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Drawn cup roller clutches
 

Drawn cup roller clutches:

 
 
  • are one-way clutches, which transmit torques in one direction ➤ Figure 1
  • are available with or without an integrated bearing arrangement ➤ Figure 2, ➤ Figure 3 and ➤ Figure 4
  • give very precise indexing
  • allow high indexing frequencies
  • have a low overrunning frictional torque
  • are available with or without greasing
  • are particularly compact in a radial direction and therefore permit extremely compact designs
  • are suitable for housing materials made from steel, light metal or plastic
  • can be combined with drawn cup needle roller bearings with open ends HK and drawn cup needle roller bearings with closed end BK
  • have an extensive range of applications, for example as indexing clutches, back-stopping clutches and overrunning clutches ➤ Figure 1.
 
   

Figure 1
Drawn cup roller clutches in tandem arrangement in an indexing system

Symbole/00016410_mei_in_0k_0k.gif  Stationary component
Symbole/00016411_mei_in_0k_0k.gif  Component performs a swivel motion
Symbole/00016412_mei_in_0k_0k.gif  Component performs a gradual rotational motion

 

imageref_22689424651_All.gif

 
 

Product design

 
 

Drawn cup roller clutches are available:

 
   
 

Drawn cup roller clutches

Drawn cup roller clutches are one-way clutches

 

These drawn cup roller clutches comprise thin-walled, drawn outer cups with a series of ramps on the inside diameter, plastic cages and needle rollers, which serve as clamping elements. Steel or plastic springs hold the needle rollers in their clamped position. Drawn cup roller clutches can transmit high torques in one direction and are particularly compact in a radial direction. The roller clutches are available with and without support bearing arrangements.

 

Suitable for applications with high indexing frequencies

 

Drawn cup roller clutches give very precise indexing, since the individual spring loading of the needle rollers ensures continuous contact between the shaft, needle rollers and ramps. They allow high indexing frequencies due to their low mass and the resulting low moment of inertia of the clamping elements. They also have a low overrunning frictional torque.

 

Preferred areas of application

 

Drawn cup roller clutches can be used in various applications such as indexing clutches, back-stopping clutches and overrunning clutches. In these cases, the drawn cup roller clutch performs an overrunning or locking function.

 
imageref_17757187211_All.gif   Drawn cup roller clutches should not be used if a malfunction could lead to personal injury. New applications, especially those involving extreme conditions, should first be verified by tests. Correct functioning can only be guaranteed if the concentricity error between the support bearing and the shaft can be kept to a low value.  
 

Drawn cup roller clutches without bearing arrangement

Suitable for supporting torques only

 

Roller clutches HF do not have a bearing arrangement, i.e. they transmit torques only and, as a result, are unable to support any radial forces ➤ Figure 2. In the case of these roller clutches, concentricity to the shaft axis must be secured by additional rolling bearings or drawn cup roller clutches with a bearing arrangement must be used. The drawn cup roller clutches are available with and without knurling.

 

Drawn cup roller clutches without knurling

 

Drawn cup roller clutches without knurling are available with steel or plastic pressure springs ➤ Figure 2. Bearings with plastic springs have the suffix KF ➤ section .

 

Drawn cup roller clutches with knurling

 

For improved torque transmission in plastic housings, drawn cup roller clutches are available with a knurled outside surface. These drawn cup roller clutches have the suffix R ➤ section . The knurling can be applied to part of the drawn cup or over its entire length. The drawn cup roller clutches are also available with steel or plastic pressure springs. Roller clutches with plastic springs have the suffix KF ➤ section .

 
   

Figure 2
Drawn cup roller clutches without bearing arrangement, with and without knurling

Symbole/00016410_mei_in_0k_0k.gif  Without knurling
Symbole/00016411_mei_in_0k_0k.gif  With knurling

 

imageref_22689597963_All.gif

 
 

Drawn cup roller clutches with bearing arrangement

Also suitable for supporting radial forces

 

Due to the integrated plain or rolling bearing, roller clutches HFL can also support radial forces in addition to torques ➤ Figure 3 and ➤ Figure 4. The drawn cup roller clutches are available with and without knurling.

