DRAWN CUP NEEDLE CLUTCH
  

Drawn cup needle clutch HF series and HFZ series

 

The drawn cup needle clutch HF, HFZ series is composed of thin wall punched outer ring and plastic retainer. There is a clamping slope which holds the needles tightly on the inradius surface of the alloy steel punched out ring . the abrasion resistance and load capacity is greatly increased after special heat treatment. Metal springs are fitted on the plastic retainer which keeps the correct movement of the needles while the needles are used as clamping unit at the same time.

Through fitting RTL drawn cup needle roller bearing HK, SCE series of the same diameter on the two sides of drawn cup needle clutch, better supporting rigidity and rotation characteristics are achieved.

 

drawn cup needle clutch HF/HFZ

 

Drawn cup needle clutch and bearing assembly HFL series and HFlZ series

 

Drawn cup needle clutch and bearing assembly HFL, HFLZ series has a two-in-one supporting bearing which can be a special space-saving support. The supporting bearings fitted be the two sides of the needle clutch bear the radical load . The support bearings are needles and the plastic retainer.

 

Drawn cup needle clutch and bearing assembly HFL/ HFlZ

 

Torque transmission capacity

 
                                 When the recommended assembling tolerances are adopted, the maximum transmitting torque is mainly decided by the
                  material, strength  and wall thickness of the  seat case and shaft. In a clutch, only enough wall thickness and appropriate material 
                  strength can sustain the force resulted. Inertial force should be taken into account. For the equivalent caused by the torque and the
                  minimum wall thickness  ,  please refer to Figure 1. The equivalent stress should be less than the stress permitted by the seat mat-
                  erial. For the relation between free torque and axle diameter , please refer toFigure 2.
 

Example:

 
     A known: drawn cup needle clutch HF3020
     Load capacity: 90% of Md
     Present wall thickness: Sexis=16mm
     From Fig 1: minimum wall thickness Smin=4.8mm
     Equivalent stress §Òequiv=380N/mm2
     B; known: drawn cup needle clutch HF1416
     Permissive stress of seat casing §Òperm=300N/mm2
     Selective ratio of the seat casing wall thickness Smin/Sexis=0.5
     From Fig 1: minimum wall thickness Smin=3.2mm
     Permissive torque Md perm=60%Md
 

The switching frequency and precision

 

The needle clutch has a very small torque due to its thin radical section. Because each needle is supported by an independent spring, a constant contacting is maintained among the slopes of shaft, needles and punched outer ring, higher switching frequency and precision are allowed. Beside the switching frequency, the switching precision is depended on the selection of lubrication and combination. The elastic deformation of the neighboring parts and driving force are transmitted through the shaft or outer ring. The driving force is transmitted through shaft when the frequency is high.

 

 

Feature inspection

 

The tools used by the manufacturer in inspection of drawn cup needle clutch are feeler gage and ring gage which are in seat hole and shaft tolerance range N6/h5 upper limit and lower limit. Meanwhile , the torque it sustains is approximately 0.15Md perm. The feeler gage used is quenched steel ring with its aperture precisely ground and the minimum wall thickness of 20mm.

Figure 2 the relationship between free rotation torque and the axle diameter in the drawn cup needle clutch.

 

Operational temperature and lubrication

 
                        With good lubrication,RTL drawn cup needle clutch can be operated for  a long time under the temperature between
              -30¡æ-20¡æ. When the temperature is below -10¡æor the speed is greater than 0.7 *nj, to ensure the normal functions of 
              the bearings,  recommended lubricants should be selected. In most cases, there are enough lubricants. So the products 
              are filled in advance the quality lithium based grease in compliance with the national  standards with the applicable 
              temperature from -10¡æto 70 ¡æ. Oil lubrication is recommended when the temperature exceeds 70¡æ.
 

Mounting tolerance

 

When mounting , the shaft and the seat hole with a chamfered angle of 15 degrees will help to get the best fitting condition. The mounting method is shown in Fig 3. The needles and the thin wall punched outer ring of the clutch will get the concentric configuration only after being fitted into the seat. No other axle positioning is necessary. The mounting tolerance is the same as that of the drawn cup needle bearing. See table 1. The seat hole surface roughnes is Ra0.8 .

 

 

Bearing seat material (rigid bearing seat)

Bearing seat hole tolerance

 

Shaft tolerance range

Without inner ring

Inner ring

 

Steel and cast iron

N6(N7)

h5(h6)

k5(j6)

Light metal

R6(R7)

 
               1)  for non rigid bearing seats, fitting tests are needed to determine the required common tolerance limit so that the operational gap can be achieved.
               2) The geometric precision of the cylinder shape of the bearing seat hole must fall into the half range of the value in IT5/2.

Special reminding:

 
                        1) Press the needle clutch into the seat hole with a fitting shaft . The clutch will be locked tightly when turning around in the arrow direction marked 
               on the side of clutch.. So, note the locking direction before fitting.
	                    2) The close locking and overdrive clutching is possible only when the recommended tolerances are used.

 

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