NNF-PP-V

Technical characteristics

NNF50-PP-V type full complement bearings have a two piece inner ring having three integral flan- ges which is held together by a retaining ring for  ease of handling and mounting.The outer ring features an integral centre flange.

These bearings are being produced with two con- tacting seals as standard.

These bearings are being preferably used as rope pulley bearings for cranes and hoisting equip- ment.NNF50-PP-V type bearings are beingsatis- factory in supporting high radial loads and axial forces acting in both directions.Due to their in- ternal geometry,they can also accommodate til- ting moments.

As these bearings are being primarily used as rope sheave bearings,they have an outer ring that is 1 mm less wide than the inner rings.This speci- fic feature allows omitting additional sleeves

or  washers.

As a standard feature,NNF50-PP-V type full com- plement bearings have two retaining ring grooves in their outer ring.

This feature allows for a simple and cost effec- tive  method  of  mounting  rope  pulleys,etc.by using snap rings.

As NNF50-PP-V type bearings are standard fitted with two contacting seals they are supplied grea- se filled by the factory with a high quality bearing grease.

Bearings of the series NNF50-PP-V operating at high speeds or under harsh conditions (e.g.the presence of saltwater,high humidity,contamina- tes etc.)require more frequent lubrication.

To allow for simple  relubrication,the  bearings are standard manufactured with two independent working relubrication possibilities;these bearings can get lubricated via lubricating grooves and

bores in the inner rings or,alternatively,via the lubrication groove and holes into the outer ring.

Appropriate snap rings

As a standard feature,NNF50-PP-V type full com- plement bearings have two retaining ring grooves in their outer ring for a simple andcost effective method of mounting rope pulleys,etc.by

using WRE and WR type snap rings or standard snap rings according to DIN471.

These snap rings are being not supplied withthe bearings.

PP Sealing

NNF50-PP-V bearings have contacting seals fitted to either side of the bearing as standard these seals are made from specifically resistant Polyu- rethane.The seals are mounted on the inner

ring shoulders and contact the outer ring raceway with light preload on the sealing lip.

These seals provide an efficient sealing against dust,contamination and splash water or water spray.

NNF50-PP-V can be supplied with different spe- cial seals or metal shields on order request.

Anti corrosion coating

VEONNF50-PP-V type full complement cylindrical roller bearings can be supplied with an effective  anti rust protection,suffix CE05.

This coating allowsbearings to work even under aggressive environments,i.e.,salt water spray or dust.

Lubrication

When  working  under  harsh  conditions,such as  the  presence  of  salt  water,high  humidity contaminates  etc.)or  when  operating  at  high speeds,these bearings require a more frequent  re-

lubrication.Due to the specific design of the bearing,arelubrication can be performed either  through the inner ring as well as via the outer  ring.

When re-greasing NNF50-PP-V bearings,particu- lar care must be applied in order to prevent the seals from popping out of the bearings during re- greasing.

Following guidelines apply:

make sure that the correct grease type is being used

make sure that the grease is clean and free from any contamination

apply the grease slowly until the old grease is being squeezed out of the bearing

make sure that the seals are not getting squee- zed out by the grease pressure.If necessary, support the PP-seals with washers to prevent them from being squeezed out

If bearings with one or no seals are required,the seals may be removed easily by using a screw- driver.For applications where oil lubrication is used,the bearings can be delivered without seals

and grease if economic quantities are involved. Otherwise the seals should be removed and the bearings washed before use.If oil lubrication is used,the speed limits quoted in the product ta-

bles can be increased by approximately 30%.

VEO  NNF50-PP-V  cylindrical roller bearingscan be supplied with special grease (suffix   -L02)for low temperatures  (-54°C).

Misalignment

Double row  full complement cylindrical roller bearings are not  able to absorb a misalignement

Tolerances

VEO full complement cylindrical roller bearings areproduced to tolerance  class  PN  as  standard.

For obtaining detailed values on tolerances  refer to the chapter  Bearing  data  and  Tolerances.

In case of bearings having anti corrosion coating, i.e.suffix  CE05,the tolerances apply  to  the bearings  in  uncoated condition.

Internal  radial  clearance

VEO full complement cylindrical roller bearings are produced  to  normal  internal  clearance  group (group   CN)as   standard.

VEO bearings can also be  produced  to  other  clea- rance   groups to  customers  order.

The  clearance  values  correspond,as  far  as  they are standardized,to the  relevant  international  standards  DIN  620  part  4  and   ISO5753-1991.

The values  of  the  different  internal clearance groups  of  seales,double  row  VEO  cylindrical roller  bearings  for  rope  sheaves  are  listed  in table  1(page    331).

Non-standardized  internal  clearance

VEO sealed,double row   full  complement  cylindri- cal  roller  bearings  for  rope  sheaves  can  also   be

produced with individually defined special inter- nal clearances to customers order. This includes the possibility of producing bearings with a clearance restricted to a part of thefull clearance

range,i.e.C3H etc

VEO sealing full of cylindrical roller bearing for the VEO of the steel wire pulley

Operating   temperature

Restricted by the seal material and the grease, NNF50-PP-V bearings are suitable for operating temperatures from -20℃ to +80°C.

Under  request,the  bearings  can  be  supplied with special seals  (suffix -PS)to  increase  the maximum operating temperature to+120C and/ or with special grease (suffix-L02)for extreme

temperatures  to  decrease  the  lower  limit  to -54℃.

Minimum  load

Rolling  bearings  require a sufficient  minimum radial load to prevent excessive sliding friction.  Particularly  full  complement  cylindrical   roller bearings require a minimum radial load of more

than 4%of the dynamic load rating Cr.

Dynamic axial load carrying capacity

NNF50-PP-V type full complement cylindrical ro- ller bearings are primarily designed to accommo- date radial loads.However,they are also suitable to accept thrust forces acting in one or both

di- rections to a limited extend.

Thrust forces applied to cylindrical roller bea- rings generate sliding friction between the roller end faces and the guiding flanges.

Hence,an  optimum   lubrication  is  crucial.Fur- thermore,every thrust load creates a tilting mo- ment on the rollers.

This requires an additional radial loading to ensu- re an effective function of the bearing.

For all these reasons together with the existence of  grooves  in  the  outer  ring,in  the  case  of cylindrical roller bearings with snap ring grooves  application  engineering  advice  is  necessary

Please,consult  VEO  application  engineering  department when axial loads are expected.

Abutment  and  fillet  dimensions

The shoulders on adjacent machine parts must be designed in such a way that the required axial support of the bearing rings is guaranteed.

The bearing rings must contact adjacent parts with their side faces only.

The  bearing  chamfers  must  not  contact  the shoulder fillet radii of shaft or housing shoulders.

Therefore,the  largest  fillet   radius(rg)must  be kept smaller than the minimum chamfer on the bearing rings(rs)given in the product tables.

Recommendations for the dimensions of adjacent parts are given in DIN 5418.

Supplementary  designations

The product tables  show the  standardized bearing configurations updated on the edition of this catalogue.These standardized configurations correspond to suffix or suffixes of each bearing.

In any case,VEO can offer,under requirement,  alternative designs,comprising the ones showed in the following table or many others,whose mention exceeds the purpose of  the present

catalogue,and can be found in specific technical publications of concrete applications or series of specific bearings.

Should you need a special design not existent in these pages,please contact our Sales Department in VEO Bearings Europe.