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Fenner Drives B-LOC & Trantorque Keyless Locking Devices from ISC Companies

As an authorized distributor of Fenner Drives and as one of our 2021 strategic partners within the Affiliated Distributors Association, ISC Companies is proud to offer the full line of Fenner Drives industrial products, including their popular Trantorque and B-LOC Keyless Locking Devices (KLDs).

Why go keyless?

When compared to traditional connection methods, Fenner Drives Keyless Locking Devices offer the following advantages:

  • A mechanical interference fit with a uniform pressure distribution similar to that achieved through a shrink or press fit.
  • A true zero backlash shaft-to-hub connection with none of the operational drawbacks of keyways or splines.
  • The ability to mount on plain shafting, which need not be over-sized to compensate for notch factors. This allows the use of smaller shafts and bearings for more cost effective designs.

Fenner Drives Trantorque and B-LOC products include:

Trantorque or B-LOC?

B-LOC Keyless Bushings provide a high capacity, zero-backlash shaft-to-hub connection by using the wedge principle. An axial force is applied by series of annular screws to engage circular steel rings and mating tapers. The resulting wedge action creates a radial force on the tapered rings, one of which contracts to squeeze the shaft while the other expands and presses into the component bore.

Trantorque Keyless Bushings—all with a single locking nut—offer easy options for mounting and adjusting position sensitive, zero backlash drive components and accessories.

Series Selection

Once you have decided that a keyless locking device is the right solution, you need to decide which series of the Trantorque or B-LOC to choose. While the underlying engineering principle for both is the same, the functionality of each may be more fitting to different applications and situations.

Fenner Drives Keyless Locking Devices Selection Guide

Internal or External Configuration

At a broad level, keyless locking devices can be split into two categories, internal locking devices (Trantorque and B-LOC Keyless Bushings) and external locking devices (B-LOC Shrink Discs, WK Couplings, Compression Hubs). Selecting an external locking device is relatively straightforward.

  • B-LOC WK Couplings: If you are joining two solid shafts at their ends.
  • B-LOC Shrink Disc: If you are connecting coupling hubs or flanges, gearboxes with hollow-shaft outputs, or similar geometries.
  • B-LOC Compression Hubs: If you are mounting a component that has a narrow hub or a short length-through-bore, like a plate sprocket.

Most applications consist of a shaft and bored component that require the use of a keyless bushing.

Shaft Size

Shaft size may immediately determine whether you use a Trantorque or B-LOC Keyless Bushing.

  • Trantorque: Accommodates shaft sizes between 1/8″ (3mm) – 3″ (75mm)
  • B-LOC: Accommodates shaft sizes between 1/4″ (6mm) – 24″ (600mm)

Fenner application engineers typically recommend a Trantorque for shaft sizes 1-1/2″ and smaller and a B-LOC for shaft sizes larger than 1-1/2″. These are considered the optimal ranges for the product lines.


The most obvious difference when comparing a B-LOC to a Trantorque Keyless Bushing is the installation method. All B-LOC units use screws (multiple) and all Trantorque units use a single hex nut.

The advantages of a single hex nut are speed and simplicity of installation and removal. With Trantorque units, simply tighten the hex nut to the specified installation torque and the connection is complete. However, the cost for this simplicity is a high installation torque requirement, which may present a challenge for larger units.

Since the force needed to draw the mating tapers of a B-LOC Keyless Bushing together is distributed among many screws, the installation torque of an individual screw is relatively low. This allows for effortless installation of even the largest units. The price paid for this low installation torque is a more timely and complex installation and removal process. The screws must be slowly and equally tightened in series until the final installation torque is achieved. Since most B-LOC units have self-locking tapers, the removal process requires loosening all screws and backing off the unit.

Other Considerations

  • B-LOC B800 or Trantorque OE: If the design requires a small OD-to-ID ratio.
  • B-LOC B112, B113, or B115 Double Taper: If the application is extremely demanding.
  • B-LOC Compression Hubs: If you are mounting plate sprockets or other thin components.

Other factors to consider include axial movement, recessed installation, corrosion protection, and RoHS compliance.

For more information about the products we offer from Fenner Drives, visit our dedicated brand page.