 

Drawn cup roller clutches without knurling

 

Drawn cup roller clutches without knurling are available with steel or plastic pressure springs ➤ Figure 3 and ➤ Figure 4. Drawn cup roller clutches with plastic springs have the suffix KF ➤ section .

 

Drawn cup roller clutches with knurling

 

For improved torque transmission in plastic housings, drawn cup roller clutches are available with a knurled outside surface. These drawn cup roller clutches have the suffix R ➤ section . The knurling can be applied to part of the drawn cup or over its entire length. These drawn cup roller clutches are also available with steel or plastic pressure springs. Roller clutches with plastic springs have the suffix KF ➤ section .

 
 

   

Figure 3
Drawn cup roller clutches with plain bearing arrangement, with and without knurling

Fr =  radial load
Symbole/00016410_mei_in_0k_0k.gif  Without knurling
Symbole/00016411_mei_in_0k_0k.gif  With knurling
Symbole/00016412_mei_in_0k_0k.gif  Plain bearing

 

imageref_22689599883_All.gif

 
   

Figure 4
Drawn cup roller clutch with rolling bearing arrangement, without knurling

Fr =  radial load
Symbole/00016410_mei_in_0k_0k.gif  Rolling bearing

 

imageref_22689601803_All.gif

 
 

Clamping direction of the drawn cup roller clutch

imageref_17757187211_All.gif   An arrow on the end face of the drawn cup indicates the clamping direction of the drawn cup roller clutch. The roller clutch clamps when the drawn cup is rotated in the direction of the arrow.  
 

Load carrying capacity

 

Roller clutches with a support bearing arrangement accommodate radial forces

 

Depending on the design (with or without bearing arrangement), drawn cup roller clutches can either transmit torques only or additional radial loads ➤ section , ➤ Figure 3 and ➤ Figure 4. For roller clutches without bearing arrangement, radial forces must be supported by additional bearings.

 
 

Transmissible torque

The rigidity of the housing determines the transmissible torque

 

Transmission of torque requires a rigid housing. The transmissible torque is therefore dependent on the shaft and housing material, the shaft hardness, the wall thickness of the housing and the shaft and housing tolerances. When calculating the torque, the maximum drive torque and the moment of inertia of the masses during acceleration must be taken into consideration.

 
 

Limiting load

Do not exceed the limiting load

 

In the case of drawn cup roller clutches with plain bearings, the product calculated from the actual speed n and radial load FR must not exceed the value stated for the limiting load (Fr · n)max. The operating limits are determined by the limiting speeds stated in the product tables and the permissible radial load.

 
 

Indexing accuracy and indexing frequency

The roller clutch must not be overloaded

 

In order not to overload the clutch, the inertia of the entire system must be taken into consideration. The high indexing accuracy is due to the individual spring loading of the needle rollers, which ensures continuous contact between the shaft, needle rollers and clamping surface. The indexing accuracy is influenced by the indexing frequency, lubrication, fitting tolerances, adjacent construction, elastic deformation of the adjacent parts and the drive method, either through the shaft or the housing. Optimum accuracy is achieved if the drive is via the shaft.

 

High indexing frequencies due to low mass

 

High indexing frequencies are due to the low mass and the resulting low moment of inertia of the clamping elements.

 
 

Frictional torque and frictional energy

 

For pattern of frictional torque ➤ Figure 5. The overrunning frictional energy at idle is dependent on whether the shaft or the outer ring is rotating ➤ Figure 6.

 
   

Figure 5
Overrunning frictional torque, as a function of shaft diameter

MR =  overrunning frictional torque
d =  shaft diameter

 

imageref_22690137227_All.gif

 
   

Figure 6
Overrunning frictional energy, as a function of speed

NR =  overrunning frictional energy
n =  speed
nGA =  limiting speed with rotating outer ring
nGW =  limiting speed with rotating shaft

 

imageref_22690139147_All.gif

 
 

Rotating outer ring

Due to the centrifugal force, the needle rollers may lift off the shaft

 

If the outer ring rotates, the frictional energy increases with speed at first but then, due to the centrifugal force of the needle rollers, it decreases gradually towards zero. At this speed, there is no longer any frictional contact between the needle rollers and the shaft. Due to the increasing centrifugal force, the needle rollers lift off the shaft.

