Overrunning clutches and backstops

Overrunning clutches are directional couplings, meaning they can engage and disengage automatically, depending on the relative direction of rotation of the driving and the driven sides.

The overrunning clutches has three different practical principles

Overrunning clutch: An overrunning clutch is used for multiple machine drives or to separate the inertia of masses of a driven machine from the driving machine after it has been switched off. The freewheel disengages automatically when the driven part rotates faster than the driving part.

Indexing clutch: Indexing clutch turns a shaft step by step, thus achieving indexed material feed or a variable speed. The freewheel allows the conversion of a reciprocating motion into a discontinuous rotary motion.

Backstop: Backstop prevents a machine shaft from turning backwards. Here, the overrunning clutch is used as a brake. The freewheel allows rotation in one direction only. It overruns continuously during operation and prevents reverse rotation if the drive is disconnected.

Locking elements

The locking elements in the clutches are in two designs: either roller clutch or sprag clutch. The roller clutches are mainly used as overrunning clutches and indexing clutches. The sprag clutches are most suitable as backstops, and primarily for the contact-free versions.

The roller freewheels feature a cylindrical outer race and an inner race consisting of ramps on which rollers are located. Springs and plungers ensure a permanent contact between the different elements for an instant torque transmission. This rugged, reliable versatile design can be used as an overrunning clutch, indexing clutch or backstop.

In the sprag freewheels the two races are cylindrical. The sprags, that are fitted in a cage, feature an active profile that ensures engagement or disengagement according to the relative motion of the races. It is possible to customise the design of sprags and cages from one model to another for significantly different characteristics

Integral bearing / freewheel

Based on series 62, 60 & 59. Type of support: Combined bearing/freewheel

To download as PDF, find the download link below the table.

Overrun. speed inner race Overrun. speed outer race Overrun. Clutch Indexing Clutch Back-stop Bores Ø [mm] Torques [Nm] Types
High High x x x 8-40 2.5-325 CSK
High High x x x 12-40 2.5-325 CSK..2RS
High High x x x 12-40 9.3-325 CSK..P
High High x x x 12-40 9.3-325 CSK..PP
High High x x x 20-30 50-138 CSK..P-2RS
High High x x x 40-60 72-250 ASK
High High x x x 20-50 51-460 GFK

Download the tabel in pdf format below.

Built-in freewheels

Built in Freewheels must be integrated in a housing that provides bearing support. Low to medium torque and speeds. Type of support: Non supported

To download as PDF, find the download link below the table.

Overrun. speed inner race Overrun. speed outer race Overrun. Clutch Indexing Clutch Back-stop Bores Ø [mm] Torques [Nm] Types
Medium High x x x 4-10 0.8-2.9 KI
Medium High x x x 6-80 2.1-1,063 AS
Medium High x x x 8-200 12-44,500 ASNU
Medium High x x x 12-70 17-5,813 AE
Medium High x x x 12-70 17-5,813 AA
Medium High x x x 8-150 20-44,375 NF
High Medium x x x 10-70 63-4,875 DC
High Medium x x x 10-70 - - DC RACES
~ Low   x   12-120 24-14,380 BAT
Medium High x x x 8-130 20-34,750 NFR

~ : Not possible

Download the tabel in pdf format below.

Self contained clutches

Sealed with integral lubrication. From small to high torques, low to max speeds. Type of support: Bearing supported.

To download as PDF, find the download link below the table.

Overrun. speed inner race Overrun. speed outer race Overrun. Clutch Indexing Clutch Back-stop Bores Ø [mm] Torques [Nm] Types
Low ~     x 25-90 375-4,875 RSBW
Low ~   x x 20-120 265-11,000 AV
Medium High x x x 12-250 55-287,500 AL-ALP
Medium High x x x 12-250 55-287,500 AL..F2D2
Medium High x x x 12-250 55-287,500 AL..F4D2
Medium High x x x 12-250 55-287,500 ALP..F7D7
Medium High x x x 12-250 55-250,000 AL..KEED2
Medium High x x x 12-120 50-20,000 AL..KMSD2
Medium High x x x 12-150 55-70,000 GFR-GFRN
Medium High x x x 12-150 55-70,000 GFR..F1F2/F2F7
Medium High x x x 12-150 55-70,000 GFRN..F5F6
Medium ~     x 12-150 55-70,000 GFR..F2F3
Medium ~     x 12-150 55-70,000 GFR..F3F4
High Medium x x x 12-80 379-6,900 FSO300-700
High Medium x x x 57-175 9,660-36,612 FSO750-1027
~ High x     12-150 288-45,000 AL..G

~ : Not possible

Download the tabel in pdf format below.

Centrifugally lift off sprags

Wear free above a given speed. High speeds with little lubrication demand. Specifically designed for gear reducers, motors, pumps, ventilators, turbines. Type of support: Non self-suppported (RSBI, RSCI, RSBF/CR), Bearing supported (RIZ)

To download as PDF, find the download link below the table.

Overrun. speed inner race Overrun. speed outer race Overrun. Clutch Indexing Clutch Back-stop Bores Ø [mm] Torques [Nm] Types
High ~ x*   x 60-240 1,375-38,250 RSBI
High ~ x*   x 20-240 212-100,000 RSCI
~ High     x 25-90 85-93,750 RSBF/CR
High ~ x*   x 30-130 313-16,875 RIZ/RINZ
High ~ x*   x 30-130 313-16,875 RIZ..G1G2/G2G7
High ~     x 30-130 313-16,875 RIZ..G2G3
High ~     x 30-130 313-16,875 RIZ..G3G4
High ~ x*     30-130 313-16,875 RIZ..ELG2
High ~ x*     30-130 80-16,000 RIZ..ESG2

* : Special working condition
~ : Not possible

Download the tabel in pdf format below.