Replacing Lenze Intorq BFK 457 458 Brakes

KEB Type 38 and Intorq BFK 457/458 – Why Make the Switch?

The BFK457 and BFK458 are spring-applied brakes originally developed by INTORQ GmbH & Co. KG, historically a Lenze subsidiary and now part of the Kendrion Group. They are commonly found in conveyors, packaging and printing machines, AGVs, forklifts, hoists, wind turbines, compressors, and gearmotors, as well as specialized systems like stage equipment, escalators, and woodworking machinery.

If you’re currently using either model, there are compelling reasons to consider the KEB Type 38 Spring-Applied Brake as a replacement.

KEB manufactures locally in the central US with stocked parts readily available, resulting in shorter lead times and more responsive service than sourcing from overseas suppliers. Second, KEB offers a high-torque variant featuring a high-energy friction lining, with a wider torque range than the INTORQ BFK458, making it straightforward to match the brake to even the most demanding applications.

The Type 38 is engineered for both static and dynamic use:

• Combistop H – optimized for static (holding) operation
• Combistop N – designed for dynamic operation, supporting high-speed engagement cycles

Whether your application requires precise holding torque or frequent high-speed braking, the Type 38 is built to handle it.

Similarities Make Switching Easy

The KEB Type 38 and INTORQ BFK series share several key physical characteristics that simplify a direct replacement.

Both brakes use a 3-point bolt pattern, and across most size variants, the bolt pattern radii are identical between the two series. Hub lengths are also comparable among similarly sized models, and KEB offers hub variations as part of the Type 38’s broad range of configuration options.

These dimensional similarities mean that in many cases, switching from an INTORQ BFK457 or BFK458 to a KEB Type 38 is a straightforward drop-in replacement with minimal mechanical modification.

How to Cross Over to a KEB Type 38 Brake

1. Download the KEB Brake Manual

Start by downloading the KEB Type 38 Instruction Manual for dimensional and ratings reference. Also gather the relevant manuals and nameplate data from the brake you intend to replace.

2. Confirm the Required Torque

Identify the torque requirement for your application and match it to the appropriate rating in the KEB manual. When selecting a model, keep the intended operation in mind:

• Combistop N is designed for dynamic stopping applications where the brake engages repeatedly under load at speed.
• Combistop H is designed for holding applications, with the added capability of providing emergency stops.

3. Verify the Required Hub Size

Measure the shaft diameter and identify the keyway type to select the correct hub. Also confirm the brake’s mounting radius and note whether all dimensions are imperial or metric. If your application involves a non-standard hub bore, such as a spline, contact KEB directly for assistance.

4. Check Whether the Shaft has a Key

If the shaft includes a key, confirm that the selected hub has a matching keyway cut. This is an easy step to overlook but critical for proper torque transmission.

5. Verify the Friction Surface

Confirm that the mounting surface is suitable for correct friction engagement. If it is not, a compatible friction surface will need to be added. KEB offers a secondary friction plate for this purpose, or an integrator may opt to install a KEB flange as an alternative solution.

Before Installing the KEB COMBISTOP Failsafe Brake, Observe the Following:

1. Prepare a Suitable Secondary Friction Surface

The friction surface should be made of appropriate cast iron or steel, with a surface roughness (Rz) not exceeding 25 µm. Avoid sharp-edged interruptions in the friction surface. If a suitable surface is not available, an optional friction disc or flange can be used instead.

2. Check Mounting Hole Circle Eccentricity

The eccentricity of the mounting hole circle relative to the shaft end must not exceed the following values:

Size 02: 0.2 mm
Size 03–06: 0.4 mm
Size 07–10: 0.5 mm

3. Check Angular Deviation of the Mounting Surface

The angular deviation of the mounting surface relative to the shaft must not exceed the following values (referenced to the bolt circle diameter):

Size 02–03: 0.04 mm
Size 04–05: 0.05 mm
Size 06–07: 0.06 mm
Size 08–10: 0.08 mm

4. Keep Friction Surfaces Clean

Friction surfaces must be completely free of grease and oil prior to installation.

5. Consider Environmental Conditions

Humidity and aggressive fumes can cause the friction lining to rust. If the brake will be exposed to such conditions, rustproof friction discs are available as an optional upgrade.

6. Protect the Air Gap

Ensure that no objects or substances can enter the nominal air gap and obstruct armature movement. If contamination is a risk, optional protective rings or other appropriate protective measures should be used.

7. Confirm Physical Dimensions

Verify that the brake selected based on torque and shaft size fits within the available installation space. Confirm that the bolt pattern aligns with the existing pattern, or plan to drill new mounting holes as needed. Download the Type 38 dimensions table for reference.

8. Select Desired Options

Determine which additional features are needed for your application. Available options include a hand release, microswitch, dust protection ring, and a variety of flanges.

 

Measuring the hub bore.

 

Measuring the bolt radius.

 

Measuring the keyway.

KEB – Your North American Source for Spring-set Brakes

If you have any questions about crossing over your brake, feel free to contact a KEB engineer today or fill out the form below.