 
 

Compensation of angular misalignments

 
imageref_17757187211_All.gif   Concentricity is an essential precondition for correct functioning of the roller clutch. Correct functioning can only be guaranteed if the concentricity error between the support bearing and the shaft can be kept to a low value.  
 

Lubrication

 

A grease to GA26 is used for initial greasing

 

The roller clutches are greased using a lithium soap grease to GA26. In many cases, the initial greasing is sufficient to last the operating life of the bearings. For applications with oil lubrication, roller clutches are available without greasing. These roller clutches are coated with a preservative. For general applications (mixed operation involving locking and overrunning), the Schaeffler initial greasing has proved effective. In order to ensure optimum function, it may be necessary to use different lubricants. The suitability of the lubricant must then be verified by means of tests.

 
imageref_18348417035_All.gif   For applications in which one operating condition (overrunning or locking) is heavily predominant, a special greasing should be used. In this case, please consult Schaeffler.  

A grease operating life cannot be calculated

 

It is not possible to calculate the grease operating life or lubrication interval for drawn cup roller clutches. If relubrication is carried out, oil should used for lubrication or a changeover to oil lubrication should generally be made. At temperatures < –10 °C and speeds > 0,7 nG, recommendations on lubrication should be requested. At temperatures over +70 °C, oil lubrication should be used. The oil level should be such that, when the drawn cup roller clutch is stationary and the axis is horizontal, it is immersed approx. 1/3 in the oil bath.

 

Suitable lubricating oils

 

Suitable oils are CL and CLP to DIN 51517 or HL and HLP to DIN 51524. Viscosity classes ➤ Table 1.

 

Compatibility with plastic cages

 

When using bearings with plastic cages, compatibility between the lubricant and the cage material must be ensured if synthetic oils, lubricating greases with a synthetic oil base or lubricants containing a high proportion of EP additives are used.

 
 

   
Table 1
Viscosity classes
 

Operating temperature
Viscosity class
°C
from
to
+15
+30
ISO VG 10
+15
+90
ISO VG 32
+60
+120
ISO VG 100

 
 

Sealing

 
 

Drawn cup roller clutches (with and without bearing arrangement) are supplied without seals. Contaminants (dust, dirt and moisture) can impair the function and operating life of roller clutches.

 
 

Sealing of the bearing position with sealing rings G or SD

Effective sealing elements for use in sealing open drawn cup roller clutches with a risk of contamination

 

If there is a risk of contamination, sealing rings of economical series G or SD should be fitted ➤ link . The sealing rings are designed as contact seals and are arranged in front of the roller clutch. They protect the bearing position reliably against contamination, spray water and excessive loss of grease. The sealing rings are matched to the small radial dimensions of the drawn cup roller clutches and can be combined with wider inner rings of series IR. They are very easy to fit, since they are simply pressed into the housing bore.

 
 

Speeds

 

Speeds for rotating shaft or rotating outer ring

 

The limiting speeds nGW and nGA in the product tables are valid for oil and grease lubrication. The limiting speed nGW is valid for a rotating shaft, while nGA is valid for a rotating outer ring.

 
 

Noise

 
 

Schaeffler Noise Index

 

The Schaeffler Noise Index (SGI) is not yet available for this bearing type    ➤ link. The data for these bearing series will be introduced and updated in stages.

 
 

Temperature range

 
 

Possible operating temperatures of drawn cup roller clutches ➤ Table 2.

 
   
Table 2
Permissible temperature ranges
 

Operating temperature
Drawn cup roller clutches
imageref_19988082955_All.gif
   
–10 °C to +70 °C, limited by the lubricant

 
imageref_18348417035_All.gif   In the event of anticipated temperatures which lie outside the stated values, please contact Schaeffler.  
 

Cages

 
 

Plastic cages are used in the guidance of rolling elements for roller clutches and for integrated support bearing arrangements supported by rolling elements.

 
 

Internal clearance

 

The enveloping circle diameter Fw applies instead of the radial internal clearance

 

In the case of bearings without inner ring, the dimension for the enveloping circle diameter Fw is used instead of the radial internal clearance. The enveloping circle is the inner inscribed circle of the needle rollers in clearance-free contact with the outer raceway. In drawn cup roller clutches with a rolling bearing arrangement, the enveloping circle diameter Fw of the bearings once fitted (in the solid section ring gauge) is approximately in tolerance class F8. Upper and lower deviations of enveloping circle diameter for tolerance class F8 ➤ Table 3.

