Suma Precision Machinery

There is a vital application of one way clutch bearings to the complex mechanical world. They are intended to drive in one direction and float or coast in the reverse or opposite rotation. This special feature makes them an persenssostíant part of use in Automotive transmissions and industrial machinery, power tools. In this article we learn how one-way clutch bearings work, including their types, working principles,maintenance, and applications.

Types of One-Way Clutch Bearings

There are variety of one-way clutch bearing designs for different applications and performance requirement. Typical systems are of two varieties: roller clutches and sprag clutches.

Roller-Type One-Way Clutch Bearings

Roller type one-way clutch bearings are employed broadly because of their simplicity and reliability. They have an outer cup (outer race), an inner cup (inner race), a group of rollers and a spring. The rollers are disposed between the inner and outer races and are held by the spring in contact therewith. Upon relative rotation of the inner and outer races in the drive direction, the rollers are forced-in to the frustopolymerscreend pockets in the outer race so as to effect a wedge action and secure the inner and outer races. This enables torque to be transferred from the second inner race to the second outer race. In the opposite direction, the rollers are forced out of the tapered pockets to accommodate the spinning of the inner race relative to the outer race.

Sprag-Type One-Way Clutch Bearings

Sprag type one-way clutch bearings, or wedge type clutches are designed to use small wedge shaped elements [sprags] rather than rollers. The sprags are inserted and held between the inner and outer races by means of a cage, or spring. When the inner race is spun in the driving direction, the sprags are moved up the angled pockets in the outer race, and this mechanical connection between the outer race and the inner race is tightened. This allows torque to be transmitted from inner race to outer race. In the opposite direction, the sprags are wedged out of the tapered pockets and the inner race is free to rotate with respect to the outer race. Sprag clutches are famous for their large torque capacity and high capability under heavy loads.

Working Principle of One Way Clutch Bearing

One-way clutch bearings operate on the locking and release principle. When the bearing is in the engaged position, torque from the drive shaft is transmitted, such that the components attached to the shafts can be turned in the desired direction. The driven shaft is rotatable without interference from the driving shaft when the bearing is in the disengaged condition.

Torque Transmission in the On Stage

In the locked condition, the rollers or sprags of the one-way clutch bearing pinch between the inner and outer races to effectuate a positive engagement. This permits torque from the driving shaft to be transferred to the driven shaft, and both shafts to rotate in the same direction. The action of the wedge is retained by the spring or the centrifugal force developed during rotation. The torque carrying capacity of the bearing is a function of the size and quantity of the rollers or sprags, material properties of the races and elements, and geometry of the bearing.

Freeplay When Not Engaged

In its disengaged condition, the rollers or sprags are disengaged from one another and are not wedged between the inner and outer races, and the driven shaft and the driving shaft are free to rotate relative to one another. It happens when the driving shaft no longer turns, or reverses turning direction. In the case of roller-type clutches, the rollers are forced out of the tapered pockets by the spring force or the centrifugal force, and in the case of the spragtype clutches, the sprags are released from the tapered pockets by the change of the rotating direction. The bearing is freely rotatable in the disengaged position allowing distortion-free operation and preventing the connected parts from being damaged.

Applications of One-Way Clutch Bearings

One-way clutch bearing products are used in many different applications and mechanical systems in which reverse rotation and rotational transmission in one direction are indispensable techniques.

Automotive Industry

In the automobile the one-way clutch bearing are applied to many automotive parts, that is automatic transmission, AM starter, alternator pulley and so on. In automatic transmissions, one-way clutches are a vital part of the shift control and are essential to the proper operation of the transmission. They permit the transmission to shift in and out of various gears, supplying the torque needed for accelerating and decelerating. Starter motors disallow backdriving of the starter by the engine using a one-way clutch when it is not used. The one way clutch is used in an alternator pulley and allows the alternator to rotate freely in deceleration of an engine not to impose a driving force on the engine and increase fuel efficiency of the engine.

Industrial Machinery

Such one-way bearing clutches are also commonly found in industrial equipment, including conveyors, index tables and packaging machines. In other conveyor equipment, the conveyer belt must start in a forward direction to position properly before accepting the load, but will then periodically jog in reverse so that material stagnation is avoided. One way clutches are used to drive the indexing table in such tables. One-way clutches are used in the packaging machines to control the operation of the packaging material for precise and efficient packaging operation.

Power Tools

It s not only power tools like cordless drills and impact drivers that require one-way clutch bearings to work properly. In battery-powered drills, ratchet drives may be employed to avoid rotating the drill bit back into the chuck or losing a fastener (not the works), such that the chuck can secure the bit. This aids in preventing the user from getting hurt and from the drill bit coming out. One-way clutches are used to deliver the torque required for screw and bolt perfect driving in impact drivers. They permit the driver to apply force with a force-carrying punch in one direction, without allowing the bit to slip under load and thus preventing it from applying force in the opposite direction.

Other Applications

Besides the above industries, Tension arm one way clutch bearings are also suitable for many other applications, such as bicycle, motorcycle, aerospace and other industries. On bicycles, one ways are commonly employed in a free wheel mechanism, which permits the bicycle rider to coast without pedaling. One way clutches are also used in motorcycles for the starting system and the transmission. One way clutches are also used in aerospace systems such as an aircraft landing gear, the aircraft engine starting system.

Maintenance and Inspection of One-Way Clutch Bearings only

In order to make one-way clutch bearings perform reliably, it is of great importance to maintain and inspect them. There are some points for the maintenance and troubleshooting of one-way clutch bearings.

Lubrication

The one-way clutch bearing must be lubricated to insure reliable operation. Apply the right lubricant, in good quality, to the specific application and working conditions. Grease the bearing as per instructions from manufacturer. Check lubricant level and condition and replace as needed.

Inspection

Periodically inspect the one-way clutch bearing for wear, damage or contamination. Examine the rollers or sprags for pitting, scoring, and cracks. Check the races for wear or damage. Test the spring for fatigue or breakage. If any faults are found, replace the bearing forthwith.

Cleaning

Keep the one way clutch bearing clean to avoid dirt, debris and contaminants from entering. Clean the bearing with bire or brush Regularly. Do not use chemicals or solvents that will damage the bearing.

Installation

With a one-way clutch bearing, be sure follow the manufacturer's recommended procedure when installing. Make sure the bearing is mounted correctly and properly combined the driving and driven is mounted. Install the bearing by using the correct tools and equipment.

Troubleshooting

If some inappropriate operation of the one-way clutch bearing is performed, that may be due to the several factors. Some typical culprits might be worn or worn out rollers or sprags, failure of the spring mechanism or the offending bearing being either dirty or being installed wrong. To determine and correct the issue, carefully examine the bearing and associated components for any damage or excessive wear. Inspect the Lubrication Level and Condition. Replace the bearing or its parts, if required.

Conclusion

One-way clutch device is widely used in various mechanical systems where torque can be transmitted in one direction while free rotation is permitted in the other direction. Due to their special properties, they are indispensable in various field like, automotive transmissions, industrial machinery and power tools. Knowledge of one-way clutch bearings, including their designs, operating modes, applications cost, maintenance and testing procedure, will allow design and maintenance technicians to properly specify the correct bearing for their application, at proper cost, and assure its reliable usage. It is very important to maintain and inspect the one-way clutch bearing for long life. Under normal use these bearings should last for years of trouble-free riding.