Morning Chuck, good question, found this while looking into it... Interesting read anyway.
Reel Bearings 301: Maintenance, Design, and Troubleshooting
Roller Clutch Bearing Troubleshooting: Roller clutch bearings are used in many reels to prevent reverse rotation of the handle shaft and other drive components. Some reels may also use ratchets or cogs in addition to this bearing, to ensure the spool does not rotate backward and to reduce handle back-play. (And still, some reel manufacturers even use a clutch bearing as part of the spool; although it increases the overall weight of the spool.) A clutch bearing essentially locks up if rotation is in the wrong direction, preventing the load (e.g. shaft, tube, handle, or collar), from rotating backwards. Reel manufacturers sometimes refer to it as the Infinite Anti-Reverse, Roller Clutch or Shaft Roller Bearing in their schematics and parts list.
Roller Clutch Bearing Unlocked (left) and Locked (right)
A typical infinite anti-reverse bearing (roller clutch bearing) uses springs that compress and allow the rollers to move freely in the normal direction. The springs also align and help position the rollers so they will lock into the tapered edges on its cage (retainer), if rotated in the reverse direction. A few designs actually work just the opposite – where springs push the roller out of the locked position. Regardless of the type, the rollers must be free to travel so they will lock, yet not so loose that they will slip due to insufficient friction with the shaft (load). The springs may be metal or plastic, and they are frequently molded onto the cage as shown in the picture.
Typical Clutch Bearing Cage and Molded Spring (left) and Diagram Showing the Locked Configuration (right)
Although a clutch bearing is a type of rolling bearing, it would be “ideal” if it did not carry much radial load. There are two reasons for this:
The alignment of the shaft through a clutch bearing is very important to its operation, since the slightest amount of radial load could cause the rollers to tilt and not initially mate correctly into the tapered edges on the retainer.
The clearances between the load and the casing (or outer race on a few designs), is usually not as close as in a regular roller bearing, because you want the rollers to be able to move freely so they lock firmly between the load and the retainer. The bottom line is that the bearing is just to ‘sloppy’ to really carry any meaningful radial load unless it incorporates many small rollers instead of a few larger rollers.
Some reel manufacturers (e.g. Daiwa and others) provide a ball bearing very close to the clutch bearing to carry any radial loads and maintain correct alignment through the bearing – and this type of design helps ensure the clutch bearing does not slip and back-play is minimized. In addition, manufacturers can often reduce the overall weight of the reel by eliminating the need for a heavy clutch bearing race and metal cage, if they use a ball bearing near the clutch bearing. Since the trend in recent reels is to reduce the overall weight of the reel, more and more manufacturers are starting to use a ball bearing at the clutch bearing to carry radial loads.
Clutch bearings can wear, become fouled, need to be lubed and get damaged similar to other bearings in a reel. When this occurs, the bearing may not lock; it can slip, chatter or feel rough; or the reel can have more handle back-play than it once did. In addition, the type and amount of lube used on some clutch bearings can also result in similar problems, due to the design configuration of the reel.
Some of the more common problems encountered on roller clutch bearings are provided in the table below. Typical causes and solutions are also provided. However remember, clutch bearing and anti-reverse schemes can vary, so the table may not be completely representative of all reels.
Clutch Bearing Problems, Causes and Solutions
Excess handle back-play (more than it once did)
Outer ball bearing damaged
Check bearing and its socket/replace
Slipping (very excessive back play)
Worn/damaged tapers on edges of cage
Worn rollers (or surface they contact on load)
Excess lube/too light a lube
Clean and re-lube
Outer ball bearing worn
Chattering (in reverse direction)
Similar to slipping
Similar to slipping
Cage installed backwards (after doing maintenance?) or not installed all the way into the housing
Check orientation of cage in case and make sure the retainer is flush with the housing
Rough (or noisy)
Outer ball bearing worn or dirty
Clean/inspect bearing and replace if necessary
Check ball bearing and its socket
Handle shaft affecting outer ball bearing alignment and rotation
Check handle shaft for corrosion, burr, etc. where it fits on center race
Chattering or noisy (in forward direction)
Debris in bearing
Handle shaft bearing fouled or worn
Check condition of shaft bearing near clutch
Not Locking (after cleaning/adding lube)
Grease is too heavy or oil is too viscous (possible over lube?)
Clean and switch to lighter lube (or don’t add as much lube)
Cage installed backwards
Check orientation of cage in the case and insure it is mounted completely into the case
Slipping (after cleaning/ adding lube)
Grease or oil viscosity too low
Clean and switch to a heavier lube (or don’t add as much lube)
Metal springs installed backwards
Check orientation of springs
Cage not sitting properly in case
Check to ensure cage is flush with case (and case is mounted properly in frame)
Outer roller bearing not seated correctly or damaged
Check condition of roller bearing located near clutch bearing
Slipping/Not Locking in low temperatures or excessive back-play in low temperatures
Lube affected by temperature
Switch to a different lube (possibly clean and re-lube with less lube)
Moisture affecting movement of rollers
Dry out bearing and consider re-lube
In a strange twist on things, you actually need some friction for a clutch bearing to work properly. Without friction, the rollers may not move correctly into the locking tapers on the cage or may not lock on to the shaft once they get there. However, too much friction (e.g. due to the viscosity of the lubricant) can also prevent the rollers from moving correctly.
A few reels (e.g. some Shimano’s and Abu’s), are especially prone to slippage or not locking due to a lack of a ball bearing near the clutch bearing, and the number of rollers and angle of the tapers on the bearing retainer. Although most problems with these reels seem to occur while using certain lubes and/or in cold weather, users have adopted one of three general approaches to preclude problems from occurring (you will have to determine what works best for your Shimano or Abu reel and situation):
Don’t do anything to the clutch bearing if at all possible. If it works fine, don’t try to fix it. (Some reels have been known to work properly over a few seasons with the clutch bearing not re-lubricated – especially if the reel is stored and otherwise reasonably maintained.) If you eventually have to clean it, then do either of the two below.
Only wipe a very small amount of lube on the rollers when servicing the bearing. One small drop of oil on a stick or dowel can be used to put a light-thin film on all of the rollers.
Only put a very small film of grease on the clutch tube when servicing the bearing. The grease on the tube will be sufficient for proper operation as it spreads through the rollers.
The condition of the springs and cages on a clutch bearing can also affect how well it performs. Springs can loose their spring force over time and they can wear, corrode, become distorted or flattened with use. Polyethylene and nylon cages are especially prone to damage from debris, and their tapers can thin due to the frequent contact with the rollers. So be sure to also inspect the springs and cages when cleaning the bearing. By the way, keeping a roller bearing clean is the best way to mitigate wear of plastic and nylon cages.
Conclusion: Could there possibly be more?! If you have completed Bearing 101 through 301 then your well on your way to becoming a bearing connoisseur, but ChuckE still has more bearing wisdom to teach the committed. Were not yet done exploring the ins and outs of bearings and the next tutorial will go even further into reel bearing applications. Stay tuned!