Flexible Couplings and Custom Coupling Capabilities > FLEXIMITE™ Flexible Disc Servo Couplings > FLEXIMITE™ Flexible Disc Servo Couplings (Size 5) > Item # B-501-2(F/E)-1(F/E)  
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Item # B-501-2(F/E)-1(F/E), FLEXIMITE™ Flexible Disc Servo Couplings (Size 5)

OUTER DIAMETER 2 1/2 Inch (63.5 mm)

These couplings are especially designed for precision instruments, encoder drives, robotics, aircraft equipment, radar, laser, optical/mechanical devices, computers, precision remote controls. UNEQUALED PERFORMANCE.

Some of the features are: Zero backlash. Low inertia. Handles offset and angular misalignment. Torsional rigidity. Uniform velocity. No friction, wear, or lubrication. Long life. Low side loads on bearings. Accurate concentricity. Unaffected by dust or corrosive atmosphere. Available in four O.D. sizes, and any bore in inch or metric.

Click the request information button to identify your hub material and fastening.

Assembly Style Options  · Specifications  · Misalignment  · Moment of Inertia  · Weight  · Torsional Deflection  · Radial Loads  · Uniform Cyclic Velocity  · WHY OUR COUPLINGS ARE BETTER

Assembly Style Options


Discs with hubs mounted at 90º with respect to each other. Outstanding for general applications. High torsional rigidity with relatively low radial bearing loads. Slightly longer than Type B.




Overall Diameter

2 1/2 Inch

Hub 1 Diameter / Number

0.25 Inch (B-501-2)

Recommended Clamp Number for Hub 11

A-101-50AR, Round Clamp

Hub 2 Diameter / Number

0.1875 Inch (B-501-1)

Recommended Clamp Number for Hub 22

A-101-50AR, Round Clamp


20 ft. lb.
1 If a clamp style hub for hub 1 is selected, it is usually fitted with a clamp that must be ordered separately. Mark the checkbox in Special Options for "Include Shaft Collar Clamps."
2 If a clamp style hub for hub 2 is selected, it is usually fitted with a clamp that must be ordered separately. Mark the checkbox in Special Options for "Include Shaft Collar Clamps."



2 º


0.010 Inch


0.020 Inch

Moment of Inertia


4.15 oz.in²



5.71 oz

Torsional Deflection


0.006 min/in.oz.

Radial Loads


7 oz./0.001 in. misalign

Uniform Cyclic Velocity

Uniform Cyclic Velocity

Many couplings do not transmit accurate angular position when misaligned - even under no load, and thus introduce errors as shown. (Note how little error is introduced by Fleximite™ compared to others.)



The function of every flexible coupling is to transmit power or motion control from one rotating shaft to another that is not perfectly aligned, without excessive bearing loads.

But since the requirements for transmitting power are not the same as they are for controlling motion, couplings designed to transmit power might well be unsuitable for motion control and vice versa.

For instance, a resilient coupling made with rubber or springs would work well delivering power because it could absorb vibration and/or shock loads, but would not work well controlling motion. Here's why: In a motion control system, every component in the drive train (including couplings) affects the accuracy of the system by the amount of compliance (Wind-Up), Inertia, Friction, Backlash, etc. - things quite unimportant when transmitting power. A coupling that absorbs vibration must by definition, have Wind-Up, Inertia, or Backlash; whereas a true-motion control coupling must have no Backlash, low Inertia, and very low Wind-Up.

There are many applications, which are extremely sensitive to these factors. Today's encoders, for instance, can discriminate down to a few seconds of arc. (That's the width of a dime seen from 2 miles away) So you see how couplings can affect the success of your design.

Torsional Wind-Up is a very important factor. Notice in the graphs how outstanding RENBRANDT Couplings are.

Other manufacturers offer similar misalignment accommodation and low compliance - BUT NOT IN THE SAME PRODUCT.

The system must also be free from imbalance, vibration, and oscillation in order to prevent hunting - especially in closed-loop systems where a null balance is established between error signals. Since 1951 RENBRANDT has been building and improving Servo Couplings that provide reliability and long life free from maintenance - at moderate cost.


·  Error, Min & Sec of Arc

·  Delay Caused by Wind-Up, Inertia or Backlash

·  Composite values on Dynamometers


Coupling Design/Type Matrix for Size 5
(PDF, 36KB)



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