• Solenoid operated indexing
  • Up to four steps per revolution
  • Indexing accuracy ±1º
  • Non-cumulative indexing error
  • Uni-directional rotation, CW or CCW
  • Non-reversing (output cannot be back driven)
  • Input drive options:
    • pulley module
    • in-line coupling
  • Phasing clamp locks and infinitely phases clutch output with shaft
  • Anti-overrun option for control of overhauling loads
  • Solenoid voltage options: 12, 24 VDC, 110 VAC, 60 Hz
  • Torque capacities: 50 to 500 lb·in
Federal supply code - 15531
Unit of Measure


Torque Capacity (lb·in)

N/A 500

Kinetic Energy Factor KEF

N/A 19.3 lb·in

Moment of Inertia x 10-6 (in·lb·s²)

N/A 2300
A + .00151 N/A .7500

B (in)

N/A 1.62

C (in)

N/A 2.85

D (in)

N/A 1.25

E (in)

N/A 4.30

F (in)

N/A 2.68

G (in)

N/A 3.33

H (in)

N/A .12

I (in)

N/A .09

J (in)

N/A .30

K (in)

N/A .18

L (in)

N/A 2.58

M (in)

N/A .20

N +.003

N/A .188

O (in)

N/A 1.44

P (in)

N/A 2.24


The CNR clutch brakes are inherently high torque indexing devices. All CNR clutch brakes comprise three major elements, an input drum, an output drum, and a brake drum. The input and output are coupled or decoupled by a clutch spring. The output and brake are similarly coupled or decoupled by a brake spring. The interaction of the clutch and brake is as follows. With the input continuously driven and the solenoid deenergized, the output is mechanically decoupled from the input, but held stationary by the brake. When the solenoid is energized, the action of the latch releases the clutch's control collar, which in turn, causes two actions to occur. First, the brake spring is allowed to relax, freeing the output to rotate. Second, the self energizing transmission spring wraps down on the input drum, coupling the input to the output. The solenoid is normally released at some time during the indexing step. Thus, as the output completes it's rotation, the stop on the control collar engages the latch, causing the transmission spring to unwind and to decouple the input. Because of it's inherent inertia, the output continues coasting. This very action causes the brake spring to wind down on the stationary drum and to bring it to a halt. An additional anti-backup spring prevents the output from being backdriven.

Available Options

Output anti-overrun ("N" option)
The uni-directional characteristics of the clutch spring inhibit its ability to control the speed of the output when subjected to overhauling loads. An overhauling torque could cause the output to accelerate and run ahead of the input prior to the completion of the indexing step. Consequently, higher braking forces would be required to bring the output to a stop. The anti I overrun feature utilizes a uni-directional spring to couple the output to the input. This spring prevents the output from running ahead of the input.

Input pulley modules ("P" option)
The pulley module mounts on the output shaft and couples by means of the three (3) dogs to the CNR'S clutch input. A ball bearing designed into the pulley module supports the driving radial load transmitted by the belt. The clutch bearings are thus effectively protected from the belt tension. Standard input pulleys are available in 1/5" and 3/8" pitches.

In line coupling module ("D" option)
The in line coupling module is designed to transmit power directly from an input shaft to the input of a CNR clutch brake ' mounted in line on an output shaft. The in line coupling module consists of two assemblies, a dog drive clamp which is installed on the input drive shaft, and a coupling tube which interfaces the clamp and the input to the CNR clutch brake. During installation the clamp part of the coupling is placed on the input shaft, the clutch brake is placed on the output shaft and the coupling tube is placed between the clamp and the input to the CNR clutch brake. When all of the assemblies are properly positioned, phased and locked the coupling tube is to have .003"–.010" of axial play. See figure 4 for a typical installation of the CNR using the in line coupling module.

Phasing clamp ("CL" option)
The phasing clamp provides a means for driving the output shaft and for setting its angular position relative to the clutch output. It eliminates the need for a drive pin often used to transfer power from the clutch to the output shaft. The phasing clamp is mounted on the output shaft. The dog engages the slot in the clutch output. With the clamping screws loose the output shaft may be freely rotated to desired stopping position. Tightening of the clamp screws locks the clutch to the output shaft.


N/A Four installation arrangements for the CNR clutch brakes are described. In all four cases the clutch brake is mounted on the output shaft. For phasing the output shaft to the clutch output the following procedure is recommended.

  • Loosen the screws of the phasing clamp.
  • Rotate the input of the clutch brake until the control collar lobe contacts the latch and the input is decoupled.
  • Rotate the output shaft to the desired angular position and tighten phasing clamp screws.

  • 1 Corresponding millimeter size bores are available as options.