 
   
Table 3
Deviations of enveloping circle diameter for drawn cup roller clutches supported by rolling bearings
 

Enveloping circle diameter Fw
Tolerance class F8
mm
Tolerance for enveloping circle diameter Fw
upper deviation
lower deviation
over
incl.
μm
μm
3
6
+28
+10
6
10
+35
+13
10
18
+43
+16
18
30
+53
+20
30
50
+64
+25

 
 

Dimensions, tolerances

 
 

Dimensions and tolerances of drawn cup roller clutches are not standardised. The thin-walled outer cups adopt the dimensional and geometrical accuracy of the housing bore.

 
 

Suffixes

 
 

For a description of the suffixes used in this chapter ➤ Table 4 and medias interchange http://www.schaeffler.de/std/1D52.

 
   
Table 4
Suffixes and corresponding descriptions
 

Suffix
Description of suffix
- Steel springs
Standard
KF
Plastic pressure springs
R
Knurled outside surface
RR
Drawn cup roller clutch with Corrotect coating
Special design, available by agreement

 
 

Structure of the product designation

 

Examples of composition of product designation

 

The designation of drawn cup roller clutches follows a set model. Examples ➤ Figure 7 and ➤ Figure 8.

 
   

Figure 7
Drawn cup roller clutch without bearing arrangement, without knurling: designation structure


 

imageref_22689467531_en.gif

 
   

Figure 8
Drawn cup roller clutch with bearing arrangement, plastic pressure springs, with knurling: designation structure


 

imageref_22689472267_en.gif

 
 

Dimensioning

 
 

The size is determined on the basis of the load carrying capacity of the drawn cup roller clutch relative to the loads and the requirements for rating life and operational reliability ➤ section .

 
 

Design of the adjacent construction

 
 

Design of housing bore

Support outer cup over entire circumference and width

 

Suitable housing materials are steel, light metal or plastic. In order to allow full utilisation of the performance capability of drawn cup roller clutches and achieve the requisite rating life, sufficient rigid support must be provided for the outer cups in the housing. The support for the outer cup in the housing bore can be produced as a cylindrical seating surface. The seating surfaces for the outer cup and the raceway for the rolling elements or inner ring (if the bearing arrangement is not produced as a direct bearing arrangement) should not be interrupted by grooves, holes or other recesses. The accuracy of the mating parts must meet specific requirements, the bore tolerances for the housing bore (rec­ommended tolerance classes) are dependent on the housing material ➤ Table 5 and ➤ Table 6. The surface quality of the housing bore should be Ramax 0,8. The cylindricity tolerance of the housing bore in metal housings should be within the tolerance grade IT5/2.

 
imageref_17757187211_All.gif   Due to the thin-walled outside surface, the roller clutches only adopt their precise geometry once they have a tight fit. As a result, the accuracy of the locating bore essentially determines the geometrical accuracy of the drawn cup and thus the functioning of the clutch.  

Provide lead chamfer on the housing bore

 

For the drawn cup roller clutches to be mounted without damage, the housing bore must have a lead chamfer of 15°.

 
   
Table 5
Design of housing bore
 

Series
Springs
Bore
Housing material
Steel
Cast iron
Light metal
Max. bore
in plastic2)
HF, HFL
Steel
N6 Ⓔ (N7 Ⓔ)1)
R6 Ⓔ (R7 Ⓔ)1)
-
HF..-KF, HFL..-KF
Plastic
N7 Ⓔ
R7 Ⓔ
-
HF..-R, HFL..-R
Steel
- - D
0–0,05
HF..-KF-R, HFL..-KF-R
Plastic
- - D
0–0,05
HFL0606-KF-R, HFL0806-KF-R
Plastic
- - D
0–0,05

 
 
______
 1    The values in brackets can be used if the actual torque is no more than 50% of the permissible torque Md per in accordance with the product table.
 
