optimally designed. 

Advantages: The contact area between the wedge and the inner and outer rings is larger, thus enabling it to transmit greater torque. However, the maximum rotational speed is usually lower than that of the roller type. 

3. Ratchet one-way mechanism

This is a more intuitive but usually somewhat jarring method. 

Structure: Composed of a serrated ratchet and one or more pawls. 

Working process: The prongs are held against the ratchet teeth by the spring force. When rotating in one direction, the prongs can slide over the inclined surface of the teeth; when rotating in the opposite direction, the prongs will get stuck on the vertical surface of the teeth, achieving locking. 

Features: Simple structure, large capacity, but it generates noise and shock during operation, and is not suitable for high-speed and precision applications. 

III. Typical Application Scenarios

The "one-way transmission" and "overrunning" characteristics of the single-direction bearing make it indispensable in numerous fields. 

Starting device: Motorcycle / Small Engine 

The foot-operated start lever of a motorcycle and the pull rope starter of a household high-pressure cleaning machine both have one-way bearings inside. When you exert force to pedal (or pull), it locks and drives the engine to rotate; after the engine starts, its rotational speed is higher than your pedaling speed, and it enters an "overdrive" state to prevent the engine from dragging the start mechanism in reverse. 

Beyond the Clutch: Bicycle Flywheel 

The rear wheel hub of a bicycle is a typical example. When you pedal, the hub locks and drives the rear wheel forward; when you stop pedaling and coast, the rotational speed of the rear wheel is higher than that of the pedal chainwheel, and the hub enters a "slip" state, making a "tap-tap" sound, and the wheel rotates freely. 

Check valve: Conveyor, Elevator 

On the inclined conveyor belt, to prevent the goods or equipment from reversing due to gravity when the machine stops. 

Intermittent cyclic operation: Mechanical tapping machine 

During tapping, the main shaft rotates clockwise, and the one-way bearing is locked. Torque is transmitted for tapping. After the tapping is completed, the motor rotates counterclockwise. At this time, the one-way bearing is in an "overrunning" state. The main shaft does not reverse along with it; instead, it returns by means of springs, etc., to prevent damage to the tap. 

Dual-speed drive: 

In some devices, the switching between "using power A at high speed and power B at low speed" can be achieved by combining two power sources with different speeds and two one-way bearings.