The duty of MB Series Bearing Lock Washers is locating, clamping and sealing a bearing that has already been selected — an accessory is chosen from the bearing or the shaft it serves, not from a load rating of its own. These are the parts that turn a bearing into a mounted bearing: the nut and washer that clamp it, the sleeve that grips a plain shaft, and the seal that keeps the lubricant in and the contamination out. The sections that follow cover the sectors that specify them, how to state the designation, clearance, sealing, cage and fit on an order, how to mount them, and the known limits of the type. Dimensions are to DIN 5406. This series is catalogued from 10 mm to 100 mm bore; the full table of boundary dimensions is further down the page.
Typical Applications for MB Series Bearing Lock Washers
The machine positions and sectors where this type is specified:
- Maintenance and repair (MRO): replacing a failed bearing where the original designation, clearance group and sealing have to be matched exactly.
- OEM machine building: designed-in shaft support on new equipment, specified from the load, speed and envelope at the design stage.
- Maintenance and repair: the parts most often missing when a bearing is changed — a lock washer is single-use and an old adapter sleeve seldom comes off intact.
- Plummer block and pedestal installations: adapter sleeves, lock nuts and lock washers used to clamp a tapered-bore bearing onto plain shafting.
- Gearbox and drive rebuilds: shaft seals renewed whenever the bearing next to them is renewed.
How to Specify MB Series Bearing Lock Washers for Your Application
- Bore: Start from the bore the shaft or housing gives you — this series is catalogued from 10 mm to 100 mm — then check the outer diameter and width against the space available. The boundary dimensions are fixed by the standard, so they are the same from any manufacturer; the load ratings and limiting speeds are not, and belong to the specific bearing being supplied.
- Nut and washer as a pair: The KM lock nut and the MB lock washer are ordered as a matched pair for the sleeve or bearing thread. The washer is single-use.
- Fit to the bearing, not to the shaft: These parts are specified by the bearing or sleeve they serve. A KM lock nut is chosen for the sleeve or bearing thread; an MB lock washer is chosen for the lock nut; an adapter sleeve is chosen for the bearing bore and the shaft diameter range. Quote the bearing designation on the order alongside the accessory designation.
- Sealing arrangement: For shaft seals, state the shaft diameter, the housing bore, the width, the lip arrangement and the elastomer — the elastomer sets the temperature and chemical limits, and it is the field most often left off an order.
- Designation and suffixes: State the complete designation including every suffix. The base number gives the type and the boundary dimensions; the suffixes carry the sealing, the cage, the clearance group, the tolerance class and any special execution — and two bearings whose base numbers match but whose suffixes differ are not interchangeable.
- Clearance and tolerance: State the running clearance or fit class the assembly requires, together with the tolerances of the mating parts that produce it. For this type the clearance is created by the parts around the bearing rather than being built into it, which is precisely why it has to be written down.
- Sealing arrangement: This type is supplied open, so the sealing belongs to the housing around it. Specify the shaft seal, flinger or labyrinth that will keep the lubricant in and contamination out — with an open bearing, the sealing arrangement, not the bearing, decides how long it survives its environment.
- Cage: not applicable: This part has no cage and no rolling elements to separate, so the equivalent decision is the sliding material or liner. That is stated above, and it plays the same role: it is what sets the temperature limit and the lubrication requirement.
- Shaft and housing fit: Specify the seat tolerances, not just the bearing. The rule is that the ring which rotates relative to the load direction takes the interference fit: for a rotating inner ring under normal radial load the shaft seat is typically k5 or k6 with the housing bore H7, and where the outer ring rotates the interference moves to the housing (N7 or P7) with a clearance fit (g6) on the shaft. Heavier loads and hollow shafts move the fits tighter. A correctly chosen bearing in the wrong fit fails anyway — too loose and the ring creeps and frets its seat, too tight and the interference consumes the internal clearance and the bearing runs preloaded.
- Standard: Boundary dimensions are to DIN 5406. Quoting the standard on the order guarantees the mounting dimensions are interchangeable between suppliers — it does not standardize load ratings, limiting speeds or internal design, which remain manufacturer-specific.
Mounting & Assembly Practice
- Fit a new lock washer every time. Bending a tab back and forth work-hardens it, and a tab that breaks off leaves a hard fragment inside the housing.
- Tighten a lock nut against a driven-up sleeve only after the bearing clearance reduction has been measured; the nut is the tool that produces the drive-up, not just a retainer.
- Fit shaft seals with the lip facing the medium being retained, and never over an unchamfered shaft end or a sharp keyway — a nicked lip leaks from the first hour.
- Check the shaft surface at the seal running track. A worn track from a previous seal is a leak path, and a speedy-sleeve style repair or an axially offset seal position is the remedy.
Common Selection Mistakes with MB Series Bearing Lock Washers
- Reusing a lock washer, or bending a tab into a slot it does not line up with.
- Ordering an adapter sleeve by shaft diameter alone; the same shaft size is served by different sleeves depending on the bearing bore they carry.
- Choosing a seal by its dimensions and ignoring the elastomer, then finding an NBR lip hardened by an operating temperature that needed FKM.
- Sizing this bearing from the boundary dimensions alone. Load ratings and limiting speeds are manufacturer-specific for this series and are deliberately not published here — take them from the catalog of the bearing actually being supplied and calculate the life against them.
Where MB Series Bearing Lock Washers Are Not the Right Choice
- These parts carry no bearing load and have no load rating; they are not a substitute for a bearing anywhere in the assembly.
- A lock nut and washer is not a general-purpose fine-thread nut — it is a bearing clamping device and it is not rated for a bolted joint.
- A shaft seal is not a bearing seal replacement where the bearing itself needs sealing; it protects the shaft exit, and the two are separate arrangements.