 
 2    Guide values as a function of the plastic used. Outside diameter D ➤ dimension table.
 
 

Minimum wall thickness for metal housings

Maximum transmissible torque

 

For metal housings, the maximum transmissible torque Md per max is determined as a function of the diameter ratio QA to ➤ Figure 9 (steel housing) or to ➤ Figure 10 (aluminium housing), see calculation examples.

 
 

Guide values for QA max with steel and aluminium as housing materials ➤ Table 6.

 
   
Table 6
Guide values
 

Housing material
Diameter ratio
QA max
Steel
0,8
Aluminium
0,6

 
imageref_17757187211_All.gif   The comparative stress σv must not exceed the yield stress of the housing material.  
 

Steel housing

 

For drawn cup roller clutches HF0612, the maximum transmissible torque Md per max should be determined ➤ Figure 9:

 
 
 

Calculation example

 

Drawn cup roller clutch
HF0612
Housing
Steel
Housing bore tolerance
N6 Ⓔ ➤ Table 5
Permissible housing stress (Rp0,2) σv
450 N/mm2
Diameter ratio QA of housing
0,9
Permissible torque Md per
in accordance with product table

 
 
 

Calculation

 

 

Md per max
=
60% Md per

   

   
=
0,6 · 1,76 Nm

   

   
=
1,056 Nm

   

 

 
   

Figure 9
Steel housing

Modulus of elasticity E = 210 000 N/mm2
QA =  diameter ratio of housing
DAi =  housing bore
DAa =  housing outside diameter
Md per =  permissible torque
Md per max =  maximum transmissible torque
σv =  comparative stress

 

imageref_22689476619_All.gif

 
 

Aluminium housing

 

For drawn cup roller clutch HF1616, the diameter ratio QA of the housing should be determined ➤ Figure 10:

 
 
 

Calculation example

 

Drawn cup roller clutch
HF1616
Housing
Aluminium
Housing bore tolerance
R6 Ⓔ ➤ Table 5
Permissible housing stress (Rp0,2) σv
250 N/mm2
Maximum transmissible
torque Md per max
10 Nm
Permissible torque Md per
in accordance with product table

 
giving Md per max/Md per
50%

 
 
 

Calculation

 

 

QA
=
DAi/DAa ≦ 0,7

   
DAa

DAi/0,7 = 22 mm/0,7

   

   
=
31,5 mm

   

 

 
   

Figure 10
Aluminium housing

Modulus of elasticity E = 70 000 N/mm2
QA =  diameter ratio of housing
DAi =  housing bore
DAa =  housing outside diameter
Md per =  permissible torque
Md per max =  maximum transmissible torque
σv =  comparative stress

 

imageref_22689594891_All.gif

 
 

Minimum wall thickness for plastic housings

imageref_17757187211_All.gif   For plastic housings, drawn cup roller clutches with a partially or fully knurled outside surface should be used (suffix R).  
 

  The guide value for the minimum wall thickness of plastic housings is:

Equation 1
 
imageref_10903639691_All.gif

Legend

 
smin
 mm
Minimum wall thickness
D
 mm
Outside diameter of roller clutch
Fw
 mm
Enveloping circle.
 
 

Axial location

A tight fit is usually sufficient for axial location

 

Drawn cup roller clutches give very easy mounting and permit simple adjacent constructions. The drawn cup roller clutches are pressed into the housing bore and require no further axial location. The precondition for this is, however, that the specifications in accordance with ➤ Table 5 are observed.

 
 

Design of the shaft/raceway

Produce the raceway as a rolling bearing raceway

 

Drawn cup roller clutches HF/HFL are usually used without an inner ring. In order to guarantee correct functioning of the drawn cup roller clutches, the raceway for the rolling elements on the shaft must be produced as a rolling bearing raceway (hardened and ground). The surface hardness of the raceways must be 670 HV to 840 HV, the case hardening depth CHD must be sufficiently large (CHD ≧ 0,3 mm). Design of raceways ➤ Table 7. If the shaft cannot be produced as a raceway, the bearings can be combined with inner rings IR or LR.

 

Provide lead chamfer on the shaft

 

For the bearings to be mounted without damage, the shaft must have a lead chamfer of 10° to 15° with a width of approx. 1 mm.

