New SIT Bushes: SERLOCK and MONOLOCK
Smart solutions to common design dilemmas – with no compromise. Now available in our online store.
In this article, we’re stepping away from the core power transmission elements – belts and chains – to focus instead on shaft locking bushes: universal components used to mount pulleys, sprockets, couplings, and other machine parts onto a shaft.
Two new arrivals from Italian manufacturer SIT are well worth your attention. The modern hybrid SERLOCK bushes combine the benefits of the Taper Lock system with the precision of backlash-free friction locking. And for quick installation, there’s a clever option: the single-ring SIT-LOCK 30 MONOLOCK bush.
No Compromise in Shaft Clamping: Innovative SERLOCK Design
A wide range of ready-to-use components and guaranteed compatibility with standard Taper Lock bushes – or backlash-free, precisely positioned connections using friction locking bushes?
It’s a common design dilemma. Or is it? SIT provides an elegant answer with its hybrid SERLOCK bush series – bringing together the strengths of both approaches.
SERLOCK Hybrid Bushes in the TYMA CZ Eshop
We are the official regional distributor of SIT. You can find the full range of SERLOCK bushes in our online store. They are available in standard Taper Lock sizes: 1108, 1210, 1610, 2012, 2517, and 3020, for shaft diameters ranging from 12 to 70 mm.
Taper Lock?
Taper Lock bushes have become an industry standard for mounting applications where maximum flexibility is needed – and where rotating components like pulleys or sprockets must be fixed to shafts without additional machining. A standardized taper is simply bolted to the component, and a secure fit is achieved using the classic combination of keyway and key.
But this method comes with a drawback. Keyways weaken the shaft and create a potential failure point. They can also make mounting and precise positioning more difficult – especially in applications requiring exact synchronisation.
Friction Locking Bushes?
In contrast, friction locking bushes don’t rely on keys or keyways. Instead, they create a backlash-free friction fit (as found in designs like RCK or SIT-LOCK).
However, the components used with these bushes are typically not pre-machined. They’re semi-finished parts that require custom machining before installation – making the process more complex, costly, and time-consuming.
SERLOCK!
SIT’s SERLOCK bushes are fully interchangeable with standard Taper Lock systems, while enabling precise and backlash-free shaft connections thanks to a friction-fit design.
Key advantages at a glance:
- Easy and Precise Installation
Axial and angular positioning without keyway limitations - Interchangeable with Taper Lock Systems
Compatible with a wide range of standard power transmission components - Shaft Diameter Reduction up to 25%
No weakening from keyways – but still usable on keyed shafts if needed
Design Concept
A pulley, sprocket, or other component is fastened to the bush using two screws – as with a standard Taper Lock bush. The friction connection is then created by tightening a set of six clamping screws on the SERLOCK bush to the specified torque.
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Tapered bush body
Ensures precise alignment with components designed for Taper Lock bushes -
Connection to rotating component
Mounting system using two clamping screws with Whitworth threads and hex sockets -
Cylindrical bore
Smooth, keyless bore for easy shaft mounting -
Backlash-free shaft clamping
Frictional system with six clamping screws with hex sockets
Once tightened, the connection reliably transmits torque and also secures the mounted component against axial movement.
SERLOCK Bushes in the TYMA CZ Eshop
New Arrival for Fast Mounting: SIT-LOCK 30 MONOLOCK
SIT-LOCK 30 MONOLOCK is a single-ring friction bush that offers an ideal solution for lightning-fast, keyless installation in low to medium torque applications.
This smart new addition to the SIT-LOCK product range is a standout development by the northern Italian manufacturer from the Bergamo region. It reflects modern engineering trends that increasingly focus on cost-efficiency – faster installation, simplified designs, and overall effectiveness.
SIT-LOCK 30 MONOLOCK Bushes in the TYMA CZ Eshop
Standard versions of the SIT-LOCK 30 MONOLOCK are available for shaft diameters from 18 to 65 mm. Custom high-torque versions are also available (up to 40 mm bore diameter).
Key advantages of MONOLOCK bushes:
- Ultra-Fast Installation
Just one screw tightened to the specified torque - Compact and Cost-Effective
Thanks to the single-ring construction - Backlash-Free, Secure Fit
Precise axial positioning with even force distribution around the shaft
Design Concept
The friction fit is created by tightening a specially shaped screw with a tapered seating surface into the tapered bore of the cylindrical ring.
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Cylindrical bush body
Single-piece construction with a tapered bore for the locking screw -
Locking mechanism
Specially shaped screw with hex socket -
Cylindrical bore
Smooth, keyless bore for easy shaft mounting
SIT-LOCK 30 MONOLOCK Bushes in the TYMA CZ Eshop
Not sure which bush is the right choice? Contact us and we’ll be happy to recommend the optimal solution for your machine.