Internal Freewheels FXN
for press fit on the outer ring
with sprag lift-off X
Features
Internal Freewheels FXN are sprag freewheels without bearing support and with sprag lift-off
X. The sprag lift-off X ensures a wear-free free - wheeling operation when the inner ring rotates
at high speed. The outer ring is pressed into the customer hous ing. This makes compact, space-saving fitting solutions possible. The freewheels FXN are used as:
Backstops
Overrunning Clutches
for applications with high speed freewheeling operation and when used as an overrunning
clutch with low speed driving operation. Nominal torques up to 20 500 Nm. The torque is
transmitted on the outer ring by press fit. Bores up to 130 mm. Many standard bores are
available.
Sprag lift-off X
Internal Freewheels FXN are equipped with sprag lift-off X. The sprag lift-off X is used for
backstops and overrunning clutches, provided that in freewheeling operation the inner ring is
rotating at high speed and providing with overrunning clutches that the driving operation
is conducted at low speed. In freewheeling operation, the centrifugal force FC causes the
sprag to lift off from the outer track. In this operating state, the freewheel works wear-free,
i.e. with unlimited service life.
The Figure shows a freewheel with sprag liftoff X in freewheeling operation. The sprags,
which are supported in a cage connected with the inner ring, rotate with the inner ring. The
centrifugal force FC that is applied in the center of gravity S of the sprag turns the sprag counterclockwise and rests against the support ring of the cage. This results in the gap a between the sprag and the outer track; the freewheel works with out contact. If the inner ring speed decreases to such an extent that the effect of the centrifugal force on the sprag is less than that of the spring force FF , the sprag again rests on the outer ring and the freewheel is ready to lock. If used as an overrunning clutch, the driving speed must not exceed 40% of the lift-off speed.
| Freewheel size |
mm |
mm |
Bore d |
mm |
mm |
max. mm |
B |
D mm |
F |
J |
K min. mm |
L |
Weight
kg |
| Standard |
mm |
mm |
mm |
mm |
| mm mm |
|
|
|
|
| FXN31 - 17/60 |
20* |
|
|
|
|
|
20* |
25 |
60 P6 |
55 |
31 |
85 |
24 |
0,3 |
| FXN31 - 17/62 |
20* |
|
|
|
|
|
20* |
25 |
62 P6 |
55 |
31 |
85 |
24 |
0,4 |
| FXN38 - 17/70 |
25* |
|
|
|
|
|
25* |
25 |
70 P6 |
62 |
38 |
90 |
24 |
0,4 |
| FXN46 - 25/80 |
25 |
|
|
|
|
|
30 |
35 |
80 P6 |
70 |
46 |
95 |
35 |
0,8 |
| FXN51 - 25/85 |
25 |
30 |
35 |
|
|
|
36 |
35 |
85 P6 |
75 |
51 |
105 |
35 |
0,8 |
| FXN56 - 25/90 |
35 |
|
|
|
|
|
40 |
35 |
90 P6 |
80 |
56 |
110 |
35 |
0,9 |
| FXN61 - 19/95 |
30 |
35 |
40 |
|
|
|
45* |
26 |
95 P6 |
85 |
61 |
120 |
25 |
0,8 |
| FXN61 - 19/106 |
30 |
35 |
40 |
|
|
|
45* |
25 |
106 H7 |
85 |
61 |
120 |
25 |
1,2 |
| FXN66 - 25/100 |
35 |
40 |
45 |
|
|
|
48* |
30 |
100 P6 |
90 |
66 |
132 |
35 |
1,1 |
| FXN66 - 25/110 |
35 |
40 |
45 |
|
|
|
48* |
40 |
110 P6 |
90 |
66 |
132 |
35 |
1,8 |
| FXN76 - 25/115 |
45 |
55 |
|
|
|
|
60* |
40 |
115 P6 |
100 |
76 |
140 |
35 |
1,7 |
| FXN76 - 25/120 |
45 |
55 |
|
|
|
|
60* |
32 |
120 J6 |
100 |
76 |
140 |
35 |
1,8 |
| FXN86 - 25/125 |
40 |
45 |
50 |
60 |
65 |
|
70* |
40 |
125 P6 |
110 |
86 |
150 |
40 |
2,3 |
| FXN86 - 25/130 |
40 |
45 |
50 |
60 |
65 |
|
70* |
40 |
130 P6 |
110 |
86 |
150 |
40 |
2,6 |
| FXN 101 - 25/140 |
55 |
70 |
|
|
|
|
75 |
45 |
140 P6 |
125 |
101 |
175 |
50 |
3,1 |
| FXN 101 - 25/149 |
70 |
|
|
|
|
|
75 |
62 |
149 H6 |