 
   
Table 7
Design of shaft
 

Series
Springs
Shaft
Tolerance class1)
Roundness tolerance
Parallelism tolerance
Recommended mean roughness value
Ramax (Rzmax)
max.
max.
μm
HF, HFL
Steel
h5 (h6)2)
IT3
IT3
0,4 (2)
HF..-KF, HFL..-KF
Plastic
h8
HF..-R, HFL..-R
Steel
h5 (h6)2)
HF..-KF-R, HFL..-KF-R
Plastic
h8
HFL0606-KF-R,
HFL0806-KF-R
Plastic
h9

 
 
______
 1    The envelope requirement Ⓔ applies.
 
 
 2    The values in brackets can be used if the actual torque is no more than 50% of the permissible torque Md per.
 
 

Mounting and dismounting

 
imageref_17757187211_All.gif   Protect drawn cup roller clutches against dust, dirt and moisture; contaminants can impair the function and operating life of roller clutches. Pressing-in forces must never be directed through the rolling elements. Drawn cup roller clutches must not be tilted during pressing-in, as this may damage the needle rollers and raceways.  

Retention for transport

 

Drawn cup roller clutches are normally packed individually in the case of small quantities. Where larger quantities are involved, drawn cup roller clutches are placed in a specific orientation in blister packaging and delivered in this form. The blister packaging then serves to retain the parts in position during transport.

 

Removing the drawn cup roller clutches from the packaging

 

Drawn cup roller clutches should only be removed from their original packaging immediately before assembly. If roller clutches are removed from a batch packaged with dry preservative, the package must be closed again immediately. The protective vapour phase can be maintained only in the closed package. Ungreased drawn cup roller clutches are coated with a preservative. Lubrication with oil must take place after pressing-in, in accordance with the specifications.

 
 

Drawn cup roller clutches should be stored:

 
 
  • in dry, clean rooms with the room temperature as constant as possible
  • at a relative humidity of max. 65%.
 

Storage period

 

The storage period for greased drawn cup roller clutches is limited by the shelf life of the lubricating grease.

 

Mounting using a fitting mandrel

 

Drawn cup roller clutches should only be pressed into the locating bore using a special fitting mandrel. Attention must be paid to the clamping direction of the roller clutch. The clamping direction is indicated by an arrow on the end face of the drawn cup.

 
 

The drawn cup roller clutch clamps if it is rotated in the direction of the arrow.

 
 

Functional inspection

Clutches without knurling

 

The function of these roller clutches is checked in a housing with the mini­mum wall thickness determined according to ➤ Figure 9 or thicker. The housing bore and shaft tolerances must be observed ➤ Table 5 and ➤ Table 7.

 

Clutches with knurling

 

The function of these clutches is checked before they are pressed in. In this case, the inspection criteria are the clamping effect and idling.

 
imageref_18348417035_All.gif   For any questions relating to the mounting of drawn cup roller clutches, please consult Schaeffler.  
 

Schaeffler Mounting Handbook

Drawn cup roller clutches must be handled with great care

 

In order that drawn cup roller clutches can function correctly and achieve the envisaged operating life without detrimental effect, they must be handled with care.

 
imageref_21602891659_en.gif   The Schaeffler Mounting Handbook MH 1 gives comprehensive infor­mation about the correct storage, mounting, dismounting and mainten­ance of rotary rolling bearings http://www.schaeffler.de/std/1D53. It also provides information which should be observed by the designer, in relation to the mounting, dismounting and maintenance of bearings, in the original design of the bearing position. This book is available from Schaeffler on request.  
 

Legal notice regarding data freshness

 

The further development of products may also result in technical changes to catalogue products

 

Of central interest to Schaeffler is the further development and opti­misation of its products and the satisfaction of its customers. In order that you, as the customer, can keep yourself optimally informed about the progress that is being made here and with regard to the current technical status of the products, we publish any product changes which differ from the printed version in our electronic product catalogue.

 
imageref_18350433803_All.gif   We therefore reserve the right to make changes to the data and illus­trations in this catalogue. This catalogue reflects the status at the time of printing. More recent publications released by us (as printed or digital media) will automatically precede this catalogue if they involve the same subject. Therefore, please always use our electronic product catalogue to check whether more up-to-date information or modification notices exist for your desired product.  
   
  
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