125 |
101 |
175 |
62 |
4,2 |
| FXN 101 - 25/150 |
55 |
70 |
|
|
|
|
75 |
45 |
150 P6 |
125 |
101 |
175 |
50 |
3,6 |
| FXN 85 - 40/140 |
45 |
50 |
60 |
65 |
|
|
65 |
45 |
140 P6 |
125 |
85 |
175 |
60 |
3,2 |
| FXN 85 - 40/150 |
45 |
50 |
60 |
65 |
|
|
65 |
45 |
150 P6 |
125 |
85 |
175 |
60 |
4,2 |
| FXN 100 - 40/160 |
45 |
50 |
55 |
60 |
70 |
75 |
75 |
50 |
160 P6 |
140 |
100 |
190 |
60 |
5,1 |
| FXN 105 - 50/165 |
80 |
|
|
|
|
|
80 |
62 |
165 P6 |
145 |
105 |
195 |
62 |
5,8 |
| FXN 120 - 50/198 |
60 |
65 |
70 |
75 |
80 |
95 |
95 |
70 |
198 H6 |
160 |
120 |
210 |
70 |
8,6 |
| FXN 140 - 50/215 |
65 |
90 |
100 |
110 |
|
|
110 |
69 |
215 J6 |
180 |
140 |
245 |
70 |
14,0 |
| FXN 170 - 63/258 |
70 |
85 |
100 |
120 |
|
|
130 |
80 |
258 H6 |
210 |
170 |
290 |
80 |
21,0 |
Application example
Internal Freewheel FXN 38 - 17/70 NX as a backstop, arranged in a housing adapter to attach to an electric motor. The thin outer ring that is pressed into the housing enables a space-efficient fitting solution. Due to the high shaft speeds in normal operation (freewheeling
operation), the sprag lift-off X ensures a contactless and hence wear-free continuous oper -ation.
Application example
Internal Freewheel FXN 66 - 25/100 NX as an overrunning clutch in the creep drive of a textile
machine. The freewheel installation is compactly solved by means of the thin outer ring
that is pressed into the worm wheel. During setup, the machine is driven by the worm gear and
the freewheel that is working in driving operation. In normal operation (freewheeling oper ation), the inner ring that is located on the high speed main drive shaft overruns and automatically disengages the creep drive. With the high overrunning speed of the inner ring, the type with sprag lift-off X is used; the sprags work in freewheeling operation without contact and hence are wear-free.
Application example
Internal Freewheel FXN 85 - 40/140 MX as a backstop fitted to the end of the first inter mediate
shaft of a spur gearbox in the drive of an inclined conveyor belt. In the case of a motor
stop the conveyor belt must be held securely so that the conveyor goods do not pull the belt
backwards and possibly cause serious damage. Due to the high shaft speeds in normal oper ation (free wheeling operation), the sprag lift-off X ensures a contactless and hence wear-free
continuous operation.
Mounting
Internal Freewheels FXN are without bearing support. Concentric alignment of inner and
outer ring must be provided by the customer. The permissible run out (T.I.R.) must be observed. The torque is transmitted on the outer ring by press fit. In order to transmit the torques specified in the table, the outer ring must be accommodated in a housing with an external diameter K. The housing is made of steel or grey cast iron in minimum quality GG-20. When using other housing materials or smaller external diameters, we urge you to contact us regarding the transmissible torque. The tolerance of the housing bore is specified in the table under dimension D. The tolerance of the shaft must be ISO h6 or j6.
Lubrication
At speeds in excess of the sprag lift-off speed, no special lubrication is required; the freewheel
functions maintenance-free. When operating below the sprag lift-off speed, an oil lubrication of the specified quality must be provided.
Example for ordering
Freewheel size FXN 61 - 19/95, type with sprag
lift-off X and 35 mm bore:
? FXN 61-19/95 NX, d = 35 mm
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